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Old 02-26-2017, 11:09 AM
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I have a D6C that I bought to lease to another co, and the owner thought it had a burnt valve. That is rare in diesels, but I can get a whole used cylinder head for $600 soooo....
I ripped the head off and the valves are fine, just had one so crudded up that it would not close anymore.

The engine has no blowby at high idle, there is no wear ridge at the cylinder tops. All bores are shiny and seem to have no crosshatch. It starts very well and oil pressure is excellent. Oil on the stick is right up to the line. Valve guides are worn oval, so I have ordered new ones and I tapped the old ones out.
Looking at the oil in the crevasses of the head I am seeing the odd little beads of water, (not antifreeze) and I think this machine has been excessively idled, and not warmed up properly. I have ordered a new thermostat.

The previous owner told me that the machine quit and would not start. He tried to solve the problem by new injectors and a pump rebuild, and a new starter and batteries. That tells me he burnt out the starter. Still no joy.
So he took off the turbo and found it was plugged solid with carbon. He cleaned out the carbon and it started. He finished his job and put it for sale.

So there is the history.
After I find someone to perform the lost art of valve grinding, I plan to re-install the head, garbage bag the radiator and heat it up real good, then change the oil.
So here is the question....
Is the cylinder wall glazing anything to worry about, and should I give it the Bon Ami treatment or just let it be?

No. I am not going to tear down and hone and re-ring.
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Old 02-26-2017, 11:16 AM
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I haven't been into as many engines as other fellas, but, no ridge, good pressures, and no blowby? I'd finish the head and run with it as is.


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Old 02-26-2017, 12:33 PM
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that obvously is a high hour poorly maintained engine but it looks like the short block has survived this far.
It seems to me that the carbon and crud buildup was a result of the valve guide issues. I would re assemble it after the head repair and see what you have one small concern I would have is possible wear to the ring grooves . This may result in broken rings once the tight head is installed and the power output goes back to near normal.
How many hours do you expect to put on it in a season? What are the terms of the lease if any?
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Old 02-26-2017, 01:06 PM
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that obvously is a high hour poorly maintained engine but it looks like the short block has survived this far.
It seems to me that the carbon and crud buildup was a result of the valve guide issues. I would re assemble it after the head repair and see what you have one small concern I would have is possible wear to the ring grooves . This may result in broken rings once the tight head is installed and the power output goes back to near normal.
How many hours do you expect to put on it in a season? What are the terms of the lease if any?
I expect to lease it dry for 1200/month and after a year I will sell it to them if they want it...if not I have someone here hankering for it.
It is a 1972 machine, with good running gear, and that is the only thing worth money on a Cat of that age.
I would say compression will not change on 5 of the cylinders, #4 was the crapped up one. There can be many reasons for this. I would be shooting in the dark as I don't know how it was operated, and for how long the problem existed.
A tight valve can cause the start of that problem, as well as a bad injector or fuel pump can. So I expect a power increase on one cylinder, clean burning, and possible ring damage can occur in the future. At present the bores are impressively wear free. I had not expected that. The turbo bearings and end play is like new....didn't expect that either.
My personal take, after meeting this guy, is that he did not use ether. There was not a can to be found anywhere. It has a block heater. I suspect there was a tight valve, and dead batteries, and he left it run rather then try and jump start it all the time. That further compounded the issue til the valve could not close. He said he did do a valve set as he thought it was an issue.

When someone tells you all the things he has done, and says there is still a problem, he is being honest. It also tells me he was treating symptoms such as dead battery, burnt starter, (left it run) and carbon production made him change injectors and pump, set valves, etc. til he gave up on it.
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Old 02-26-2017, 01:37 PM
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Since no wear in the cylinder walls, I would just do the guides and start it up. You can do a hand lap on the valves with lap compound which should be enough since the valve was not burnt. You can get a valve lapping tool (like a dart with a suction cup at one end). They work quite well. As soon as you have a shiny ring all around the valve your all set.
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Old 02-26-2017, 01:43 PM
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Quote:
Originally Posted by greywynd View Post
I haven't been into as many engines as other fellas, but, no ridge, good pressures, and no blowby? I'd finish the head and run with it as is...
I feel the same way. I don't have the engine experience that some of the others here do but I'm usually in the "if it ain't broke, don't fix it" camp, especially for a machine of that age. Cats are like Fords and Chevs and Dodges; some people love'em and some people hate'em but generally if you've got a good runner you're good for more miles or hours.

