Strange oil leak and smoke - Pontiac GTO Forum
User Tag List

LinkBack Thread Tools Display Modes
post #1 of 3 (permalink) Old 10-31-2017, 03:06 PM Thread Starter
Join Date: Oct 2017
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
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.
Attached Images
File Type: jpg 2017-10-29 09.44.16.jpg (1.36 MB, 31 views)

Last edited by topless70GTO; 10-31-2017 at 03:31 PM.
topless70GTO is offline  
Sponsored Links
post #2 of 3 (permalink) Old 10-31-2017, 07:48 PM
PontiacJim's Avatar
Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Posts: 3,666
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
Quoted: 391 Post(s)
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: 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.
PontiacJim is offline  
post #3 of 3 (permalink) Old 11-01-2017, 10:06 AM Thread Starter
Join Date: Oct 2017
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
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.
topless70GTO is offline  
Sponsored Links

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO General Discussion

Quick Reply

Register Now

In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
Oil leak: rear main or oil pan? Tbryan 1964-1974 Tempest, Lemans & GTO Complete Engine Compartment Discussion 5 07-24-2017 11:40 PM
Oil Leak, Please Help Me! Thanks NickelN58 Engine Discussions 6 01-11-2015 09:39 PM
Help! Misfire/Blowby/Oil-smoke in tailpipe Tanksta Engine Discussions 7 06-25-2013 09:00 AM
oil leak 64lemans 1964-1974 Tempest, Lemans & GTO General Discussion 2 06-09-2012 08:25 PM
Blue smoke, oil puddle. Valve stem gasket? KingJacobo 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 14 01-15-2012 02:54 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome