Wondering if I have low compression in 003

[Crawdaddy]

I'm working on getting my MEP-003 genset running. It has not run since I got it from GL and was missing an injector line, and various other lines were disconnected. It also looks like the IP was pulled at some point.

Anyways, I decided to try to turn the motor over by hand with the blower wheel bolt. I grabbed my breaker bar thinking it would require a lot of force to spin the motor, but I was able to spin the motor over with a simple 1/2" drive ratchet. When spinning the motor using the ratchet, I can do so with moderate force, and I feel some hard spots that I think is compression. It seems entirely too easy to spin the motor. Should I be also suspecting low compression on this motor?

The throttle arm on the IP is pretty bound up and the pump doesn't appear to be pumping fuel to injectors, so I know the IP needs a rebuild, but I was hoping I don't need to do a head gasket or anything.

 

[Keith_J]

Low compression usually isn't a leaking head gasket but most often valves. First, check valve clearances, 0.010" intake, 0.007" exhaust. Remove the intake tube and listen for leaks there, then listen through the exhausts.

Yes, with a 10-12" ratchet, you can turn the engine over. Using a breaker bar is risky as IF the engine fires, you could have problems.

If you have small fingers, you can remove the throttle arm assembly without pulling the IP, saving some trouble with timing. Once removed, it is far easier to clean. It must move freely. With both throttle arm and fuel inlet removed, soaking the IP in Berryman B12 Chemtool will remove any varnish in the pump, just don't let it soak more than 30 minutes as it swells the O-rings. Blow out the IP with clean compressed air, then give the IP a shot of clean diesel or light oil.

You will need a small mirror to visualize where the control collar slot is to reinstall the throttle arm. Align the pawl on the throttle arm and hold it in place with grease. Also lightly grease the throttle arm O-ring. The throttle arm will only seat properly and rotate fully in both directions when the pawl is seated properly. Reinstall screws and bend tabs to secure. Replace throttle limit screw, this is the smoke limit screw. If this screw is too far in, the engine will droop under partial load. If too far out, there could be too much fuel on starting, leading to black smoke.

 

[Crawdaddy]

Checking valve clearances is on the agenda. I pulled the valve covers, and the tops of the heads were bone dry and look like they've never had any oil up there. I didn't have any feeler gauges to check the clearances with, so I didn't adjust them then. This machine never fails to surprise me. It only has 100 hours or so on the meter.

Another thing that confused me about this set is when I first got it, when using the starter to spin the engine, it would have trouble spinning the engine and would bind up and the starter would start smoking after only a couple seconds of cranking. I've since replaced the starter, and this one will spin the motor with no problem, but still starts smoking after a couple seconds of cranking.

The IP throttle arm moved pretty freely when I got the generator, but has since started binding up. The IP has never made any evidence of injecting an iota of fuel out of the injector ports. I have bled the fuel filters and left the master switch in the prime position long enough to hear a good constant stream of fuel getting returned back to the fuel tank. I think there's more wrong with the IP than a bound up throttle arm. I suspect it's either mistimed and/or seized up. I will be pulling the pump off to see what's going on.

Only once or twice did I see any smoke coming out of the exhaust ports. The couple puffs of smoke were somewhat blackish.

 

[derf]

Starters should not smoke. You should find out why it is smoking and make it stop.
If there is evidnece that the IP has been off and it was missing injector lines then the injector pump timing is probably off.
You can check for movement in the pump without removing it. There are good instructions in a thread somewhere or in the wiki.

 

[Crawdaddy]

Thanks derf, I knew starters weren't supposed to smoke. I still don't know why it is, but I'm inclined to say it's not exclusive to the starter itself because I got a second, used starter and it does the same thing, just not as bad. The original starter could only turn the motor in 2/3rds rotations, but the newer one I got can spin the engine freely. Since they're both old and of unknown working function, they may need rebuilding.

I was also suspecting the timing being off, but now I have to deal with freeing up the throttle arm, so I'll probably pull the pump to free it up and/or get it rebuilt and make sure the timing is correct on reinstallation. I'll check the wiki for that information.

I'm hoping to get this set up and running before next hurricane season. You still have that 003 for sale derf?

 

[derf]

Yes, we got it running but now it needs a 24V charging stator. I think I have a source for one or I can rewind the old one but finding time to get to it is the problem.

In electrical stuff smoke generally means excessive heat which generally means excessive resistance. Make sure the wires going to the starter are good and the connections are good. Once things get hot enough to smoke insulation failure is very near. Insulation failure leads to short which leads to more smoke which leads to replacement of expensive components. It costs a lot to get the magic blue smoke back into an electrical device. You want to keep the magic blue smoke inside.

