M7500DT Troubleshooting and V4000 A Rebuild

[Ranscat]

I purchased this 1982 M7500-DT with the V4000 A engine June 2023 in non-running condition for $5,000, knowing it would take some work to get it running smoothly. For what I am looking for compared to a new machine or other used ones in the Pacific Northwest, this was a good deal for me as an experienced mechanic. It was a little fat getting it home on my deck between trailer, but keeping speeds low it was a successful 5 hour drive with only one tire lost. Fortunately, the drive was enough to convince my wife it was time for a nice deck over trailer with 8k axles! I’ve had the tractor running and driving, but it takes substantial cranking to get it going after warming up the intake with a heat gun and adding a little oil to the cylinders. For good measure, I replaced the glow plugs and tested the injectors with a popper. There is nearly a stream of oil drizzling out of the crankcase breather when running and blue-white smoke coming out of the exhaust when cranking and running. It stumbles and cranks quickly but doesn’t like to fire without a little ether help, which I am not a fan of for the obvious reasons.

I did bleed the fuel system after servicing the injectors. I just wanted to troubleshoot the basics before moving onto internal items. I will be back with the machine in a couple of weeks, after some work travel, and am going to perform a compression test through the glow plugs, dry to wet. I am pretty confident I will find worn rings. The machine has a whopping 7265 hours. The seller’s father was the owner/operator and his son who I bought it from reported it was used on a dry dusty field in Eastern Washington and that the air filter was not regularly serviced. Assuming the compression test fails, I will pull the head, oil pan, and check the crank journals for wear. A full in-frame rebuild kit is about $1,100. I would consider just replacing the rings and honing the cylinders if everything looks good to save on costs and time, but that’s not really an issue once it’s already apart. It’s likely I’ll replace everything. I wanted to get this posted a little early to get some comments started before I start tearing things apart.

I noticed there is not a whole lot of literature online about the V4000 A engine, so I figure I ought to document my winter project to help the community. I do have the WSM and will try to take lots of pictures as I go. The only other issue this machine has is the steering linkage needs some attention to restore the turning radius, it only likes to turn one way.

 

[fried1765]

I purchased this 1982 M7500-DT with the V4000 A engine June 2023 in non-running condition for $5,000, knowing it would take some work to get it running smoothly. For what I am looking for compared to a new machine or other used ones in the Pacific Northwest, this was a good deal for me as an experienced mechanic. It was a little fat getting it home on my deck between trailer, but keeping speeds low it was a successful 5 hour drive with only one tire lost. Fortunately, the drive was enough to convince my wife it was time for a nice deck over trailer with 8k axles! I’ve had the tractor running and driving, but it takes substantial cranking to get it going after warming up the intake with a heat gun and adding a little oil to the cylinders. For good measure, I replaced the glow plugs and tested the injectors with a popper. There is nearly a stream of oil drizzling out of the crankcase breather when running and blue-white smoke coming out of the exhaust when cranking and running. It stumbles and cranks quickly but doesn’t like to fire without a little ether help, which I am not a fan of for the obvious reasons.

I did bleed the fuel system after servicing the injectors. I just wanted to troubleshoot the basics before moving onto internal items. I will be back with the machine in a couple of weeks, after some work travel, and am going to perform a compression test through the glow plugs, dry to wet. I am pretty confident I will find worn rings. The machine has high hours, around 5000 if I remember correctly. The seller’s father was the owner/operator and his son who I bought it from reported it was used on a dry dusty field in Eastern Washington and that the air filter was not regularly serviced. Assuming the compression test fails, I will pull the head, oil pan, and check the crank journals for wear. A full in-frame rebuild kit is about $1,100. I would consider just replacing the rings and honing the cylinders if everything looks good to save on costs and time, but that’s not really an issue once it’s already apart. It’s likely I’ll replace everything. I wanted to get this posted a little early to get some comments started before I start tearing things apart.

I noticed there is not a whole lot of literature online about the V4000 A engine, so I figure I ought to document my winter project to help the community. I do have the WSM and will try to take lots of pictures as I go. The only other issue this machine has is the steering linkage needs some attention to restore the turning radius, it only likes to turn one way.

I can certainly understand why you bought a new trailer!

 

[JohnDB]

A full in-frame rebuild kit is about $1,100.

Might be worth checking: if your rebuild kit includes semi-finished liners (most do) and if you plan to install them in-frame (hopefully not necessary) then you will need in-frame boring to size them correctly.

