Yanmar 1GM10 Cylinder Head Removal...

[Venomgrass]

Evening everyone,
I'm in the process of trying to repair my yanmar 1gm10c engine. The boats sat for 2 years before I purchased.

Symptom:
Sat unused, starts and runs for few min then cuts out.

Speculation:
Back pressure from exhaust elbow, possibly corroded and salt water got into cylinder head? Common problem I think.

Today I removed the cylinder head and exhaust elbow, here are the photographs I took, let me know what you think? Could this be the issue, is it easy to clean or repair, a new cylinder is almost £500+!!!


PIPE FROM EXHAUST ELBOW TO SILENCER


appears to have blistered inside, potentially als soot build up and melted internal pipe maybe causing a restriction.




EXHAUST ELBOW, removed from cylinder head






Corrosion and soot buildup. The seawater input hole looks very corroded and was completely blocked when I first opened it.








CYLINDER HEAD & CYLINDER
Side view


Looking into the engine cylinder below cylinder head






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[RichardS]

There's nothing there that you shouldn't be able to clean / scrape and refurbish. The blocked seawater inlet into the elbow would have tended to cause overheating but I doubt that would have stopped the engine in just a few minutes. The exhaust flow is somewhat restricted which would have affected power output but it's not serious enough to have stopped the engine.

I suspect that you have a problem with fuel flow caused by air leakage into the fuel system or a blocked fuel filter or air filter or tank vent. It might be difficult to pin this down until you clean and re-assemble the engine and get it running again.

Richard

 

[JumbleDuck]

Today I removed the cylinder head and exhaust elbow, here are the photographs I took, let me know what you think? Could this be the issue, is it easy to clean or repair, a new cylinder is almost £500+!!!

It doesn't look too bad. I'd give it a jolly good scrub, then clean out the exhaust port with a decoking brush in an electric drill. When you've got it clean, check carefully for holes between the exhaust port and the pushrod space, and also for cracks in the head: they are notorious for cracking between the exhaust valve seat and the injector hole.

If it's dodgy, bite the bullet and replace. Yanmar heads are around half the price in the US, and though dealers there can't sell to the UK, a 1GM10 head fits easily in hand baggage.

However ... I don't think issues with the head explain

Sat unused, starts and runs for few min then cuts out.

which sounds much more like a fuel problem to me.

 

[jobbie]

Be careful with the de-coke, particularly the exhaust port. I scrapped mine out with a bit too much elbow power and poked a hole thru' to the oil gallery. I changed the elbow for a stainless one from the States. £73.00 inc postage. http://exhaustelbow.com/

I found this article on PBO quite useful.

http://www.pbo.co.uk/expert-advice/replacing-a-yanmar-1gm10-cylinder-head-20467

Cheers, Kim

 

[JumbleDuck]

Be careful with the de-coke, particularly the exhaust port. I scrapped mine out with a bit too much elbow power and poked a hole thru' to the oil gallery.

I'd give it a bit of welly while decoking for just that reason. You won't be able to make holes if it's any good and if it it's any good the best time to find out is while it's on the bench being decoked.

 

[Mel]

I agree that the port looks reasonable and should be cleaned up with rotary brush on your power drill.

Check the elbow by cleaning and then put water hose from domestic supply onto the water inlet and look into the gas side to see if any holes are visible as water jetting into the gas side.

You could remove valves, and clean and grind in. Remove the injector now head is off - replace seals, gaskets on injector after cleaning up.

For comparison of faults --- it can be noted that my 1GM10 ran reasonably with only a small opening in the exhaust port of about quarter inch diameter !

 

[Venomgrass]

Thanks guys, after having the head inspected, the elbow is scrap metal (severe corrosion blocking the water inlet) it needs replaced. The exhaust valve is very coked up on the head, it's soaking in a parts washer then it'll be cleaned. The valve face is slightly corroded. The thermostat is stuck "OPEN" I don't know if this would have contributed to an issue.

Therefore I need to buy replacement parts/gaskets and service kit:
Head gasket and rocker cover gasket
New thermostat not sure if this has a gasket
Exhaust elbow and gasket

Service kit:
Water impeller and gaskets
Alternator belt
Oil/fuel filter
The previous owner removed injector, might need a gasket.

Where do I buy these parts? Do they need to be Yanmar parts, or can I get the sizes/types and buy from somewhere online ? They're so expensive from yanmar dealers.

Thanks

 

[JumbleDuck]

Therefore I need to buy replacement parts/gaskets and service kit:
Head gasket and rocker cover gasket
New thermostat not sure if this has a gasket

Any Yanmar dealer. I use Marine Power.

Exhaust elbow and gasket

Aftermarket elbow from www.exhaustelbow.com. Gasket from Yanmar

Service kit:
Water impeller and gaskets
Alternator belt
Oil/fuel filter

I get these through eBay from a Manx company: http://www.ebay.co.uk/itm/YANMAR-Engine-Service-Kit-1GM-1GM10-Genuine-YEU-SERVKIT-001-/161229166200

The previous owner removed injector, might need a gasket.

