Special wrench needed for MF135 injectors?

Hi. It's been a while since I've been on this forum. Greetings, all.

Got a problem with my 1074 MF135 perkins diesel. I was changing the lift pump & air got into the fuel lines. First time it's happened to me. So, following the Operator Manual, I started bleeding the system. Got as far as the top injector pump vent plug, but then stalled out at "Step 8", trying to loosen the injector connectors, My wrenches will fit on the connector, but there's no space in there for the wrench to move. Is there some special tool needed? If so, where can I get one?

Thanks. I'm stalled on this one. No amount of engine cranking seems to push fuel up that last little bit of line. It looks like I have to loosen those injector connectors. It's got me beat. Time to talk to you experts.

Sorry. "1974" not "1074". The forum editor isn't working.

There's 2 ends on lines going to injectors, try loosening at where they connect to pump. Also try holding your hand over the air intake that works like choking a gas burner.

A tubing wrench may work better for you or grind away some of the outside of the wrench jaws on a large head open end wrench.

It is best to bleed at the injector as you are trying to clear the air from the line. Air can compress and not open, or"pop", the valve in the nozzle, where a solid column of fuel will not compress and will pop the valve in the nozzle, spraying the fuel into the cylinder.

Interesting, I don't think I ever heard of holding a hand over the intake of a diesel to "choke" it; only blocking the air intake (and not with a hand) to shutdown a runaway diesel engine. GMC two strokes had a flapper valve, at the inlet of the blower, one could trip specifically for emergency stops.

My 135 3 cyl. perkins lost prime and after following bleed sequence 2 or 3 times to no avail I hand choked and it caught. Could have been on verge, don't know.

I bleed air as per pictures...as well as throttle 1/2 open...stop control in run mode.....crack fuel lines at pump...

Bob..Owner 1963 MF 35 X.......

(quoted from post at 10:16:44 05/31/20) My 135 3 cyl. perkins lost prime and after following bleed sequence 2 or 3 times to no avail I hand choked and it caught. Could have been on verge, don't know.

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I say just timing of when it started. If the injector lines have air in them it will compress, fluid won't. If the line isn't full of fuel and the fuel isn't under pressure (like 2500 to 2750 psi) at the valves inside the nozzles, the valves won't open so fuel is not sprayed into the cylinders. I don't see how "choking" would pull fuel through the valves inside the nozzles. JMHO

Thanks. I looked up tubing wrenches. Clever. What size are those final connectors? My 17mm was too big and my 14mm was too small. Are they SAE or metric?

Hello. Thanks. I tried the "choking", to no avail, but will try again after I try a tubing wrench. I love these tricks from you experts!

Thanks for the pix. My Operator's Manual is obviously a xerox of a xerox of a xerox, because the pictures are so dark you can't see much of what's in them. Looking at these, I can see I did OK as far as I got. The problem is just not being able to get those final injector connectors loose.

(quoted from post at 17:48:48 05/31/20)

(quoted from post at 10:16:44 05/31/20) My 135 3 cyl. perkins lost prime and after following bleed sequence 2 or 3 times to no avail I hand choked and it caught. Could have been on verge, don't know.

Click to expand...

I say just timing of when it started. If the injector lines have air in them it will compress, fluid won't. If the line isn't full of fuel and the fuel isn't under pressure (like 2500 to 2750 psi) at the valves inside the nozzles, the valves won't open so fuel is not sprayed into the cylinders. I don't see how "choking" would pull fuel through the valves inside the nozzles. JMHO

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Thanks for that explanation, Jim. It helps me understand why simple cranking won't force fuel through those injectors. The lines need to be full of incompressible liquid.

It helps a lot to be able to think like the machine we're working on.

(quoted from post at 15:19:04 05/31/20) Thanks. I looked up tubing wrenches. Clever. What size are those final connectors? My 17mm was too big and my 14mm was too small. Are they SAE or metric?

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Try 5/8 and 16mm. I don't have a 135 with the Perkins to check, but those fit the injector line nuts on the 4.236 in my CAT loader hoe.

(quoted from post at 22:19:54 05/31/20)

(quoted from post at 15:19:04 05/31/20) Thanks. I looked up tubing wrenches. Clever. What size are those final connectors? My 17mm was too big and my 14mm was too small. Are they SAE or metric?

Click to expand...

Try 5/8 and 16mm. I don't have a 135 with the Perkins to check, but those fit the injector line nuts on the 4.236 in my CAT loader hoe.

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I just ordered a 16mm combo wrench w 15 degree angled head. Mine aren't angled. Maybe that's the secret. If not, I may try two things, 1) grinding down the jaws of the open-ended side a bit, and/or 2) cutting the box-end to create a 1'4" opening, making a dedicated "box-end tubing wrench". Both things would weaken the wrench, of course, and might end up not working. But, I'll report back here. Wrench is due to arrive circa 10 June. What with the pandemic, it may be later. Stay tuned.

I've had to re-prime several MF diesels over the years and I have NEVER cracked an injector. ALL of them started with the battery or more often a quick pull with another tractor. One was a 255 with a rebuilt injector pump, I primed it to the pump then pushed it over a small hill. By halfway down the hill it was purrin' like a kitten. I also use FULL throttle when trying to get running but ALWAYS a hand on the throttle at the first sign of life. That is MY experience, yours may vary. If you don't want to wait for a wrench try pulling it. If it's primed properly it will light off....unless you have Multi-Power, I never did. Good Luck with it!

If it's not a MP I'd suggest towing it.

Thanks, guys. Mine's not a Multi-Power. I capped the PTO with an overrunning clutch for safety. Once that wrench arrives, I'll give it a shot, including fashioning that "box-end tubing wrench". If none of that works, then I'll try pulling it with the truck.