 

[PeterD]

...
In electrical stuff smoke generally means excessive heat which generally means excessive resistance...

Actually it means excessive current, not resistance. Generally, excessive resistance causes current to drop, and less heat is generated.

I suspect there is a possibility he has gotten two bad starters.

 

[derf]

Yes, that fits better with the E=IR thing. I was thinking bad connections have higher resistances than good ones.

I was thinking maybe he got two 12V starters. That might make for weak turnover and smoke, eh?

Check your voltage before and while turning motor over with the starter. Maybe a battery with a weak cell?

 

[Ken_86gt]

Bad connections typically have higher resistances's. Try thinking about watts, you get heat generated when you have a bad connection. To keep it simple the DC equations for watts: W = V x I or W = I2 x R or W = V2 / R.

If Crawdaddy is only using 1 12v battery, it would probably toast his starter and battery fairly quickly because of the increased current draw.

 

[Crawdaddy]

I'm definitely using 24 volts to power the genset. I don't have batteries dedicated to it yet, so I pull the whole battery box out of the deuce and use it to power the genset.

 

[ETN550]

I would not be concerned about the compression until it has spun fast enough to start and is white smoking, knocking and not starting. The rings can be sticky from sitting and valves do not always seal that well at slow hand crank speeds. Cylinder walls can have light rust on them causing low compression. Once it tries to start and when it warms up it will develop good compression.

However, if it gets to good cranking speed and is puffing white smoke under room temperature conditions and with operable glow plugs then you may have a problem.

What excatly is it doing or not doing at this point?

Once it is running oil consumption can be monitored for ring wear and seating. Valve adjustment is a good idea as mentioned. Injectors can be tested at a diesel shop for cheap. A good spray pattern does wonders for starting and crisp running without black smoke. Injection pump timing could be an issue if you believe the pump was off of it. Not sure how these engines are timed.

Here is what I would do based on a lot of diesel experience:

Turn it over by hand at least two full revolutions to make sure nothing is binding.

Make sure the intake is clean and dry. Sometimes shop rags are left in there!

Make sure the fuel transfer pump is delivering fuel to the injection pump and back to the tank.

Verify the glow plugs are working. 002 and 003's are prechambered engines and really need the glow plugs for a crisp start.

Get it cranking on the starter at a respectable rpm. Correct any starter issues if not cranking good and fast.

Try to start it and see what it does. If it does nothing then the fuel system is not working. If it puffs white smoke (and glow plugs are good) then it may be bad injector tips or timing. Could also be low compression, but usually the glow plug will ight the fuel if the spray is good even with horrible compression. If it is white smoking and picking up rpm as it cranks keep trying to glow plug and crank for half a dozen cycles. Watch that the starter does not overheat. A lot of times multiple crank cycles and extened cranking get it going.

Many times when starting a engine for the first time after a long sitting or improper storage once it gets running and goes through a few heat cycles, (stop, cool, start, run) it will get better at starting and running.

Only if it makes bad mechanical noises would I stop trying to get it started and tear it down. It may be worn out but it should still start and run.

For the initial start make sure it is at room temperature throughout.

 

[PeterD]

I've got to second everything that ETN550 is saying. Double check the glow plugs for operation, and as well the cranking speed must be correct or it won't start.

I also don't feel you can do a meaningful compression test on an engine that has been sitting for a while.

 

[Crawdaddy]

Well, I think I've found out the main reason why the genset wouldn't run. I pulled the IP off the set last night to find that the gear face on the pump is pretty well seized up. With a pair of channellocks and some force I can rotate the gear, but it's really tight. There's evidence of wear on both the gear face on the IP and on the gear on the camshaft, but I don't think either is messed up enough to affect operation once the IP is rebuilt. The fuel metering collar in the pump that hooks up to the throttle arm also seems to be seized. The throttle arm initially moved easily when I first got the set, but it got stiff later on. So, off to the rebuilders the pump goes. Hopefully the hydraulic head is still good so it's not a 800 repair versus a 300 repair without the HH.

Another thing I noticed when I pulled the pump off was the shim pack for the IP is rusted pretty bad and barely hanging on. Is there a good source where I can obtain new shims to put under there? I know the shim pack controls the gear mesh with the cam. Is there any easy way to measure the total thickness of a quickly disintegrating shim pack? I'm thinking just a caliper would do the job.