Buying Advice YM1110D (2T72) Head - need advice!

gbirky · Mar 27, 2003

OK all you diesel mechanics and experts...
I pulled the head off of a YM1110D (2T72 engine) because it was running poorly. I expected a leaking exhaust valve on one cylinder. I wasn't prepared for what I found. It looks like the cylinder head rusted badly inside the no 1 cylinder. I haven't removed the valves yet, but I took a digital photo of the cylinder head. I attached a small version here, but here is a link to the page on my website with the larger version.

Please take a look at the photo and give me your opinions and advice. What could have caused this damage? Do I need to replace the head? If I get the valves to seal, is there any reason to believe that the head wouldn't work OK?

Any advice is welcomed!

normde2001 · Mar 27, 2003

Is that actually pitting that we see, or just heavily carbonized?

gbirky · Mar 27, 2003

That is actually pitting - or material removed by oxidation. The surface looks like it is heavily rusted.

normde2001 · Mar 27, 2003

Had to be water getting in there, (head gasket, head or block crack). I'm no expert, but I believe I would check it over closely for cracks, clean up, valve job, head gasket, maybe shave head, good to go. For sure let a machine shop handle the head. That may be the cavitation, (pitting), caused by the wrong type of antifreeze that I have heard about on these forums.

EFC · Mar 27, 2003

The guys are right, it is water that ran down the open exhaust pipe and entered the cylinders through the valves. The exhaust valve seat will be bad. That is also caused by sitting for long periods of time without running and condensation builds up. It is a very normal problem with 4 cyl Mitsubishi heads. Have the head shop do new valves and seats and your good to go.

gbirky · Mar 27, 2003

The cavitation from the wrong antifreeze happens on the coolant side of the cylinder sleeves. There is no evidence that the head is cracked - no oil in coolant, no coolant in oil, no overheating, no mysteriously disappearing antifreeze, and no bubbles in the antifreeze. The gasket surfaces on the head and block look very clean and nice. The other cylinder is very clean and shows none of the pitting.

The only thing I can think of is if the engine sat with the exhaust valve open to that cylinder for a long time, and got moisture in the cylinder. Then the head rusted - but the sleeve looks good with some minor imperfections down low in the bore. I suppose its possible that the coolant was leaking into the cylinder, but in that case I would have expected bubbles and overpressure on the coolant side - which I didn't see.

Anybody else with ideas???

gbirky · Mar 27, 2003

Buck,
Thanks - you must have posted just as I was posting my last one. On these heads, the valve seat is just the head material - there is no insert. If I replace the valves - that means new guides as well doesn't it? I just need to know what parts to get.

Greg

normde2001 · Mar 27, 2003

I like Buck's explanation. Looks like you just need to rework the head and put it back together.

EFC · Mar 27, 2003

The head shop will cut out the old seat and plug it with a new one then grind. You will need a new valve but every time I have had it done they just turn an oversized one to fit and hand it back to me like it is the easiest thing to do in the world. The last Mitsu head I did needed to new valve seats and new valves and it cost around 150.00 to get it done and put together.

kayssupply · Mar 28, 2003

I had a YM 1700 head that looked worse than that and had a crack between the valves. I sent it to a head shop that welded it and filled in the pitts and then remachined it. They said if you didn't do that the compression would be different between the cylinders. They also put the hardened seats in like Buck said. It's still working hard as far as I know.