How to inspect a diesel?

[njlarry]

Hope this is the right forum; How are diesel engines checked out? Compression test? Injector spray? Couldn't find much using search function. Are there any sites dedicated to marine diesels?
Thanks much.

 

[Don S]

Re: How to inspect a diesel?

Compression tests, injector tests both can be done, depending on type diesel you are talking about.

 

[njlarry]

Re: How to inspect a diesel?

ok Thanks Don.

 

[HT32BSX115]

Re: How to inspect a diesel?

What sort problem are you having? Is this a "Pre-buy" test or are you having a problem with your current boat?

If its a pre-buy test, you can tell a lot about a diesel by how it starts when cold and whether it smokes (a lot) under load. Is it turbocharged or normally aspirated...is it a pre-combustion chamber engine (glow plugs?) or direct injection. Is it an old engine or something much newer (and electronic controlled) ?

If it has a problem, compression and cylinder leak-down tests can give you info on whether the valves are leaking or the rings are faulty. injector spray tests are done with a hand operated pump and tell how well the injectors are working. Fuel injection shops can do the injectors and bench check the injection pump to determine if the injectors or pump is causing a problem. Injection timing only a few degrees off can cause BIG problems in starting and running when cold. There is also usually a "lift" pump (that pumps fuel to the injection pump) that when defective, will cause problems running problems when under load.

There's a lot of stuff that can be checked. The stuff required to do injector, pump, compression/leak-down tests etc are not things the average guy has the correct equipment & tools to do......


Regards,


Rick

 

[QC]

Re: How to inspect a diesel?

Yeah, I'd add that these tests and checks depend on which make and model too. A 2 cycle Detroit is a heck of a different animal than a CAT 3208 which is a very different animal than a CAT 3126E, give us a few more clues and we can probably help a lot more . . .

Examples are that not all injectors can be bench tested, white smoke at startup may not be a big deal with some older models, while an electronic engine with white smoke would probably scare me.

Also, there are some things that are the same as gasoline engines, raw water pumps, manifiolds etc. all take a hit and can be very expensive . . . Get us some more specifics and we can be specific. Lots of talent here.

 

[HT32BSX115]

Re: How to inspect a diesel?

Yeah....I'd expect a little white smoke cold-starting a 6-71 even with a little whiff of ether!

Don't go near a glow plug engine with ether unless you want to be chasing down air cleaner! Nothing like a deezle!

 

[Robj]

Re: How to inspect a diesel?

I wouldn't even touch an old Detroit two cycle either. They are fuel pigs and there is a reason they are being replaced with four cycles. If you are really serious about the condition, get an oil and even coolant analysis done. That will give you an indication of engine condition.

Have a great day,

Rob.

 

[njlarry]

Re: How to inspect a diesel?

Thanks for all the info. I asked as a "pre purchase" concern. I am thinking 30+ foot cruiser and some of them are diesel powered. I have no experience with owning a diesel so feel intimadated just looking at one.

 

[HT32BSX115]

Re: How to inspect a diesel?

If you're going to buy a 30+ ft diesel cruiser, you're talking about a substantial amount of money.

Before you buy any boat like that it's probably a good idea to pay a reputable bonded surveyor to thoroughly inspect it and present you with the results. The cost would be a fraction of the purchase price and would probably save a lot in the long run.


Cheers,


Rick

 

[QC]

Re: How to inspect a diesel?

Agree ^^^^^^ a half sick diesel can cost more to repair than buying two new gassers . . . be careful. Let us know and we'll give you some good preliminary info. A well maintained 2 stroke can be a great engine, and there are a lot of older ones around, a poorly maintained newer electronic 4 stroke could be a nightmare, although that is exactly what I would want with the exception of the poor maintenance . . .

 

[njlarry]

Re: How to inspect a diesel?

I'll be sure to get a survey if I find the right boat but I need some idea of how to weed out the poor canidates. BTY a survey of my present 20' single engine bowrider was worth every penny.