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This is a 2007 Dodge Caliber 2.0 CRD (which uses a VW Golf 5 TDI engine).

The valves on only 1 piston have come into contact with the piston, causing chaos in that cylinder. The other three are fine.

The engineers who overhauled the head say that the mechanic got the timing wrong because he never used the special tool (it's just a pin with a handle) to set the timing. Actually the guy used an Allen key instead of the tool to keep the timing belt gear in place, so I can't see what difference that would make to the timing.

If it was a timing issue, surely the valves on all cylinders would be affected, wouldn't they?

Is it not more likely to be a fault on the valve itself? A spring, or a material defect, or valve seating or something like that?

Please help, Thanks, Mark,(South Africa)

[![Only one piston was damaged

Only one combustion chamber shows any signs of valves contacting pistons

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  • Commiserations on the damage. This is a very interesting question!
    – Zaid
    Feb 28 '18 at 8:59
  • There is evidence of damage on far left cylinder (above the valve at the 3 oclock position) and on the far right (again above the valve at 3 oclock position). Whatever caused the catastrophic failure in cylinder 3 (from left) may have also been stopped by the failure... if the piston and therefore crankshaft came to a hard stop then no further damage to the head would occur. Also it appears that there is the shape of the valve imprinted in an "OK" piston.
    – Mauro
    Feb 28 '18 at 10:39
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It sounds like your engineers are trying to pass the blame after they've messed up.

The valve(s) in that cylinder look like they have 'fell out' due to either faulty parts or incorrect fitting of the collets.

If the timing was incorrect the valves would not leave the head because the stems would bend and jam the valve into place.

There is also nothing wrong with using a allen key or bolt if the correct tool is just a pin with a handle.

No matter how bad the timing was out, or how bad the timing/tensioner failed it would be very rare for the valve to end up right inside the cylinder, normally the valve would just bend and damage the piston and/or head.

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1

I can only speculate, but perhaps the collets failed on the valves for that cylinder causing the subsequent damage.

I suggest this as if the timing was the cause then all the valves for all pistons would show evidence of contact / damage, as it is only one then another cause has to be considered in my opinion.

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  • Restating : The keepers/collets on one valve failed and dropped a valve into the cylinder.. It could have been worse, I did it once and the piston remains came out with the oil /water drain.
    – blacksmith37
    Feb 28 '18 at 17:12
  • I saw one where the valve dropped flat (standing on the head) onto the piston and the stem punched holes through the cylinder head... made a really impressive mess : scrap only , no chance at welding...
    – Solar Mike
    Feb 28 '18 at 17:15
  • For mine, the bare rod and wrist pin made a hole in the cylinder wall in the couple miles to home; but I guessed the engine was junk anyway. It had come apart at 5000 rpm , Olds V8.
    – blacksmith37
    Mar 1 '18 at 20:18

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