First view of VOD as part of EFI conversion

[DrJeff]

Here is a video I took (sorry about the out of focus at the start) of the first inspection of my VOD as part of my EFI Conversion project.

Any advice on the black guck would be helpful.

Other than that... it looks like the VOD is dry and will just need a good vacuuming :)

http://www.youtube.com/watch?v=T36wlfaYo_I&feature=youtu.be

[NightFlyer]

Here is a video I took (sorry about the out of focus at the start) of the first inspection of my VOD as part of my EFI Conversion project.

Any advice on the black guck would be helpful.

Other than that... it looks like the VOD is dry and will just need a good vacuuming :)

http://www.youtube.com/watch?v=T36wlfaYo_I&feature=youtu.be

VOD looks good to me.

Not sure about the black stuff, but I suspect that it is oil/carbon deposits. I'd try cleaning the affected areas with a throttle body / air intake cleaner or maybe even a little phosphoric acid.

Best of luck with the EFI conversion!

[DMC5180]

Black stuff is Oil/Carbon. It comes from the PCV (oil filler cap) the system is designed to draw the crank case gases/blow-by back into the combustion process. We all will get that build up over time. It's absolutely normal.

Your VOD is about at good as one could expect. Nice and dry with no major piles of crap. You will still want to get in there clean things out though.

[David T]

The black residue you see in the intake valve passage is from unburnt fuel. The fuel injector sprays fuel at the intake valve. Looks very unremarkable. The best news is you don't appear to have broken any bolts (yet). You should consider removing the "Y" pipe and replacing all of the seals, hoses, and water pump while the intake manifold is removed.

[DrJeff]

The black residue you see in the intake valve passage is from unburnt fuel. The fuel injector sprays fuel at the intake valve. Looks very unremarkable. The best news is you don't appear to have broken any bolts (yet). You should consider removing the "Y" pipe and replacing all of the seals, hoses, and water pump while the intake manifold is removed.

The Y pipe is coming off today. All the coolant and vacuum hoses are being replaced. I wasn't planning to pull the water pump as the car's cooling was working perfectly (just 26k miles).

I got into the deep channels with a small diameter hose attached to the shop vac. Luckily they only contained about 2-3 inches of sand.

Treasures discovered include... small bolt, small nut, copper (?) washer, piece of adjustable hose clamp

[David T]

The Y pipe is coming off today. All the coolant and vacuum hoses are being replaced. I wasn't planning to pull the water pump as the car's cooling was working perfectly (just 26k miles).

I got into the deep channels with a small diameter hose attached to the shop vac. Luckily they only contained about 2-3 inches of sand.

Treasures discovered include... small bolt, small nut, copper (?) washer, piece of adjustable hose clamp

That sand is what remains after you evaporate anti-freeze that leaked. If the water pump is original you are correct that it has "only" 26K miles but it has over 30 years! At a certain point age necessitates replacement.

[DrJeff]

That sand is what remains after you evaporate anti-freeze that leaked. If the water pump is original you are correct that it has "only" 26K miles but it has over 30 years! At a certain point age necessitates replacement.

Actually it was sand - like you find on a beach or in the desert. Evaporation residue is fine and crystalline - there is some of that, but not much. The VOD was full of just plain old sand. The PO kept the car garaged for 26 years, but the original owner must have stored the car in the California desert at some point. I've found sand in every nook and cranny on the car - just tonight I knocked sand loose from the front crumple tubes.

The water pump was working perfectly - my car never had cooling issues - so I don't see the logic in tearing apart or replacing the water pump. I'm going to leave it alone unless I have a symptom that suggests that failure is imminent. When it fails I'll fix it, until then I'll leave well alone.

[Bitsyncmaster]

You may want to get the water pump bolts removed, cleaned and anti-seized. So if your have a water pump problem in the future, you can replace it quickly.

[DrJeff]

You may want to get the water pump bolts removed, cleaned and anti-seized. So if your have a water pump problem in the future, you can replace it quickly.

Dave, do you mean just the 3 M8 bolts that mount the water pump to the block?

[Bitsyncmaster]

Dave, do you mean just the 3 M8 bolts that mount the water pump to the block?

Yes. It's very common that top bolt is frozen. Much easier to drill that out at home if you break it.

[DrJeff]

Some photos now that the Y-pipe and Coolant Return pipes are out.

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About the only exciting bit was during removal of the RH long bolt on the Y-Pipe. It seemed to be extracting smoothly for the first 3/4 in or so, and then it make a crack sound. Then after that despite turning the bolt many times it wouldn't withdraw any further. Turns out it had made it clear of the head and was just stuck in the Y-pipe through hole. For a brief moment I had that 'broken bolt' sinking feeling.

Next up - water pump bolts.

[DMC5180]

Given that you had success with the RH long bolt. It's a pretty good indicator you should have success with the WP bolts. One thing that works well is small impact wrench. I've had great success using a small Dewalt 1300 inlb cordless impact on things like that. The vibration really helps Crack things loose without having too much torque that could Snap the heads.

[DrJeff]

...If the water pump is original you are correct that it has "only" 26K miles but it has over 30 years! At a certain point age necessitates replacement.

David T, you were right! Since I found pitting on the Y-Pipe and I'm changing out the coolant hoses, I pulled the water pump out and gave it an inspection. I found some pitting on the back plate (minor and not in a critical place).

