Testing Compression

[Jetexas]

I'm working very hard to bring a 1984 Westerbeke 10 Two back to life. The motor had been partially submerged in freshwater, but it was sealed, so while the starter bendix was frozen, I found no water in the engine oil, and the internals seem fine.

After flushing the fuel system and changing all filters and fluids, the electric fuel pump is working. As far as we can tell, the injectors are working.

The glow plugs heat up and glow red quickly.

The starter had to be completely disassembled, scrubbed up and put back together, but now it seems to be working.

We put a new impeller in the saltwater pump.

The water pump was pulled and cleaned. The freshwater system has been cleaned out, the block backflushed, the heat exchanger cleaned, and new hoses have been put on it.

The engine will now crank over all day, but it never catches. Can we test compression using the injector or glow plug holes the way you can test compression on a gasoline engine using the spark plug holes?

The engine is very easy to turn over by hand. Should it be that easy or should it get very hard as each cylinder makes compression? Do we perhaps just need to pour oil in each cylinder to try and get a seal going or does it sound like we need to pull it all apart and investigate the pistons and rings?

Any other ideas of what we can check? So far we've dumped about $300 into this project for fluids, filters, impeller, a new ignition switch and a couple other odds and ends. I hoped it would start once we went through all the systems. If it has a compression problem, is it worth trying to tear down and rebuild or should we just pick up one of the various running used Yanmars that occasionally pop up on craigslist for around $1000?

[sigmasailor]

Does the engine have a decompression lever which happens to be in the 'on' position?
Is the valve distribution still working?
Maybe water got in via inlet or outlet and corroded the valve seats; did you pull the head before you tried starting it?

Compression testing is similar but diesels have higher pressures and no spark plug connection; you would need a diesel tester.
Normally, even when hand cranking, you should be able to feel compression building up.

[Artful Dodger]

There are a few things you could do, one you could remove one injector, but leave it hooked up and point the injector into a can and see if in fact it does develop fuel. At the same time one could use something to put in the cylinder to check and see if the injection corresponds with the piston at top centre, you must think about that as what every you use has to be sure not cause damage to the cylinder, I always use 8 inch zip ties they are plastic. The other thing one could do is remove all the injectors and put oil in each cylinder a small amount about two squirts from an oil can. Then replace all the injectors and see if this helps it kick. To buy a diesel compression testor can be expensive, I made myself one, and it wasn't to hard.

[Jetexas]

I've never heard of this compression lever thing. I'll search my manual to see if there is one.

How much compression should I feel? I feel a little bit, but should it get really hard to turn or is a little bit all you feel with little engines? I'm used to working on large V8s, and you can definitely feel the compression, but it's more and larger cylinders.

[Artful Dodger]

If you have very little compression, then the rings are your problem, instead of oil put in some tranmission oil and let sit for a couple of days, that should work some of the rings free. Before you put the injectors back in make sure you turn the engine over a few times to get the excess oil out. As for compression enough compression is needed to ignite the diesel fuel. In checking my book for my Yanmar they say 3.43 MPa(kgf/cm2) Not sure what that represents, going to see if I can convert it.

[Jetexas]

How does transmission fluid free the rings? How is it different from engine oil?

We took the injectors out and put a little Marvel Mystery Oil in each cylinder before ever trying to turn it over just to make sure things were lubed up. I hope that didn't mess anything up.

[Artful Dodger]

I've worked in the auto industry for some thirty years and have come accross several seized engines, tried everything to free they up. The only thing which brought them around was transmission oil, there is something in it which migrates to free things and clean. To me it sounds like the rings are the problem and they need sealed or freed up some how.

[Jetexas]

I'll try the transmission fluid tomorrow and let you know how it goes.

Incidentally, there's a 33 Morgan for sale here for $6500. The only details the guy will give over email is that it "needs TLC." I may check it out this weekend although I hate to abandon the Starwind 27 halfway through the project.

[Artful Dodger]

be interested in knowing about the Morgan, make sure to check the deck to hull seam, also the deck for soft spots.

[sigmasailor]

Normally you would be unable to crank a diesel through its compression (about double that of a normal petrol engine at 20/1). That is why you need the decompression lever. The built up inertia in the flywheel will push it through for you while hand starting.
The 3.43 figure mentioned above is a little under 500 PSI.

Rule of thumb: 100 ponds (as in PSI) equals 7 kgs (as in kg/cm2).
MPa to kg/cm2 is a factor 10 (1 bar equals 0,981 (take 1) kg/cm2 equals 100.000 Pa).

[Chief Engineer]

When you try to start it, advance the throttle to 2/3-3/4.

hold the glow plug button for 30-40 seconds

drain your water lift muffler....if full te engine will not start.

Finally....you need strong batteries to ensure a proper cranking speed....
If it's too slow...it's a no go.

Do not even think about ether/starting fluid and any other starting aids

and....make sure your stop cable is not pulled out (if it has one)

[Jetexas]

Thanks Chief. We emptied the water muffler because we had to remove the exhaust hoses to get the fuel tank out to clean it. Was that an amazing smell?!!! We've got a new 1200 amp battery, cleaned all grounds, and now that the starter has been cleaned out, it's cranking very fast.

It amazes me that this motor has no air cleaner of any sort - just a rubber tube that runs off the air intake at the rear of the engine back into something on the front of the engine.

My gut tells me it's a compression issue, but I'll go back through everyone's suggestions.

[never monday]

Originally Posted by Jetexas

The engine is very easy to turn over by hand.

it's dead

[doug86]

Are you sure you bled the air out of the injector pump? The Westerbeast is notorious for being hard to bleed, and I would spend time making sure that fuel is getting to the injectors before I worried about compression.

Try a squirt of WD-40 into the air intake while you crank. It will work like starter fluid, but won't damage the motor. If the motor tries to start on WD-40, then I suspect you aren't getting fuel to the injectors.

We have a mantra where I work: bleed, bleed, then bleed some more. If that fails, try bleeding the motor.
Doug

[johnar]

I have used Marvel Mystery Oil alot and love it, but I also agree Trans fluid works very well to free up rust.

I have a Morgan O.I. 33' and love the boat, they are fat and slow but great for live aboard. That is a very nice price but check very close for blisters and if the A/c electrical system has not been updated it would be the first thing I would do, when they made the boats they used solid core wire and very small ga. with a joke of a breaker box.


Best of luck,

Dutch