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Leak at riser stud after installation of new riser and elbows.

N

Ngeogh

Member
Just finished installing new Osco risers and elbows on a 1986 Crusader 454. I followed the instructions on several threads in this forum and in the crusader manual. Apart from getting the old risers off, which was a major pain, the rest of the installation went smoothly. After running the engines and and ensuring that everything was operating normally I began to re-check the torque on the studs and noticed that I have several very small raw water leaks coming from the tip of the shorter studs. The water seems to be coming from the head of the nut between the threads.

I have noticed that the three studs that are leaking are slightly shorter than the one that is not. I used new Osco studs, bolts etc but now i am wondering if I installed the studs the wrong way around. Has anyone encountered this issue before, and if so how big a deal is it. The leak is a very slow drip and i have been considering loosening the nut and placing some sealant on the threads, to see if this will stop the leak.
Any thoughts?
 
I had the same thing happen a few years ago when replacing my risers and elbows on 1990 Crusader 454s. I used Crusader risers and elbows but OSCO Stud kits. I noticed that the OSCO stud has one end with a longer threaded section than the other. If memory serves me correct, the shorter end should be towards the manifold leaving more thread and a longer section of stud for the washer and nut. The copper washers are used to block off water from leaking out the bolt hole which is not closed off to the water. The elastic nuts (with plastic insert) actually are suppose to prevent water from leaking down through the threads in the studs. So it may be possible that your short studs that are leaking were installed with the longer threaded end into the manifold. Also OSCO, and I asssume others, recommends that the washers and nuts not be reused.

Good luck and hope this helps.

Erich
 
Erich,
Thanks for the input. I think that what you described is exactly what has happened to me. The shorter studs do not allow the plastic insert to go all the way over the threaded portion of the stud. It is short by about half a turn. What I am wondering if rather than disambelling the entire system again if maybe a little gasket sealant on the threads might take care of the problem. The new studs and nuts seem to torque down tight enough to hold the risers.
Ngeogh
 
I just finished the exact same project.....and same mistake. I am going to try the thread sealer option first. Please let us know how you make out.
 
Will do. I am now thinking that I might just apply sealant to the end of the nut without loosening it, to see if that will stop it. My guess is that, after not very long the corrosion and salt will seal the little bit of water that leaks out along the bolt threads anyway.
 
Ngeogh said:
Will do. I am now thinking that I might just apply sealant to the end of the nut without loosening it, to see if that will stop it. My guess is that, after not very long the corrosion and salt will seal the little bit of water that leaks out along the bolt threads anyway.
Click to expand...

hmmm, bad plan. Take off each leaky nut, one at a time. Apply non-hardening permatex to the exposed stud, torque nut to 20 lb-ft.
 
diver_dave said:
hmmm, bad plan. Take off each leaky nut, one at a time. Apply non-hardening permatex to the exposed stud, torque nut to 20 lb-ft.
Click to expand...

Dave,
Thanks for your input. I was concerned that loosening the nuts might screw up the gaskets or cause coolant to leak but I will try one at a time and see what happens. Will report back with results. Now I will be more careful on the other engine.
Ned
 
Followed Dave's advice and applied Permatex thread sealant to all nuts on all the short bolts. Loosened one at a time and immediately retightened after applying the sealant. Ran the engines up to operatint temp and no leaks. i will watch them closely for a while before I declare it a success.
Thanks for all the input.
Ned
 
Yep, you put the offending ones in backwards. Short threaded end goes into the exhaust manifold.

If you have enough exposed thread on the offending studs and the installation is recent, you might be able to install a standard nut followed by a jam nut, and by tightening them against each other, use a wrench to remove each stud one at a time and reverse it.
 
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