cylinder head removal yanmar 3HM35

[BOBBIN]

I think I have a leaking cylinder head gasket ( white smoke from exhaust).
Unable to find a local mechanic who fills me with any confidence I am going to remove the cylinder head to have a look and replace gasket if there is nothing any more seriously wrong with the head.
I have never done this before and would welcome informative and supportive comments from anyone who has undertaken this themselves, especially anyone with particular experience of Yanmar 3HM35's.
Thanks in advance. <span style="color:blue"> </span>

 

[greatspirit]

suggest accurate diagnosis first; do you mean steam from exhaust? water vapour in the exhaust is normal and more noticeable if the humidity is high; is the engine otherwise ok? do you have a fresh water/heat exchanger or raw sea water cooling system? if the former then is there coolant loss? also if the head gasket is leaking there will be exhaust gases in the coolant (this can be tested for their presence); is the engine overheating?; are cylinder compressions equal?
regards, Tim

 

[BOBBIN]

Tried everything, fuel system,raw water system, exhaust system. Definitely steam no oil/fuel in exhaust, no water in oil.

 

[ShipsWoofy]

I don't know that engine, is it raw water cooled or fresh, if the latter then are you losing freshwater level. If not then it is unlikely to be the head gasket. But I do not know the engine. Is it ally or cast iron?

When you say you have never done this job before, do you mean on that particular engine, diesels or any engine.

The problem with diesels and head removal is the extreme tolerances and putting it all back in the right place. I have done all sorts of work on petrol heads, even boring out my ol' ezzy head.

But, I lost my bottle when my Citroen diesel blew the head gasket, actually a hairline crack in the head as it was found. With a petrol you just scrape off the old gasket material with a chisel, any accidental cuts into the metal are wet and dried away.

You can't do this with a diesel and damage means you have to have the head re-worked, a thou of an inch off the head means also lifting the valves by a thou and the combustion chamber etc.

Would I do mine now, I might have a go, but, if I could not remove and polish the gasket I might send it to a workshop for that part of the job. I realise the difference between putt putts and car diesels, hence I would probably have a go at it myself, but I would be extremely careful.

Also, ensure you lock the crank and cam before removing the belt, getting this wrong on a diesel does not just mean ropey performance, it can often finish off the engine. When you have it all back together, ensure no clunking be slowly turning the engine by hand with the injector out.

There is no reason you can't do this job, but it would definitely pay to read up on the job first and buy a workshop manual too.

 

[ShipsWoofy]

Also

When the head gasket went on my Citroen it pressurised the water jacket and actually blew the water out of the radiator cap. To get through the pressures of a diesel the water would have to enter the exhaust at a very low pressure point, not sounding like the head to me, but that is only from my limited experience.

Did you check how much water is coming out, the more I think about it the more I think you are probably running too hot. Try removing the thermostat and see what happens. Maybe a good flush will sort your problems, if it is raw water cooled they are known to get clogged when bit of corrosion shift about.

 

[BOBBIN]

Tried everything, fuel system,raw water system, exhaust system. Definitely steam no oil/fuel in exhaust, no water in oil.

Its a raw water system, a cast lump both block and head. Did a petrol engine 30 years ago and have a manual. Am prepared to 'have a go' as so called mechanics charges are prohibitive.