Blown Head Gasket - DIY? what else to inspect/replace?

So my DeLorean sat still for a few years, and didn't really want to start for us after all that time. Eventually got it running by push-starting it, enough to move it to its new garage (~1hr driving). On the way, though, I noticed when I'd push down on the accelerator, it'd kinda sluggishly get around to accelerating - not at all responsive like it used to be (at least for an old & heavy car). I chalked it up to bad gas at the time.

Diagnosed the startup problem and ended up replacing the original starter (finally). Started right up, but then huge plumes of white smoke. Ok, back to the bad gas problem (or so I thought)... Pulled open the gas tank access and stuck my phone in access w/ flash on - gas looks fine - no major 'floaties' or sediment or anything. Ok... google 'white smoke'... oh crap.

Now I'm pretty sure I have a bad head gasket, and I'm hoping that's it for the moment. Correct me if I'm wrong ;)

So it looks like a few hundred in parts and either a few grand in labor or, using the procedure on dmcnews, a good 8-10hrs (or more) of meticulous tear-down and rebuild. I think I'm up for the challenge, unless you'd recommend having a shop just do it at this point. I didn't have any issues with the starter or getting into the fuel tank, and have done lots of other miscellaneous things to it, but nothing this major.

Oh, and the modified/expanded procedure calls for a custom angle-aluminum bracket to keep the timing chain, and implies it's a bunch more work without it, then at the end says it's probably better to do it without the bracket and just redo the timing... thoughts on that?

Also, while I'm at it, what else should I really consider replacing or at least inspecting? I'm not super interested in dumping a ton of money in it at this point, so I don't want to go hog-wild replacing every sensor and tube, but if there are some things to look for in particular it makes sense to do it while in there already. I think the water pump was replace 10-15 years ago at this point, for what it's worth.

Thanks!
Josh
v7120

Modern fuel is bad within a year or less. The absence of debris doesn't indicate the quality of the fuel.

Unless the car has been severely overheated multiple times it's unlikely you have a blown head gasket, especially if you were able to drive for more than 10 minutes

You most likely have a fuel delivery issue. Symptoms, diagnostics and repairs are all discussed on this forum.

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Originally Posted by Ethan Rode

Modern fuel is bad within a year or less. The absence of debris doesn't indicate the quality of the fuel.

Unless the car has been severely overheated multiple times it's unlikely you have a blown head gasket, especially if you were able to drive for more than 10 minutes

You most likely have a fuel delivery issue. Symptoms, diagnostics and repairs are all discussed on this forum.

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This!

I would drain the fuel by siphon. Look what you got then. Clean what you can. If it wasn't too bad, put new fuel and unhook the return line turn the pump on. Pump it till it looks clean. Then MAYBE it will be better.

The car has overheated, at least once with me, but that was years before it was put on ice, so to speak (fan relay went out in ~80°F city driving, overheated and spewed coolant all over). My dad owned the car before me and said he wasn't surprised when I suggested it looked like the head gasket was blown.

The coolant level is dropping a bit when it runs as well, which coupled with the dense white smoke and sluggish/lower power seemed to make sense as a head gasket.

I haven't done the oil change yet, but I gather milky-oil is a good indication of coolant leak as well. Should I start with an oil change? I was going to do that after replacing the gasket. Or can I tell just by draining a little oil if it's milky? Do I need to run the engine for a bit first to 'stir it up'?

Or should I continue down the fuel system route? I bought a bunch of carb cleaner expecting to drain the tank and spray a bunch of that in there to clean it out, so I think all I have to do is activate the pump relay to drain the tank (though perhaps not best to pull the old gas through all the lines?), and then clean the tank and replace the fuel filter?

You should start by pressure testing the cooling system to rule it out instead of guessing.

Ethanol fuel goes bad much faster than a year, it is stated to last up to three months but I notice it go bad in a month of sitting or sometimes less like three weeks. You can try running some cleaner additive in your fuel and replace the filter if it's been a while. The last time I had white smoke with K-jet, my fuel distributor was shot and dumping way too much fuel into the engine.

That sounds a lot easier than head-gasket ;) will do some research, thanks!

