Can You Run A Cylinder Head That Has Some Pitting?!? - Snowmobile Forum: Your #1 Snowmobile Forum

mwinters · 11-18-2009, 08:40 AM

My 1996 Mach Z 780 needed a top-end rebuild. When I took off the cylinder head, I noticed that the middle combustion chamber has some pitting and also what looked like melted piston on it. The sealing surface is clean obviously with no markings.

I took out the Dremel and lightly sanded down the imperfections and now only have some pitting. It came out really nice and is smooth to the touch, but will this not work?

I dont care if I loose a little performace, I just want to make sure its safe for the engine, and will run right.

Thanks,
Matthew

xcr440 · 11-18-2009, 08:59 AM

mine has some light pitting also, from a piston coming apart. It runs fine. no issues at all.

nothingbutair · 11-18-2009, 09:02 AM

yeah mine was like that on my 400, still running strong, just open it every once in awhile to check it out.

**kccats** · 11-18-2009, 11:37 AM

Chuck it up in a lathe on the spark plug and turn the pits out with sand paper!

mwinters · 11-18-2009, 01:56 PM

Yeah tha'ts what I did, made it nice and smooth. I didn't know if it had to be perfectly flat due to the combustion in that area.

But its sweet to know people are running pitted just as I will be!

I did see that they were cheap on ebay, but I have so much into this overhaul right now I just want it over with.

Thanks!

**kccats** · 11-18-2009, 08:23 PM

The problem is the pitts will cause hot spots and preignition and running it long enough it will melt down!!!!

**smallengineguy** · 11-18-2009, 08:47 PM

If the pits are very small, it should be OK.

mwinters · 11-19-2009, 10:34 AM

Yeah the pits are small, there are many of them but I would say the largest one is no bigger than half the size of a pen tip.

orin250 · 11-19-2009, 10:42 PM

ive seen the heads get pretty dinged up from a ring breaking apart and hammering the crap out of it. the only problem with sanding it smooth is that it will change the compression ratio slightly in the one cylinder then it will not be even. i have put multiple motors back together with dinged up heads and not one of them has had a problem

stangcruzin · 11-20-2009, 08:20 PM

It'll be fine.Make sure there are no fragmented pieces that will come off.

mwinters · 11-21-2009, 09:06 AM

Yeah I'm starting to get the consensus that it will be alright to run. Seems like a pretty common thing. Thanks for the input guys!

dougisnow · 11-23-2009, 01:08 AM

i have some pitting on one piston also, and I think something metal did it :-( not a ton of damage, but even the slight pits can be a prob? not sure what did the pitting, the rings were intact. here's my story: http://www.snowmobileforum.com/engin...case-hill.html
i'd love some advice, and i'll pay $50 an hour to whomever can help me fix this!
thanks!

**RJ Gleason** · 11-23-2009, 09:37 AM

^^^^^^^^^^^^^^^^^^
Smooth it off the best that you can and run it, unless there are real big dings, then replace piston.

dougisnow · 11-23-2009, 02:29 PM

the small pits are definitely from something metal, my guess is a bearing part but not sure which and i can prob sand/dremel the imperfections but need to find out what broke off and did the damage, right? ... i've never opened a bottom case before, or the crank. any suggestions? thx

**RJ Gleason** · 11-23-2009, 04:02 PM

Definitely should check it out, could be wrist pin bearing came apart, or crank bearing.