hh100 head warp

thanks Smalljob, At my work I have the ability to get this head machined. it is hard to find real info about this. So far what I measured is. Both valves are .075 above the block deck. There is at most .005 piston pop up, above block deck. The head is just shy of 3/8th thick through out the whole combustion chamber.

The first one I had done I too was concerned even though my machine shop was not. So to ease my concerns , I developed a habit of always laying the milled head back on the block without the head gasket and turn the engine over by had to ensure that neither the piston note the valves are making contact. If no problem I "assume" that adding the head gasket gets me that much more clearance. So far so good.

Well I have an update. I pulled head and brought it to work. Cleaned it up and placed it on the granite surface. Right away I could tell it was not flat. I was optimistic that resurfacing would get me up and running again. Unfortunately it only had to take .006 to make it true. I was a little disappointed thinking .006 would have been taken up in head gasket crush. Reassembled it and sure enough it same thing. Cold compression was 110/115ish. Engine never really ran, just sputtered enough to give you hope. Pulled flywheel cover off and now I can see remnants of fuel leaking between head and block on the left side. As it engine warmed up a bit trying to start, compression went down to 60.:banghead3
How likely are these engine blocks to warp? Cast iron block and aluminum head, kind of doesn't make sense. Thoughts?

Mncdriver you shouldn't get more than 60 PSI on a compression test on that engine if the valves are gapped correctly. Those engines had a compression release system that at cranking speed is supposed to bleed compression to make it easier to start the engine. Either the compression release is broken on the cam or as I said the valves are gapped wrong. I think it is the gap that is wrong because the warm 60 PSI number is more correct and that could be because the engine gap is coming back into spec as it heats up. 100 PSI is way to high for a HH100 engine when cranking. Roger

I torqued the head as specified in the manual. Today I rechecked the compression and it is spot on at 60 psi. Do I need a cylinder leak down tester? How come I can see fuel weeping between head and block around #5 and #6 head bolts?
Is there a way I can check to see if the EzEE start system is working correctly?
Thanks for the help.

I have never had a head gasket issue that was not corrected by milling the head, but I guess something could be wrong with the block. Did you lay a metal straight edge down along the block where you are being the problem? I have never seen fuel either, only oil leaking when I have had a head gasket problem.

Was this running OK and then developed a problem, or did you acquire this tractor and you are trying to clean it up?

I acquired the tractor in August from my father. I live in NC, the John Deere tractor lived its life in CT. The tractor did not run when I brought it home. However earlier on in the summer it was working. After a starter solenoid and new Key switch, it cranks over. So here is what I have done so far, new plug, air filter, fuel line, drained and cleaned fuel tank, fresh gas, rebuilt carb. Manual says compression should be 100 - 120psi at 1000 rpm. I got 60psi while cranking???(maybe not enough rpm to over come ezee start?), pulled head and found slightly warped, .006 to make flat, new head gasket, torqued to spec by manual. Now all I have is a non running tractor in really good condition an head ache and frustration meter pegged!!!

Put it back together & tell it to work...lol

Just use a 'big flat mill ******* file' and work the deck till it cleans up somewhat flat, some might remove the valves to pull this off. I would have said the same about the head, but you already had yours cleaned up.

Buy another new head gasket, replace the one that ain't making it. If you don't wanna buy another new gasket, and the one you have is of the 'new type' that is NOT metal clad, those don't have a fire ring like the old type gaskets had...if your real tricky and you have some scrap sheet stainless, ya might make your own fire ring, but ya gotta be real good to make that repair.

The piston sticking up past the deck ".oo5" sounds strange to me, because those old Tecumsehs I use to time the ignitions using a timing dimension off the piston from TDC...I don't think I ever saw one that the piston protruded above the deck...just saying! Except in the valve relief area, on those with the relief, you can see the side of the piston top. (not much, just .030" or so)...but only in the relief area, that relief won't effect the fire ring sealing area of the head gasket.

Just for fun, make sure your bolt lengths, washers/spacers, threads are clean, (oil them if ya want) and the bolt holes, you might chase with a 5/16" course tap.

wwxx

wwxx, thanks for the reply. As I read and "Dream up" a solution. Could the crank case vent be an underlying issue? Maybe building up too much crank case pressure and popping head gasket? IDK?? if I can get cyl leak tester tomorrow I may be able to learn more.
FYI my piston pop out of .005 was a bit primitive. I just bolted what I thought was a 1/2 inch thick, flat piece of aluminum across piston and used a dial indicator, FWIW.

mncdriver said:

My apologies for posting in wrong section:hide:
Thanks for the replies. So can you guys tell me how much you could mill off? Did you have to mill clearances for valves and/or piston? Any idea what the valve to head clearances are? same for piston?
:thanku:

Click to expand...

I think they only mill off enuf to make it flat again.. sometimes that will be a couple thousandths.. sometimes a lil more.. 10 thousandths is nothin to worry about.. the valves will not hit the head.. & the piston only comes up to the top of the bore..

also there is a proper sequence in torquin the head bolts.. this is to b done twice.. once at the rebuild stage.. the second time is after the engine has been run enuf to get it all warm..