94' Kubota M7950DT engine??

[Orange1works]

Hey everyone I was working on my recent purchase of a M7950dt loader tractor. I bought it not running which i dont know if it was the best move pretty sure I bumped my head. I checked the engine oil and changed the filter. I skipped the sediment bowl and the main fuel tank. I ran a new line from the diesel can to the primer bulb. I changed the fuel filter and I got the fuel filter and injection pump bled and primed. I have fuel at the injectors bled the air to that point. Tractor to my knowledge has sat alittle while. New battery and new battery wires both (2/0).
It just cranks Does not fire. Gave it a small wiff of ether very small and nothing. Took glowplugs out and tested them they are bad. Tip to tip and nothing happens on my meter.
Does the tractor really need the glow plugs that much to start??? Am I to think the engine is really that worn out to start?? 6k hrs on it.
Injection pump CAV looks to be new. Its nicely painted up with green dots like it was checked off at assembly.
I did a test with the glowplugs out. Checked the very first cylinder for compression closest to the rad. This was a dry test I got 220. Next one in I got 150. The last 2 I have not checked yet. A friend of mine thinks the rings could be stuck from sitting I put some trans fluid down in the glowplugs holes to get the rings to let go. A couple days of that im going to slowly bump start that fluid out of the holes and do a wet compression test with the gauge again.
What do you guys think so far???

 

[North Idaho Wolfman]

DO NOT use the starter to get the ATF out of the cylinders, turn the engine by hand.
Yes It absolutely need glow plugs to start.
Have you actually confirmed that the injectors are injecting diesel?
Any smoke while cranking?

 

[Orange1works]

DO NOT use the starter to get the ATF out of the cylinders, turn the engine by hand.
Yes It absolutely need glow plugs to start.
Have you actually confirmed that the injectors are injecting diesel?
Any smoke while cranking?

What a pain in the butt tho it is to try and turn the engine by hand. I dont think they make a barring tool for these engines and that dang crank pulley is really buried down in that frame area. I got some new glow plugs coming for the tractor as well. The exhaust was actually putting out exhaust smoke when me and my friend were cranking the engine over. That was before I did the atf in the cylinders. I haven't done anything else yet. I was just going to let the atf sit in there a couple days maybe hand crank it alittle then pour more in. See if I can get the rings to perform better after a week of the fluid sitting on them.

 

[North Idaho Wolfman]

You said the injection pump looked new?
Wonder if they bothered to time it when they put it in?
Timing on that model is a little trickier than a standard pump setup.

With the glow plugs out you should be able to turn the engine via the fan.

 

[Caden]

The chances of cold starting my tractor without glow plugs is roughly equivalent to that of winning the lottery.
Working glow plugs are a must in my experience, winter or summer.

 

[Orange1works]

You said the injection pump looked new?
Wonder if they bothered to time it when they put it in?
Timing on that model is a little trickier than a standard pump setup.

With the glow plugs out you should be able to turn the engine via the fan.

The injection pump had blue paint on it with painted on green dots on certain bolts. It looked like it had gone throught a rebuild type check for quality. It most certainly did not look like 1994 original pump and was not hardly dirty at all. Well im not sure i took the timing cover off just over the pump gear the one day. I failed to rotate it to look at the dots see if they were close to being lined up. I will have to take it back off and look again at it. To take the rest of those front covers off its a real bear you have to rip the whole front of the engine apart to look at all those gears. Im going on the assumption that it was in time and the PO installed the gear back in place correctly. Just that the rings/injectors are now my holdup for it not starting. I will try to check this weekend the timing again to see if the dot on the gear lines up with the idler gear I think they call it. Then see where the piston is in relation to tdc. Are these engines interference engines if its off alot??

 

[Orange1works]

The chances of cold starting my tractor without glow plugs is roughly equivalent to that of winning the lottery.
Working glow plugs are a must in my experience, winter or summer.

