Oil Leak at Intake Manifold Bolt 327

[Ed S.]

[Donald H.]

Re: Oil Leak at Intake Manifold Bolt 327

I had the same problem. I used Permatex High Temperature Thread Sealer. It comes in a small white tube and you can get it at most auto supply stores. I would suspect the RTV referenced in your post is Black RTV, again found at most auto supply stores for automotive use. I prefer the thread sealer since that is what it is made for. You may end up needing to do it to both center bolts on both sides. I believe these four bolt holes are threaded through the head to the lifter valley and that is where the oil comes from. Someone with more mechanical knowledge than me may confirm or correct my comment.

It is an easy fix.

Don

[Ed S.]

Re: Oil Leak at Intake Manifold Bolt 327

Don,
Thanks for the quick reply and advice. Thread sealer makes more sense than other RTV products. Will definitely do all 4 bolts - one at a time - as you suggest.

This brings another more philosophical question to my mind. Why did this bolt leak in the first place? GM didn't use thread sealer or some other like product when the engine was assembled (or did they?). What might have changed to cause the leak to occur now? Can anyone shed some light on that question.

My rear main seal is also leaking slowly. I know how to deal with that but it makes me wonder if I have another problem that is causing the oil leaks, like pressure build-up in the block from blow-by or poor breathing / venting that is forcing the oil out. Will check that out soon.

[Ed S.]

Re: Oil Leak at Intake Manifold Bolt 327

Don,
I do have a relevant follow-up question for you. Where along the bolt should the tread sealer be applied? Since it is a "tread sealer" I am assuming it should only be applied on part of the threaded surface, the part that grips the head as opposed to the entire length of the threaded surface of the bold?

[William F.]

Re: Oil Leak at Intake Manifold Bolt 327

Try thread sealer if you like, but didn't work for me. First clean oil off bolt and hole( with pipecleaner , etc, and lacquer thinner or brake cleaner) then apply ULTRA black RTV to threads and install bolt. This is what finally worked for me.

[Larry M.]

[William F.]

Re: Oil Leak at Intake Manifold Bolt 327

Try thread sealer if you want but didn't work for me. Use ultra black along entire bolt, not just threaded part tighten, but don't overtighten and you can forgetabout it.

[Ed S.]

Re: Oil Leak at Intake Manifold Bolt 327

My thanks to all the experts that responded to my inquiry. Greatly appreciated. This is a fantastic community. I wish I had the knowledge to contribute as many do instead of just drawing on your expertise. For what it is worth, I intend to take the overkill route with my oil leak problem and apply the advice of several responders. I will be applying thread sealant to the threads and using a gasket type sealant product by Permatex up around the bolt head. Hopefully the combination of the two approaches will resolve the problem. Thanks again to all.

[Ed S.]

Re: Oil Leak at Intake Manifold Bolt 327

Thanks to all that replied. FYI - I put a box end wrench on the offending (leaking) bolt as the manifold configuration with the Holley carb in place would not allow me to put a torque wrench on it. To my surprise the bolt was quite loose. I tightened it a bit - figuring that the torque applied to a nine inch box end wrench was no where near the prescribed 35 foot pounds. I found several other bolts a bit loose as well. Bottom line - problem solved - no leak. Thanks again to all.

[Roger G.]

Re: Oil Leak at Intake Manifold Bolt 327

Make sure its not gas leaking from the carb, it looks just like oil when it evaporates on the manifold

[Ed S.]

Re: Oil Leak at Intake Manifold Bolt 327

Thanks Roger - I am cognizant of that - that it could be gas. Having started with a clean valley (i.e., no fluid next to the bolt) - after a short drive a small puddle develops. Smells like oil, looks like oil, and feels slippery like oil. I am pretty confident it is oil as there are no fluid stains leading up to the carb. These old cars are amazing - they definitely need a lot of TLC - always something - but they sure are fun to drive. Thanks again.

[Michael H.]

Re: Oil Leak at Intake Manifold Bolt 327

I had the same problem with 2-3 bolts allowing oil to seep up the threads. I removed them and cleaned them good and applied Toyota FIP sealer which I swear by is the best. The next problem I had was I started using oil ( 100 miles to a Qt ), it appears the intake manifold gaskets weren't sealed good because of the bolts being loose thus allowing oil to be sucked up under the gaskets. I replaced the intake manifold gaskets and no more oil consumption. If you start using oil look at changing the intake manifold gasket first.

Mike

[Ed S.]

Re: Oil Leak at Intake Manifold Bolt 327

Thanks Mike, I'll watch for that - wouldn't surprise me if the intake manifold gaskets did leak, a few of the bolts were really loose. As far as I know my oil loss (which is not all that much) is from: a) a rear main seal leak and b) a good puff of blue smoke upon start up after the car sits for a good while. I attribute the later to valve guide seals. I plan to address both problems this winter.