I'm also curious about why your customer is willing to pay 1200 bucks a month for a machine of that age? Leasing can be a great way to acquire the use of a new machine but, to me at least, it doesn't make sense for one that old. I'd think that a D6C of that era and in that condition should be worth somewhere in the range of $25,000-$35,000 so for a year to a year and a half worth of payments they could own a machine outright...
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Old 02-26-2017, 03:31 PM
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Due to the hardness of the cylinder walls in a Cat, they are subject to wet stacking or "Slobbering". If that goes on long enough they will carbon up the valves, exhaust system and if the have one, the turbo. The usual cure is to take them out and work them hard.
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Old 02-26-2017, 04:00 PM
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refer to the first post it is getting new valve guides therfore it will need at least a gseat and valve grind to get back to concentricthe wear on the guides and the carbon suggest vthat some cylinders were not always working this leads to fuel washing of the cylinder walls and possible wear on rhe rings and ring lands
those hard liners can hide some ring and piston damage . only time will tell.
I suspect that Gerry will be his own customer on this thing.
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Old 02-26-2017, 06:40 PM
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Originally Posted by LKeithR View Post
I feel the same way. I don't have the engine experience that some of the others here do but I'm usually in the "if it ain't broke, don't fix it" camp, especially for a machine of that age. Cats are like Fords and Chevs and Dodges; some people love'em and some people hate'em but generally if you've got a good runner you're good for more miles or hours.

I'm also curious about why your customer is willing to pay 1200 bucks a month for a machine of that age? Leasing can be a great way to acquire the use of a new machine but, to me at least, it doesn't make sense for one that old. I'd think that a D6C of that era and in that condition should be worth somewhere in the range of $25,000-$35,000 so for a year to a year and a half worth of payments they could own a machine outright...
It is hard to impossible to put a leased machine into a captive space where the owner cannot retrieve it in the event of failure to pay. Also the usage if paid by the hour meter would be very low. If you are BHP and have world wide operation then it is no sweat. Also, if the guy offering to lease the equipment owns a million shares in your company, you tend to favor him.

I am not fond of hand grinding because you end up with the situation that cause the head to be removed all over again. Hand grinding creates a wider and wider seat over time.
A valve seat should have 3 angles ground on it with the major at 30 degrees. This leaves a narrow seat that crushes any carbon buildup. The valve is ground at 29 degrees, so the contact zone is quite small. It wears larger with age, and then Shade Tree Joe comes and does a hand grind, making it wider still. This does work for a while, but soon then later, you are faced with the same issue of crap building up on the valve face and seat.

but I will if I have to....I guess
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It is tempting to blame others for all this, especially those in control of the system, but don’t forget that for decades you voted for people who routinely lied before elections, and told you what you wanted to hear, that you could have it all right now and to hell with the future – well, that future has now arrived. Clive Maund

Even duct tape can't fix stupid ... But it can muffle the sound.
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Old 02-26-2017, 06:47 PM
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Quote:
Originally Posted by Norm W View Post
Due to the hardness of the cylinder walls in a Cat, they are subject to wet stacking or "Slobbering". If that goes on long enough they will carbon up the valves, exhaust system and if the have one, the turbo. The usual cure is to take them out and work them hard.
My sentiments, exactly. In cold and windy conditions it is best to have the rad wrapped in a tarp and monitor the engine heat. I remember pushing rip-rap on the well head islands in Norman Wells at 30 below, and being stripped to my T shirt and was very comfortable. With all the air directed back and recirculated with a tarp wrap, it was still impossible to put the needle into the hot zone.
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It is tempting to blame others for all this, especially those in control of the system, but don’t forget that for decades you voted for people who routinely lied before elections, and told you what you wanted to hear, that you could have it all right now and to hell with the future – well, that future has now arrived. Clive Maund

Even duct tape can't fix stupid ... But it can muffle the sound.
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