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Creative ways of curing oil pan bolt leakage


Str8-8-Dave
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One area of my 31 Buick 8-66S I have yet to seriously address is oil leakage from the pan bolts.  This does not appear to be seal leakage, oil is just dripping from the heads of some of the oil pan bolts and makes a mess on my garage floor.  I suspect the leakage is due to the fact the pan bolts are exposed to engine oil in the crank case.  One approach I have considered is installing Bartite stainless over rubber sealing washers between the lock washers and the oil pan rail but I'm not sure they will fit between the bolt holes and the sidewall of the oil pan.  Another approach would be to remove all the lock washers and go with copper sealing washers to hopefully establish a seal between the heads of the bolts and the oil pan rail.  Has anyone done this and if yes was it successful?  Other ideas??

 

Thanks.

Dave 

Oilpan 001.jpg

 

Oilpan 002.jpg

Edited by Str8-8-Dave (see edit history)
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A common problem I see is that the bolt holes are cupped from overtightening in the past. You should be able to drop the pan, flatten all the holes on the oil pan, then snug them up with a new gasket and stop the leaks. I would think that if you don't want to drop the pan, a fiber or copper washer could also work. (I'm assuming your oil pan is stamped steel, not cast - if it's cast, please disregard everything I just said! :) )

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4 hours ago, misterc9 said:

Are the bolt holes dead end into the block?  Or do they go through to where the oil is? 

 

15 hours ago, Str8-8-Dave said:

I suspect the leakage is due to the fact the pan bolts are exposed to engine oil in the crank case. 

misterc9 your question was answered in the original post.

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8 hours ago, Tinindian said:

 

misterc9 your question was answered in the original post.

So I'm leaning more toward a thread sealer of some kind.  The threads of the bolts are exposed to crankcase oil and there isn't much room from the bolt holes on the reinforced flange of the oil pan and the vertical sidewalls of the pan.  Bar-tite sealing washers are out because the OD of the washer would interfere with the vertical sidewall of the pan.  It's either copper sealing washers which invite trouble if they loosen or thread sealer. 

 

Who has a recommendation for a good oil proof thread sealer?

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22 hours ago, Ken_P said:

A common problem I see is that the bolt holes are cupped from overtightening in the past. You should be able to drop the pan, flatten all the holes on the oil pan, then snug them up with a new gasket and stop the leaks. I would think that if you don't want to drop the pan, a fiber or copper washer could also work. (I'm assuming your oil pan is stamped steel, not cast - if it's cast, please disregard everything I just said! :) )

 Hi Ken- The oil pan on this car is not cast but it is an unusually heavy stamping and the sealing flange is reinforced with 1/8" thick steel plate.  There is no evidence of cupping or depression.  You would likely strip threads off either the bolt or the block flange or break the head off the bolt before you deformed this baby. 

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I have developed same type leak on cam cover... Gasket holes were too small and wiped all seaer from threads as bolts were tightened.... My cure was to slightly enlarge gasket holes to allow bolt threads to "fall" through hole with sealant intact.. problem solved.... I use indian head sealer..... Old bottle, but good thick sealer...

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4 hours ago, Matt Harwood said:

Blue Loc-tite will fix it. Blue is low strength and easily removed but is a viable sealer for threads.

I'm wondering about the blue Loc-tite, I have some of that.  If I remove the bolts and clean them thoroughly in lacquer thinner, then apply Loc-tite, I wonder if it is better to reassemble right away or should I let it cure, then install bolts?  There will be oil residue on the block threads that will not be easy to clean off.  I'm thinking if I let the stuff cure on the clean bolt threads first it will have adhered solidly to the bolt threads and be crushed into female threads in the cylinder block and seal. 

 

Nickel for your thoughts Matt...

Edited by Str8-8-Dave (see edit history)
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Loc-Tite cures in the absence of oxygen so it won't set up properly unless it's threaded into the hole and torqued. It may become gummy or tacky out in the open, but I wouldn't trust it to work properly if it was allowed to just set up in the air. Clean the bolts, put a small drop on the threads, install, and torque to spec all in one shot. Letting it set up before installing it might lead to leaks or failure and isn't how the product is designed to be used. Blue Loc-Tite, as I mentioned, is pretty benign and easy to remove, but does hold the bolts in place so they don't back out and it does offer a good seal. I use it on almost every fastener I remove and reinstall just as a matter of course. It's not permanent like the red stuff. I'll be using it on the head studs of my '35 Lincoln, many of which go into the water jacket and require sealer to prevent leaks--Loc-Tite is ideally suited to this task.

