Foton 250a Run Away Engine/Crankcase filling

[jimogeek]

Hey folks,

I've got a 2006 Foton, 250a model with the laidong engine. I may have conflicting symptoms here but the engine recently started running on periodically, yesterday I thought I was going to lose it but was able to get it shut off by loading it down and pulling up a hill while shutting off fuel with the cut off. I just switched to some diesel I'd been storing, so there could be something wrong with it? Not sure if it's got 'bugs' or clogging things up and not sure how that would contribute, and I checked the crank case oil yesterday and it seems much higher than I remember but I could have just over-filled it. I read on a few forum postings about injector pumps or injectors leaking in and filling the crankcase, not sure how that works though. I'm going to go with the bad fuel theory first, change my crankcase oil and see if that fixes it, but curious about any other inputs. If the head gasket was bad I could see antifreeze leaking in to the oil, but would thinned out oil with antifreeze let the diesel run on?

Thanks!

 

[Sysop]

Seems to me there is likely more than one issue going on with the symptoms you describe. I'd start tackling one thing at a time and start with the simple stuff first. Draining the crankcase and refilling is a good start. If the fuel is suspect, I'd do the same with the fuel tank. Probably a good time to change the filter too. I'd also clean everything as I went. Sometimes things just don't look right and it's impossible to see through the dirt.

 

[OccDave]

Have a Jinma 284 and one the the concerns is the hydraulic pump leaking fluid into the crankcase and causing engine running. Have you checked to see if you are losing hydraulic fluid?

 

[RonMar]

Yep, "growing" engine oil is a problem. IF your hydraulic pump is mounted to the engine case, a blown shaft seal on the pump could force hydraulic fluid into the crankcase. This fills the case till it either forces oil up past the rings or keeps oil from draining down out of the head and the oil overflows into the breather hose connected to the intake manifold. Either way will fuel a runaway.

I doubt it is fuel in the oil. If it was enough to notice, the oil would seem thin like diesel, and also pretty obviously smell like diesel.

Hydraulic fluid in the reservoir would not change the consistency too much. If it still had the chinese oil in the hydraulics, it may be nearly the same type as the engine oil Check your hydraulic reservoir, I think you will find it low...

 

[Agvg]

If I understand you right, did the engine start to increase rpm by it self?
If so either the pump/regulator are defective or it gets fuel from somewhere else, do you have a thermostart? Those can leak fuel in to inlet manifold. Did it smoke?

 

[erj]

Does you engine have an injector pump? If so, when was the oil checked/changed?

 

[Bob Rooks]

Ok. Did the engine run on or did it run away? Two completely different scenarios caused by different issues.
Running on means that the engine will not stop when the stop handle/knob is pulled. Running away means that the engine's governor can no longer function to control engine speed and the engine continues to accelerate by itself.
Which is it?

 

[jimogeek]

Sorry folks, didn't realize people had responded to the thread, my email stopped updating me!

The engine ran away, increased in RPM and was shooting out thick black smoke, I even had some oil spatter out of the exhaust onto the tractor. I've worked on some older diesels and have had it happen before but usually when the rings were worn and oil was allowed to leak through. The oil definitely wasn't diluted by diesel, I suspect it's a leaking head-gasket. I drained and changed the oil to just the right level again, and will monitor it. I also just recently topped off the combo hydraulic fluid, not sure if over-filling it could have caused it to get into the crank case? Anyway, it's at the proper level now also, so I'll keep an eye on things and see if quantities start shifting. I may have another problem also, checked the injector pump oil and it was diluted with diesel and completely full. Not sure if that could contribute to the run on?

 

[Bob Rooks]

Sorry folks, didn't realize people had responded to the thread, my email stopped updating me!

The engine ran away, increased in RPM and was shooting out thick black smoke, I even had some oil spatter out of the exhaust onto the tractor. I've worked on some older diesels and have had it happen before but usually when the rings were worn and oil was allowed to leak through. The oil definitely wasn't diluted by diesel, I suspect it's a leaking head-gasket. I drained and changed the oil to just the right level again, and will monitor it. I also just recently topped off the combo hydraulic fluid, not sure if over-filling it could have caused it to get into the crank case? Anyway, it's at the proper level now also, so I'll keep an eye on things and see if quantities start shifting. I may have another problem also, checked the injector pump oil and it was diluted with diesel and completely full. Not sure if that could contribute to the run on?

The fact that your injection pump was full of fuel can only be attributed to two different things: 1) The O-ring seal has failed on the lift pump push rod. 2) One or more barrel and plunger assemblies have failed due to wear or corrosion (dirty fuel and/or diesel bugs). This usually means a new fuel injection pump/governor assembly because barrel and plunger assemblies are not sold separately, and cannot be accurately calibrated without a test bench.
I also suspect the governor flyweights have failed due to being run totally submerged in oil. Checking governor oil should be on your pre-start checklist. Is it?

This issue is not just with Chinese tractors/engines. It happens to the best of them.

 

[greg_g]

It doesn't have to be that complicated. I've had 4 Chinese tractors, all with the same design injection pump. Given that I had the same problem on all 4 tractors, I'd say it's a pretty normal thing on these low end Chinese engines. I simply made it an item on my scheduled maintenance list; twice a year drain IP lube oil and refill with fresh. Out with the diesel contaminated stuff - in with the new.

Overfilling the hydraulic sump will not cause your other issue, but a damaged injection pump seal can permit hydraulic fluid to flow from the pump through the drive gear housing and into the engine crankcase. That's the most common reason for the engine oil level mysteriously rising. Run on is likely due to the high sump level. Crank is splashing contamined engine oil too high. It's getting past the rings and into the combustion chambers. Hence oil splatter out of the exhaust stack.

Drain the engine oil, refill to a level where you can use a chemical engine flush. Run it that way for a few hours, then drain and refill again. If that doesn't fix your exhaust stack splatter, that's when you can start thinking head gasket.

//greg//