Compression testing

[Happydays66]

I have been recommended by a surveyor following a pre purchase survey to get an oil change then a compression test. Boatyard have quoted £250 for this. Is that a fair price or a rip off?

[MtB]

Seems a lot.

 

An oil change and a compression test might take an hour or two, depending on the make and model of engine. What is it?

[Burgiesburnin]

Why is the surveyor recommending this?

Is it a lack of compression?

If he suspects this then he must think that the engine is underpowered.

 

£250 sounds a lot.

[Chewbacka]

I think a compression test is not a bad way of looking at the general wear and tear on an old engine - valves and seats, cylinder bores, pistons and rings etc. is the engine fairly old, or is there another reason to be concerned with the engine? Did you ask the surveyor about the engine when you commissioned him to do the survey?

[MtB]

I think the fact that the surveyor has suggested you have the oil changed and a compression test done is actually all you need to know.

 

It is surveyor code for "I think the engine is a bag of shyte" but he can't actually put those words in the survey document.

 

I suspect he may have tried to start it and found it wouldn't fire up, hence his advice to get a compression test. And I suspect he pulled the dipstick out and found either nothing, or a blob of black treacle on the end hence the suggestion to change the oil.

 

Neither of the things he suggests will have any effect on the general condition of the lump.

 

 

 

 

 

 

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Edited September 18, 2015 by Mike the Boilerman

[Alan de Enfield]

So - you have paid £100's in a pre-purchase survey, lift out, & drop back in, the surveyor has given you a warning that all may not be as good as you would like but you still propose to spend another heap of money (£250) - Why ?

 

If the tests come back with a poor result, what do you then do - walk away having given the owner a free oil change and mini service ?

 

There are enough good boats out there without buying 'trouble', however, if you are looking at the bottom end of the market (say below £15000 for a NB) then you have to accept that you will need to spend lots of money, or just live with the problems.

 

Walk away.

[RLWP]

I have been recommended by a surveyor following a pre purchase survey to get an oil change then a compression test. Boatyard have quoted £250 for this. Is that a fair price or a rip off?

 

What engine is this?

 

Richard

[Happydays66]

Thanks for your feedback.

 

It is a lister 2 cylinder engine. The surveyor reported that the boat was in good condition for its age and was surprised by the good fit out inside. He sId I had offers the right price for what the boat was worth. He said the engine oil had been well over filled, was dark brown and very thin. He said there was a little amount of white and black exhaust under load but otherwise it performed okay. He said Initially the engine seemed a bit slow but that lister engines generally are. On the basis of those finding he advised me to get an oil change followed by a compression test. I have had the test done now and The test revelled piston 1 at 300 psi and piston 2 at 295 psi. No leaks from fuel pipes or injectors.

[Traveller]

Had a Lister SR2 on our old boat (is that what you have?). it just seemed to run and run and run with very little maintenance other than routine oil changes. Indestructible comes to mind :-)

[Tony Brooks]

Thanks for your feedback.

 

It is a lister 2 cylinder engine. The surveyor reported that the boat was in good condition for its age and was surprised by the good fit out inside. He sId I had offers the right price for what the boat was worth. He said the engine oil had been well over filled, was dark brown and very thin. He said there was a little amount of white and black exhaust under load but otherwise it performed okay. He said Initially the engine seemed a bit slow but that lister engines generally are. On the basis of those finding he advised me to get an oil change followed by a compression test. I have had the test done now and The test revelled piston 1 at 300 psi and piston 2 at 295 psi. No leaks from fuel pipes or injectors.

 

 

Dark brown and not black = good. Dark brown and very thin oil = possible internal fuel leak = needs attention.

 

If I had found that on a boat I was looking at I would be more concerned about the potential fuel leak than the compressions and would have explains it to the buyer.

 

Happydays - assuming one of the smaller air cooled Listers (SL SR etc.) they have a nasty habit of developing internal fuel leaks. These cause the oil to thin, raise its level, smell of diesel, clean carbon from the inside of the engine and eventually either seize the engine up or cause it to run away.

 

It may be that the previous owner was assiduous on oil changes and just used a thinner oil than normal (sniff it for diesel smell) but it is more likely to be the said internal fuel leak. Please keep a careful eye on the oil level. If it starts going up you know what it is so get it investigated with a degree of urgency. Take the rocker covers off and run the engine. Look for leaks from where the large and small pipe unions fit onto the injectors. If no leaks there take the push rod side cover off (may have to remove "tin" air ducting first) and inspect the two injector pumps. The pipe unions, the bleed screw, and the element securing screw at the back - feel for a leak from this one. Look for leaks from broken copper fuel pipes as well. If you are 100% sure there are no leaks in either place then it could be the lift pump diaphragm or even leaks from the bottom of an injector pump but I have never seen one from there. However I worked on relatively newish engine, not 40 year old ones.

 

In my view these Lister are a bit slow to accelerate both on the starter and when running and think it is just down to the inertia in the large flywheel when compared with a modern Beta etc.

Edited September 18, 2015 by Tony Brooks

[RLWP]

I must do something about Lister fuel leaks. Something with pictures and pointers for what to look for

 

Richard