What really surprised me was the hole I found in the thermostat housing cover. There was a build-up of crud on the inside of the pipe and a small mark on the outside. When I cleaned it I found a hole right through the housing.

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This could be a little more challenging to fix? Any ideas? From the picture showing the hole from the inside of the pipe, there are a few points to the right side that look like distorted metal - perhaps a new breakthrough point?

[Delorean Industries]

That is actually typical. The best thing to do is have it welded.

[Bitsyncmaster]

That hole in the housing probably would not have shown up as a leak since the clamp is past the hole. I would check the aluminum pipes near the engine for corrosion also. That is where I found corrosion and decided to replace all the pipes. But it only showed up on pipes in the back on my car. Also the corrosion was only where the hose was over the pipe.

[DrJeff]

T...I would check the aluminum pipes near the engine for corrosion also. ... Also the corrosion was only where the hose was over the pipe.

Do you mean the two 'flanges' that sit on the heads and are connected to the water pump with the short pipes?

I'm curious why corrosion would only show up on the pipe under the hose? That must mean that the hose has a role in promoting the corrosion. I wonder if the hose might create a locally less alkaline (more acidic) environment that is found with just coolant and pipe. Away from the hose connections the pipes and from what I can see into the head and block the aluminium looks like new.

Found this article (http://onlinelibrary.wiley.com/doi/10.1002/maco.201106222/pdf)which says "In addition, the morphology of the clamped EPDM rubber hose region connected with the failed Al alloy shows concavo–convex damage and microcracks, as shown in Fig. 6(a), whereas no significant damage is observed in the surface of the unclamped EPDM rubber hose region [Fig. 6(b)]. The hardness values of clamped and unclamped rubber hose are measured at five different samples. The clamped region exhibits a quite higher hardness (range of 82.5–87.7) than that of the unclamped area (range of 72.7–79.9). The above finding suggests that the existence of physical load (i.e., clamping) may facilitate surface damage. It should be mentioned that the microcracks and surface damage could provide the leaking path of coolant, leading to the severe corrosion products on the Al alloy system."

and also "In general, crevice corrosion initiates in an electrolyte when a corrosive liquid is trapped in narrow gaps between metals or between nonmetal and metal. Once the liquid has settled in the gap, massive corrosions are produced in the crevice"

This would also be consistent with AL corrosion around the o-ring location on the Y-pipe - as it's under load and likely to see non-flowing coolant.

So it sounds like load and non-flowing coolant is the cause of corrosion under hose. Two causes that are going to be pretty hard to avoid.

[DrJeff]

... I would check the aluminum pipes near the engine for corrosion also...

Dave, you are spot on. I checked the two aluminium flanges (short hoses off the water pump) and the RH one has a corrosion hole in it - just behind the lip and under hose.

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The LH flange is also very close to developing a through hole. I can feel the depression on the inside of the pipe and found a deep pit on the outside. If the 'depression on the inside and pit on the outside' is a sign of a near breakthrough, then there's a good chance my thermostat housing has one or two more soon to be holes.

I also inspected the water pump itself, in particular the hose connections off the pump. Both have large pits, but no breakthroughs.
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So I got lucky in that I hadn't experienced any coolant leaks, but they were definitely in my future :)

[NightFlyer]

I specifically run DexCool (the orange stuff) coolant in my DeLorean, as it's specially formulated to be gentle on aluminum components.

[Bitsyncmaster]

I think my otterstat pipe was the most corroded. I do think the hose clamped on it had the effect of causing the corrosion,.

[SS Spoiler]

Is there any kind of sealer that can stop rot. Applied to the fitting before a hose goes on?

[DrJeff]

Here is a fairly detailed video of the corrosion (http://youtu.be/-Qrr0rjWD08) occurring on the aluminum connections in the cooling system, specifically where the connection pipe is covered by hose and clamp.

The video shows corrosion on the flanges, the water pump, the thermostat housing, and the pump back plate.

The article I posted earlier in this thread suggested that accelerated corrosion (albeit this corrosion took 30 years) will occur where the metal is under pressure and there is pooling coolant. Some interesting patterns to note... there were no pits with a very narrow opening that broke through. This would suggest that the corrosion is not tunneling but rather once it gets started in a spot it grows from that spot almost equally in all directions. When the pit is as wide as the metal is thick you get breakthrough. The pressure points might be where the corrosion starts and then once started, pooling causes the spot to grow.

[David T]

This corrosion shows up on cars when the anti-freeze was left in too long and became corrosive/conductive. The best preventative is to test the anti-freeze annually and change it every 5 years. It can be difficult to weld up pinholes, especially in aluminum. On some cars (not Deloreans) I have seen the vanes on the impeller for the water pump completely GONE from corrosion. No surprise the car had cooling issues! If you still have the plastic tank radiator and the plastic header tank, they should also be replaced. Once the anti-freeze becomes acidic you get electrolytic corrosion because of the dissimilar materials in contact with the anti-freeze. It acts like an electrolyte and in essence you have a battery. Can also happen if you have a defective battery charger and it is hooked up continuously.

[DrJeff]

That's the funny thing, my car wasn't exhibiting any cooling issues. I've been checking around the other parts and haven't found problematic corrosion yet... But I'm ready.

Jeff

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