Major overheating issue caused coolant system to "explode"

[bfloyd]

Just like the title says... My cooling system literally exploded today coming home from a car show. Cruising down the highway at speeds of 60-70 mph everything was working perfectly. Temp gauge was sitting right where it always does at just a hair north of the white line between the 100 and the 220 mark on the gauge. As I got closer in towards town, traffic started getting congested and the temps started creeping up. It got to the 220 mark but I wasn't real worried yet. As I got to the center of town I got stopped at a red light and the gauge crept up to the 240 mark. I was worried now, as it's never gotten that high before. Light turned green and I drove less than a quarter mile through the town square and it pegged at 260. Windows started steaming up inside. With buildings right next to the street in the center of town I had nowhere to pull off. Drove it about two more blocks and everything just kinda "exploded". It blew the overflow hose off the stainless steel coolant tank. It blew the hose off connecting the down pipe to straight pipe behind the right rear tire, steam and antifreeze everywhere. It looked like Thomas the F'ing Tank Engine. Immediately pulled off the road into a convenience store parking lot and turned the engine off. As soon as I turned off the engine steam started pouring out of all the interior cabin vents.

Found a guy to load me up on a trailer and take me the two miles the rest of the way home. We let it cool down for about 20 minutes before I started the engine and drove it up onto the trailer. Got it home and drove it off the trailer and into the garage. There is water standing in a puddle behind the passenger seat - but it does not smell or feel like antifreeze. Have no clue where that came from?

Cannot figure out what exactly happened? Heater core blow? Thermostat stuck? Air pocket trapped in the system? It seemed like one small problem built into another and it kept growing from there. I haven't checked the oil yet to see if I blew a head gasket. I'm hoping I didn't.

I've got all new hoses (DMCH hose and clamp kit) and water pump (2015), stainless coolant tank, new DPI (Delorean Europe) aluminum radiator, and Delorean GO fans and shroud, and Toby's bleeders on the front and rear.

[Michael]

Water pump hose/belt still attached? I'm thinking you lost the waterpump or coolant flow due to thermostat or busted hose and boiled the coolant out.


For future reference to anyone reading this thread, if it overheats, stop right then and there.

[bfloyd]

Water pump hose still attached?

As far as I can see yes. I saw no coolant coming from anywhere near the valley and both side hoses are still attached. I'll have to get my endoscope camera to look under the intake.

[Michael]

Also, if you are sure the cooling system is OK, make sure your fans are working properly.

[DMCMW Dave]

It's all a guessing game until you clean it all up and find the leak. My guess at this point based on your writeup? ….. Fans failed (anything from the otterstat to the fan relay or just wiring issues) (so it was fine on the highway and overheated right away afterwards) and then a defective/failed/incorrect radiator cap allowing the pressure to get way past 15lb. This blew the heater core and then the other stuff. I've never seen a system do this, typically with an overheat it blows out through the radiator cap and into that short hose that is aimed at the ground at the back of the engine compartment. You mention that the overflow hose blew off - could that have been plugged or kinked? It's pretty weird because you'd expect that the first failure (the heater core?) would relieve the pressure (unfortunately into your interior) and nothing else would fail.

Keep in mind that there is slight possibility that the first failure was one of the two small heater core hoses. That connection is very close to the drain hole for the plenum, so a sudden release of steam/hot coolant would get pulled in via that drain hole that is right above the fuel pump and into your interior. Most of it would be going on the ground, but assuming you had the A/C on fresh air (not recirc) and the fan on high you could pull quite a bit into the system and into your car. Long shot. Since it kept steaming after you turned off the car (and the blower) this is probably not the case.

My suggestion would be to hose everything off, bypass the heater core (i.e. tie the two small hoses that go to the heater core together). Replacing the heater core is a huge pain and you probably don't drive the car in cold weather. You can fix that later.

Fix the other obvious leaks. Put coolant (water is fine for the moment) back in the system and see what else is leaking. Check your engine oil for coolant contamination (a good way to do this is slowly loosen the drain plug and see if anything other than oil comes out, no need to dump the whole pan yet). If you see any antifreeze in the oil, you're done for a while.

Now for the bad part. This sort of overheat is very hard on the head gaskets. That is what you are looking for with the oil drain test.

I can guarantee that if it wasn't an otterstat (fan temp switch) failure, the otterstat is bad now. They don't take overheats well. So during this test phase just jumper it out so the fans run all the time. If the fans don't run with the otterstat jumpered, you've found the rood cause and need to fix that.

BTW message to anyone - if you see it hit that sort of temp, i.e. much above 220, shut it off NOW unless its a truly dangerous place to stop.

