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#1
02-14-2004, 09:56 AM
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So what do your pistons and valves look like?
What's 'normal' look like?
We now have the cylinder head apart. We have ordered a micrometer that reads to three decimal places but it hasn't come in yet. So we can't give you any measurements, but since we're novices, we're wondering what these are SUPPOSED to look like, and whether any diagnostics can be done from what you see. History-- This is from a 1981 300TD. The previous owner said it suddenly started smoking badly one day (at around 200k km, or 140k mi), then failed aircare. He had compression testing done, with readings as follows: Cylinder 1- 271 Cylinder 2- 238 Cylinder 3- 294 Cylinder 4- 264 Cylinder 5- 235 Bleck! The owner then sold the car to us, we pulled it and are hoping to put it in to Buttercup. BTW, we expected the car to barely limp home, but it had a lot of power. Anyway, have a look and tell me what you think. I don't think valves one and two are supposed to have that build up, and valve 3 looks wet. Nothing really matches with the compression readings. The cylinder walls look pretty good.
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Natalie 
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#12
02-14-2004, 10:19 AM
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Looks like number three is the one that was smoking just as you suspected. looks more like a valve guide or seal than anything else though.
What does the cylinder look like on the number three cylinder? Also, get an inside micrometer gage to measure the cylinder wall at 90 degree offsets both at the top and bottom of the cylinder to check for out-of-roundness and do this with all the cylinders. Chech for scoring and if you can see the x-hatch then the scoring is likely OK. Otherwise, it could mean stuck or broken rings. Good luck, Adam
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#13
02-14-2004, 11:51 AM
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Ok,,, how about a picture of each of the pistons at the top of the block like one you showed...
This really shows the precombustion chamber holes orientation.. Perhaps a good pic of number three will suggest by the pattern that the some of the holes are clogged...
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#14
02-14-2004, 12:00 PM
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Nat,
I don't know a whole lot about the insides of these diesels but a lot of the gassers I've pulled apart over the years had similar degrees of carbon build-up on pistons and valves. So, this doesn't appear all that strange to me. Did you check the valve adjustment before pulling the head? What kind of smoke was it making? My admittedly uneducated guess is that the valve guides on a couple of those cylinders are bad and you've got a couple of weak cylinders (ring-wise). FWIW, I'd do a valve job and guides too, look at the cylinder walls for obvious signs of a broken ring(s) and, if it looks OK there, slap it back together leaving the bottom-end untouched. Even though the compression is out of spec, you know there are loads of 617s out there with lots worse compression and this one was making plenty of power before. OTOH, you have it out, maybe the thing to do is go ahead and pull the pistons, hone it and replace the rings too. It's not like you have to have this car next week for a trip to the market.
__________________
Never a dull moment at Berry Hill Farm.
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#15
02-14-2004, 12:03 PM
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Did anyone else click on the fact that the most heavily encrusted piston is #1...the one right next to the notorious EGR valve?
Pox on EGR valves!
__________________
Never a dull moment at Berry Hill Farm.
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