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Oil Seeping Out One Exhaust Manifold Bolt

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Martinld123

Martinld123

Jedi Hopeful
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When removing my 100 BN2 exhaust manifold I noticed oil seeping out around the number 4 bolt. It was the only one out of the 6 that had any oil leak. I guess there must be a pocket of oil in that area. Should I do anything to seal it or just tighten it down first before installing new exhaust manifold? I have heard that if these bolts are too tight they can maybe cut through into water or oil areas?? So do I just tighten it down or do I try to clean area so thread sealant might help.

I noticed this when replacing my old 100M carbs with a new pair of 100M carbs from Moss. My engine has not been running smooth so trying new carbs plus sent distributor out to Advance Distributor for rebuild 6 weeks ago. I just reached a point where I needed to start fresh. So any ideas on this oil seep problem before I put things back together? Thanks Marty
 
I've seen this umpteen times on siamese port cylinder heads. I've never had a problem just sealing the threads and reinstalling the manifolds.
 
Actually I would not read to much into a little seepage in that area. To rest your mind at ease you may want to check your oil for any contaminants. If you really suspect something is wrong you can mail in a sample of your oil and coolent to a company such as SOS for a highly detailed analyses which would detect various acceptable and non acceptable contaminates in your oil or coolent. They will mail or email you the very high detailed report. Just contact them and they will send you out small containers you fill with your samples and you just mail it back to them. Most likely it's a little oil getting past a Valve guide and nothing to to worry about.

If I where you I would apply a little anti seize on all the stud threads short of the stud outer end, then seal the outer portion of the threads with Hylomar before you torque it down. Use the Hylomar non Harding blue racing formula that stays flexable.This is really great sealent and is oil, fuel and heat proof. I understand it's used on jet engines as well. A little expensive but well worth it belive me! I ordered mine from my local Napa auto part store. Actually, I live very close to you in New Lenox. I hope I see your Healey on the road someday!
 
Last edited:
drambuie,
Thanks for the tip. First coat stud nut end with anti-seize. So as I understand it I next pull out stud, clean it, then try to clean head threads, then coal with Hylomar and reinstall? Sounds like a plan. If given time I would think oil will stop draining then I could clean head. Thanks for tip. Marty
 
Actually, I was not implying that you attempt to remove the threaded exhaust manifold studs at this point for fear of snapping one off! I would rather suggest that you simply apply the Hylomar At the base of the stud as to form a seal between the manifold flange and base of the stud to form a seal.

It would not hurt to apply more Hylomar to the outer end of the stud and the face of the nut as well. Just make sure all surfaces are clean and oil free before application of the Hylomar. The blue racing formula Hylomar is non hardening and stays flexible.

I would only suggest using anti seize on the stud threads if you HAD to pull out the studs and replace them, which I would not recommend at this point.

Note: Please Re read my first post as I needed to edit it to make my points more clear.
 
If there's oil leaking from the stud, it'll probably come out, the thread can be cleaned with brake cleaner and Loctite thread lock used to prevent a re-occurrence.

I haven't used Hylomar or any of the World War Two gasket cements since Loctite 5699 appeared in the seventies. It is vastly superior and will seal up to 1mm gaps! Also it removes easily and does no harm if it goes through an oilway.

Check out the correct one for each application here: https://www.loctite.co.uk/gasketing-9224.htm
 
I wouldn't think the stud would be seized in there if oil is getting past the threads. When the car was running, was oil coming out? Or was it only after you pulled everything apart and loosened the tension on the stud did oil come out?

My car is in the seemingly never ending restoration process. When I took the peripherals off the engine a couple years ago so it could be painted (including the manifolds and studs), I seem to remember some oil being in a couple of the holes. However, it was one of the very few areas this engine wasn't leaking from when it ran previously.

p.s. also right up the road from you, grew up in Barrington and now live in Wisconsin, right over the border from Richmond in the Twin Lakes area.
 
WaltCasten said:
I wouldn't think the stud would be seized in there if oil is getting past the threads. When the car was running, was oil coming out? Or was it only after you pulled everything apart and loosened the tension on the stud did oil come out?

My car is in the seemingly never ending restoration process. When I took the peripherals off the engine a couple years ago so it could be painted (including the manifolds and studs), I seem to remember some oil being in a couple of the holes. However, it was one of the very few areas this engine wasn't leaking from when it ran previously.

p.s. also right up the road from you, grew up in Barrington and now live in Wisconsin, right over the border from Richmond in the Twin Lakes area.
Click to expand...

Walt,
When I took off manifold I noticed a wet oil spot by that stud. It was only hand tight so I removed it easily then oil started coming out. I put stud back in to stop oil flow. All the other studs were tight with no oil leak that I could see. Thanks Marty
 
Marty,

Again, I don't remember for sure exactly how many stud holes the oil came out of or how much. It wasn't a lot though, I remember just cleaning the holes out with a Q-tip with brake clean and that did it. If I remember correctly, the old studs did not appear to have any sealant on them so when I installed the new ones, I did not use any. Hopefully I don't have a problem.

And just a reminder but I'm sure you know this, those studs and nuts are BSF, not US threads so you can't just run down to Ace or True Value and buy fasteners. My car had a couple of those studs with UNF nuts jammed onto them which is why I replaced them. Although my car will not be concours correct, I am trying to fix as much of that kind of crap that happened to it over the years as possible.

Hopefully someone with more experience with the 4 cylinder engines will chime in if those studs need sealant or not.

Later,
Walt
 
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