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19 hours ago, Matt Harwood said:

Loc-Tite cures in the absence of oxygen so it won't set up properly unless it's threaded into the hole and torqued. It may become gummy or tacky out in the open, but I wouldn't trust it to work properly if it was allowed to just set up in the air. Clean the bolts, put a small drop on the threads, install, and torque to spec all in one shot. Letting it set up before installing it might lead to leaks or failure and isn't how the product is designed to be used. Blue Loc-Tite, as I mentioned, is pretty benign and easy to remove, but does hold the bolts in place so they don't back out and it does offer a good seal. I use it on almost every fastener I remove and reinstall just as a matter of course. It's not permanent like the red stuff. I'll be using it on the head studs of my '35 Lincoln, many of which go into the water jacket and require sealer to prevent leaks--Loc-Tite is ideally suited to this task.

Matt,

I suggest Permatex #2 for your head bolt application. You want something non-hardening so you can re-torque the heads without bolt leakage .  I know all the Flathead Cadillac owners use this as the headbolts go into the water jackets on that application and requires a couple of re-torques during break-in as the gasket relaxes during the first few heat cycles.  The Blue Loc-Tite will break its seal once cured.

 

Permatex #2 would also work for the oil pan bolts but less critical to have a non-hardening sealer so the Loc-Tite or Aviation Permatex would work just as well since you shouldn't have to re-torque.

Scott

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What ever you use clean both the bolt and  hole threads with something that will dissolve the oil and leave the threads clean.

Probably a squirt can for the female threads and some air to dry. Maybe twice would be prudent.

As for the rubber impregnated washers, (if I am thinking of the same thing you are) one could trim one side a bit but they don't seal the threads and you may still get oil thru the gasket.

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You will definitely have to remove  the  oil pan and flatten the lumps on the holes . One important point , as one member said, enlarge the holes in the gasket so that the bolts goes through freely. Then wash the threads in the block with brake cleaner thoroughly and blow dry. Wash the bolts also. Use any good thread sealer  and it will be  fine.

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43 minutes ago, trini said:

You will definitely have to remove  the  oil pan and flatten the lumps on the holes . One important point , as one member said, enlarge the holes in the gasket so that the bolts goes through freely. Then wash the threads in the block with brake cleaner thoroughly and blow dry. Wash the bolts also. Use any good thread sealer  and it will be  fine.

 

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My 1933 Graham eight uses copper washers under the timing chain (front 3 bolts) only way I have been able to stop them from leaking, they are the only holes that go through to the oil galley.  Easy to anneal, just get them red hot, or I just use new copper washers.

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I use Teflon Plumbers paste (never the tape). With the threads of the bolts cleaned and coated with the paste the oil won't wash it out like some gasket sealers that need to be put on a dry bolt and hole and allowed to setup before hot oil gets to them. And it won't hurt the engine if bits of paste get in the oil, like some sealers and tape can.

 

Only put the paste on the bolt threads, not in the bolt hole, or the bolt will just push the paste up into the engine and not seal well.

And use new lock washers, not squashed old ones.

 

Also works for the threads of fuel line fittings.

 

Paul

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I respectfully disagree with using sealing washers of any kind on an oil pan application. They work fine when the crush washer IS the gasket, like on the oil pan drain bolt. But when you're securing an oil pan, you have a gasket, the sheetmetal of the oil pan itself, then a crush washer, then the bolt head. You will have to torque the hell out of the whole thing to get the crush washer to crush, which will distort the pan rail and the gasket. Even then, you've still got two places where oil can leak: between the block and the gasket and between the gasket and the pan, neither of which will be sealed by the crush washer.

 

Sealant on the threads is absolutely the right choice for this application. Washers won't do the job because there are other places for leaks to happen before the oil even gets to the washers.

 

 

Edited by Matt Harwood (see edit history)
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My 1933 Graham came with copper washers on the front three pan bolts under the timing chain from the factory.  The copper washer seals between the pan and the bolt head, I just snug them up.   I agree thread sealant will work.

 

The copper washers are listed in the factory Graham parts book.

 

image.thumb.png.82b34d9ff1163a0f7c085a7beffdb334.png

 

 

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  • 3 weeks later...

Many good suggestions here. I have had success with a good sealant applied to thoroughly cleaned threads. A key step is to thoroughly clean both the bolt threads and the threads in the block with a clear solvent like acetone. Use a clean rag or paper towel with the solvent and then dry with a clean paper towel then blow with air. Make sure every surface is clean and dry. Then apply the sealant to the threads, then install. I have had good luck using non-hardening black permatex on the threads. I like to wait over night before adding the oil so the permatex and any gasket sealer or silicone at the front or rear of the pan has time to set. In agreement with others, the pan surfaces that mate to the block must be flat.

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