Kubota B7100 Overhauled now will not run

[truckdiagnostics]

Well, check fuel PSI after the lift pump? got me stumped.... can't imagine having the injection pump rebuilt or checked is going to be cheap. I have a little walbro fuel pump by pass lift pump and come out of your own fuel can??:confused3:

 

[Sanddog]

Well, check fuel PSI after the lift pump? got me stumped.... can't imagine having the injection pump rebuilt or checked is going to be cheap. I have a little walbro fuel pump by pass lift pump and come out of your own fuel can??:confused3:

OK, thanks. I will check out the walbro fuel pumps and see if I can find in my repair manual what the fuel pressure should be after the lift pump. Guess I will have to spend a little more for a fuel pressure gauge; sure it is cheaper than a visit to the Kubota dealership. I had read of others that had gone to an electric fuel pump but could not remember what they used. The Walbro name sounds familiar. Thanks again for the help.

 

[Egon]

Have you looked at the injectors?

Any help here?
[video]http://www.kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/[/video]

 

[truckdiagnostics]

He is correct if you haven't you want to have the nozzles checked. Spray pattern going into the pre combustion chamber on those small high rpm diesels is a big deal. Dealer should have a pop tester to check them. When I replace mine I have a diesel injection shop rebuild or I buy new from them. Last time i did it, cheaper than dealer pricing. I can't count how many of those Bosch nozzles i have replaced.

 

[Sanddog]

He is correct if you haven't you want to have the nozzles checked. Spray pattern going into the pre combustion chamber on those small high rpm diesels is a big deal. Dealer should have a pop tester to check them. When I replace mine I have a diesel injection shop rebuild or I buy new from them. Last time i did it, cheaper than dealer pricing. I can't count how many of those Bosch nozzles i have replaced.

I have new injectors purchased from Kubota. I did this as part of the overhaul just to make sure I had a good running reliable tractor. Hopefully, I am almost at my goal. Just purchased a fuel pressure tester gauge on-line to check out the fuel pump. Thanks for the input.

 

[Sanddog]

OK, I checked the fuel pressure and it is good.

Today the tractor started and ran just fine for probably 40 seconds and then slowed down and died like it was under a load. I could see a slight increase in black smoke as it died. Held glow plug and started back up with some black smoke when starting. It did then same thing on the third start; just seemed to bog down. I checked exhaust while running and I don't have anything to compare to but it did not seem to be particularly strong. Each time I have started it over the last few weeks while checking it, small pieces of rusty metal continue to blow out of the muffler. It does not cover the floor, but definitely a rusted up muffler.

I checked the motor and the radiator was pretty hot. The head was hot and touching the block, it was cooler toward the bottom and hotter just below the head. Pulled out the dip stick and the oil was not hot?? It seems like it is getting hotting quickly and that is causing the motor to try to seize up. It quickly cools and will restart but hard to turn over when hot.

Is it possible the muffler is so rusted that it will not allow the exhaust to flow as required and this is leading to heating of the motor. Seems strange that the radiator would be so hot and oil not hot at all??? It was overbored with new oversize pistons as part of the overhaul and everything went back together without any indication of any clearance issues??

Any new ideas as what to check next?? The muffler appears to be rusted onto the exhaust manifold or I would have already removed it, but may have to try harder.

 

[truckdiagnostics]

Time to buy another tool? I would shoot it with my infrared thermometer. Maybe I am missing something, but the length of time you are running it i don't think it is long enough for the radiator to get hot. restricted exhaust could cause what your talking about, as far as for run times, i think...... If it wasn't for the the radiator getting hot I would swear, issues with water pump or thermostat. In-fared thermometer will help. Nice Fluke FLIR camera would be nice right about now!

 

[4570Man]

The radiator shouldn't be more than barley warm after that short of run time. Due the the small muffler discharge size ( I think mines 1" ) the exhaust feels pretty strong. Probably equivalent at 6" to blowing on your hand with an air compressor from about 18". This tractor is equipped with a compression release. If malfunctioning it could cause a similar problem, but it would have to be opening and closing or else the tractor wouldn't start at all. I'd remove the muffler from the manifold, and see if it will run. Take extreme care not to break off the bolts. If at all possible I wouldn't remove the manifold from the engine block because breaking bolts is likely.

 

[Sanddog]

I removed the muffler this morning. On third attempt, a little cold natured, the engine started and appeared to run strong for about 20 -30 seconds, no smoke. Then, as before, the motor just slowed down and died. It acts like there is a load on the motor. I checked and the head was hot, not extreme, and possibly normal. The block was still pretty cool, the exhaust manifold only warm, and I could feel hot water entering the top of the radiator (no water pump on this tractor). I then rechecked the injection timing again, and it appears to be on the mark (25 degrees BTDC). I took off the throttle control lever and the cover on top where it enter the timing gear cover. The spring in on the governor control arm and I could not see any obvious problems with the governor.

What else is there?? Free air flow in and out, injection timing appears correct. Seems to start OK but then acts like it is under load and dies after running only short time. And, if I repeat this several times, the head does get really hot.

 

[Egon]

Is the lower radiator getting hot also. Your description gives thoughts on circulation restriction. Running a water hose in either direction on the bottom hose should indicate if all is clear. Any head gaskets that could stop/interfere with circulation? Remember it is thermo syphon and there is no water pump.