New Member/Western North Carolina RE: MEP 003A

[dangier]

Something is bothering me-OP reported 200 lb reading on all cylinders. There has to be a common problem. If one cylinder has issues with compression, the others would normally read higher if in good condition. Is this a general wearing of the rings and cylinder wall? What would cause it to happen over a short time? IIRC OP said he had been running this unit off and on for two years. Any signs of overheating or blocked airflow? High temp limit switch should cut out if running hot, but if it should malfunction, would that cause excessive wear? Exploring possibilities....

 

[Munchies]

Check pushrods for straightness. Pull a head and inspect.

 

[Ray70]

Not sure on a diesel, but I've seen cars with a small head gasket leak between the cylinders where the result was lowered compression due to pressure going back and forth between 2 adjacent cylinders. When you disassemble, look closely at the gasket and block/head surfaces for either damage or a dark sooty stain, this would indicate pressure transfer from one cylinder to the adjacent cylinder. Still very odd that all 4 cyls. are equally low but just something to look for. Also check it the head bolts were too loose or the head warped. AND like dangier said, look for a restriction in the air intake.... like a mouse nest or something crazy like that!
The one other thing I have seen personally on a single cylinder yanmardiesel was a wiped connecting rod bearing that was lowering compression by altering the piston to head clearance at TDC. The engine would start (with assistance from some carb cleaner ) and really didn't knock that much louder than a typical diesel but the connecting rod bearing was totally wiped out due to the machine ( a drum compactor ) rolling on its side and continuing to run with no oil pressure. ( probably due to a faulty oil pressure cut out switch). Very small chance of all 4 conn. rod bearings being blown and not hearing it, but just something to look for if you don't find any other smoking guns! Hopefully you find something simple up in the head area!

 

[dangier]

Straight from the TM (34) under poor compression:

Normal cylinder pressure is between 350 and 450 psi depending upon engine condition. Maintenance should be considered if pressure is below 325 psi or if there is a 15 percent or more difference between cylinders.
Check for loose cylinder head (paragraph 7-9).
Properly tighten head.
Check for leaky head gasket (paragraph 7-9).
Replace gasket.
Check for broken valve spring (paragraph 7-9).
Replace broken springs.
Check for sticking valves (paragraph 7-9).
See sticking valve section below.
Check for leaking valves (paragraph 7-9).
Clean and, if necessary, regrind valves and valve seats.
Check for worn or sticking piston rings (paragraph 7-10).
Replace rings if necessary. Check condition of cylinder walls.
Check for worn cylinder walls and pistons (paragraphs 7-10 and 7-19).
Refinish cylinder walls. Repair or replace pistons.

Hope this helps,
David

 

[Isaac-1]

Something odd is certainly going on here, if those low pressure readings are right, and even across the board, given everything else we have heard, I might start suspecting something cam shaft related.

 

[massey]

Post a pic of your compression tester if you get a chance.

 

[Jimc]

whatever it is, there is only one way to find out.........start rippin it apart!!!

 

[screejunk]

Read this beastly thread! Sounds like compression, which is a big deal in terms of labor. I'm assuming that you pulled each injector to inspect for fuel spurting from each injector as you crank it over...Just want to 100% rule out bad injectors...This is easy to replace...If all 4 are spitting at the end of each injector...this is most likely not issue...Compression in one or more cylinder can cause this, but one would think you would still get plenty of smoke and turnover...just not enough to get the unit running...If there is little to no smoke, I still think injectors could be an issue... When you get the unit running, crack each injector line to ensure that each cylinder has compression...When you crack each injector, the unit should noticeable lose power (i.e. it means there is some compression in that cylinder)...If you crack a line with no impact on the engine, you have a non-functioning (no compression) in that cylinder...Usually you can get the unit working on 3 of 4...but you may have 1-2 bad cylinders (broken rings, sticking rings)...No leaks around the head gasket? Oil pressure solid? Just want to rule out that type of massive compression loss...Also...have you very very carefully inspected the metal fuel lines for any leaks? If you have leaks in those lines, that will radically reduce pressure to force fuel through the injector...But that should be noticeable with first test of seeing fuel squirt out of each injector...Look for consistency across all four injectors...I don't think it's glow plugs as if you are above 50 degrees, the units should eventually get going even with poor plugs...It might be hard, but should still work...Note that when one glow plug goes, the others will fail more quickly as well...So this could be exacerbating the problem, but is probably not THE problem...

 

[ZeusDiesel]

Hope to do one more compression test today (saturday) to get a (hopefully) more accurate read on the numbers. K.I.S.S. (right?) Not looking forward to a tear down, especially with Winter bearing down. Guess I'll have to check the TM to see what this will entail.

