Diesel Struggles Under Load

[strqaightv8]

Originally Posted by a64pilot

Looking at the new picture, it could be just a heavy carbon layer.

Does it scrape off? Don't scratch the head, but see if it just scrapes off.

It appears to be a combination of both, some light scraping definitely removed a bunch of carbon and helped even it out, but it still looks pretty bad. I'm also not bearing down on it too much, I'll let the pros handle that


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[Hard Rock Candy]

The whole depression is called the combustion chamber. The head is cast Iron I would gamble and it will not scratch easy. You could clean it with a power wire brush. I personally would take it to an automotive machine shop and have it cleaned and the valves reground and seated. Diesels, because of their very high compression and high temperature burn need to have very well fitting valves to remove the heat when they are closed. You also have trouble seeing any damage by water when the head has so much built up carbon on it. Usually as mentioned before, the steam would have cleaned the compression chamber very well, In the leaking cylinder. Mac

[a64pilot]

what do the bores look like, do they all still have the cross hatch? Is there enough of a ridge at the top where the rings stop to catch your fingernail? See to me, that looks an awful lot like excessive carbon build up and one source of that is oil

[a64pilot]

There may be no depression at all, I know the John Deere Diesel I have on my backhoe, the combustion chamber is actually in the pistons, the head is flat with valves mounted in it. Like this
https://www.deere.com/en_US/parts/pa...s/pistons.page

[strqaightv8]

The head is flat, but the piston sure doesn't look like that, it's mostly flat with two small divots for the valves. Didn't get a chance to look at the block anymore

Took it to the head shop yesterday, they cleaned it up a little bit, it's severe pitting on the head, valve seat, and even in the exhaust port behind the valve. Basically, no good. The professional opinion was go buy another one. Haven't had any luck searching so far.

He also said it looked like the water was coming in from somewhere other than the head gasket. Only other place is a leak inside my exhaust manifold. I need to take it apart and look, but if that's shot as well I might be looking at a complete swap


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[a64pilot]

That Sux, what is the base motor? Maybe it's a common one and you'll get lucky.
Your an indirect injection motor which means you have a chamber in the side of your head the fuel is injected into and its the majority of the combustion chamber is why it seems you have no volume in the head when the piston is at TDC.
Before I condemned the engine if you can't find where the water is coming from I'd make sure the head isn't cracked, although that should only be fresh water and I assume you weren't losing coolant?

[strqaightv8]

It's a Mitsubishi k3d, tons of complete motors but not a plethora of parts available. The indirect injection makes sense, I was wondering about that

I was losing coolant, but it was a new issue where it was leaking from somewhere around the exhaust manifold/head junction

I'm planning on taking the exhaust manifold apart to see if it's leaking internally


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[HappyMdRSailor]

Well this is a complete bummer....

So... did your diesel guy say it was toast=unrepairable if you can't locate another head??? I'd think that the recess for the valve is your main concern... I've seen welding and machining miracles performed on heads that weren't even worthy of a dingy anchor...

[strqaightv8]

His answer was the only way he would recommend performing the work is if I absolutely had to have that motor and I couldn't locate another head globally, and then I would have to sign something saying I understand all the work has only a 50% shot of working.

The whole recessed valve area is damn near gone, he thinks removing any more would take away too much meat

Although I have heard there's almost no such thing as an unworkable head


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[HappyMdRSailor]

Originally Posted by strqaightv8

His answer was the only way he would recommend performing the work is if I absolutely had to have that motor and I couldn't locate another head globally, and then I would have to sign something saying I understand all the work has only a 50% shot of working.

The whole recessed valve area is damn near gone, he thinks removing any more would take away too much meat

Although I have heard there's almost no such thing as an unworkable head


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Well .... I think that's your answer then... I get the impression your diesel guy is pretty sharp, and pretty stand up...

To me, it seems like there's balance point where it might not make sense to buy a head for $500 + $500 in parts + all the labor to put it together...

That being said, investigate whole used motor swaps, and if the marine head is any different... I see that there's a few around for $1500ish...

[strqaightv8]

Originally Posted by HappyMdRSailor

Well .... I think that's your answer then... I get the impression your diesel guy is pretty sharp, and pretty stand up...

To me, it seems like there's balance point where it might not make sense to buy a head for $500 + $500 in parts + all the labor to put it together...

That being said, investigate whole used motor swaps, and if the marine head is any different... I see that there's a few around for $1500ish...

At this point I'm waiting to see about the exhaust manifold, that's a westerbeke only part and pretty damn expensive. If it's only the head it gets a little better, as far as I can tell there's no difference between marine or not.

I'd much rather spend 2k on a rebuilt than $1500 on parts, considering how bad of shape everything else was in who knows what the bottom end looks like


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[a64pilot]

If you can R&R the thing yourself and get a "fresh" overhaul for 2K, then I think you have your answer, I didn't think you could get one that cheap.

[strqaightv8]

It takes some looking, but living in the yachting capital of the world helps too


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[strqaightv8]

I may have jumped the gun on a 2k motor, I was looking at a standard Mitsubishi block, non-marinized....


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[strqaightv8]

Alright guys, back in business. Took the head for a second opinion yesterday, that guy couldn't do it but directed me to a race car engine building shop, long story short, so long as it's not cracked I'm all set.

Which means I'm back to the exhaust manifold and cleaning everything else up. Moving forward!


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