Retorqued Intake but still seeping oil between intake/heads

[Jack O.]

Re: Retorqued Intake but still seeping oil between intake/heads

Perhaps I spoke too soon. I did a good job of taping a paper towel "buffer" at the top of valve cover where it's leaking at what I thought was the source for the oil down between the intake and head. The oil is back but the area between the paper towel and the pooled oil down at the intake is clean, i.e. the area of the head between the valve cover and intake, which brings me back to believing the source is between the intake and head. Another thing I notice is that I see the pooled oil, it's very small pool maybe 1/8" wide at most, when I first check after driving the car but after about 15 minutes the pool is gone and all that's left is a bit of staining on the intake. It's as if it's being sucked back in. I don't what else would explain it.

So I checked the torque on the two center intake bolts, they're the closest to the area, and they took some torque to get to 30 ft lbs. I don't get it, is it normal to still be having to re-torque these intake bolts after at best another hour or 2 of operating time? The bolts are new, and threads clean and I used thread sealer. I did check it while it was still hot, could that explain them being < 30 ft lbs?

[Leif A.]

Re: Retorqued Intake but still seeping oil between intake/heads

Jack,
It's not uncommon and, actually, recommended that you re-torque bolts after they've gone through a couple of heats cycles. All bolts on the engine and exhaust system (when first assembled) should be checked and re-torqued after driving a few times. Totally normal.

[Jack O.]

Re: Retorqued Intake but still seeping oil between intake/heads

Thanks Leif. I was hoping to hear that. Having to re-do the intake install will be a crusher. I'll wait for it to be totally cooled down and go through the entire sequence in the correct order.

[Owen L.]

Re: Retorqued Intake but still seeping oil between intake/heads

You're positive it's oil and not fuel leaking down (since it disappeared (evaporated?)?

[Philip A.]

Re: Retorqued Intake but still seeping oil between intake/heads

Permatex #2 on every intake bolt for me since 1978 and never had a leak issue. Be careful though its almost as bad as anti seize for getting everywhere no matter how careful

[Thomas S.]

Re: Retorqued Intake but still seeping oil between intake/heads

I had the same problem and the 567 sealant worked. You might want to consider putting a UV dye in the oil. Clean up everything prior to doing this. If it’s the bolt leaking you shouldn’t see anything on the gasket unless that is also leaking. You would also rule out fuel. The dye will stay in the oil for awhile so you can repeat the search more than once as long as you clean up in between.

Delco has a product. https://www.amazon.com/ACDelco-10-50...50857018&psc=1

but there are many other versions out there that would do job. Obviously you will need a UV light but they aren’t expensive. Also helps to do this inside with dim lighting.

[John F.]

Re: Retorqued Intake but still seeping oil between intake/heads

Are you sure it is oil or gas leaking from the carb? Also, is the intake to head true and level?

[Joe M.]

Re: Retorqued Intake but still seeping oil between intake/heads

Ftacek has it right, fit of intake to heads and block.

[Jack O.]

Re: Retorqued Intake but still seeping oil between intake/heads

I'm convinced it's oil coming from between the intake and the intake gasket and that re-torquing is not going to correct since I've re-torqued a 3 or 4 times and right after the last time it was immediately leaking. To isolate I cleaned it up and then took a paper towel and pressed it into the area while the engine was running and it came away with oil.

As far as the fit of the intake to heads and block, best I could tell it was okay but all I could really check was the gap between the intake and the front and rear of block. But I didn't have this type of leak before I did this R&R. I did use an original GM NOS gasket which differed from the one I removed in that it had much less extra material beyond the intake in this area which "shouldn't" be needed but perhaps that extra material prevented this.

Before I remove the intake for a complete redo I'm going to clean the area well and try a small bead of Permatex RTV Black in the problem area and hope it seals it. I've had luck with this approach on the front and rear areas before but in this case I going to try and very small and less noticeable application since part of the point of all this was to make everything look fresh and original.

Thanks again everyone for the advice and help. Much appreciated.

[Jack O.]

Re: Retorqued Intake but still seeping oil between intake/heads

Not surprisingly adding a small amount of RTV did not work. There's some pressure there and the oil actually "pops" tiny holes in the RTV.

Wouldn't there be evidence of oil on the intake bolt threads if the issue were that the oil was coming from the bolt hole? I've removed my bolts a few times to re-coat them and have never seen oil.

Assuming it's NOT the common bolt hole issue has anyone had a sealing issue between the intake and the intake gasket resulting in oil seeping out? Even if I re-do the intake I need to know what's causing the issue or it will just happen again. As I said the intake seemed to fit properly, as best I could tell visually, and I used a NOS intake gasket.

Thanks.

[Thomas S.]

Re: Retorqued Intake but still seeping oil between intake/heads

I had previously suggested using a ultra-violet dye to determine the source of the leak. Have you tried that?

[Jack O.]

Re: Retorqued Intake but still seeping oil between intake/heads

Have not. I have no doubt that it's oil and not fuel. However the dye I suppose would give me a better indication of whether there's any leaking up through the bolt threads than just a visual check.

[Jeff S.]

Re: Retorqued Intake but still seeping oil between intake/heads

Jack
I believe what you are experiencing is hot oil in vapor or gaseous state that migrates up the fastener threads, then condenses into liquid state pooling in the (relatively) cooler intake manifold casting. After fighting it for years, this is what worked for me (two years dry as a bone w/o oil pooling so far)

Remove carburetor to gain good access to the troublesome 4 locations.
Use a thread chaser -- not a tap -- to clean the female threads of the debris from previous sealing attempts.
The thread chaser will have 3 or 4 narrow slots that can be packed with grease & will not cut/produce metal filings
Use brake-clean or similar to further prep the female threads
Use ARP thread sealer per their instructions

[Jack O.]

Re: Retorqued Intake but still seeping oil between intake/heads

Thanks Jeff. Perhaps I haven't gotten the threads clean enough as I did not use a thread chaser but I have cleaned them and used the ARP thread sealer. When you had this issue was there any evidence of oil on the bolts? I've pulled the bolts several times and I don't really see any oil. Perhaps because it's vapor as you say so it does not readily show.

[Jeff S.]

Re: Retorqued Intake but still seeping oil between intake/heads

Jack - I really don't know ... been a couple years now. Both female and male threads should be very thoroughly cleaned during preparation for the ARP sealant. Apply it on the bolt threads & under the hex head. Believe I let it cure for a day or two then did some gentle heat-cycle drives to verify.
Jeff