Well I have a new kubota set i found coming. Im slowly learning they play a big role on tractors. My friends 2018 new holland he said is like that even in the summer in the barn it wont start well without the glowplugs. They seem to be a must and maybe buy some spares as well.

 

[Caden]

Im slowly learning they play a big role on tractors.

At least on older Kubotas like ours.

Then again, my neighbor has a newish Yanmar that I run for her sometimes, and it really couldn't care less if I use them, unless is it significantly below freezing.

I still always use them though, at least in my head it makes the starter's job easier.

Best of luck to you.

 

[Orange1works]

At least on older Kubotas like ours.

Then again, my neighbor has a newish Yanmar that I run for her sometimes, and it really couldn't care less if I use them, unless is it significantly below freezing.

I still always use them though, at least in my head it makes the starter's job easier.

Best of luck to you.

These older kubota's im learning had different ways they did stuff. Its probably just that im not very familiar with older big tractor world. This tractor having a loader it makes me excited to want to use it and move stuff it's just really comes down to the engine if it will come around. Thanks!

 

[Caden]

These older kubota's im learning had different ways they did stuff.

They did. On my 1979, there's a label on the dash that says in near freezing or below, to heat the plugs for 60 seconds. That took me by surprise cause I'd always heard 10 to 15.

But it was right. About 45 seconds is the sweet spot for me. There's a coil in the dash instead of a light. It says to hold your finger over it, and when you can't comfortably hold it there any more, then the plugs were hot. I burned my finger a few times till I figured that out.

 

[North Idaho Wolfman]

It says to hold your finger over it, and when you can't comfortably hold it there any more, then the plugs were hot. I burned my finger a few times till I figured that out.

I guess I'm doing it wrong, I just look at it glowing to know it's ready.

 

[john_circumnent]

With those glow plugs dead, I’d replace them first before chasing it too far. Some of those older diesels can be real hard to light off cold without heat, especially if it’s been sitting.


That compression reading is concerning though. 220 and 150 is low/uneven, so I’d finish testing all cylinders, then do a wet test after the ATF soak. Make sure it’s spinning fast too. Good battery cables help, but a slow crank will make a diesel act dead.


I’d fix the glow plugs, verify cranking speed, then recheck compression before blaming the pump.

 

[Orange1works]

With those glow plugs dead, I’d replace them first before chasing it too far. Some of those older diesels can be real hard to light off cold without heat, especially if it’s been sitting.


That compression reading is concerning though. 220 and 150 is low/uneven, so I’d finish testing all cylinders, then do a wet test after the ATF soak. Make sure it’s spinning fast too. Good battery cables help, but a slow crank will make a diesel act dead.


I’d fix the glow plugs, verify cranking speed, then recheck compression before blaming the pump.

Thanks! I already poured a decent portion of atf in all the cylinders so next i will try to hand turn the engine to puke all that out the glow plugs holes. Im suppose to be getting the glowplugs today in the mail. I have a new interstate 1250ca battery will make sure its charged up and my friend has a charger we'll hook to it with a booster. Just have to see what these rings will do if I can get better compression out of them on the gauge on a wet test. By the weekend I should be trying to fire it back up if my checks are looking more postive.

 

[Caden]

I just look at it glowing to know it's ready

May have been a mis- translation from Japanese on my part, but it works pretty good - I usually have a hard time seeing the glow unless its dark or dusk outside.

 

[007kubotaguy]

With that low of compression it is not going to start. With or without glow plugs. Take the hose off the intake manifold. Look inside and see if it is full of dirt. My guess is that the engine sucked dirt. These are great machines. I have one that I take care of that has 15,000 hours on it and has never been opened up. Have done the injection pump a couple times. Have you checked valve adjustment?

 

[Orange1works]

With that low of compression it is not going to start. With or without glow plugs. Take the hose off the intake manifold. Look inside and see if it is full of dirt. My guess is that the engine sucked dirt. These are great machines. I have one that I take care of that has 15,000 hours on it and has never been opened up. Have done the injection pump a couple times. Have you checked valve adjustment?

