MF35 rebuild or not?

[Al470]

Hi all - 1963 MF35 w/Perkins was suffering from severe blow-by. Otherwise runs good. Figuring engine needed total rebuild we started to tear it down. Before removing engine we took the head off and discovered the source of blow-by - a blown head gasket. Fortunately leaking into the cam area, not into the cooling system. Cylinders looked fine with no scoring but on closer inspection we noticed a hairline crack in 2 of the cylinders, running nearly vertical, starting at the top, 3/4 inch long in one cylinder, 1.5 inch in the other.
We figure cracks are not new and probably have been there for some time. Tractor is not heavily used - a bit of road grading and some front end loader work - about 4 hours/month. Question for discussion is, do we overhaul head and replace head gasket and call it good, or do we bite the bullet and do a complete rebuild?

 

[Masseynut(Australia)]

I have never been one to "half do a job", I figure if you have seen a potential problem, then fix it now. Saves going back later on, and having to re-do the job again.
Those "cracks" that you see, can turn into an expensive rebuild, if one of those sleeves ends up in the sump later on, believe me. These are not an exxy motor to rebuild.

My two cents worth, Evan.

 

[DavidP,South Wales]

Hello,
It is difficult to decide which to do. Irrespective of the work that is planned for the tractor there will always be that doubt in your mind as to whether the cracks have got any worse. One thing is for sure they aint gonna get any better. The block would not have to be removed from the tractor to replace the liners. They can either be pulled out or carefully chipped away. Removal of the sump (pan) is straight forward as long as the tractor is well supported under the belly inspection plate. This would give you an opportunity to inspect the con-rod bearings and some of the mains. You will not be able to remove the rear main. Yes, its more work and some more expense BUT you will have the satisfaction of knowing that those cracks are no longer there.

DavidP, South Wales

 

[Al470]

Thanks for the reply's. Mic'd the cylinders and they are "out of round" so seems like there are underlying problems? .

 

[DavidP,South Wales]

Hello,
Have the mic'd the parent bores or the liners within the bores?
Wear ovality in the liner in situ is normal but not of course in the parent bore.
If the bores are out I'd be very concerned about anything over about .003-4"

DavidP

 

[Texas Blues]

Rebuild it. It will last another 40 years. I struggled with the same thing when I got mine, smoking like a freight train. I thought of all the things that could be causing it to smoke, and in the end gave in and rebuilt it. Glad I did. It took about 5 months or so to get all the parts (and money). Did all the assembly work myself. Bought a used block, had the crank turned, had the rods reconditioned and wrist pins bushings installed. All new bearings, pistons, rings, and seals. New oil pump also. New clutch, and probably some more I cant remember. It did run over a grand in all, but well worth it as I got the tractor for a song. My motor is the perkins gas, which is the same block as the perkins diesel. Good Luck, TB