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cburger 10-05-2006 14:04

Perkins 4.108
I have a Perkins 4.108 that has been removed from a 1976 Westsail. As I am in the process of recomissioning the vessel I would like some insights as how to proceed with the motor. It has been reputed that the engine was rebuilt and the meter shows a couple hundred hours. However I have no way of confirming this. The other issue is the boat has sat for about eight years with out the engine being run. Should I take the engine to a diesel mechanic, try to start it and then perform all the appropriate tests, do I perform a simple rebuild with the Perkins rebuild kit and carry on, or do I go for a remanufactured Perkins soup to nuts, with a nice long warranty and the peace of mind that should bring. I am anticipating that I will be using the boat offshore.


Chris Burger

hellosailor 10-05-2006 17:08

Chris, you might try to contact Mack Boring, they are known for running some excellent hands-on diesel training classes and I'd suggest that after one of those, you'd be able and willing to do the work entirely on your own. (Or at least, enough work to find out how the engine is.)

If the engine was put away properly and there is no rust in the cylinder bores (and you might need to pull the head to check that, but if it can be turned when decompressed they're probably OK) you could probably just change the oil, pre-lube it, and fire away. It would be worthwhile checking the condition of the injectors as well, or maybe just sending them out for a rebuild and knowing they're in top shape.

A warranty is good, but knowing how to evaluate and rebuild the engine yourself might be even better.<G>

Alan Wheeler 10-05-2006 22:40

The one main advantage of the Perkins engines is, they are a very reliable work horse. Rock the engine by hand(you will need a spanner or something for a little leverage) and see if it is free to turn. If it is, you are home and hosed. As stated above, fill with fresh oil and then turn the engine over for a good 30seconds with the kill knob out, to ensure oil is up around all moving parts. Then fire her up and see how she runs. Get it under some load and give it a good hard run so as any possible marks in the bore are cut away and the rings are well bedded in.
As for finding out about the condition, it wil be next to impossible without a pul down. Look for new looking gaskets and seals etc, but otherwise you will find it hard to know. If it runs OK, don't worry about how many hrs it's done. These engines are good for 5000+hrs no trouble.

cburger 11-05-2006 07:46


Thank you for your insights regarding my engine. I am fairly mechanical and have broken down diesels before. I really like the idea of just trying to get this engine running. Considering the motor is out of the boat and the tranny and the wiring harness
are disconnected how can I go about starting this motor in my garage? Would like to be able to determine the motors status without having to reinstall everything. Is it possible to build an engine craddle out of wood that will withstand a running motor. This is a heat exchanger cooled model how will I provide cooling water. Finally is there a way to jump start the motor without ingnition switch and wiring harness?



hellosailor 11-05-2006 08:27

"and then turn the engine over for a good 30seconds with " You are braver than I. Most starters are only built for intermittent service and 30 seconds in a row WILL overheat them, or risk overheating them. I'd give it 10-15 seconds, make sure it is cool or let it cool, then do it again. (Or do it marine aviation style and install a pre-start electric oil pressure pump to make my engine love me.<G>)
Wood cradle, no problem. Many engines are just bolted down to a 2x4 stringer. Of course the engine mounts take up a lot of motion, so you might find something made of 4x4's more suitable and assume it will "walk" if it isn't sandbagged or something.
Exhaust is just a matter of ducting it outside and downwind of you, a length of aluminum dryer ducting should work for what you want to do assuming you will be using a wet exhaust.
Ignition on a diesel engine? Isn't there. If you have glowplugs they just need 12v power but can be ignored in the engine is warm. The only other power need is 12v to the starter. A running hose into a bucket and the water intake line stuck in the same bucket full of water should give it enough cooling water, too.
The rest? Well, you might have engine temperature and oil pressure guages in there. It would be nice to get that info but they're incidental to the engine running. Easy to rig if you have them, and guages or a multimeter.

cburger 11-05-2006 08:58

I will use 4x4's and place corners on sanbags to prevent walking. By pre lubing do you mean just turn the engine over manually a couple of times?
Regarding the pre oiling pump can I really justify the expense and time to install at this time if I don't even know the motor runs?

hellosailor 11-05-2006 09:23

<can I really justify the expense and time> I wouldn't worry about it for just testing an engine.
Although most electric pumps could be used on most engines, i.e. if the engine is no good, move the pre-lube pump to the next one. A pre-lube pump is almost unheard of for boat engines, but it is "the" best way to run any engine, if you can, since it essentially ends any main bearing wear from startups, which is almost the only wear the main bearings get.

Turning the engine over manually a few times might help oil it, but assuming it has been sitting (wherever) you'd want to suck out the old oil before you even bother testing it, since there probably is water contamination in it. Then pour in the new oil, and as that is running down inside the engine, it will also lubricate on the way down. Try turning it over & starting it up right after that, and you'll have as much oil in as many places as it is ever going to get from a cold start.
The big question really, is whether you can turn it over (by hand, decompressed) or whether the cylinders are frozen from rust.

You'll also need some fuel...probably simplest to use a quart bottle and let it gravity feed, or run the lines into a gallon can (less chance than spilling a bucket) since you'll need to run both the supply and return lines into it, but you won't need A LOT to just fire it up for ten minutes.

cburger 11-05-2006 09:33

Does the Perkins have a compression release on it? Will also have to prime the motor pre start? Do yu know wher I could get the engine manuals?


Alan Wheeler 11-05-2006 11:31

Your right, I wasn't clear. I meant 30secs decompressed, which I don't believe these engines have a decom lever. So that would mean removing the injectors.
The oil galleries will all have drained over that time, Including the pump. So it will take some time to get oil up around critical places. The main area of concern is the Cam shaft and main/big end bearings. Everywhere else is OK for a short time. The cam tends to be the last place oil gets to, and you have no oil pressure till the gallery in that is fill. so you have no oil load to protect the main /big end bearings. So DO NOT start the engine till oil has had time to travel and you will know when it has by the pressure gauge. Once you have pressure, your right.

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