I should clarify my post to say if you don't know how old the gas is, get it out of there. Then you can change the filter and run the clearer through to see what happens. I clear the tank by removing the hose from the pump (which may be difficult if you have original plastic lines, mine are rubber), install another rubber fuel line routed from the pump to a fuel container and then jump the pump or relay.

As far as pressure testing, you can get a tester on amazon or rent it from a store such as autozone.

Thanks for follow-up!

I'm assuming you had to replace your fuel distributor, then?

Is the pressure-tester good for anything else, or just radiator? I see the MotoRad MT-300 mentioned here, and it's about $80, but if it's single-purpose it probably makes sense for me to borrow at this point, especially with an Autozone about 15 mins from me, so I'll try the rental option. Though in that thread, they also recommend buying it and using it once or twice a year, so...

If I'm replacing the fuel filter anyway, can I just unplug the distributor feed hose and drop that into the gas can and pump the gas through? I've seen that suggested round here as well, which then doesn't require you to open up the tank again; though I suppose I have to open the tank to clean it out anyway, so... :shrug:

Yes, at the time I did have to replace the fuel distributor.

The pressure tester has no other uses and unless you work on multiple vehicles, it makes more sense to rent one than to buy one.

There are multiple ways to evacuate the fuel from the tank, I only did it the way I did so that I wasn't pushing more crap down the lines. Go with which ever way you find it to be easier for you as long as you can reach your goal of removing all the fuel. It wouldn't hurt to check the tank once it's empty and check the hoses/pre-filter and wipe up any debris off the bottom.

What about the oil route as well? I purchased the EZ Oil Drain Valve Kit from DPNW, so I figure I could pull the drain plug and install that and get at least some idea of the quality of the oil. I don't recall offhand if I need to drain the oil fully to install that plug or if I can sorta do it quick enough to get it back on without causing too much of a mess. I suspect with the engine cool the oil & water will have separated back out, so I guess I probably won't know if it's 'milky' until I drain it empty, or perhaps run the engine for a few minutes to mix it up?

If you don’t know how old the oil is then change it. If you think it’s contaminated then drain it instead of circulating it further. If there is coolant in it, you’ll know.

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Originally Posted by dn010

If you don’t know how old the oil is then change it. If you think it’s contaminated then drain it instead of circulating it further. If there is coolant in it, you’ll know.

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This!

If the coolent is not mixed, it will come out first. (The oil floats) if it is mixed, it will be milky.

You should always get hard evidence of a blown head gasket before assuming you have a blown head gasket. Water/Coolant in the oil, exhaust gas in the coolant, significant white smoke consistently coming out of the exhaust, etc. Replacing a head gasket on these engines is not something you jump into on a whim.

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Originally Posted by dn010

If you don’t know how old the oil is then change it. If you think it’s contaminated then drain it instead of circulating it further. If there is coolant in it, you’ll know.

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It 100% needs to be replaced as it's several years old at this point, but I figured I'd do that after getting it running, in case I need to drain it anyway for whatever needs to be fixed... Coolant also needs to be flushed & replaced, as I don't know when that was done last either.

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Originally Posted by Helirich

This!

If the coolent is not mixed, it will come out first. (The oil floats) if it is mixed, it will be milky.

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Right - oil floats on water - duh. That will make it a bit easier.

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Originally Posted by Nicholas R

You should always get hard evidence of a blown head gasket before assuming you have a blown head gasket. Water/Coolant in the oil, exhaust gas in the coolant, significant white smoke consistently coming out of the exhaust, etc. Replacing a head gasket on these engines is not something you jump into on a whim.

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I'm so glad I posted here then, at least I hope my fears end up being unfounded...

You're going to lots of trouble when one test will show it right away. Get an engine compression tester, pull the plugs, test the compression of each cylinder. If it's as blown as you describe it one cylinder will be way down compared to the others. Also the plug on that cylinder will be super clean or very
different from the others. Don't give up yet.

i did head gaskets on mine a few years ago when i did the dpi cams.. not too bad if you take your time.. .i just recently did head gaskets on my olds intrigue with the 3.5 shortstar engine and that makes the Delorean engine a cake walk!! .. the olds engine took me and my friend around 30 hrs to complete... the D engine took me maybe around 15.. but i also replaced chains and all that stuff....

