Author Topic: Piston Damage  (Read 1707 times)

February 15, 2018, 03:54:37 pm

Ruby Doom

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Piston Damage
« on: February 15, 2018, 03:54:37 pm »
I'm thinking this isn't so bad, only this piston seems marked, it might leak a little compression, but I think it'll run.




Reply #1February 15, 2018, 04:04:20 pm

libbydiesel

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Re: Piston Damage
« Reply #1 on: February 15, 2018, 04:04:20 pm »
That has severely hammered the valve.  It looks like there might be a valve imprint in the piston next to it, but it's hard to see in the background pic.  Post a pic of each piston.  Replace every valve that contacted a piston.  The contact weakens the valve stems and valve heads tend to fall off down the road a bit and completely destroy the engine.  Usually the rod doesn't get bent, but I'd double-check piston protrusion and see if that piston is significantly lower than the others.   

Reply #2February 15, 2018, 04:17:18 pm

Ruby Doom

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Re: Piston Damage
« Reply #2 on: February 15, 2018, 04:17:18 pm »
Oh yeah, the head is off, and that valve is being replaced for sure, I just meant the short block itself should be usable. When I bought this I knew I was taking a chance on the whole thing being an anchor.

No the other pistons are fine, the lighting is just real bad in the back of my garage with an inspection lamp. And I didn't drain all the fluid out because I fear the thermostat elbow.

Reply #3February 15, 2018, 05:19:41 pm

libbydiesel

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Re: Piston Damage
« Reply #3 on: February 15, 2018, 05:19:41 pm »
That isn't just a single valve/piston tap.  Those hammered together for a long time to displace that much piston metal.  It is very uncommon to see a single valve/piston hammer each other to that extent without some other factor, e.g. valve adjustment totally out of whack, valve stem stretching.  Definitely inspect lifter as well. 

I'm not sure what you feared from the thermostat elbow.  They are not expensive to replace and even if the bolts snap, that just means water pump replacement was past due and is also very easy to replace when the timing belt is off.  I always pull that flange to dump the coolant before pulling the head.  If you don't, then it dumps some of the extra coolant into the cylinders and you risk rust on cylinder walls or on the crank journals.  Probably not an issue if your coolant is less than 2 years old and the buffers aren't used up but still not a risk I like to take.

Reply #4February 15, 2018, 07:46:39 pm

Ruby Doom

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Re: Piston Damage
« Reply #4 on: February 15, 2018, 07:46:39 pm »
Well the vehicle is new to me. Bought it knowing the timing belt had snapped, and would need at least the head done.

You think that valve failed causing the belt to snap, rather than the other way around? All the other valves and pistons have a smooth covering of carbon, like you'd expect, I can't see any signs of contact, though admittedly I was focused on getting the head off before the weather turned.

Only that one valve looked clean, it was very distinct.

I had awful luck changing thermostats on different VW diesel vehicles, sheared the bolt twice, tried EZ-outs etc. didn't want to do the pump, hindsight maybe should have, couldn't get it to seal right after changing etc.

 

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