Yanmar 1GM 10 head repair

[Sailing steve]

Well the inevitable has happened after I changed a leaky Yanmar exhaust elbow a while back - there's now a pea sized hole corroded through the exhaust port into the adjacent oil gallery.

I know cast iron is a tricky material to work with heat-wise but anybody had any success or go to recommendations for either welded or bored and sleeved repair on this notorious piece of top quality design rather than forking out an astonishing amount of beer tokens for a new head?

 

[lexi]

There is a video on YT from a guy called Doubleboost sleeving a 1gm head and brazing it. He has a workshop and a fair bit of savvy. That's what I would be doing and keeping my £850 for other pleasures.

 

[Sailing steve]

There is a video on YT from a guy called Doubleboost sleeving a 1gm head and brazing it. He has a workshop and a fair bit of savvy. That's what I would be doing and keeping my £850 for other pleasures.

The bit I haven't got is a workshop like Doubleboost's. and if my metalwork is anything like my carpentry then even if I had all the gear I'll be reducing an awful lot of raw materials to swarf in the attempt.

I'm told the hole could possibly be brazed up and I've just got a quote from a toolshop for doing pretty much the same boring and sleeving job on the head for around £500. No guarantee it'll work mind, and if it doesn't then that's £500 down the pan as well as a potential opportunity to get acquainted with my local RNLI crew too...

 

[vyv_cox]

I had an automotive cylinder head welded by a company in Aberdeen known as The Headshop. More than 40 years ago so they very possibly no longer exist. Welding was carried out at a temperature above the austenitic temperature (730C).

 

[rotrax]

Lots of options, including a DIY one.

In 1981 a Welsh Nuclear Physicist called Peter, a racing friend and near neighbour offered me a racing motorbike. It was a Drixton Aermachi fitted with an ex works GP 350cc engine with many unique parts fitted.

"There it is boyo-you fix it, you can ride it. Bill me for any big stuff!"

I fixed it, rode it for 3 years without any failures on the track. He never got a bill.

The engine had been fitted with a 42mm Del Orto downdraught carb, the size one would expect on a 500cc race bike. To accomodate this oversized instrument the inlet port had had serious enlargement. The 'enlarger' had #ucked up big time, breaking through into the valve spring area of the aluminium cylinder head.

I cleaned it all thoroughly and used Belzona metal repair two pack to make a long lasting repair. AFAIK it is still in place.

In 3 years hard racing it never failed. Many two pack metal repair options are on the market these days, and for not much money.

Give it a whirl, it worked for me. Ensure it goes through the hole and is flattened both sides to 'key' it in place.

Good luck.

PS - Cleaning VERY well and roughing/centre dotting the area for extra grip is a good idea.

 

[lexi]

Would not pay £ 500 to get it welded. Someone is making sucking noises through their teeth with that price. You could ask Doubleboost if he would do it. He has a garage and is on Migwelding uk forum. Somebody on there might repair it for you. If Belzona is a two pack polyester, I don't think I would use it. If it is Epoxy, then it wont take the heat. I once tried Chemical Metal on an exhaust flange and it broke up. you don't want any debris where valves are opening should it fail.

 

[Poignard]

Perhaps you make the hole circular, then taper it very slightly before driving in a plug made from a piece of steel rod with a matching taper.

Then silver solder the plug in place.

For the silver solder to 'take' the plug must fit tightly and the mating faces spotlessly clean.

Finally grind off the protruding parts of the plug.

 

[rotrax]

Would not pay £ 500 to get it welded. Someone is making sucking noises through their teeth with that price. You could ask Doubleboost if he would do it. He has a garage and is on Migwelding uk forum. Somebody on there might repair it for you. If Belzona is a two pack polyester, I don't think I would use it. If it is Epoxy, then it wont take the heat. I once tried Chemical Metal on an exhaust flange and it broke up. you don't want any debris where valves are opening should it fail.

I have repaired exhaust port threads on air cooled motorbikes with Belzona metal, as well as the cylinder head on a successful racing motorbike.

Heat was not a problem.

Belzona was, perhaps still is, a very expensive product. It was used at the AP Automatic gearbox factory to seal porous sand cast casings. AP Automatic gearboxes got bloody hot too! And, very full of high pressure thin oil.