GVI diesel engine miss. Please help!

[dan osborne]

Looking to buy a GVI diesel I found but engine has a miss. Has a recently rebuilt standadyne injection pump owner had done, but did not cure miss. It's smooth at idle. Running in a tall gear, it's smooth accelerating up from idle to full rpm. But at any constant rpm above idle, it has a fairly steady miss. Engine has some blowby, but not real bad. Could this be injectors or something fairly minor? Don't know anything about the energy cells. Someone has welded on one of the injector feed lines. Doesn't blubber out of exhaust, just white smoke every time it misses. Sure don't want a money pitt. Any comments greatly appreciated.

 

[shinnery]

You might try one of the Infra-Red Digital Thermometers on the exhaust manafold right where it comes out of the head. A cool reading compared to the others would be an indicator of a good place to start looking.
Bryce

 

[Offandgone]

What is this you are saying about something welded onto the injector lines. Look at this real close and be sure that there is no leak there. I would try to rig up to do a compression test.

 

[dan osborne]

It looks as if somebody tried to patch the line where it rubbed a hole in it. I wonder if perhaps some weld material or slag could have gotten in and reduced the amount of fuel delivery. But why wouldn't it do it all the time? How would I do a compression test?

 

[Anonymous-0]

I doubt that you're looking at a money pit, at least on account of that miss and I don't know how much work you can do on a tractor that is not yet yours BUT, you need to start by determining which cylinder isn't behaving. That's easiest done by loosening fuel lines at he injector of each cylinder one at a time while the engine is running until you find the one where it doesn't make any difference. After that I'd check valve clearance in that cylinder, then I'd have the injector inspected and then the energy cell. Of course that assumes that fuel is in fact getting to the injector. A compression check would be good but it's about the last thing I would do because I'd have to chase down a tool to get that done. Good luck and keep us posted.

 

[guido]

Hello dan osborn.
Start the engine and feel each exhaust port for heat, I use the back of my hands, you can use a infrared thermometer to do the same testing.
Craking a fuel,line at the time(NOT MUCH COVER WITH A RAG) will find the missing cylinger.
It sounds as if you have eather a low compression cylinder or an bad injector, the repaired line should be replaced. To maintain fuel quantity all the lines are the same length.
White smoke from the exhaust is unburned fuel, not properly atomized from a defective injector or poor compression. You can swapp injector and see if the miss moves to onother cylinder.
If the smoke as a sweet smell to, it may be coolant leaking into the combustion chamber.
Guido.

 

[Offandgone]

That is something to look at also when a line is welded on it could have a pinhole leak in it. I have seen a leak that would allow a pressure drop that would hardly be noticeable as far as diesel coming out. I always wonder about a high pressure line that has welding done on it.

 

[KJS]

did you ever let the tractor warm up properly?

my G706 and GBD will miss on one or two until it warms up. try putting it to some work to help it warm up faster.

 

[Russ Schultz]

hello,
my MF 95 (same as MM GVI) missed when i bought it too. turned out to be 2 broken pushrods. a trip to the local salvage yard, $20 for pushrods and an hour to install them. not sayin yours could have the same problem, but it was the problem for mine!
good luck,
Russ