[bfloyd]

Dave..

Fans failed (anything from the otterstat to the fan relay or just wiring issues) (so it was fine on the highway and overheated right away afterwards)
Both fans were still running as the A/C system was set on MAX. When I drove it up on to the trailer - both fans were running.


then a defective/failed/incorrect radiator cap allowing the pressure to get way past 15lb. This blew the heater core and then the other stuff. I've never seen a system do this, typically with an overheat it blows out through the radiator cap and into that short hose that is aimed at the ground at the back of the engine compartment. You mention that the overflow hose blew off - could that have been plugged or kinked?

The radiator cap was securely fastened, and the "blowing out through the radiator cap into that short hose" part did work. However it came out with so much pressure that the hose blew off and it sprayed all over the engine bay and inside face of the rear fascia.

I'll check the oil when I get home tonight.

[DMC-81]

Oh man, sorry that happened. :(

You've got good advice here so far. I'll add also checking for a thermostat failed in the closed position (mentioned by Michael). I had that scenario occur 3 times on 2 non-D vehicles, and the temperature gauge climbed fast all three times.

[bfloyd]

Just got home from the theatre (2:05am) and went out to the garage to check on the car.

Checked the oil via the dip stick and its a nice pure amber color, and doesn't seem to have any other smell to it than just oil. I just changed it out in mid-May, and have only driven the car a few short trips around town.

As expected, the coolant bottle is presently bone dry. The entire passenger side floor board and carpets are completely soaked and standing in water. Seems like the heater core blew.

I'll bypass those hose like Dave mentioned and put a pressure tester on the system and see what happens.

[Michael]

Just got home from the theatre (2:05am) and went out to the garage to check on the car.

Checked the oil via the dip stick and its a nice pure amber color, and doesn't seem to have any other smell to it than just oil. I just changed it out in mid-May, and have only driven the car a few short trips around town.


The PRV doesn't like to be overheated but if it was a quick "hot flash" and not allowed to stay in the red for long, it may be ok. It is something you will want to keep an eye on, although the oil may not be milky, you can still have oil leaks or oil consumption issues.

[CFI]

I feel your pain. After 4,000+ trouble free miles in 8 months of driving my car finally had to be towed. Temp kept creeping upward. As soon as it went above the half way mark I pulled over. I’ve sat in stop and go traffic for an hour on a 95 degree day and never saw it even get close to half on the temp gauge so I knew something was wrong.

As soon as I opened my door I could smell coolant. There was a massive leak from the water pump area. Reservoir was bone dry. I haven’t heard from the shop yet but I’m guessing the water pump blew a seal.

[David T]

Could have been a stuck thermostat. Years ago during a club event we were driving through Provincetown RI and, stuck in traffic, a radiator blew on one of the cars. When you suddenly release hot coolant under pressure it flashes into steam and makes an impressive cloud. The liquid on the passenger side could be condensate leaking from the A/C.

Put the system back together, fill with water, pressurize to see if it holds and run the motor to cycle the fans. I would replace the thermostat just because and the rad cap too. When you get the system leak-tight drain the water and fill with anti-freeze. if you are very lucky you didn't get the motor hot enough to pop the head gaskets.

[bfloyd]

Started the process of putting this all back together.

Put the rear up on ramps and drained about a quart of oil from the pan to check for water. The oil that came out did not have any water in it. Maybe I got lucky here.
Ordered a new thermostat and otterstat yesterday and those should be here in a couple of days.

Pulled the seat and carpet from the passenger side on Monday and got that mess cleaned up. Hung the carpet on the back yard fence and pressure-washed the coolant and crud out of it. I was surprised to see so much SOAP come out of the carpet.
https://i.imgur.com/EkfSpsEl.jpg

Since its fairly obvious that the heat core blew out, I pulled both hoses from the core and installed a 5/8" 180 degree "Heater Core Bypass Hose" with two 5/8" barbed fittings from my local Autozone. Since I don't really drive the car during the winter months, having no heat really isn't going to be an issue. Next time I take the car to DMC-Midwest, I'll let them replace the core while it's there.
https://i.imgur.com/lBcbgVol.jpg

I'll put the pressure tester on the system on Saturday and check for leaks anywhere else in the system.

[81dmc]

Worse case scenario I know, but I wonder if your head gasket just started to let go. It is a possibility that can't be ruled out.

Before I pulled my original PRV, I was beginning to see temps creeping up to 220 even with a 160 thermostat and excellent fans. After talking to Stephen at DMCH, he seemed convince that my head gasket was beginning to let go, even though there were no obvious signs in oil or coolant.

