I am having issues with blowing head gaskets, I know what the problem is ; the block has some pitting around where the gaskets blows and water starts to rise up through one of the head studs and leaks out of the nut/stud on top of the head, this then becomes progressively worse until the head gasket blows between the two studs in this area, I want to fill in the pitted area on top of the block and intend using liquid metal, my question is has anybody done this before successfully ?
Additionally the stud that leaks coolant up through it has been Heli coiled in the past so this may be giving a problem also. the last time I changed the head gasket I used new studs and liquid PTFE on all the studs to make sure they did not turn on tightening the studs down
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7 Location: Salop
Car type: '28 GE Cup. '28 AD Chummy '30 RL Saloon. '34 RP Saloon. Too Many toys!
09-09-2021, 04:23 PM (This post was last modified: 09-09-2021, 04:25 PM by Hedd_Jones.)
Some will chuckle at this, but Ive seen it done. Reports were that it worked fine.
This was on a post war side valve Fordson tractor. An engine built up from a number of others, and used exclusively for ploughing matches. So an engine which was not molly coddled. It had a similar issue with regularly blowing head gaskets because of the poor top surface of the block. Fordsons use head bolts, not studs. But a number were helicolied when built up from the bits.
Take all your valves out, bung up the threaded holes.
Plaster the top of the block in belzona. Thin layer.
Put rags in the bores.
Use a surface plate or piece of glass with some emery cloth to take as much of the belzona off as possible, but still leaving you with a flat face. Essentially the ideal is you fill all your pits with belzona, but have none on the rest.
There will a hell of a lot of clean up.
Glue the studs in with loctite. Don't be mean with it.
Put the valves back in.
Lap the head onto something flat. You can do the same with belzona if neccassary.
Fit head gasket with your choice of goo. But not dry.
My mate reported no more problems, but when he did eventually take the head off, the belzona in the combustion chamber was long gone.
Hi thanks for input guys
I will strip her down in a couple of weeks when the season ends and have a good examination of the head and block and look for cracks maybe with dye penetration, and if the block needs attention I will take the engine out and see what fixes are available to me, skimmed block = Gasket issues ?
replacement block with new liners ( by the way the pistons are standard so I guess it has been lined at some point) = new pistons /rings
or stitch weld any cracks ? = possibly cheaper to replace the block
or I might bodge it with Liquid Metal!
the joys of vintage motoring !
Mike
I suspect many touring engines are running round happily with one or two hairline cracks from that centre stud, it's quite common. The liners stop them propagating any further. In themselves they don't necessarily cause gasket leakage/failure as long as you can still torque the centre head nut adequately.
The "water past the stud thread" effect is exacerbated by the use of helicoils. Austins used fairly tight fitting studs, possibly with some sort of assembly sealant ? but who knows. The aftermarket studs I have encountered have sometimes had ragged threads and don't seem to have been made to tight tolerances, so this doesn't help. I have had success sealing threads with a PTFE loaded paste compound made by loctite. If you use normal threadlocker it may cause problems with the helicoil if you ever have to remove it. Again, this leakage isn't necessarily going to upset the gasket, it is not under any appreciable pressure.
In your case I think the gasket trouble is more likely to be related to the pitting/scoring or a low point where someone has been a bit too vigorous with the emery/scraper/chisel in the past. A light skim of the block (and maybe the head as well) may be the best way forward. Unfortunately this means removing all the studs and is an engine out job. If you have an HC head, watch out for insufficient piston to head clearance at TDC after block skimming, and if necessary put a shim plate or thicker base gasket between crankcase and block.
For a quick fix, maybe metal loaded epoxy like JB weld applied to a localised area and then carefully ground flat would work.