Thanks for the encouragement!

ZeusDiesel

 

[ZeusDiesel]

Compression Test

WOW, you guys are great!! Thats a lot of input!!

I ran the compression test again today with a more accurate gauge. Weather: Sunny and 36 dgF. Pulled all 4 glow plugs. Cranked the engine with these results: #1 280 psi, #2 280 psi, #3 280 psi, #4 295 psi. Screwed in 3 glow plugs and tested #4 again, #4 295 psi. Based on previous rec's, I did not pre-warm the engine before testing. The intake manifold was pulled to allow room for testing, there was no evidence of any blockage in the intake manifold system.
As mentioned before the glow plugs test showed 2 measured @ 5.4 and 2 @6.0.

As mentioned above, I would concur that it was running fine until I tried to start it, what, ? 3 months ago, and it would not turn over, seems odd that all would lose compression in the same amount at the same time. The steel injector tubes have been inspected and no leaks have been found. The injectors have been inspected twice, the IP once. Once started with ether, it runs like a champ, 5 hours straight last time.

Engine has 3408 hrs on it.

I'll re-read the recent posts and opinions see what else I haven't checked yet.

Wanted to bring you up on the latest. Sunday Evening.

ZeusDiesel

 

[Jimc]

well if something was goin on the last time you ran it and you were slowly starting to score the cylinders then you shut it down and now its extremely hard to start. just yank the heads and see whats goin on. its very easy to do.

 

[aheilmann68]

Are you getting fuel to the injectors? Have you hooked up eveything so you cab see the injectors pop or have yo put a guage on the injector lines to verify pressure? You might not be delivering fuel to the cylinders. I also had an ip where the fuel cutoff linkage was 180deg out from where it should be, off was fuel open and one was closed. I had to hold the governor arm down.

 

[Harleyd315]

Just a thought, what type starter do you have on your set? The new gear reduction type starters do a much bettter job of spinning over these engines than the old models. Maybe a weak starter and your just not spinning over fast enough to light off. Did you check valve adj? And when the unit was running did you remove the dipstick and see blowby coming out the tube? Does the engine smoke at all when it is running?

 

[storeman]

Zeus/Jim,
What is happening? Haven't heard from you in a while.
Jerry

 

[ZeusDiesel]

Jerry:
Sorry for the in-activity, was finishing up rebuilding my Hot-water solar system before Winter set in and then left town for Thanksgiving.

Have gotten a lot of input. Was hoping that the compression test results might point to something specific. Am reluctant to just start tearing it down without knowing what I am looking for, especially since it is mounted outdoors and Winter coming.Once again, going back to the original issue, it was operating fine, until I went to start it, and it wouldn't. We have been thru the injectors twice, the IP once, all the cylinders showing compression close to one another (280 psi). It runs well once started w/ether. The batteries and starter cranking are strong. No obstructions in the air intake, oil pressure is good. One thought, while I believe the alignment of the flywheel (pc mark) was correct when I re-installed the IP, could that be throwing off the timing of the IP (if its off by a degree or two) enough to cause the poor starting? I will try to include here a pic of my modified compression tester. The adapter is a drilled out (1/4" bore) 7/16-20 bolt with a braised-on quick connect. Just looking at the test results (280 psi) they are all low but very consistent.

As mentioned before, if I pull an injector and mount it externally on the steel injector line to run a pop test, I get a splurge of fuel out of the injector return line, Like that old saying "when your knee deep in alligators...its hard to remember that your trying to observe the injector spray..."

So that's kinda where I'm at. As always open to suggestions, with K.I.S.S. as my mantra.

ZeusDiesel (Bill)

 

[dangier]

Bill,
Hope you had a good thanksgiving.
Your compression readings are too low for the diesel to ignite. Hence the starter fluid kick to get it going. I will also bet that if you loaded the unit fully, you would find it would stall out (due to it not having the proper compression). If you want to resolve this, I would pull the heads as a start. You may find something simple. Otherwise, I think you have maxed out the testing and results without going into the unit.
Wish we were closer-I would give you a hand...
David

 

[walker]

Next step would be to do a dry compression test, then a wet (oil) compression test to determine the shape of the rings, and then do a cylinder leak down test to determine the shape of the valves.

 

[ZeusDiesel]

I have 2 appointments and a Webinar (school) to attend tomorrow, but will try to squeeze in a full load run to test the idea. Not opposed to pulling the head if its needed. I have the tools but am also in the middle of re-configuring my hot water solar system before Winter sets in. As the saying goes, we will .

Thanks,

Bill