MF 175 Injection pump seal questions

mf175s

Member
Hello,

One of our MF 175 diesels has been leaking fuel around the shut off and throttle controls on the pump. I finally took the cover off and found
that the seals for this pump are 3/8" OD, 1/4" ID and 1/6" thick. Can these be replaced with hnbr o-rings of the same dimensions? The seals I
took off appear to have a square outer edge vs. the round outer edge of the new ones - that's the main reason I ask. Perhaps that is just
from time and being compressed for years?

Also - what do you suggest to use for a new cover gasket? This one appears to have been fiber of some sort and is in dis-repair.

Thank you all, Randy.
 
Those o rings are your "messenger". They are trying to worn you about the age, and conditions of ALL the o rings and seals in your pump. You can change just the leaky cover rings, but keep an eye on the dip stick. Your driveshaft seals are just as old and hard. Sometimes you catch an engine making oil. Sometimes you dont, and wind up washing out the bearings. Take time to really think about getting that pump resealed. It is a simple cheap repair now. Very expensive when noticed to late. Al
 
Thanks Al. How expensive is it generally to get a pump resealed? Is it something a non pro should avoid doing?
 
If you have good mechanical knowledge like being able to rebuild a engine, and other major repairs you can do the job yourself. Replacing the seals in the injector pump is not really a big major job, but if you do something wrong it could cost you big $$. There are some videos on Youtube (search for MF, and or CAV injector pump reseal) that you can watch before hand that shows how to re-seal these pumps so you may want to watch a couple of them, then you can get an idea of if you feel like you can do the job, or not.
 
Al is 100% correct, patch jobs don't last as other leaks will show up soon. I've been seeing more head and drive area leaks lately. Best in the long run to reseal the complete assembly after all parts are inspected for wear..
 
P# for the gasket kit is> 7135-110 about 25.00 comes w/ gaskets and seals to do the pump.
DONT try to substitute any orings or gaskets or you'll be doing it twice..
USE the ones in the kit..
BUT like the others have said.. it NORMALLY leaks somewhere else once the throttle is patched.
You can get one done for around 400.00 but a fuel shop is gonna charge around 650.00 due to overhead..
The videos on the web are OK but lacking.. like anything else in this world.. you get what you pay for..
I tell my customers when they ask, if I think they can rebuild it..
Do you know how to build a watch.??
 
Rebuilding the pump is one thing, resealing it is another. When I reseal a pump I don't take it any further apart than absolutely necessary to replace the seals. Also when re-sealing a pump you need a clean area to do it in, I have also resealed just the top cover in the field while it's still on the tractor (when hay is on the ground, rain is coming, and the tractor is the only tractor big enough to run the bailer its hooked to). If the tractor is running bad, and its determined that the injector pump needs rebuilding then I take the pump to a shop to have that done. While the videos maybe lacking in some areas, which I why I suggest watching more than just one video. It at least gives you an idea of what has to be done to reseal a pump, and you can determine if you can reseal (not rebuild) it.
 

It's a CAV pump...here's what I do with those...go down to the John Deere house and have them look-up the parts for like a 2640 CAV pump...get the throttle shaft and kill shaft 0"rings and the top-cover gasket(like six or eight dollars)...clean pump and surrounding area clean-clean...remove cover gently and un-hook internal spring(noting how and what hole it's keeper doo-hicky is in)....clean and replace parts in top-cover...fit gasket...gently reassemble. Make sure levers work smoothly because you can smash the cardboard gasket or get it out of place and bind things up
 

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