Burnt valve?

Now the Dozer, we did some testing to it today. It took a long time to get the pony started. We found that the Pony air cleaner is plugged up. Not sure what with, but it wont run with it on and it appears to be sucking oil from it big time as the pony smoked like hell.

When engaging the diesel, the pony bogged down like it was spinning the transmission, Shifter in neutral and forward \ reverse lever in neutral and it still did it. Had to leave the clutch lever out for it to act normal.


The test results are:


1) It appears that all the fuel injectors are acting normal and all are functional and delivering fuel to each cylinder.

2) Injection Timing is correct.

3) All lift pumps to injectors are functioning properly and at the correct pressure. I have the gauge to measure this.

4) UNABLE TO TEST COMPRESSION because I do not have the 1 3/4" adapter to fit the head nor does my compression gauge go up to 2500psi.

5) I did take up my therm o induction meter and found that the problem is definitely CYLINDER #1. this is the one in front closest to the radiator. It is running extremely hot where as cylinders 2 thru 6 are at normal operating temperature . 99% chance is that the cause of this is that the exhaust valve is not opening. This may be due to a bent push rod OR the push rod poked through the rocker arm. Long Story short, The valve cover must be removed to determine the cause before going any further on the engine.


THANKS FOR checking it out. I need to get the time to get up there and do some work on the Cat. So much to do, so little time! Steve

Hi, you will need to add some more specifics about your engine, ie what model tractor is it in, d4,d2, d8 etc, serial number helps a lot.


Compression will never reach 2500 psi, depending on compression ratio it would be between 180 and 300 psi on a diesel engine. fuel delivery is not going to cause excessive temps on one cylinder unless the fuel was extremely excessive, but you would see this in the exhaust pipe, also the engine may rev higher than normal or be knocking on one cylinder. sounds like you may have a coolant circulation issue from the temp issues you mentioned. burnt valves cause misfires from lack of compression as they no longer seal and you cannot compress the fuel air mixture enough to get it hot enough to ignite. a broken valve rocker, or bent pushrod usually ends up in a misfire or a cylinder that is weak due to reduced time that the valve is open.

how long was the engine running? what was the exhaust of the diesel like? could you here a misfire? could be that number one cylinder is working correctly and the other three all have minor issues causing a lower temp.

It's a d8 2u ser# 12593

Hi Tireddozer,

have you had the side cover off the injection pump.
In there you will see the rack which in turn moves all the quadrant gears on the individual pump plungers.

There are timing lines grooved into the rack and a similar line on the plunger gear--check they are timed correctly.
If they are correct, then swap number one pump with say number two and see if the problem follows the swap.
If it does, then the problem is in the previous number one pump.

Sometimes people force a stuck rack that in actual fact is a stuck plunger. This action can turn the gear out of time to the Factory set position on the plunger. This then sets the plunger to either inject more or less fuel than specification--depending on which direction the rack was forced.

For future reference only:-
Usually a stuck plunger will be stuck in the upstroke position, if the engine has been turned--before attempting to move the stuck lifter/plunger be careful that the cam lobe is facing down or you will be forcing against it and may break the brittle lifter yoke.
Best way to loosen a stuck pump plunger is to spray in some loose juice and very gently lever the lifter/plunger up and down until it is returning to contact the cam freely by the return spring on the plunger.
A turned plunger gear can be reset against a known good pump on a Fuel Pump Test bench by the volumes delivered per a series of rack settings, but it usually easier and cheaper to fit a good used pump.

Start with these checks and report back so we can help you thru this a step at a time.
Hope this helps.
Cheers,
Eddie B.