 

[North Idaho Wolfman]

You should not even consider an in frame rebuild as you will not be able to get to half the parts.
This is a sleeved engine, and it's very very likely you will need to replace the sleeves as well as the pistons.\
and yes they will need to be pressed in and then bored to size.
And you can't / shouldn't do that in the tractor.
I would count on the pistons and possibly the rods being damaged, ether / starting fluid does a lot of damage to these engines.
You will need to check the rise of all the pistons and compare them, if they are not all the same then you have bent connecting rods.

 

[Ranscat]

I was able to complete the compression test yesterday. The wet test included about 10ml of oil injected through the glow plug hole with a syringe. Numbers are PSI.
Cylinder 4 135D/160W (35)
Cylinder 3 220D/270W (50)
Cylinder 2 140D/150W (10)
Cylinder 1 150D/190W (40)

The WSM states 439 PSI is my reference pressure, and 302 is my allowable limit. These poor numbers across the board give me hope my problem lies within the head gasket. Off with their head!

 

[Ranscat]

Thank y'all for the comments and tips! After getting the head off today, which only took 2-3 hours, I will probably just try a new top end gasket set and see how it goes. We will probably use the machine about 50 hours a year, so if a head gasket does the trick, I can handle a little blow by from the wear on those sleeves. I bet it was just the gasses pushing oil out of the breather. The pistons and valves look great (steam cleaned if you will). I don't plan on lapping them unless the head needs machine work. I will put my ruler to the head and block to check for warpage in the next couple of days to decide if it's going to the shop for a kiss or not. I did not see any obvious cracks. Keep the tips comin! They're very much appreciated.

From my notebook (numbers are nut/bolt bags):
A.
1. Remove engine side covers and hood

B.
2. Remove upper coolant hose.
2. Remove small clamped coolant hose.
2. Remove 3x13mm bolts from thermostat housing.

C. Remove 4x 17mm injector lines.

D.
3. Remove intake manifold.
3. Slide coolant hose down between 2 & 1 intake ports.

E.
4. Remove exhaust manifold

F.
5. Remove 4x13mm caps from valve cover.

G. Remove coolant temp sensor wire.

H.
5. Remove valve train and push rods. (Camshaft has c-clips on the ends so the parts won't go flying)

I. Remove chassis mounted fuel line.

J. Remove oil cooler 2x 7/8 hoses on bottom.

K. Loosen clamps holing oil cooler.

L. Remove coolant line next to oil cooler.

M. Remove 2x13mm oil housing bracket.

N. Remove 2x10mm bolts form unddersid of thermostat housing connecting head assembly to block half.

O. Remove 18mm head bolts. They're all the same size.

Most of the nuts and bolts were pretty loose. All of the head bolts were quite tight. I believe this is the first time the head has come off this machine by the look of the grime buildup. I was pleased to see the surface rust and deteriorated gasket sections. between the block and head. The sleeves have noticeable grooves up top from wear. All of the push rods are straight. I will check piston height to make sure none of the rods are bent in the next couple days. And get some feelers between the piston and wall.

Plan is to just order a top end set and not even open up the bottom if the pistons are even.

 

[North Idaho Wolfman]

Having bad compression numbers on a pair of cylinders might point to a head gasket issue, but those bad of numbers on all the cylinders is pointing to a much bigger issue!
Best of luck to you but I think your odds of a head gasket fixing your low compression issue is shooting the moon.

 

[Ranscat]

I will open up the bottom and do the rings. What trickery am I overlooking to get this front driveline off? Do I need to split this one to slide it out? I’ll work on it more in the morning. Also, any recommendations for a gasket kit supplier? I see full gasket sets with rings on eBay and Amazon for about $350. The cost isn’t a concern, but the quality of parts. I’ve had these eBay sets fail on me before with cars where I will use the sets for everything else but the head gasket. But I don’t see “genuine Kubota” parts anywhere with how old this machine is.

 

[Ranscat]

The driveshaft came off nicely with a fresh set of eyes this morning. Just remove the tube covers, slide them back, remove c-clips, slide back the collars, and it comes right out.

There was a wonderful surprise waiting for me in the bottom of the oil pan. 4 thrust bearings.

After a spin of the crank, the rods look straight. Cylinder 4’s sleeve has the worst of it for wear.

 

[North Idaho Wolfman]

Do you have the WSM (aka service manual) for it?
If not get it.
If you do, it will have a number for max cylinder diameter.
On most of these engines when it's worn enough to need rings it's also worn enough to need the cylinder liners replaced too.
And to do that the entire engine needs to be removed, broke down and cylinder liners removed and replaced then bored to size.

ADDED EDIT: The fact that you have main bearing parts in the oil pan, dictates that you pull the engine and repair that also!

 

[Russell King]

You should be able to get the head gasket from your local dealer or from an online dealer