Diesel Oil Analysis prior to purchase

[mvweebles]

Originally Posted by kenbo

Out of curiosity, how many owners would allow a compression test/borescope on say a Yanmar without glow plugs? I know I wouldn't. Falls in line with why surveyors do not remove anything during a survey. In most cases, a properly performed oil analysis and full temperature run-up is about as good as your going to get to assess the running gear.

I fully agree that a compression test and borescope is more informative on an engine you own or have been authorized to evaluate but on a pre-purchase survey?

Kenbo- what's your concern about doing a compression test? It can be difficult to find the right adapter, but it's not an intrusive test if performed by a qualified mechanic.

For others compression tests on diesels are much less frequently performed than on gas engines.

Just curious why the concern about compression test.

Peter

[kenbo]

Originally Posted by mvweebles

Kenbo- what's your concern about doing a compression test? It can be difficult to find the right adapter, but it's not an intrusive test if performed by a qualified mechanic.

For others compression tests on diesels are much less frequently performed than on gas engines.

Just curious why the concern about compression test.

Peter

Peter,

I have absolutely no concerns about performing a compression test on my engine or one that I'm asked to evaluate. The test can be very informative to diagnose top end issues.

The part of your question that contains the troubling statement is "if performed by a qualified mechanic". Who determines the qualifications of the mechanic, the buyer, the broker or the owner? The buyer selects the surveyor, or should, and a surveyor reports a on whether systems are operating or not. There is no disassembly to diagnose.

When I sold my last boat, which was equipt with a Yanmar without glow plugs, there was no way I would allow anyone to pull the injectors without a non refundable deposit in hand.

Maybe I'm jaded but I've seen too many not fully qualified mechanics. An experienced diesel mechanic can evaluate an engine and running gear by a cold start to full temperature run up to include max rated rpm. If there's hard starting, excessive smoke, uncontrolled temperature or other issues that raise questions it's not the buyer's right or responsibility to break out the tools to diagnose the problem. The buyer either negotiates or walks.