I have the head off my 2GM20F and in the head-shop for servicing.

Manifold and heat-exchanger are off. Right now, there are no issues with the manifold and heat exchanger. I could pull them apart and clean them up..... but do I want to?

What is the panel's opinion on this please? If the heat exchanger gets damaged by pulling it apart, which is obviously an occupational hazard, it is going to be incredibly expensive to replace.

I pulled the heater changer off 18 months ago, the core was stuck in the manifold, multiple studs had snapped off, one of the bronze end caps was bent and cracked. I thought it was cooked.

The little engineering shop I took it to soaked it for days trying to free it up, he was worried about breaking it trying to remove the core. In the end I just said just force if it breaks it breaks, the 20 ton shop press did the job.
It came out, I sourced a second hand end cap and the engineering shop repaired the snapped studs. Finally a bit of jb weld to fill some pitting and sealant and new o rings and its been good so far. I intend to do a full coolant system service again we we get home in spring.

IMO the longer you leave it the worse it will be.

What is the panel's opinion on this please?

Pull the end caps off, at least.

gary

the heat exchanger is a regular service item, issues of constriction from debris from broken pump impellers & calcium build up are part of routine service. Also the anode should be replaced regularly. Orings & other bits are cheap from bearing service or engineering shops, get a few to have on hand if you have an issue in an inconvenient place you should have basic parts on hand. Clean the threads with a wire brush & maybe some anti seize before reassembly and you will be doing future you a favour

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woko said..

That's the boy!

Cam scared me with the 20 ton press story.

OK gents thank you. One of my crew is going to have a crack at it for me. Hopefully "crack" is not the operative word.

Where do you get the gaskets from (#14 in Woko's picture). 50 bucks each on ebay....

Hi Jon.
RE: 50 bucks each on ebay....


Recently I was in my local bolts and bits parts shop here in Japan.
A guy pulled up in a van with Yanmar painted on the side.
He had a pair of Yanmar overalls on.
He walked up to the counter to pick up some o rings and vee belts.
Paid a few dollars (yen actually) and walked out with a smile on his face.

I suggest you take your o rings to a parts shop, lay them on the counter and let the staff handle it.
Even Supercheap could be a winner.

gary

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garymalmgren said..
Hi Jon.
RE: 50 bucks each on ebay....


Recently I was in my local bolts and bits parts shop here in Japan.
A guy pulled up in a van with Yanmar painted on the side.
He had a pair of Yanmar overalls on.
He walked up to the counter to pick up some o rings and vee belts.
Paid a few dollars (yen actually) and walked out with a smile on his face.

I suggest you take your o rings to a parts shop, lay them on the counter and let the staff handle it.
Even Supercheap could be a winner.

gary

That's gold Gary! There are plenty of parts places in Dandenong, I'll hunt around when we get it apart.

Bearing supplies, engineering shops, tractor parts. Lots of options. It maybe necessary to purchase 1 of the brand items so it can be accurately measured. It's good to keep a record of oring sizes to make reordering easy, and a template of an original gasket to assist with cutting your own. Likewise you can tap a thread ( or grind & jam) on the correct diameter zinc rod to make pencil type anodes. It might seem a bit tight arse but its also it a bit of self reliance. A long tow home because an impeller went through your heat exchange and blocked it, and you didn't have spares on hand would to me be embarrassing, though others may enjoy the adventure

Interestingly.,,The o rings for my 3ym's heat exchanger where not a generic size.

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woko said..
a long tow home because an impeller went through your heat exchange and blocked it, and you didn't have spares on hand would to me be embarrassing, though others may enjoy the adventure

This is exactly why I'm trying to do as much of this myself as I can.

Whilst cleaning it for the first time in years is scary you make a solid argument for knowing that I can pull it apart at sea in a jam, so better to do it now to make it easy on future.

OK you lot are bloody great. My mate pulled it apart (came apart fine!) and it was full of seagrass.

So that explains what f****d the water pump.

Grass should never get through your filter!

Heads off, water pump f***, sounds like you may have overheated the little motor ? You have two cooling systems there one to cool the coolant ie raw water pump & heat exchange, the other will be engine coolant ( probably glycol) that is cooled by the heat exchange &circulated through the engine cooling journals by a coolant pump. IMHO it's worth the effort to clean the coolant system ( glycol or whatever) with a purpose made cleaner, and replace the coolant pump & hoses and clamps. Then you can be comfortable in the knowledge it's all good. How do the cylinder bores look ?

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woko said..
Heads off, water pump f***, sounds like you may have overheated the little motor ? You have two cooling systems there one to cool the coolant ie raw water pump & heat exchange, the other will be engine coolant ( probably glycol) that is cooled by the heat exchange &circulated through the engine cooling journals by a coolant pump. IMHO it's worth the effort to clean the coolant system ( glycol or whatever) with a purpose made cleaner, and replace the coolant pump & hoses and clamps. Then you can be comfortable in the knowledge it's all good. How do the cylinder bores look ?

Not quite. The raw water pump never stopped working but no doubt it was working too hard hence the blown seal and leakage. The reason it's f****d is because the shaft is scored so an aftermarket pump is the same price as a rebuild kit with a shaft from the USA which looks like the only place I can get one.

Head's off because of poor starting. Head guy came back to me today. Need a couple of exhaust valves - they're worn. Suspect one of them was leaking oil back into the cylinder while the motor was stopped which is why she was running fine once she'd burned it off.

Bores are good, no scoring etc.

Anyway your point about pulling it apart was well received, Had I not done so (or at least, had my crew not done it) I would have put the clogged heat exchanger back on the boat. And now I know I can pull it apart on the boat, in a pinch.

OK team....

I would like to avoid pulling the starter. Can I take advantage of the head being off to see when the pistons are at the top, mark both spots on a belt (bit of white paint or the like?) in order to identify TDC so when I put it back together I know where to gap the valves?

Cheers,

Jon

Re; mark both spots on a belt (bit of white paint or the like?) in order to identify TDC so when I put it back together I know where to gap the valves?

Sorry Jon. This is not going to work.
Every time you start, rev or stop the engine the belt will slip fractionally.
Over a (very short ) time these tiny slips will mean your TDC marks will be way off.

Try to look at making removing your starter motor easier.

That is easy for me to say!!

gary

Well you could, but you will have to be able to identity if it's the top of the combustion stroke or top of the exhaust stroke, the push rod lifters should give you a hint, but why not undo a couple more bolts take the starter off clean & inspect it while you're on the job ?

I'll take that as a "no" then.. Thank you gentlemen.