Yanmar 1500 head gasket

[HGM]

I'm always learning....
the block has 6 stud bolts....so there's not any head bolts, just the nuts to pull the head down. i don't know how to get the studs out of the block and really didn't want snap one or do any damage. i think there is plenty of thread for torqueing the head down. should i be doing anything different??

The machine shop called and said they had to take .010 off to get the head straight. he said thats a lot for such a small head??
I'm learning a lot.....i have wrenched on a lot of things but, this is my first time playing a "Yanmar mechanic".


Thank's again to all the help.
Dave

Cool, I think at this point(with studs) the head "bolts" are irrelevant.. I learned something too.. Never had the head off of my YM2000..

Can't help but notice, that's an Australian web site, inhabited by the same folks that inhabit S. Africa.

Yea, I'm in the Austrailian portion of Georgia ...You caught me... .. It just happened to be the first sight I saw that backed up my babble, never really looked at it myself other than to make sure it was talking about the same stuff..

as old as these motors are he may want to see what the cost would just to replace these bolts. When I would go through my race engine I would order a new set of head ,rod, & main bolts. AS much compression as these engins produce,It may not b a bad idea to replace them while he's there.
(Just an idea)

Thats kind of where I was going too, not really believing they were tq to yeild, but questioning the stretch factor..

 

[kenmac]

DR M Did the guy at the machine shop say that you should check valve to piston or piston to head clearence ? I don't know if taking that much off would make any difference or not with these engines. It wouldn't hurt to ask someone that knows .( just a suggestion) It should make a little more difference in compression

 

[bruce1966us]

Geez, at the most .007 should smooth the head to acceptable standards.

 

[kenmac]

That's why I said check with someone that knows . I don't know how close the machine specs are on these engines & didn't want him to break anything . I know, I use to have .30-.40 taken off auto engine heads with out any problems.

 

[HGM]

That's why I said check with someone that knows . I don't know how close the machine specs are on these engines & didn't want him to break anything . I know, I use to have .30-.40 taken off auto engine heads with out any problems.

I agree, International(for example) recomends that if any machine work is needed, you should replace the head..Now, that is from a waranty point of veiw.. But if they dont feel comfortable guarantying the head if its cut, I would seccond guess it myself... A diesel engines combustion chamber is designed to be a certain shape and size.. The valve protrusion may change enough to make a difference, maybe an inherant knock that you cant do anything with, a hard start that eats starters, or maybe smoke and lack of power because of a different characteristic of the chamber.... These things seem to be a little exadurated to me even though I am presenting them for thought, but I really dont know for sure... I would definitly ask someone who has done this type of work on these engines, the machine shop doing the work will certainly say its good.. Just my $.02, hate to create problems..

 

[mark777]

I'd like to add that repositioning or shimming the head to the original height would be critical.

Even when the resurfaced head is flat the .010" will dramatically change the valve travel. Now you're faced with grinding the valve stems (top) to shorten the overall length by the same .010". or the valves will hit the piston tops. You would think that doing this would solve the travel distance problem, but it did NOT. The machined chamfer, that holds the stem retainers (keepers) remains at the stock height and original travel.

A not so simple, but ingenious method, was to fully assemble the head, spray Dykem bluing on the piston tops, add the stock head gasket and torque at mid point (approx 45 ft lbs). The engine was rotated by hand with a dial indicator contacting the rocker arm pocket end and each valve showed reverse travel by nearly .004". The head was removed and 'sure enough' four fingernail sized crescent moons were imprinted on the Dykem indicating the valves touching during the compression and exhaust cycles....I'm pretty sure that if the head had been fully torqued and the engine fired up it could have been disastrous.

We ran into this problem with one of the odd YM models where parts were very difficult to acquire...and the owner took his tractor home and finally had an oversized (laser cut I think?) copper head gasket made (for his YM2200).

Wish I could take credit for what transpired during that test....but I was more the tool holder and observer. And I'm doing this from memory so I hope I haven't omitted any steps...

Mark

 

[normde2001]

You might consider doubling up on the head gasket, assuming a thicker one is not available. It's been done, but I'm not sure how sucessfully in the long run. I would try it the normal way first, however. It's hard to believe any stock engine only has .010 valve to piston clearance.

 

[kenmac]

They do offer thicker gaskets for autos . Don't know about tractors. Most head gaskets have a steel ring where the cylender holes are .Don't know how well these 2 gasket surfaces would match up as far as sealing without blowing under that much pressure.

 

[Dr M]

Thank you guys,
these are some good points, i don't think i would have thought of some of those.
i called the machine shop, they milled the head .010 and in turn cut the valve seats and re seated the valves to .010 also. the shop mrg said i shouldn't have any problem, but i will still turn by hand and check before torqueing.

i should have the head and all of the parts in on Thursday. i will give it a go again.

Thanks for all of your help. I will keep you posted on the out come.

Sincerely,
Dave

 

[kenmac]

sounds good. Do you know the max clearence that you should have between the piston & valve ? If you bring the piston all the way up push ( the valve springs will have to be off to do this )down on the exhaust valve & take a measurement with feeler gauge. Is iT within specs without hitting piston? (usually need a little more room than spec)Now same with intake. If it's like autos the intake could be in specs & not hit piston ,where the exhaust may hit piston. Usually the exhaust valve opens more that the intake valve.
I may be telling you something you already know .
GOOD LUCK!!!