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Jim Saraceno

Looking for oil leaks...

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Ever since I rebuilt my engine, it has had oil leaks. I'm not sure if I over torqued the pan gasket, didn't get a seal in properly, didn't get a good seal at the oil pump or what.

I assume what I need to do is to clean everything up, take it for a short drive, then hope I can see where it is coming from. I was even thinking of putting masking tape around the oil pan to see if that would show up better.

Anyone have any suggestions on how to narrow down exactly where it is leaking?

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Check for leaks at oil pump, fuel pump, front timing cover gasket, rear main seal too.

Maybe the pan gasket isn't leaking at all, but may be from somewhere else, even the valve cover gaskets.

I replaced my oil pan gasket last spring, quite confident it does not leak, but still get leaks a bit from oil pump, from timing cover gasket too. I place a large sheet of thick cardboard under the car in the garage, and unless I have to pull the engine, not going to worry about. Hey don't Old Harleys leave there mark too........Fred

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drive and retorque my 47 I know was put together right, but it has plenty of leaks. Guess what, I hear when you get over sixty everything leaks and drips :eek:

hehehe, something for me to look forward too, going to be 49 soon.

I have heard of situations like yours, rebuilt engine, and still oil leaks from places like the rear main seal, and some engines, don't leak much if any, just the way it is I suppose.

I look at the pavment at stop lights, parking lots, and a lot of modern engines are leaking oil too, go figure.........Fred

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Guess what, I hear when you get over sixty everything leaks and drips

Ah-ha-ha! Been there... doing that!:D

Yeah, I put a piece of cheap paneling down on the garage floor. I don't worry about it much, just thought I'd give it a try.

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If your really serious about detecting that leak than buy a can of Spot Check developer. It sprays a mist that turns into a powder and it will show you right away where that leak is at. I used in the shipyard for just this purpose and it worked great.:)

http://www.markingpendepot.com/browseproducts/SKD-S2-Spotcheck-Developer-16-Oz-Aerosol.HTML

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I sure am glad I'm not the only one with the drips. With my Triumph motorcycle if it didn't leak it was out of oil. But the Plymouth - I can't figure it out. I see the results on the floor. I've been under the car and wiped the pan clean. Looked at the valve covers, fuel pump. I can't see where it's coming from. I just came off a 400 mile trip - one quart. Don't know - poltergeist perhaps?

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Thanks Don C.....................lol...........just wet meself again...........lol...........would like to meet you sometime, I appreciate your sense of humor........andyd

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Well I plugged the oil leak in the transmission and narrowed down the locations of the engine oil leaks.

1. front of engine

2. oil pump

3 rear of engine

As far as the oil pump goes, it may actually be coming higher at the valve cover gasket. That should be pretty easy to determine.

The rear could be the oil pan gasket or the rear seal.

The front again could be the oil cover gasket or the timing chain cover.

Any suggestions on how to differentiate the front and rear leaks?

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I think the valve cover gaskets may be suspect. the whole assembly is kind of iffy. Although there really shouldn't be a lot of oil in there, I thik if they are overtightened, it causes the covers to distort and the gaskets not seal.

Clean it up real well and just let it run, then see if you can find the source. Driving at speed and the fan blows stuff around obscuring the source. I know most of my drips are on the pass side of the car but with driving and fan pushing it around it hard to tell where its coming from. I know my rear main is leaking. I have snugged the pil pan gasket and the valve covers but the drips persist. Also gotta wonder why if the oil is down in the pan, below the level of the gasket why would it leak, unless there is a build up of pressure in the crankcase when the engine is running forcing it past the gaskets then collecting and dripping on shut down.

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Clean it up real well and just let it run, then see if you can find the source. Driving at speed and the fan blows stuff around obscuring the source. I know most of my drips are on the pass side of the car but with driving and fan pushing it around it hard to tell where its coming from. I know my rear main is leaking. I have snugged the pil pan gasket and the valve covers but the drips persist. Also gotta wonder why if the oil is down in the pan, below the level of the gasket why would it leak, unless there is a build up of pressure in the crankcase when the engine is running forcing it past the gaskets then collecting and dripping on shut down.

So how can you know if the leak is the rear seal or the pan gasket? Are you saying that if it is leaking from the rear, it must be the seal?

There is not enough of a leak for it to show just running and sitting in the garage. Yes, the air blowing things around does make it hard to determine exactly where it is started. What I've been doing is to clean things up, take it for a short drive then run it up the ramp to see where it's starting.

The next trip should determine if one leak is coming from the oil pump or valve cover.

What about the crankcase down tube? I used to have oil dripping from there.

No, I see no oil dripping there. Wow! I actually have a spot that doesn't leak oil but someone else does? Cool beans!:)

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Jim, all I am saying is that the oil at the rear main seal is is most likely because, the oil there is under pressure from the pump, and the oil in the pan is "not pressurized" but mearly a reservoir/ collection area. So it seems most likely the seal would be the culprit.

