Any good products to fill hole in cylinder head and retap it

[rumpelstiltskin]

Pals made abit of a mess of his cylinder head,a bit of a bolt snapped off and he tried to drill it out and now he has an oval hole!Are there any good products that can be smeared in the hole that will harden fully,,then be drilled,and then retapped?

[B19GRR]

Hmmm, depends what's bolted in to that hole. If it's something that's not under any stress then I'd go with JB Weld. If it's something more critical then I'd be off to the local engine builder to have them fit a helicoil type thing.

Cheers,
Rob

[rumpelstiltskin]

Should have mentioned that,its just to hold a small,light,plastic water outlet at the front of the head.

[GreenV8S]

Drill out and retap a couple of sizes up?

[rumpelstiltskin]

I cant retap bigger as the plastic water outlet that bolts onto the head has two mounting holes that wouldn't allow bigger bolts to be used,hence i thought refilling hole and redrilling,tapping to original bolt size.I'll try JB and see how i get on,cheers!

[GreenV8S]

If you're going to do that, you might consider glueing a stud in permanently rather than tapping a hole to take a bolt.

[steve-v8s]

JB Weld do two products, strong and very strong. Suggest you need the stuff that takes longer to set.

[Boosted LS1]

Can you get a metal plug made with an outside thread and screw that into the hole. Obviously the hole will have to be machined circular and have a thread cut. Then you would drill and tap the plug and fit a stud. This means removing the head but it would be a permanant repair.

Or, as suggested by Greenv8s, us a stud because the loads are spread better then if using a bolt.

Boosted.

[GreenV8S]

Think Automotive supply a variety of plugs and thread adapters that might come in handy if you decide to take that approach.

[catso]

May be able to fill the hole with weld, then redrill/tap in the correct size?

[steve_D]

To keep the threads the same size and pitch you could try a helicoil but it sounds like the hole is already larger the one thread size up on the original.
If so then you could try a Keensert. These have larger outside threads than a helicoil and do not require any special tooling to fit. You drill and tap the larger hole and screw it in. You then hammer home the pins in the side of the Keensert. See this picture Figure 21 which should make sense of it. I would also fit it with loctite for good measure.

Steve

>> Edited by steve_D on Wednesday 26th April 22:39

[rumpelstiltskin]

Well i've gone the JB weld route first and that failed dismally!Stuck two studs in the holes with this stuff,it 'seemed' to go hard but when the nut started tightening the stud started turning too??4,500 lbs of pressure my arse,looks like i'll have to try another of your options,thanks guys!