Re-ring JD 4400 CUT

[BCinVA]

Beenthere, I have owned this one since new and it used to start good. However a lot of my problems started after I had a fuel contamination problem. That is why I had the pump went through and cleaned the injectors. I was going through the whole fuel system. I am guessing at this point the dirty fuel may have caused the compression problem. Of course, after the fuel problem I thought once everything there was clean it would fix the starting, but it didn't. I think I have exhausted about every other possible cause of hard starting except for compression. I think the 42-43-4400 series are good tractors though. There are mostly reliable and being pre-emission they are pretty simple to maintain. Good luck with yours, I hope it keeps on going on.

 

[PCABE5]

When was the last time you adjusted valve lash?

What was your fuel contamination issue?

 

[BCinVA]

PCABE5, Valve lash was checked when the injectors were out. I checked the compression then and it was 390 PSI on all three. The compression spec for this engine is 398 min to 498 PSI. So the compression is just a hair below the min spec. Since it is pretty even across the cylinders, I am guessing rings instead of valves. I don't know what the contamination was. My son was using it and got some bad fuel somewhere or got it in a dirty container. It had water and was muddy looking. I'm surprised it didn't plug up the fuel system and quit entirely, but it ran on it. I drained it and cleaned the entire fuel system including tank, lines, filter etc. I took the pump to a shop to go through and cleaned the injectors. As I said above I thought that would fix the starting issue but it didn't.

 

[super55]

Is the engine running fine once it starts or is it lunging where the RPMs go up and drop and such. Also is this thing at least trying to fire on it's own with an occasional ignition? To me it sounds like it might still have a little air still left in the lines and is getting compressed at the slower cranking start. Once running the pump is running fast enough to agitate them into smaller bubbles to allow fuel to pass through to injector.

I would try cracking the lines at the injectors then have someone crank while you bleed them out before going after the rings. Might want to double check the timing on the fuel pump as well. Could be off by one tooth where your injection is being retarded causing a no-fire situation.

Those Yanmars are pretty dependable engines. I have over 4k hrs on my 4400 and the motor still runs great without issue.

 

[Tx Jim]

TS Jim, You are right, it does have heat in the intake. It works fine, but doesn't help much when it doesn't start. When I am cranking and it don't start, I usually try the heat but it still won't start. I can give it just the smallest burst of ether possible, (just hit the button on the can and release immediately) and it will start right up. Of course I have to wait for heat elements to cool in intake before the ether.

Has inj pump timing been checked lately. I suppose timing has been checked since I just read you had inj pump serviced.

I think you're correct in that compression is a little too low for good starting

 

[Tx Jim]

These engines are known to go for thousands of hours. I've seen them with 5000 hours still running.

TxJim, How does one know if their intake heat is working?

I'm shooting from the hip due to the fact that my experience of JD tractors built after '91 is limited & I have no access to 4400 TM.

1st check for 12 volts when ign switch is in correct position. Next insert ampere meter between supply wire & heater wire post. With ign switch in correct position an amp draw should be noted if heater is operational. Another option would be aiming a laser thermometer at the heater housing & checking temp..

 

[jaydee325]

I've never heard of contaminated fuel causing excessive cylinder/piston ring wear. The common cause of this kind of wear in engines of low hours is leakage of dust/dirt into the intake side of the engine.

Compression testing is only part of the story when trouble shooting. While the readings are at the low end of the specification, the speed of the engine cranking has an impact. I'm suggesting the battery could be weak and not cranking the engine fast enough. Even a few hundred RPM increase in cranking speed could put the compresion readings in the middle of the specs.

I'd be looking into the fuel system. Speak to the shop that did the pump rebuild. Was it run on a test stand post repair to ensure it is delivering fuel within specifications? Injectors rebuilt correctly and providing good atomization and pattern?

I know before I'd be disassembling a low hour engine for rebuild, I'd be doing a leak down test to compliment the compression test.

Good luck.

 

[Kyle_in_Tex]

PCABE5, Valve lash was checked when the injectors were out. I checked the compression then and it was 390 PSI on all three. The compression spec for this engine is 398 min to 498 PSI. So the compression is just a hair below the min spec. Since it is pretty even across the cylinders, I am guessing rings instead of valves. I don't know what the contamination was. My son was using it and got some bad fuel somewhere or got it in a dirty container. It had water and was muddy looking. I'm surprised it didn't plug up the fuel system and quit entirely, but it ran on it. I drained it and cleaned the entire fuel system including tank, lines, filter etc. I took the pump to a shop to go through and cleaned the injectors. As I said above I thought that would fix the starting issue but it didn't.

It sure seems that it would run, being that close to minimum spec. I was also wondering about proper atomization like jaydee.

 

[Tx Jim]

It sure seems that it would run, being that close to minimum spec. I was also wondering about proper atomization like jaydee.

I agree pop testing injectors should be performed if not already done.

 

[BCinVA]

Thanks to all the replies and ideas up to this point. Most of the things mentioned have been checked. The tractor runs good once started. Smooth, no surging, smoking, correct idle speed and top speed, and has good power. It has been run quite a lot since the fuel pump rebuild. Sometimes after cranking a bit it will start, but many times it won't. I have a good bit of work to do with it right now. When I get to a good place where I can put it in the garage and do some more troubleshooting on it I will. I will recheck some of the more obvious stuff, like valve lash, injectors etc. I will come back and post the results when I do that. Thanks again everyone and if you have further ideas I appreciate it.