Does anyone know if it is possible to repair a leaky manifold stud hole on the cylinder head with a Helicoil while the head is on the motor? The rearmost stud in my brother's van leaks coolant and I would like to repair the hole without pulling the head (or even the manifolds), if possible. I know I would at least need to send a skinny magnet into the hole to collect metal shavings, but is there anything else I should be worried about?

Thanks!

Reed
Ive done it. But its not easy if its the back one on a door car. I would not have been able to if the stud did not come out.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Heli-coils are not solid and are not the best choice for hole repair when the hole enters the water jacket. I had a head that someone put an oversize exhaust stud into as a 'fix'. When the head was at the machine shop I had a solid thread repair insert installed.

_________________
Joshua

If you can get the stud out....install a new one with lots of sealer on it.

If you cant get the old one out you will be removing the manifold at least.

Old trick.....using a sharp prick punch....carefully peen the head around the stud till it seals. This requires more finesse and skill than you would think.

_________________
Yeah....Im the one who destroyed this rare, vintage automobile.....

Hmmm. Thanks guys. This is in a van, so the rearmost stud is actually the one with the easiest access. Currently, the head is holding water and pressure at full temperature by sticking the stud back in covered with teflon tape and high temp RTV gasket maker. It is holding, but I just hate this lame fix. The hole isn't big enough to run a oversize bolt in (tried that), but it isn't small enough to clean up with a tap (tried that too- gets a wee bit tight then spins).

I will look into solid thread repairs. If this wasn't my oversize valve head I would just move on to another head. But, since I have over $500 invested in machine work already, I want to salvage it if I can.

Thanks!

What about a metric size that's just a little bigger instead of the next larger sized SAE that's too big?

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

With a Helicoil drilling will most likely be involved. I did this exact thing on my D350 with a 360 in it. I am most positive that it is the same size stud even. Getting the hole drilled straight was the worst part. The tap would not start in my hole so I had to drill it first. I installed the Helicoil dry and the stud with just a dab of sealer, and it has been holding for over 9 years, and probably 50k miles or so. They can leak, especially if the hole is to big or you "wobble" the tap going in. The solid insert is better, but this can be made to work. I have seen people use all kinds of epoxies and putty "metals" on the Helicoil when it goes in, with fair success too. If you do that it is best to cut a bolt of the same thread like a tap (a dremmel with a cut off wheel works good) to chase the Helicoil with once it is set. Don't use a real tap, it will kill the Helicoil, use the cut up bolt. If you do use epoxy or putty give it plenty of time to set up.

Good luck

TopHat

How 'bout a stepped stud that's got bigger threads on one end and smaller on the other? Dorman #675-097. It has 3/8"-16 threads on the head side, and the stock 5/16"-24 threads on the manifold side. Overall length is a little shorter than the 675-092 standard replacement stud, but that's of no consequence. That's what I wound up successfully using at the end of a long comedy of ignorant errors and dumb mistakes* a long time ago on my '65. All you have to do is overdrill the hole straight and true. Head on engine: Not a problem. Manifold on head: Not a chance.

Use Loctite (not RTV or teflon tape) on the head-side threads, which means you need to clean the coolant and tapping oil out of the overdrilled head hole using something (alcohol or brake cleaner, e.g.) that won't leave a residue. The head threads are 7/16" deep on the 675-097, while the original-type 675-092 has 9/16" of head threads; if you're careful and mark your tap accurately with a loop of masking tape, you can make (leave) a ledge at the "bottom" of the overdrilled head hole to bolster stud seating and sealing.

*-involving a hammer drill, "EZ-out", jigsaw, tap extractor, JB-Weld, Plexiglas heater, and assorted other inappropriate tools and supplies

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hmmm. Very interesting idea Dan. I may give it a shot. I will hopefully be swapping to dual exhaust manifolds in a month or so on the van, so the head will be bare of manifolds.

Get the hole as clean and dry as possible, then install the stud with JB Weld. End of problem.

_________________
Official Cookie and Mater Tormentor.

I've used this stuff in the past with good results. Once on a motorcycle oil drian plug thats still holding after 15 years.

Just make sure you follow the directions.


http://www.permatex.com/products/Automo ... Repair.htm