Test your fans and also test your thermostat in a pot of boiling water to determine the actual cause.

[bfloyd]

Worse case scenario I know, but I wonder if your head gasket just started to let go. It is a possibility that can't be ruled out.


Very true possible scenario, and really won't be able to tell anything until I put the pressure tester on the system. However, I can tell you than back in May when my wife and I took the car on a 4 day trip to the mountains of northern Georgia, every now and then we'd get a whiff of antifreeze smell coming out of the center vents. Nothing really strong, but it was obvious it was there. It's also entirely possible I didn't get the system completely bled after I replaced the radiator and cooling fans back in April.

My fans were indeed working when this happened. I had been running with the A/C set on MAX COOL and my indicator lights showed both fans on, and they were both running when I pulled it up on the trailer to get it home.
I'm replacing both the thermostat and the otterstat as soon as they get here. I ordered them yesterday afternoon, so they should be here by the weekend or Monday.

[Parzival]

Man that is a scary story! That over flow hose must have been clogged or the cap was stuck and the pressure went above 15PSI, then the hose popped off from over pressure, or the cap finally opened up and all the extra pressure pushed the hose off.
DMC Midwest can replace the heater core. When I had my AC evaporator replaced DMC FL also changed the heater core since the hard work was done. Before that I had a coolant hose break, I saw my temp start to peak over 220, and it was engine off for me, then coasted to a stop. I was pretty pissed but it was my fault for not changing a hose I knew was old.
I'm interested in your over flow cap. The coolant system pressure checkers you can rent at auto zone have attachment for testing the caps. Check it and see if your cap is holding up to 15PSI and then releasing anything over that.

[AirmanPika]

heh this reminds me of a couple decades ago when the radiator hose blew on my mom's car. It wasn't overheating. It just came off catastrophically. Water and noise everywhere.

[bfloyd]

From what I can tell I may end up being the luckiest Delorean owner alive.

Got my new parts in from DMC-Midwest over the weekend and got everything put back together. Ran a pressure tester on the system and found one small leak at the top radiator hose connection on the drivers side.
https://i.imgur.com/qFVMzaGl.jpg

Replaced the clamp with a new one and it now holds pressure without any leakdown.

Refilled the system with antifreeze last night and let it idle in the garage for about 45 minutes, bleeding the system twice in the process. No leaks anywhere. No water or steam coming out of the exhaust pipes. Temperatures holding steady right where they should, and both fans are engaging when they should.
https://i.imgur.com/NVq9ZcHl.jpg

Still have to put the interior back together, but that's not a huge issue.

[Col Bennett]

From what I can tell I may end up being the luckiest Delorean owner alive.

Phew! Great news.

[bfloyd]

In regards to the coolant tank radiator cap. My pressure tester has an adapter to test the cap. I hooked it up the other night and if I pumped it up anywhere over 15psi it would just open up and release the air behind it. Fairly confident it's working like it should.

All that's really left to do is reinstall the carpet and interior pieces. It needs a really good bath. I don't think this car has been this sticky and dirty since mid-summer of 2015.

[Riley88]

Good to hear! Awesome progress man

[Parzival]

have you tested to see if you get any exhaust gasses in the coolant? You can basically test it for free. Just get the tester at advanced auto. Rent it for 30 bucks, and you get that beck when you return it.

[Acmetowers]

Lucky there wasn't anyone in the passenger seat. One thing I would say in that situation is that I've always been told to turn off the ac to reduce load on the engine and put the cabin heater to max heat and fan to take the heat out of the system. You'll get hot but you'll have more time to keep the situation under control. Probably easy for me to say as I live in the uk with our temperatures!

Sent from my SM-N950F using Tapatalk

[bfloyd]

Finally got it all put back together. I've let it sit in the driveway with the engine running for a little over an hour. No overheating issues so far, fans kick on and off like they are supposed to.

I got the interior re-installed yesterday morning, and then sanded down and repainted the trunk with two coats of SEM trim black. Re-applied new stickers in the trunk where they go.

https://i.imgur.com/6WBQQwTl.jpg

https://i.imgur.com/zeCEDh7l.jpg

[JBaker4981]

Very nice Barry! It's unclear to me but what ended up being the culprit?

[bfloyd]

Gonna have to say a a slow leaking heater core. I did have a small weeping drip going on at the left side of the radiator, but with the tell-tale signs of smelling antifreeze inside the cabin every now and then, it likely was the heater core. I'm going to take it out for a test run tonight to see how it does under driving conditions.

[JBaker4981]

Got it! Hope 3294 is running well now :)