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Originally Posted by cdrusn

You're going to lots of trouble when one test will show it right away. Get an engine compression tester, pull the plugs, test the compression of each cylinder. If it's as blown as you describe it one cylinder will be way down compared to the others. Also the plug on that cylinder will be super clean or very
different from the others. Don't give up yet.

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Oh, I'm not givin' up that easily - I'll get her running... Good suggestion on compression tester - another thing I haven't done before, but should be straightforward enough I think. So from AutoZone I need an engine compression tester, a radiator pressure tester, and a torque wrench... may be able to borrow the last from a friend instead...

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Originally Posted by painterdave72

i did head gaskets on mine a few years ago when i did the dpi cams.. not too bad if you take your time.. .i just recently did head gaskets on my olds intrigue with the 3.5 shortstar engine and that makes the Delorean engine a cake walk!! .. the olds engine took me and my friend around 30 hrs to complete... the D engine took me maybe around 15.. but i also replaced chains and all that stuff....

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Yeah I was thinking 15, split over a few days... was hoping maybe 10 would be enough but probably not good to bet on it - I don't tend to be fast at following detailed instructions on important tasks ;)

A definitive test is to test for combustion gasses in the coolant while the motor is running and heated up. A compression test is done cold and it may not leak during the test. If you are blowing coolant out you probably need a head gasket. "Reading" the spark plugs can also indicate a blown head gasket.

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Originally Posted by JCochrane

I suspect with the engine cool the oil & water will have separated back out, so I guess I probably won't know if it's 'milky' until I drain it empty, or perhaps run the engine for a few minutes to mix it up?

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I believe once the oil and coolant are mixed and become milky, they will not again separate. Oil with coolant in it and then running the engine is like putting them in the blender. Don't run the engine again once you see the oil is milky. The oil will have lost its lubricating property, you're done with it. You'll only see oil and coolant separately if you have not yet run the engine with coolant already in the oil (and of course, you then drain the oil into a pan so you can see it).

You'll be able to tell if the oil is milky by a quick look at what comes out on the dipstick.

...

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Originally Posted by David T

A definitive test is to test for combustion gasses in the coolant while the motor is running and heated up. A compression test is done cold and it may not leak during the test. If you are blowing coolant out you probably need a head gasket. "Reading" the spark plugs can also indicate a blown head gasket.

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By "reading" the spark plugs, do you mean just taking them out and checking their condition? See if one is significantly cleaner than the others?

So to check for combustion gasses in the coolant, I need a test kit and test fluid - is the kit usually something I can loan out from AutoZone? I'm assuming I'd have to buy some quantity of the test fluid. And then do I test that at the coolant tank?

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Originally Posted by Citizen

I believe once the oil and coolant are mixed and become milky, they will not again separate. Oil with coolant in it and then running the engine is like putting them in the blender. Don't run the engine again once you see the oil is milky. The oil will have lost its lubricating property, you're done with it. You'll only see oil and coolant separately if you have not yet run the engine with coolant already in the oil (and of course, you then drain the oil into a pan so you can see it).

You'll be able to tell if the oil is milky by a quick look at what comes out on the dipstick.

...

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I would expect oil and water to separate out over time, but perhaps not. The dipstick, last I checked, actually looked ok... clean, brown oil...

If you have a leaking head gasket, a compression test will show lower compression in that cylinder and maybe the one next to it. Cold, you should get around 120 psi in the good cylinders and the one with a leaky head gasket about 90 psi. I think everyone is waiting for you to do some of the tests we have all been recommending and report back with the results.

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Originally Posted by cdrusn

If you have a leaking head gasket, a compression test will show lower compression in that cylinder and maybe the one next to it. Cold, you should get around 120 psi in the good cylinders and the one with a leaky head gasket about 90 psi.

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Roger, thanks for the specific values.

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Originally Posted by cdrusn

I think everyone is waiting for you to do some of the tests we have all been recommending and report back with the results.

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Fair 'nough - I'm out of town this weekend but have next week off, so plan to do some of these diagnostic tests then, assuming I can sort out the parts/tools I need... Thanks all for patience & guidance thus far!

