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Have a bighorn 3.1 diesel (push-rod motor) I am wishing to purchase. Pre insprection purchase showed compression imbalance 97 100 87 97/ While not so worried about the 3% variance I am concerned about the 13% variance and wonder how/what is needed to repair. How to check it done satisfactorily. Engine oil is also dirty and noted to be noisy engine. From other comments it would appear that servicing has not been high priority in this vehicle past (169K). Also problems with alternator and battery is very old.

Judging by the compression figures you mention I would definitely be worried. The heart and sole of a diesel engine depends strongly on having high and even cylinder compression.

I think you should get the vehicle into a diesel specialist for a more in-depth engine inspection before making any commitments.

thank you for your reply. the compression has been rechecked and reads evenly. when questioning the discrepancy have been told that the previous reading was a variable compression and that this vehicle should have been run for 3 mins prior to doing a compression test. Somehow the glow plug interferes with the readings. Apparently the tappett on cylinder 3 was too tight and has been altered and the engine is no longer noisy. Is this a feasible explanation or am I being told porkies

I am still very nervous about this vehicle to be honest. Who rechecked the compressions and what are the readings exactly?

A tight tappet will not cause an engine rattle. You may be meant a lose tappet which I can accept.

If you are buying privately, remember there are no warranties after the sale has been made, so make sure you get as many independent checks done on this engine (and the rest of the vehicle) as the current owner will allow.

Be careful and be prepared to walk away if you have doubts about what you are being told.

thank you for that and the warnings.

am buying through a dealer. Have taken vehicle to an ex AA service manager who I have had association with over many years and is someone who has never given me reason not to trust them.

compression done manually gives 480 480 440 460 and he tells me that they are all within given specs. Did not think the motor was noisy given it age and mileage though found it had faulty glow plug. Checked the tappets and found three was tight and adjusted it. Charge rate for alternator was 13.8 so did not feel that there was a problem there. Said bighorms and teranno's needed to run for three mins before checking charge rate as glow plus affect reading.

He felt that the vehicle would suit my purpose and that for its age felt it was in a reasonable repair state provided the servicing happened promptly