Rebuild or Send to Salvage

EricP

New User
My 1964 MF 135 diesel starting using oil heavily and putting out blue smoke recently. It is using at least a quart of oil per tank of diesel, maybe more. It went from not using any oil to using a lot all at once. I do not believe the tractor has overheated, oil pressure is 40+ psi, compression checked out good, and there is no blow-by when you remove the oil cap. Hour gauge was broken when I got the tractor so I have no idea how many hours it has. I've put about 5 to 6 hundred hours on it since I bought it in 2012.

I took it to a mechanic I trust and he thinks it needs a rebuild. He says for $2000 he can do a partial rebuild (replace pistons), but would prefer to do a total overhaul (valves, re-machine head, and crankshaft if warranted) at a cost of $4500.

Other than the blue oil consumption this is a good tractor. Since purchasing it I've replaced/rebuilt a lot of the components (electrical, hydraulics, starter, steering, radiator, generator, tires, spindles, etc.) and done the routine maintenance. I hate unplanned downtime and keep my equipment well maintained.

With all that said is there any possible cause for the oil consumption other than bad piston oil rings? I'd hate to pay for a rebuild when the cause is something cheaper. A scrap yard will give me $1200 for the tractor. I'm having a hard time justifying the repair costs and am considering walking away from it but sure hate to lose the capability.
 
Hello,
The last thing that I would do is to scrap it. In the UK 135s are appreciating in price. The $2000 at todays rate works out at around ?1500. A complete engine overhaul kit over here would cost around ?180 including VAT which is a form of purchase tax. The kit includes everythin. pistons, liners, gaskets, valves but not shell bearings as clearly the crank size is not known if already machined to undersize. Assuming the worst case where the head needed machining, new guides etc this would come to around ?250 including tax. That puts the bill at around ?430 or $563 leaving around $1500 for labour. Turning that back to pounds gives ?1145...... I would be absolutely delighted to overhaul an AD3.152 for that sort of money. What is the hourly labour charge being used here?
It's certainly worth a rebuild especially if you have done other work on it but I'd be looking for a lower labour cost.
Today's rate is 1.31 dollars to the pound and the prices are from UK supplier Agri-line.
 
Check the air intake system for blockage
causing high vacuum sucking oil past the
rings and intake valves. Could be very
dirty filter, bird nest, wasp nest, etc
 
I may be way wrong but the parts I come up with on this site come to $600.00(overhaul kit, bearings and gaskets). That is a lot of labor.
 
If it started to use a lot more oil quickly, I would suspect something else,
especially if the compression is still good. Valve seals maybe, if the oil is not
draining back down to the pan fast enough. Hmmmm....
Ben
 
Appreciate the input.

The first thing I checked was the air filter. I wish that had been the problem but it wasn't. I may take the tractor to another repair shop and get their opinion and estimate. I agree, the labor cost seems pretty high but this is my first tractor overhaul so I've got nothing to go off. The mechanic indicated machine shop fees were a big part of the cost.
 
Another piece of info that may be helpful. For some reason when I bought the tractor it did not have a thermostat. So it always ran on the cool side unless I was working it hard. I read this can cause piston rings to stick. Is there a remedy I could try to unstick the piston rings, assuming one or more is stuck, without tearing the engine down?
 
A diesel that runs on the cool side tends to build up deposits that look like black oily drops of goo in the exhaust. Also happens when they are not allowed to warm up to operating temps. I would suggest getting the correct thermostat installed, double check the cooling system and give it a workout with a plow, bush-hog, or something that loads up the engine for a few hours. Keep an eye on the oil level of course. May want to add some 50:1 2 cycle oil to the diesel at either 1 or 2 ounces per gallon for a time.
I certainly would not scrap it, oil is a lot cheaper than an overhaul for a time. Good luck with it.
 
(quoted from post at 14:08:29 09/17/18) A diesel that runs on the cool side tends to build up deposits that look like black oily drops of goo in the exhaust.

That is another detail I forgot to mention. Before it started burning oil I was getting a tar looking black goo seeping out of the exhaust manifold to tailpipe joint. It had never done that in all the years I owned it. Is it possible that black goo stuck the piston rings causing it to burn oil badly? What could have caused it to start accumulating that black goo all of the sudden? Chicken and egg type of question. Did the black goo cause the rings to stick, or did the sticking rings cause the black goo?
 
That goo is called "slobber". I would say it needs to be worked WITH a thermostat installed. Diesels like to be worked at operating temps, no t-stat interferes with that in addition letting it idle around while using the least throttle needed, especially in cold temps. Push up that throttle and put it to work. I would "guess" that the slobbering affected the rings to some extent.
 
I just spoke to the mechanic and discussed the tractor not having a thermostat. He wasn't aware and is going to install one and then I will work the engine hard to see if the blue smoke and slobber goes away. He isn't real optimistic but agrees it is worth a try. Also, I was incorrect about the compression being "good". He said he got around 280 lbs psi on each cylinder and that it should be around 340. That information is what makes him think it's time to rebuild. He may be right.
 
Your mechanic is priced way too high. Look
around for another. If tractor otherwise in
good condition would keep for sure. Good
luck
 

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