Strange oil leak and smoke - Pontiac GTO Forum
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post #1 of 3 (permalink) Old 10-31-2017, 03:06 PM Thread Starter
 
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Strange oil leak and smoke

Hey fellow Goat lovers.

I have a 70 GTO with a 400 in it. While I know the car pretty well, I am somewhat baffled by the current issue on hand. On both the passanger and driver sides, I am getting a lot of smoke coming from two different locations, but very likely related. 1) the exhaust header on the passenger side, and on the driver side behind the block once the car is warmed up. The valve covers and headers were pretty dirty, so I cleaned them off to find the source. After cleaning, I ran it again, with no apparent leaks visible from the valve covers themselves. However, there is still a ton of smoke coming from the back of the block, driver side IN ADDITION to some smoke coming from where the exhaust header meets the block, on the passenger side. I can see very small bubbles coming out from the flange.

I have replaced the PCV valve, as it was a possible simple solution. At this point, I think the next step is to replace the valve cover gaskets, and degrease the motor again. However, if anyone else may have some tips or ideas, please let me know. I believe that the oil leak may be coming from the valves (hence the bubbling). The car has 50k since a rebuild, and is firing on all cylinders and no excessive smoke coming from the tail pipes. I have also pulled the plugs on the passenger side, to see if they were dirty. The only indication of any dirt/oil is around the base of the plug, the tips are clean.

Any tips or ideas to get this ol goat back on the road so I can get it into the paint booth to fix the front bumper?! I am trying to prevent having to shell out the money for a rebuild at this point till next year. I have included a picture of the header issue/bubbling location.

EDIT: I also understand the exhaust leak is an issue, but the oil leak is the main issue that I would like to resolve first.
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Last edited by topless70GTO; 10-31-2017 at 03:31 PM.
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post #2 of 3 (permalink) Old 10-31-2017, 07:48 PM
 
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Looks a bit too oily to actually determine where the oil leak is. I would pressure wash or degrease the engine clean as step 1. However, seeing what I see, my guess is the rocker arm cover gaskets. Often, the valve covers don't have the valve cover hold down tabs as they get lost or thrown away. Check these out so you can see what I am talking about: https://www.summitracing.com/parts/spe-5324/overview/ They come in different sizes and chrome if buying aftermarket. These tabs spread out the clamping force under the bolts used to tighten the valve cover. When they are not used, the bolt is tightened down and it can distort/pinch the valve cover points at the bolt rather than provide a good even clamping.

If you do not have these this is what I would get first. Get the correct sized one for your valve cover bolts. Longer is better if you are OK with some of the chrome ones or simply paint over them. Then pull the valve covers and look at the holes where the hold down bolts go. These need to be flat. If they have been over tightened, they will be dimpled and are only pulling down at that point and not really clamping down on the valve cover gasket. If this is happening, the oil can seep right under the gasket because it is not being clamped effectively. I usually turn the valve cover upside down, find a flat surface to support the valve cover edge/lip, and take a hammer to it and gently tap it flat again.

I have no recommendation on gasket material as some are cork and some rubber and I have used both. You just want to make sure they are not some kind of "Made in China" thin paper gasket material. FelPro is usually a good brand.

The leak at the rear could also be from the valve cover gaskets or even from the distributor hole. Never had a problem with the distributor hole, but there is supposed to be a thin paper gasket under the distributor - so look around the base of your distributor And the intake as well.

My next suggestion would be to go to your local auto parts store and get an oil leak detection kit. It will include a liquid dye you add to the oil which will show up under a UV light. Never used one, but never had the need for one either, but if I did have a stubborn oil leak, I think this is the way to go. They are not too expensive. Hope that helps.
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post #3 of 3 (permalink) Old 11-01-2017, 10:06 AM Thread Starter
 
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Thanks a ton. I am trying to locate a buddys garage so I can clean it off some more. Currently the car is in a storage unit, so my options are somewhat limited. Cleaning it should help a lot with diagnosis.
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