New to me D6C - have some issues

phrac · Sep 20, 2021

Hello all,

I've been reading the forums here and recently picked up a D6C for basically scrap price. The machine runs and drives but has some motor issues.

After cleaning off a lot of mud and great build up, I finally found the serial number 74A1792.

The issue I'm currently having is water leaks. Water is leaking out of 2 of the injector pre combustion chambers and also water is blowing through the turbo. Is this caused by the prechamber seals or could there be other issues further down? How do you think I should proceed? I've already ordered the special tool to remove the prechamber a, and have also ordered a parts and services manual, but have not received them yet.

Here's a pic of the old girl.

mekanik · Sep 20, 2021

The pre chambers crack at the radius above the threads.
They can also crack further up from overheating.

Bluox · Sep 20, 2021

You have a cracked head .
Bob

kshansen · Sep 20, 2021

Bluox said:
You have a cracked head .
Bob

That would also be my first guess on the water coming out the turbo. The leaks around the top of the pre-chambers are probably what caused the cracks. Leaked coolant and was ran with low coolant and overheated cracking the head.

Depending on your plans for this machine and how it runs as it is right now you might be able to get by with a replacement head.

phrac · Sep 20, 2021

Well thanks for the replies even if it's not what I wanted to hear. I guess I'll be pulling the head and having a look. I'll report back what I find.

Lindsey97 · Sep 21, 2021

Drain the engine oil asap and refill with new oil. Antifreeze etches main and rod bearings. Do it even if your not planning on running it.

phrac · Sep 21, 2021

Lindsey97 said:
Drain the engine oil asap and refill with new oil. Antifreeze etches main and rod bearings. Do it even if your not planning on running it.

Will do, but I'm not seeing any telltale signs of water in the oil. It's black as midnight.

phrac · Sep 23, 2021

Well I started into getting the head off last night. I was only able to get the intake and turbo off in the amount of time I had. Looks like I'm going to need a new turbo now as well.

Debating on whether or not I should continue or just cut my losses now?

mekanik · Sep 23, 2021

It looks like something went out the exhaust into the turbo. Dropped
valve or seat or piece of piston crown.

Vetech63 · Sep 23, 2021

Decide what you are comfortable spending on this project. If it isn't much then cut your losses now

phrac · Sep 23, 2021

mekanik said:
It looks like something went out the exhaust into the turbo. Dropped
valve or seat or piece of piston crown.

There were big chunks of what appears to be rust past the turbine. I'm wondering if the stack was left uncovered and water rusted the inside of the manifold and then took out the turbo on startup.

Vetech63 said:
Decide what you are comfortable spending on this project. If it isn't much then cut your losses now

I paid $3900 for the machine. Don't know what it would be worth of the motor was in better condition. Appears to have near new rails (berco), sprockets are decent, needs a few rollers. Haven't messed with the winch yet. Also the fan/water pump was locked up so that probably helped with overheating. Hour meter on the motor is showing 2900 so I'm guessing the motor had some work done at some point or the meter isn't working.

Vetech63 · Sep 23, 2021

phrac said:
There were big chunks of what appears to be rust past the turbine. I'm wondering if the stack was left uncovered and water rusted the inside of the manifold and then took out the turbo on startup.

I paid $3900 for the machine. Don't know what it would be worth of the motor was in better condition. Appears to have near new rails (berco), sprockets are decent, needs a few rollers. Haven't messed with the winch yet. Also the fan/water pump was locked up so that probably helped with overheating. Hour meter on the motor is showing 2900 so I'm guessing the motor had some work done at some point or the meter isn't working.

You can forget about that meter being close to right. You are only scratching the surface of what will be needed ide bet. I personally see this as a BIG dollars project

kshansen · Sep 23, 2021

Vetech63 said:
You can forget about that meter being close to right.

Yes! no telling when that meter worked last or how many have been on it since it left the factory!

56wrench · Sep 24, 2021

The engine will be the cheapest and easiest part of that machine to repair but if the rest of it is in overall good shape, it could be made into a good-running machine. Depends how far you want to go with time and money

D6c10K · Sep 25, 2021

You'll know more when you get the head off and see if pistons & liners look ok.
I was in your shoes a few years ago with my 10k D6c. As it ended up I've worked on every part of the machine except the torque converter.... some things more than once.
You'll likely need a replacement head plus water pump and turbo at a minimum. Probably radiator work, maybe oil cooler.
Did you run it enough to know if it shifts, brakes, and turns like it should? Oil pressure? Final drives leaking? Loose sprocket bearings?....(check for sprocket movement with long pry bar)
Pic looks like it has plenty of engine leaks.
To make it dependable there's 1000 things to check/fix.
Not trying to discourage you, just the reality of old neglected equipment.

TomA · Sep 26, 2021

There have been dead axle problems with D6C. Very expensive to fix. Not sure how to check.

phrac · Sep 27, 2021

D6c10K said:
You'll know more when you get the head off and see if pistons & liners look ok.
I was in your shoes a few years ago with my 10k D6c. As it ended up I've worked on every part of the machine except the torque converter.... some things more than once.
You'll likely need a replacement head plus water pump and turbo at a minimum. Probably radiator work, maybe oil cooler.
Did you run it enough to know if it shifts, brakes, and turns like it should? Oil pressure? Final drives leaking? Loose sprocket bearings?....(check for sprocket movement with long pry bar)
Pic looks like it has plenty of engine leaks.
To make it dependable there's 1000 things to check/fix.
Not trying to discourage you, just the reality of old neglected equipment.

This is a direct drive unit and when I drove it off the trailer clutches and brakes worked. Never got it out of first gear to see how the rest of the transmission gears worked. Oil pressure was good, fuel pressure good. Left track was loose but it did take grease and tightened up but we'll see if it stays that way. Slowly working on getting the head off. Water pump is out, needs bearings and seals but looks like rebuild kits for the pump are pretty cheap. The radiator is holding water at least but I haven't run it long enough to see if it will hold pressure.

This should be a fun project, hopefully it isn't too difficult. I'm not really well equipped to handle some of the heavy stuff so we'll see how it goes. I'll keep this thread updated as I progress and I appreciate everyone's help!

D6c10K · Sep 27, 2021

TomA said:
There have been dead axle problems with D6C. Very expensive to fix. Not sure how to check.

Been there too.... twice. First time it didn't stay and the dead axle would still rotate some so it got bored out and bushing put in. If you get it ready to do run, take the sprocket shield off and paint a stripe across the hubs and the inside end of the axle. That way you can tell if it's moving.
If you have to do dead axle work, find a good independent shop. They'll be much cheaper than cat. You'll probably still have to have Cat come out and do the boring and make a bushing. They don't give out the info to make your own.

phrac · Oct 2, 2021

I finally had done time to pull the head and you guys were right. Found cracks at the number 4 & 5 prechamber threads. Is this repairable or is a new head in order?

Liners and Pistons look ok, still see the cross hatches on the liners.

mekanik · Oct 2, 2021

It is repairable, There are shops that do that kind of repair.
I don't think the repair comes with a guarantee or warranty.
The pre-chambers need to be tested for cracks as well.

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