O-ring and gasket as a minimum, maybe the heat shield, maybe even the copper gasket and precombustion chamber. Here's what should be in there, taken from p147 of the workshop manual

Have you really carefully checked for cracks?

 

[RichardS]

Try ASAP Supplies for some of the items and search the web for others. It's all out there somewhere so I usually just buy wherever it's cheapest.

Thermostat stuck open would not make the engine stop after a few minutes but would probably make the coking up worse.

Richard

 

[Mel]

Try Keypart.com
I got most of my parts for a top end overhaul from them

 

[Venomgrass]

Damn we found a crack in the cylinder head exhaust valve..... I have such bad luck. Can't afford another £500 for a replacement. Surely cheaper replacing the entire engine!!

 

[RichardS]

Damn we found a crack in the cylinder head exhaust valve..... I have such bad luck. Can't afford another £500 for a replacement. Surely cheaper replacing the entire engine!!

Sorry to hear that Venomgrass.

Depending upon how deep the crack is in the valve seat and how far it extends into the head you might be able to get a new valve seat insert put in. You need to contact a few engine machine shops. It's not a difficult job if they can obtain or fabricate the new insert and might be £50-ish. Its certainly worth a few calls.

Richard

 

[greggron]

If it's the exhaust valve rather than its seat that is cracked then just replace the valve. Can be bought from marine parts

 

[JumbleDuck]

Damn we found a crack in the cylinder head exhaust valve..... I have such bad luck. Can't afford another £500 for a replacement. Surely cheaper replacing the entire engine!!

Very common. When I took my head in for some work at my friendly local machine shop (McKean's in Dumfries) he warned me that the last four 1GM10 heads he had seen had been (a) cracked and (b) scrap. Mine, as it turned out, made five. If you have contacts in the US, the heads are not much more than half the price there, but US dealers can't sell to the UK.

 

[Venomgrass]

 

[Pords]

Just completed overhaul due to cylinder head corroded. Exactly like the pictures shown. Cannot be repaired needs replacing I'm afraid. Along with new elbow as mentioned. Cost with mates rate was a little over £1100 taking into consideration gaskets service parts. Had the injector serviced and bore deglazed and new piston rings. Runs sweet now.

 

[nemodreams]

Just completed overhaul due to cylinder head corroded. Exactly like the pictures shown. Cannot be repaired needs replacing I'm afraid. Along with new elbow as mentioned. Cost with mates rate was a little over £1100 taking into consideration gaskets service parts. Had the injector serviced and bore deglazed and new piston rings. Runs sweet now.

I thought it looked bad !

I have just done a refurb on a 1gm10 head - the wall thickness of the exhaust port at either side is very thin. Its a hole though a square casting basically - the hole is only about 5mm smaller diam - than the width of the casting.

Some info on the precon unit - maybe of use to others.

The drawing shown earlier is wrong ( Yanmar non-updated manual ! ) when they changed to non - asbestos heat proof washers, they added a copper shim penny washer directly under the injector base. This is I think beacause these grafite heat washers stick and break apart when split.
Its showing on the parts database at Rib Marine Parts.

The pic bottom is the pre con parts - they all slide out the injector tube.

The lower unit has a small pin - which slides in the groove . All the rest is free to spin around in the tube - including the injector itself.

Right - copper washer - under lower precon half chamber.
Lower precon chamber ( expensive )
Copper washer between the two precon halves.
Top precon chamber half.
Heat proof washer fits into recess in the top of upper precon half.
THEN - the copper shim washer ( directly under the injector base )

not shown - the O ring,
this is not in the tube - but fits around the shoulder of the injector at the top of the tube - forming a dust/moisture seal at the top of the tube.

As said - precon unit and injector do not come with a new head !

There is more on 1gm10 head reburb on my site.

http://www.lena.geoffrichings.co.uk/sail_site/headoff-13.html

 

[MagicalArmchair]

I don't know if it will be any help to you now, but I tracked down the workshop book for the GM and HM Yanmar engines and posted it here:

http://www.albinballad.co.uk/how-tos/yanmar-2gm20-engine-winterising-and-service/

French Marine have helped me in the past when I have considered that all hope is lost - https://www.frenchmarine.com.

Also there appears to be a full 1GM on ebay at the moment: http://www.ebay.co.uk/itm/Yanmar-1gm-marine-engine-/191721677901 - at least you won't run out of spares any time soon if you go that route?

Good luck!

 

[greggron]

Our hole was a bit smaller but we found a specialist who welded it closed...

 

[jimmcgee]

found this on another forum , first thing I thought

" It is possible to get the head bored out into the exhaust port and then a sleeve inserted. The last person i told this method got a machine shop to do the work for 150 pounds. the sleeve was steel and they used liquid nitrogen to cool it before inserting it."