OK, I have an engine compression tester, coolant pressure tester, and torque wrench from O'Reilly's. I took the air filter box off today to start getting at the plugs, and drained the oil, installed the EZ-drain, and refilled with O'Reilly 20W50 - I plan to change the oil again after it's run it's course a bit, and replace the oil filter then as well.

The oil itself looked normal - mid to dark brown (not black) and clear, maybe small bubbles near the top but not foamy or milky.

I was able to loosen all the plugs without removing the intake manifold, and it looks like it *may* be possible to do the test as-is (ran out of time today). However, I could see that there was debris (looks like nut pieces left by mice or something) on the intake manifold, and I can only assume the VoD is awful... the engine's overheated before and it's all covered in a film as it is...

Should I remove the intake manifold to do the compression test & clean out VoD, or just remove the plugs carefully and do the compression test and see where that puts me?

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Originally Posted by JCochrane

OK, I have an engine compression tester, coolant pressure tester, and torque wrench from O'Reilly's. I took the air filter box off today to start getting at the plugs, and drained the oil, installed the EZ-drain, and refilled with O'Reilly 20W50 - I plan to change the oil again after it's run it's course a bit, and replace the oil filter then as well.

The oil itself looked normal - mid to dark brown (not black) and clear, maybe small bubbles near the top but not foamy or milky.

I was able to loosen all the plugs without removing the intake manifold, and it looks like it *may* be possible to do the test as-is (ran out of time today). However, I could see that there was debris (looks like nut pieces left by mice or something) on the intake manifold, and I can only assume the VoD is awful... the engine's overheated before and it's all covered in a film as it is...

Should I remove the intake manifold to do the compression test & clean out VoD, or just remove the plugs carefully and do the compression test and see where that puts me?

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Don't overcomplicate this; pull the plugs, stick the compression tester into the hole, and crank the engine.

OK, I finally got around to taking the plugs all the way out and inspecting.
Attachment 66636
I think they look pretty dark/bad, but not sure how old they are - I'm thinking they should be replaced either way, yes?

Now to the compression test. I gather from the workshop manual that the cylinders are numbered 1-3 on the 'L.H. bank' (which I think is on the right of the engine looking from the back?) and 4-6 on the 'R.H. bank' - with '1' being closes to the front of the car. If that's wrong, I'll edit this post to compensate ;)

I started 1/2/3 and everything looked fine, being careful to hand-start the adapter so as to not cross-thread. Then 6, after hand-starting, was super hard to get fully seated. Ran the compression test and like 40psi... pulled it back out to test and there's no rubber ring gasket on the adapter anymore - pretty sure there was one before, at least for #3 - so either dropped in/after #3, or borked it up during install to #6... pulled out boroscope and poked it around the block a bit but didn't see anything. Down #6... sad day - there it was crumpled and broken along the edge... put the hook on and fished it out, then tested compression again without the deepsocket adapter - just twisting the rubber hose in to get it seated - got higher but still significantly lower than the others.

(front of engine here; do tables not work? I tried with formatter but it's not showing... will reproduce below...)
PSI | Cyl# | PSI
160 | 4 | 1 | 155
150 | 5 | 2 | 165
105 | 6 | 3 | 160


Here's a look inside cylinder #6, when I had the boroscope down there - there's some discoloration on the wall... I also have video of the extraction and turning over a bit, if either of those would be interesting/helpful to see
Attachment 66637

So does that confirm a busted head gasket? Or should I run the combustion gas test as well?

Low compression does NOT confirm a low cylinder, it only indicates further testing. Low compression could be a bad valve or a cracked ring. A coolant combustion gas tester is a definitive test for a blown head gasket. Either way it looks like that head is coming off!

