Originally Posted by
shack
Hi all,
Just pulled the pistons out of my defender, it has had a knock since just after I bought it, maybe it had it before but has just got more noticeable over the journey.
Anyway due too a clutch failure I've pulled the motor, it was still running fine, just knocking.
Here are the pistons:
Is this from overheating?
There has been previous water ingression in the bores by the look of it,I guess before I owned it, as it doesn't use water or much oil really.
And would this be enough to knock?
I could have sworn it was a big end knock but did them a couple times with little change
Cheers
James
Without seeing them in the flesh, I would hazard a guess that the engine has overheated at some stage.
Assuming the pistons in the picture are from left to right, 1 to 4, number 1 has suffered the most, then progressively down from there.
That would tend to point to the knocking being piston slap, rather than bearing knock. Not so much from piston wear, as from the rings losing tension.
Seeing what, if any, scoring was evident in the bores would paint a better picture.
Also, measuring the bearing gap, against the factory specs, may help.
This doesn't necessarily mean overheating to the point of seizing, but probably not far off it.
Depending on your plans for future use of the vehicle, either a comprehensive rebuild, or a set of rings and maybe bearings would be the solution.
Hope that helps
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1999 Disco TD5 ("Bluey")
1996 Disco 300 TDi ("Slo-Mo")
1995 P38A 4.6 HSE ("The Limo")
1966 No 5 Trailer (ARN 173 075) soon to be camper
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