But as we know the character of these vehicles does not always support the obvious.

I would think that oil on the pan would come from the oilpan gasket of the valve cover area. Oil on the bottom of the transmission that is not gear oil will be from the rear main.

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Hey, Jim,

My first response is to think, “My engine leaks now, and I’m considering a rebuild?” :D

I’ve been fooling with Model A flathead four bangers for too many years to count. On several forums dedicated to this motor the question of engine oil leaks comes up on a regular basis. The Ford motor is a famous leaker, and many have tried more modern improvements to help reduce the size of the puddle. One such remedy is the reduction of crankcase pressure by the use of a PCV (Positive Crankcase Ventilation,) system. I have experimented with a couple of these on Model A motors with a moderate degree of success. Your post and the garage floor under my ’33 PC have prompted me to begin considering a PCV for my engine.

The principle, as I understand it, is that any internal combustion motor builds pressure within the crankcase when operating. The solution in the early days was to provide a passive system incorporating the use of a “road draft” tube and a ventilated oil fill cap. (The model A, and many earlier motors didn’t even have the tube, instead relying totally on the vent at the oil fill.) Most road draft systems work best at highway speeds, when the tube, (supposedly,) creates a vacuum from the slip stream, as the car moves forward. A newly rebuilt motor is likely to produce even more pressure inside, due to the better seal of the new pistons/rings and valving. Picture your motor with oil under pressure trying to escape, especially at idle, or low speeds: if the factory attempt at relieving this pressure is inadequate, all openings, (seals, gaskets,) are subject to this pressure from within. This condition is an open invitation to leaks.

The concept of a PCV uses the introduction of a negative pressure to the crankcase in the form of engine vacuum. Some form of baffling at the point of entry/exit of the plumbing is sometimes necessary, depending on the location of the vacuum line port, to prevent suction of engine oil out of the motor. Usually a PCV valve is installed in the line to prevent back flow of air/gasses into the crankcase area when the motor is not running.

In the few Model A Ford motors I've converted, I've installed a ⅛” pipe nipple to ⅜” fuel line into the valve cover of the motor, then, run a line to the intake for the vacuum source. (On one of these engines, the leaks almost completely disappeared, and the others showed marked improvements in the size of the puddle underneath and the dampness of the gasket surfaces on the engines.)

The Mopar six has two such valve covers, and either may be a good candidate for the installation of the vacuum line. Looking at my motor, the running of a ⅜” line from the rear valve cover, up and around the back of the exhaust manifold to the vacuum port on the the intake would be pretty much a no brainer. I’ve read, and been told, that the choice of the PCV valve should be to look for a valve designed for a motor close in cubic inches to the one to be fitted. My past experience shows a parts counter man with some savvy can be helpful, here.

Not to hijack your thread, but I’m thinking maybe the best way to prevent leaks is to possibly relieve the inside engine pressure that may be the main cause of them. I’m too new here to know if this is all “old information,” but a search of the site didn’t net any direct reference to a PCV installation. My 3 cents. . . GA

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i found the perfect thing to find leaks while working at the tractor dealership ..they sell a blue pen lite ,,and when you shine it on the oil it glows green ... you can wipe the area clean ,, with some carb cleaner ,, start it up ,, and shine the lite on it ... you will see a trail of florescent green oil start to flow .. they sell the blue penlights at any auto parts ... the cost is around $20.00 for them ,, but well worth the money ...try it ,, you WILL be amazed....

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...snip... The Mopar six has two such valve covers, and either may be a good candidate for the installation of the vacuum line. Looking at my motor, the running of a ⅜” line from the rear valve cover, up and around the back of the exhaust manifold to the vacuum port on the the intake would be pretty much a no brainer. I’ve read, and been told, that the choice of the PCV valve should be to look for a valve designed for a motor close in cubic inches to the one to be fitted. My past experience shows a parts counter man with some savvy can be helpful, here. ...

Unless the draft tube is clogged, there should not be pressure in the crankcase. Even at idle.

If you wish to add a PCV system to a Plymouth L-6 engine, you can use the factory designed unit for military vehicles available from Vintage Power Wagons. Or do it yourself. Typically it involves removing the draft tube and installing an adapter there for the PCV system. Search the archives of this forum for PCV and you should come up with a few threads at least one of which has pictures of all the pieces to make your own pretty professional looking setup.

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Thanks for all the input. Actually, it may have been the transmission doing most of the leaking. I still have the oil coming from the engine but not much.

So I'm guessing replacing the oil pan gasket is not a solution to any of the drips, replacing the rear seal is more work than it's worth. I'll try to identify the source of the side and front leaks and go from there.

Now that I've stopped the leak from the tranny, I may just move on to the one from the differential.

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