You have a ways to go before taking anything apart. The plugs look quite rich, they should be tan in color, put new ones in, make sure to use anti sieze on the threads. A reading of 105 does not in itself make it a headgasket problem. Given the history of the engine I would more likely suspect a "stuck" compression ring. I've run engines with less than 90 lbs. and they run o.k. so your readings except for the one cylinder at 105 is healthy so you need to concentrate on that cylinder. Get some Marvel mystery oil, use a clear tube hose (available at ACE Hardware) and put in enough to cover the top of the piston. Check it after 24 hrs. to make sure the level is going down. Keep doing this until you've gone through the bottle. Don't worry when it drains into the oil it's still o.k. to run it and will actually help free up the other piston rings. Run the engine for 15 minutes with the water pressure tester on the overflow cap. While running check for a blip from when that suspect cylinder would fire. If the engine will run without overheating I would run it around for awhile. Yes, the combustion gas test is the ultimate test for a blown head gasket. :race:

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Originally Posted by JCochrane

I plan to change the oil again after it's run it's course a bit, and replace the oil filter then as well.

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Change the filter now! (Both times.)

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Originally Posted by cdrusn

You have a ways to go before taking anything apart. The plugs look quite rich, they should be tan in color, put new ones in, make sure to use anti sieze on the threads. A reading of 105 does not in itself make it a headgasket problem. Given the history of the engine I would more likely suspect a "stuck" compression ring. I've run engines with less than 90 lbs. and they run o.k. so your readings except for the one cylinder at 105 is healthy so you need to concentrate on that cylinder. Get some Marvel mystery oil, use a clear tube hose (available at ACE Hardware) and put in enough to cover the top of the piston. Check it after 24 hrs. to make sure the level is going down. Keep doing this until you've gone through the bottle. Don't worry when it drains into the oil it's still o.k. to run it and will actually help free up the other piston rings. Run the engine for 15 minutes with the water pressure tester on the overflow cap. While running check for a blip from when that suspect cylinder would fire. If the engine will run without overheating I would run it around for awhile. Yes, the combustion gas test is the ultimate test for a blown head gasket. :race:

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+1

...I would add, bring your pressure tester up to 2-3 lbs before you start the engine (dead cold). Then see if the pressure begins to rise right after you start it. Normally it takes a while for the engine to heat the coolant enough to make it expand and raise the pressure. ...Then watch for the blips and/or the pressure raising well above the cap's rate faster than normal....
If I understand correctly, there is no coolant going on the ground or into the oil, so it would have to be 'burning' it. If that's the case, the coolant will usually leave the spark plug noticeably cleaner than other plugs. (Hard to say looking at the pics and seeing how rich it has been running -- fingers crossed!.)

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Originally Posted by JCochrane

Down #6... sad day - there it was crumpled and broken along the edge... put the hook on and fished it out, then tested compression again without the deepsocket adapter - just twisting the rubber hose in to get it seated - got higher but still significantly lower than the others.

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This isn't clear to me; are you saying you tested cylinder 6 with no o-ring on the compression tester?

We assume you checked all of the cylinders the same way. If you didn't do it "correctly" at least they should all be done the same so you can compare the results even if the absolute values are not accurate. By that logic cylinder # 6 has a problem. BTW, to do a "proper" compression test you start with a fully charged battery. Remove all of the spark plugs, turn off the fuel pump, and block open the throttle. Count the number of "bumps" and do it the same for each cylinder. Repeat the test after squirting in some oil into each cylinder and compare the results. A significant increase with oil is indicative of leaky rings. Further testing can involve a leak-down test to figure out exactly what is leaking excessively. A leak-down test is where you pressurize each cylinder at TDC and see where the air is escaping, through the rings and into the crankcase, through the intake valve into the intake manifold, or the exhaust valve into the exhaust. Besides being able to measure the size of the leak, you can actually hear the air leaking. Is the motor using oil? That is a clue to the rings leaking. Does it backfire? That would be a valve. Check the valve adjustments on that cylinder. All we can see from the plugs is that the motor was running very rich.

Sorry it's been a while since I posted back.

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Originally Posted by David T

Low compression does NOT confirm a low cylinder, it only indicates further testing. Low compression could be a bad valve or a cracked ring. A coolant combustion gas tester is a definitive test for a blown head gasket. Either way it looks like that head is coming off!

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So I finally put the plugs back in to run the coolant combustion gas tester. First of all, no white smoke when starting it up, warming it for test, or running it - curious. Test came back negative. Let it sit for a few hours, then warmed it back up for a while and ran the test again - still negative, and still no white smoke - or at least not a lot like before.

