# MF135 Newer Rebuild Issue



## Tntoadboy (10 mo ago)

Hello 👋 everyone! I am here before I attempt to fix an issue I’m having with my MF 135 Perkins. I bought the tractor barely running, 2 cylinders, and took it to a repair shop. They did a rebuild and the tractor ran great. It was used for about 12 hours, the same year, and it worked perfectly. Due to some health issues, the tractor was parked for the better part of 2 years before it was put back in service. Before starting after the hiatus, the oil, fuel, and air filters were changed. The tractor started and ran great. I was bush hogging for a couple hours and noticed the oil pressure was dropping off? I parked it. Checked oil. Level was good. Next day, started, running, same thing. Oil pressure fell off. I immediately called the shop that had rebuilt it. They were fairly helpful at first. But as soon as they heard it was over 2 years (regardless of hours) they suggested bringing it back (100 miles) for them to repair again. They quoted me $50 an hour plus parts/shop supplies. The initial rebuild was north of $3k, and at this point, I don’t want to spend any more than I absolutely have to, to get my classic running right again. Thus, I am going to attempt the repair. I’m familiar with cars/trucks but haven’t ever wrenched on tractors. Hopefully I’m not getting in over my head?
So, with all that in mind, I’m here asking for advice and guidance to accomplish this repair. I’m going to ease into this. I understand that I may need a bottom end (bearings) repair, at which point I’ll probably hire it out? But I can at least tear it apart? It’s already broken! I’m asking for those of you who are familiar with the system to share your knowledge and help me map out my attack plan. Thanks for reading and chiming in!


----------



## sixbales (May 18, 2011)

Good Morning Tntoadboy, welcome to the forum.

You said the oil pressure drops off, the question is how much? It is normal for the oil pressure to drop some after the engine has warmed up. What is the pressure when the engine is cold, and also when the engine has reached operating temperature. Do you lose engine performance at the lower oil pressure.


----------



## Tntoadboy (10 mo ago)

sixbales said:


> Good Morning Tntoadboy, welcome to the forum.
> 
> You said the oil pressure drops off, the question is how much? It is normal for the oil pressure to drop some after the engine has warmed up. What is the pressure when the engine is cold, and also when the engine has reached operating temperature. Do you lose engine performance at the lower oil pressure.


It has 55lb oil pressure cold, steadies out around 40 lbs, then drops rapidly to less than 20 lb. I haven’t run it while the pressure is that low, so I don’t know if it’s losing performance?


----------



## SidecarFlip (Mar 25, 2021)

20 pounds is fine in my book with hot oil


----------



## Tntoadboy (10 mo ago)

Well, I am stumped now. After reading the replies, I decided to run it and see how low the oil pressure would get. Well, without any attachments, I drove the tractor around for an hour. Pressure started high in the green (normal range). After an hour the pressure had dropped to just below halfway in the green (normal range). Engine temp 180. I am going to hookup to the bush hog tomorrow and mow for a while to see how the oil pressure does under working load? I’ll post anything new. Strange


----------



## SidecarFlip (Mar 25, 2021)

Tntoadboy said:


> Well, I am stumped now. After reading the replies, I decided to run it and see how low the oil pressure would get. Well, without any attachments, I drove the tractor around for an hour. Pressure started high in the green (normal range). After an hour the pressure had dropped to just below halfway in the green (normal range). Engine temp 180. I am going to hookup to the bush hog tomorrow and mow for a while to see how the oil pressure does under working load? I’ll post anything new. Strange


If the oil pressure was marginal, you'd have spun a bearing already. Oil clean or dirty? Dirty oil usually shows lower pressure than clean oil....and the gage might be wonky too. After all it's old.


----------



## Tntoadboy (10 mo ago)

SidecarFlip said:


> If the oil pressure was marginal, you'd have spun a bearing already. Oil clean or dirty? Dirty oil usually shows lower pressure than clean oil....and the gage might be wonky too. After all it's old.


I thought about the oil pressure gauge. I replaced the sender and gauge before I started it. The new gauge doesn’t have a numerical scale, but has red green red range scale. I’m bush hogging this evening and I’ll see if I lose oil pressure.


----------



## SidecarFlip (Mar 25, 2021)

Even if it gets slightly in the 'red zone', you are still good. Again, is the oil fresh and clean or not? Dirty oil when hot will be thinner than clean oil,


----------



## Tntoadboy (10 mo ago)

New oil. I had already changed it before I restarted it. So, it can be run as low “slightly” in red safely?


----------



## SidecarFlip (Mar 25, 2021)

Most likely. So long as there is some oil pressure the rods and mains will be lubricated enough to avoid spinning an insert. If you are apprehensive about it, change to a higher viscosity oil. Don't have a clue what you are using now but those older engines don't do well on modern multi grade synthetics like Rotella T6 or Delo. They prefer a non synthetic straight weight motor oil. If it was mine, I'd be running a straight 40 weight detergent natural oil, not synthetic (if you are). Multi grade oils are chemically designed to flow like a lighter weight oil but provide the boundary film thickness of a heavier weight oil. The ease of flow or 'flowability' is what contributes to lower oil pressures when hot.

Good example of low oil pressure at low rpm are my Kubota's. They have plain bearing rods and mains but at a base idle hot, they make around 10 psi of oil pressure and that is perfectly acceptable.


----------



## Tntoadboy (10 mo ago)

6 hours of steady bush hogging and the oil pressure stayed just in the green. No discernible power loss. Engine temp steady at 180. I have about 30 more acres to mow, and I’m tickled that the old girl is running so well!


----------



## Tntoadboy (10 mo ago)

Now, if I could only figure out “what” my MF is? It has no id plate anywhere I can find. I have found some numbers cast on the right side of the front section, on the engine block, and the left side front. So far none of the numbers have produced any hits on Google?


----------