Im not positive on it cuz you cant see much in that intake but it appears to be pretty clean. The air filter itself is from 2018 who knows if thats how long it sat. I will say the air filter is not very dirty ir dusty at all. Had no mice or chew marks anywhere either. This weekend either way I will find more info out and report back. I've been on midnights and under the weather so its been tough to get out and work on it. I will see what I can gather from today and tomorrow.

 

[Orange1works]

Update tonight:: Its tough to get that engine to rotate by hand the fan pulley just spun and the alternator pulley didn't hold onto the belts either. Tried to rotate by using the timing injection pump gear tho it started to turn so I went the other direction back to tight on it. I lightly bumped started alittle at a time the fluid out. I had rags all over it to catch the fluid then took a rest on the starter. Than after that seem to clear up better we went back to the compression test. From the Rad side to the firewall. 350,220,220,220. Holding pretty true on those figures. Checked the lash and ones near the back are about .020 front seems to be about 18 maybe a hair less but feel tight. Idk if that would matter alot for the engine starting? I would think it would still fire on those valve lash numbers. Put more atf in this time as idk if I got much to make it all the way around the rings. Going to put a torpedoe heater aimed up on the pan tomorrow to get some heat on the block. Drain the atf then some MMO put in and test cylinders again. We're thinking if we can get 1 more cylinder to come around to spec 313pressure it might get the other 2 to loosen up to fire.

 

[North Idaho Wolfman]

Update tonight:: Its tough to get that engine to rotate by hand the fan pulley just spun and the alternator pulley didn't hold onto the belts either. Tried to rotate by using the timing injection pump gear tho it started to turn so I went the other direction back to tight on it. I lightly bumped started alittle at a time the fluid out. I had rags all over it to catch the fluid then took a rest on the starter. Than after that seem to clear up better we went back to the compression test. From the Rad side to the firewall. 350,220,220,220. Holding pretty true on those figures. Checked the lash and ones near the back are about .020 front seems to be about 18 maybe a hair less but feel tight. Idk if that would matter alot for the engine starting? I would think it would still fire on those valve lash numbers. Put more atf in this time as idk if I got much to make it all the way around the rings. Going to put a torpedoe heater aimed up on the pan tomorrow to get some heat on the block. Drain the atf then some MMO put in and test cylinders again. We're thinking if we can get 1 more cylinder to come around to spec 313pressure it might get the other 2 to loosen up to fire.

Valve are not set right lash is .01.
Reset lash and check pressures again.
Might not matter but every little thing helps.

Your compression numbers are in the crapper.

 

[Orange1works]

Well guys I dont have any easier way to say it...... the compression never changed. We did more atf in the cylinders let it sit 3 days. Today I put the torpedo heater on the bottom of the engine to try and add some heat into the block while the atf was still in there. Then got that stuff out of the cylinders and poured MMO into them let it sit about an hour and half with the heater on the block again. I then got that stuff pyked out of the cylinders. Then wiped everything off and did a compression test on the first two cylinder from the rad and still no change. If anything they were a tad bit lower. We did adjust the valve lash right about 0.10. That didnt make that much any change.
Idk now can I Re-ring this tractors pistons without pulling the whole engine??? Like could a guy pull the head and the lower pan to get to the caps and pop the pistons out through the top. Plan to re-ring them and maybe put a slight crosshatch on the liners from a ball Hone and put back together?? Im at a wall and wondering how far its gotta come apart?

 

[Caden]

Im at a wall

Okay.
I'm not exactly recommending this, but I have seen it done successfully.

Put a relatively small amount of very thick oil (foam air filter oil) in each cylinder, and crank engine over a few times before reinstalling injectors/glow plugs. You don't want to get all of it out of the cylinder, but rather you just want to coat the cylinder walls and not have standing oil on top of the piston.

This might get you enough compression to start the engine. If you have completely worn out rings it might start and not start again. If you have partially stuck rings, it might start, get hot, and free the partially stuck rings and be okay.

If anyone else has knowledge of this method please weigh in.