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On the 56 Olds the tapped holes in the block for the exhaust manifold run all the way thru into the water jacket. Why don’t they leak with the original exhaust systems in place? I presume that is because they stay tight. How do they avoid working loose with the heat/expansion/contraction, the vibration and stress placed on them from the stress of the rest of the exhaust system? The reason I’m asking is that with the Fenton cast iron headers I have, and dual exhausts, I can’t keep the bolts tight enough to keep from them from leaking after a period of time. It’s mostly the two rear lower bolts near the exhaust pipes but several others have showed a small drip at some time. I originally had stainless bolts installed for appearance’s sake but after several hundred miles or at the end of the season they showed leakage. For an experiment I replaced one of the rear bolts with a steel grade 8 and installed it with a some TFE paste on the threads and a lock washer. The TFE is rated to 600 degrees and since the end of the bolt is in contact with the heated coolant, 190 degrees, I figured some of the paste would not be affected by the manifold heat and keep the threads from leaking; but it still leaked. So, was the lock washer the problem? Did the manifold heat weaken it enough to let the bolt loosen? I’m guessing that one of the reasons the original bolts don’t leak is they accumulate some rust that keeps them tight and leak free. With the Fenton headers, the rear bolts are very difficult to get at since they both exit at the rear of engine whereas the stock, single exhaust exits near the front of the engine on the driver’s side and uses a crossover pipe to reach the passenger side.
I don't think I would use a lock washer just a flat as I would think the hot cold cycle would cause them to loose temper and loosen. I've never had that issue on the manifold bolts leaking but the ones that penetrate to the water jacket are almost always a bitch to get out if they have been in there a long time.
I'm envious of your Fenton headers they are on my bucket list for a vintage hot rod build, a very rare piece of hot rod history....Tedd
The 1956 Oldsmobile Shop Manual says on page 8-3, "If manifold studs show signs of coolant leakage, remove studs and apply C. P. No. 9 sealer (Nat. Machine Prod. Co.) to stud threads. Torque manifold to head bolts and nuts to 19-25 ft. lbs."
I think this (studs) is the key. A lot of Chrysler engines have the two end exhaust manifold holes drilled through to the water jacket but they always have studs in those positions compared to bolts. I would use studs with any type of good thread sealer and I bet it will take care of it.
BillK, Thanks for your input. I think you are right about using a stud with sealant to stop the leak, any suggestions on how to keep the nut on the stud tight? Thanks Chuck
FWIW, I have a 6.9l IDI in my 86 Ford F250 and it has 4 water pump/timing cover bolts that go into the coolant jacket and oil gallery. SOP when doing a R/R on a water pump is to coat the threads with Permatex. Not a classic Oldsmobile engine, but...
Chuck,
I bet if you use studs with a fine thread on the outside, they will probably stay tight. If not i see no reason why a lock washer wouldn't work ? If not, how about Stage 8 nuts ? The Harley guys use them and if a Harley engine wont shake them loose, nothing will
FWIW, I've used the Stage 8 hardware on the headers in my 71 98; as well as, the Percy's locking bolts. They didn't seem to do a good job fastening the headers. I have no idea how they'd work for Chuck.
Thanks guys for all your input and comments on my engine picture; it is certainly appreciated. Although the Permatex works well on the water pump application, the water pump isn't subject to the heat and vibration on the headers. I looked up Stage 8 fastener's, a new one for me, and determined that there is no room for the retaining arm in my application. I looked up Percy's and according to their website, they have no stock... don't know what that's all about. Followed the name and found them at Auto Zone but no info on how they work or they retain themselves. Got me to thinking and went locking for locking fasteners on line. Leading me to' "Summit" and saw some Chevy header bolts that use an insert on the threads as well as a serrated contact point. Don't know if the serrations will bite into the ceramic coating on my headers on the where the bolt will seat, but the insert on the shank warrants some more consideration. Still haven't ruled out using a stud with maybe hardening Permatex into the block, and maybe a stainless lock washer would maintain it's "spring" and keep a nut tight? Thanks again for all the input it has certainly given me some ideas whereas b/4 I think I was suffering from tunnel vision. Chuck
It sounds like those Chevy header bolts you saw on Summit are similar to the Percy's header bolts. I got the black anodized header bolts and they ended up corroding after a few years (even with 0 winter driving). If you get specialty locking hardware I suggest the chrome ones. Good luck, keep us posted!
Olds64: Is this a picture of the Percy bolts? Sure looks like they might work. They didn't come loose but corrosion was the problem, is that correct? Thanks Chuck
Still haven't ruled out using a stud with maybe hardening Permatex into the block, and maybe a stainless lock washer would maintain it's "spring" and keep a nut tight?
If the holes go into water I would absolutely use studs. Once they are in they will never turn and come loose to leak. Like I said earlier, get the ones that are coarse thread where they go into the block and fine thread for the nut. The fine threads have better clamping force and probably will stay tight without anything special. Not sure what size yours are or how long they need to be but ARP should have something that will work. Just snug them up after a couple of warm up and cool down cycles.
I went thru this a few months ago and i used permatex #2 on studs. Flat washers and nuts. Figured if i had to remove that manifold again, that the stud would remain. Just my 2 1/2 cents. Good luck with yours.
The lower header bolt on the D-side is almost impossible to get at. Even after removing the starter getting the wench on it is a bear, and trying to start a bolt using just two fingers is difficult. It would be impossible to install a stud due to the space confines. There is only 3/4 inch space between the exhaust manifold and the steering column. With the stud installed there wouldn't be enough room to get the manifold over the end of the stud. Either pulling the engine, or pulling the steering column is not something I would like to do at this point. I think my best bet is to remove the stainless bolt that required the use of never- seize and put a standard grade 8 bolt with Permatex #2 on the threads. I think that maybe most of my problem was that I never re-tightened the bolts after several heating and cooling cycles as suggested by Bill K. I did do some re-tightening on the some of the bolts at a later date that showed some leakage, but not after the original installation. So current plan is to install bolt/Permatex, no lock washer. Car is on jack stands now, put starter back in, bring engine up to temp and cool down over 3-4 times. Pull starter, re-tighten as needed, putt starter back in and put the car back on the floor and hope for the best. Interestingly, it has never leaked while on the jack stands, only when the front is on the floor or when totally off of the stands.