Oh yeah, and the test showed no apparent leaks either - bulb would stay compressed and not be able to draw more air through if I held tester tight to the container. I'd then loosen up a bit to release pressure and try again, but it never lost pressure if I kept it tight to the reservoir and pumped the bulb a few times.

For what it's worth, I'm using this kit: https://www.amazon.com/gp/product/B06VVBSFTF/

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Originally Posted by Nicholas R

This isn't clear to me; are you saying you tested cylinder 6 with no o-ring on the compression tester?

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Sorry, there was still an o-ring on the tester itself, but I had been using the deep-socket adapter, which I could screw in first (by hand at first, almost entirely) and then screw the compression tester into that. Once the o-ring was ruined on the adapter/extender, I just twisted the compression tester (rubber hose with metal plug end and o-ring, so still enough clearance, just not wrenchable at all) directly into the plug socket. I also repeated measurements on all other cylinders to make sure the new configuration was acceptable - that I was getting it tight enough and whatnot. Same readings, so I assumed it was sufficient.

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Originally Posted by David T

We assume you checked all of the cylinders the same way. If you didn't do it "correctly" at least they should all be done the same so you can compare the results even if the absolute values are not accurate. By that logic cylinder # 6 has a problem.

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Yep, rechecked the same way when I took the adapter out of the picture.

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Originally Posted by David T

BTW, to do a "proper" compression test you start with a fully charged battery. Remove all of the spark plugs, turn off the fuel pump, and block open the throttle. Count the number of "bumps" and do it the same for each cylinder. Repeat the test after squirting in some oil into each cylinder and compare the results. A significant increase with oil is indicative of leaky rings.

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The battery probably needs to be replaced, but had a charger on it prior to running the test, and after running the test, and I came back to some of them a while later (after recharging) just to ensure that the battery state also wasn't causing differences in measurements.

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Originally Posted by David T

Is the motor using oil? That is a clue to the rings leaking.

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Nope. No appreciable oil usage, at least in the little it's run recently.

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Originally Posted by David T

Does it backfire? That would be a valve. Check the valve adjustments on that cylinder. All we can see from the plugs is that the motor was running very rich.

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Nope. Doesn't run the smoothest, but purrs when idling and don't recall any backfires at all.


Should I drive it around town a bit and see how it does? Maybe the oil change fixed it, at least enough for now - obviously a cylinder measures low so there will be work at some point, but it may have been like that for years I think, based on my experience with the car and my dad's recollection and suppositions... I should also drain the super-old fuel fully and replace...

If it is not using oil and there are no combustion gases in the coolant I suggest doing a valve adjustment. That just might get the compression back on that one cylinder. If it doesn't help, then try some STP or Marvel Mystery Oil, maybe a stuck ring or a leaky valve. A leak-down test will tell you what the problem is with that one cylinder. You might just get by without having to remove the head. It will never run as smooth as it should with that one cylinder so low.

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Originally Posted by David T

If it is not using oil and there are no combustion gases in the coolant I suggest doing a valve adjustment. That just might get the compression back on that one cylinder.

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Looks like that's not too hard, but still have to take off the head, so new valve cover gaskets & such, right?

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Originally Posted by David T

If it doesn't help, then try some STP or Marvel Mystery Oil, maybe a stuck ring or a leaky valve.

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STP/MMO is just pouring into spark plug hole and letting it sit 24 hr and checking that the level drops, right?
That seems like an easier/quicker check. Probably not the 'right' solution, or you'd have mentioned that first, but would it be unwise to start there and proceed to more-intrusive valve adjustment if it doesn't help?

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Originally Posted by David T

A leak-down test will tell you what the problem is with that one cylinder. You might just get by without having to remove the head. It will never run as smooth as it should with that one cylinder so low.

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Would I do the leak-down on just the one cylinder? Since the others seem to have good compression? If that may indicate the problem without having to remove the head, would that be a better place to start than just attempting the STP/MMO route?

To check and, if necessary, adjust the valves, you just have to get the valve covers off. You slowly pour the STP or MMO in the intake while the motor is running. You can do a leak-down check on only one cylinder. I would check ALL of the valves, do that first. If you need a lot of adjustment on #6 then that may fix the low compression.