Yanmar Problems

[Charlie]

Del I bet that is one of those problems that can heal itself when it is stationary or at a low temp. Hard to track down.

[delmarrey]

Yeah! I've seen it in old fire hoses. The rubber liner delaminates and some water starts shooting out the side, which also slows down the flow to the nozzle. Thank you Navy.

[Dockhead]

More follow up:

On the advice of Yanmar tech support, we took the injection pump to the authorized service center, who put it on a multimillion dollar bench to test 40 functions or something like that, including the lift pump and governor. They pronounced the pump as good as new -- no problems, and they repaired nothing.

Put it back on, and the damned thing runs like a Swiss watch! Full revs, in fact, even more than -- saw 4500 rpm in neutral.

WTF?????? This is one of the most mysterious mechanical problems I have ever experienced. I simply cannot imagine what has been going on with my engine. I guess the only thing I can do now is hope that it is cured, whatever it was!

[DeepFrz]

They pronounced the pump as good as new -- no problems, and they repaired nothing.

Were you there for the test? Any chance that the tester adjusted the governor?

[terrylad]

Originally Posted by Dockhead

More follow up:

On the advice of Yanmar tech support, we took the injection pump to the authorized service center, who put it on a multimillion dollar bench to test 40 functions or something like that, including the lift pump and governor. They pronounced the pump as good as new -- no problems, and they repaired nothing.

Put it back on, and the damned thing runs like a Swiss watch! Full revs, in fact, even more than -- saw 4500 rpm in neutral.

WTF?????? This is one of the most mysterious mechanical problems I have ever experienced. I simply cannot imagine what has been going on with my engine. I guess the only thing I can do now is hope that it is cured, whatever it was!

ONE possibility is that the IP had some varnish or something binding on the lifters or maybe the governor shaft train that was cleaned off in the test process. My symptoms match yours and my IP is still at the workshop and I can only hope that my results are the same. Although there's no testing the governor on the 3GM30 engine without hauling the timing cover/crankshaft pulley off.

[svserengeti]

Dockhead,

I have precisely the same problem that you have been reporting. I also have the exact same engine - Yanmar 4jh3-hte. I am in the early stages of diagnosing the problem.

Any further thoughts or input would be greatly appreciated.

Again, all of my symptoms are exact to yours.

SVSerengeti

[terrylad]

My problem turned out to be the fuel pump (on a 3GM30 Yanmar). There was a very small abrasion on the diaphragm, letting air and occasionally engine oil into the fuel line. It also let fuel get into the oil pan.

I found this after I reinstalled the injector pump that had been reconditioned at a cost of $930.00! The old parts were in perfect condition, but they rebuilt it anyway.

[rtbates]

piston rings could be a problem..maybe sticking, maybe broken. turbos respond to cylinder volume being passed out the exhaust and blow by caused by bad rings will cause both the oil being pumped out via pressure in the crankcase and a reduced turbo spinning hence power reduction.. Bad turbo seals will pump oil into the exhaust. Any exhaust blue smoke?

[hpeer]

Originally Posted by Dockhead

More follow up:

On the advice of Yanmar tech support, we took the injection pump to the authorized service center, who put it on a multimillion dollar bench to test 40 functions or something like that, including the lift pump and governor. They pronounced the pump as good as new -- no problems, and they repaired nothing.

Put it back on, and the damned thing runs like a Swiss watch! Full revs, in fact, even more than -- saw 4500 rpm in neutral.

WTF?????? This is one of the most mysterious mechanical problems I have ever experienced. I simply cannot imagine what has been going on with my engine. I guess the only thing I can do now is hope that it is cured, whatever it was!

I just saw this thread. I had a similar thread running in June as I had a similar problem. 4JH4-TE. Would run up to 1,800 load or no load. Sent the pump to a rebuild shop, they said that although it was dirty there was nothing wrong. They cleaned it, checked adjustments, and returned it.

Problem solved.

My conclusion was that something was mucking with the governor bit of the pump.

I contend that it is a misnomer to call these gizmos fuel pumps. Yeah, they do that. But they do a WHOLE lot more also. I think it is far more accurate to call them MECHANICAL COMPUTERS.

2¢

[CAELESTIS]

Any further updates on your engine? I am getting almost the same symptoms on my 4JH4-TE at only 490 hours.

My turbo does have play, so it could be binding or reducing the turbine rpm as I am not hearing the turbo spool up.

[svserengeti]

As I reported earlier, I have had the same low rpm issues reported earlier at the beginning of this thread & in fact, the exact same symptoms.

After scratching my head, cleaning turbo chargers, etc. for 4 months now, I decided to go back to basics. As we all know, basics with regards to a diesel engine mean ----Fuel, Fuel, Fuel.

Although I fully believed that my fuel supply was 100%- I tried isolating parts of it to make sure. I bypassed the dual Racor primary filters and also the secondary yanmar filter on the engine. I ran the engine and also returned the fuel into a 5 gallon can. Lo and behold, the engine ran up to rpm's at no load and also under load. Next, I plumbed the 5 gallon diesel can to the supply side of the yanmar filer & the engine also ran fine and came up to 3600rpm under load at full throttle.

So, I have not closed the book yet, but i know that in my case, the problem lies somewhere between the fuel manifold (I have two separate tanks) and the Racor primary filter and/or fuel lines up to the secondary yanmar fuel filter on the engine.

I'll keep you posted on my progress. What really pisses me off, is that I know that fuel is almost always the problem with a diesel engine, but I naively thought that my fuel supply system was intact. The filters were clean, and there did not appear to be any leaks or air intrusion into the supply lines. Obviously, due to my earlier mentioned discovery, that is not the case. I suspect that I have air leaking somewhere into the supply lines between the manifold and the secondary filter. The other possibility is that I have a blockage somewhere in that vicinity.

I am happy to be finally chasing this problem down to a manageable outcome

[bstreep]

Originally Posted by CAELESTIS

Any further updates on your engine? I am getting almost the same symptoms on my 4JH4-TE at only 490 hours.

My turbo does have play, so it could be binding or reducing the turbine rpm as I am not hearing the turbo spool up.

If you can eliminate fuel as a problem, it's not a big deal to pull the turbo. About an hour or 2 of work.

If you've not been good about running your turbo HARD, then it's likely carboned-up. OUT OF THE ENGINE, I've used Easy-Off oven cleaner very successfully.

[CAELESTIS]

The turbo is off. I cannot say if this is the final fix but there was almost a 1/8 inch amount of play on the shaft, soot on the compressor, and other evidence of bad shaft/blow-by.

Hard to understand how this could happen in 490 hrs, with zero abuse and 50hr oil changes.

I'll report back when the new one is installed.

[bstreep]

Turbos can be rebuilt rather than replaced. These are very common turbos (they are used on diesel automobile engines all over the world - I found out about using EZ Off from a VW forum). Rebuild kits aren't that expensive, and it's not that hard to do.

[DeepFrz]

CAELESTIS, I don't know what kind of air filter you have on that engine but you might want to take a look at the Walker Airsep for turbo engines. It has a very good filter on the front end and also helps quiet the turbo noise.