And, thanks for the tip on starting with full throttle. I had wondered about that, since it seemed logical in this special circumstance.

I really appreciate the coaching from all of you. You're giving me priceless information. I've got the Operator's Manual, the Shop Manual, and a looseleaf folder with probably half of the highly detailed repair-shop instructions for a lot of the sub-assemblies. Still, none of that mentions the kinds of things y'all have said. So much is left out, for instance the Special Tools necessary to do certain things. It's like this period in history--around 1960-70 or so--represents some kind of shift, where manufacturers started backing away from building machines designed for us regular folks to repair.

Hi Bill,

Some differences in what people have for tools comes into play here. Wrenches to fit those lines aren't special tools, if those are some of what you are referring to. The variety of different style wrenches a mechanic would have is likely greater that what may be in your tool box. I have many different styles and sizes to over 3" since being a field mechanic was my trade for years. I have often modified wrenches to fit things over the years as well. The special tools normally mentioned in the service manuals will be pullers, testing, equipment, etc., things the shop would supply for the mechanic to use vs. wrenches which are personal tools in many cases.

Also you must remember the service manuals for these were written for the dealer mechanics, not like some of the DIY manuals you can get for things these days that tell you all the tools you need to do the job.

Pulling it, or jump starting it on a hill, will usually spin it faster/longer than the starter and doing so may allow the Injection pump to compress the air in the lines enough to pop the nozzle valves. Just be careful, like many towing jobs the when the towed unit starts it doesn't always stop as quick as the towing unit.

You are doing well at overcoming these things, gaining experience, and as you see you can get a variety of answers on how to do things and what works for each of us. Hang in there you are doing fine.
Jim

I appreciate the encouragement, Jim. I really love this old tractor. When it's running well, it's a real workhorse. I've read that it's one of the most popular ever made. We're restoring 127 acres of prairie here in Central OK, and I use it with a 6' Woods mower to brushhog & cut access roads through prairie grasses that can get 3' tall, and to dig holes for post oaks with a Rhino auger. Someday I may trade up for something a bit bigger, with 4WD and a FEL to dig out ponds. But, this was my first tractor, and it's kind of like your first girlfriend--something you never forget.

So, you were a field mechanic? That's way cool. My daddy was an engineer & very handy as well. He introduced me to tools, and the creative process it takes to fix things. Since age 5 I've thought that anybody who can restore order to something not working is one of that special group creating & maintaining civilization. I see it as almost a mystical talent.

Hello again. Very frustrating day. The new 5/8" (16mm) 15-degree offset wrench arrived & is the correct size for the fuel injector compression fittings, But, it doesn't work. Not enough room to fit it. So, I went to plan "B", creating my own special tool, a "box-end tube wrench", by cutting out a 1/4" slot in the end of the box end. Still not enough clearance to use this. Plan "C"--cut the wrench in two, to eliminate the "big knob of the open end".

THAT finally worked. So, the tool is now an open-ended part of a combo wrench, but with the open-ended part cut off so that the box-end tube wrench has about a 4" handle on it.

With all this, I finally cranked the engine & got fuel up to the injectors, tightened the compression nuts back up at the injectors, cranked 'er over, and she ran for a few seconds. I turned it off--and then wasn't able to start it back up again.

I think I see what my problem is. There's fuel slowly leaking from the gasket that lies between the lift pump and the crankcase. I tightened it as much as I dared. Still, no good. It leaks about 1 drop of fuel every 8 seconds. Just enough so that when I crank it over, it sucks air through that leak & deprimes the fuel line. That's my guess.

What material is that gasket made of? It looked like cardboard when I installed it. I put Form-a-gasket on it, let it dry some, and then installed it. But, something obviously went wrong.

I think I need to use a slightly thicker gasket. Can I fashion another one out of regular cardboard, and coat it again with Form-a-Gasket, or do I need to use some special gasket material?

I believe this must be the lift pump gasket. It has the correct engine type associated with it (3152) as noted in the shop manual, an looks just like the one that came with the lift pump.

https://shop.perkins.com/parts/gask...seals-fuel-systems/fuel-pump-gaskets/36862235

That gasket looks to be the one that is where the lift/transfer pump mounts to the side of the engine block. Oil would be the only thing I would expect to see leak from it. If you have fuel coming out there, between the pump mount and the engine block, your lift pump is real bad. Are you sure the leak is not from around the manual primer lever? Air bubbles going from the lift pump to the filter is a sign the lift pump is bad. From your description it sounds to me you need a new lift pump along with the gasket. If you look at the lift pump parts breakdown, in the parts book, the fuel should only be on the top side of the diaphragm, it should never get to the engine block. JMHO

Hi, Jim. Thanks for the reply. Yes, it seems to be leaking at the gasket between the pump and the engine block. I had stuffed some paper towel underneath the pump, and it saturated with what looked like a mixture of oil and diesel. It was definitely not just one or the other. That would be (expletive deleted) if it were a bad pump, since I bought it new through a private vendor off Amazon.

Yesterday I tightened the bolts a third time. Today, I'll check again to see if it's still leaking, and report back to you.

I'd ask you if you've ever had a frustrating time trying to repair an old tractor, but a little bird tells me you'd probably come back at me with a whole book of them, eh?

I'll holler at you soon. Thanks again. I really appreciate this.

The service life of transfer/lift pumps varies greatly, many only last a couple years, especially if it is a knock off. And Perkins used a number of different pumps on the same engines, I went through that when I had to get one for the 4.236 in my CAT loader hoe; ended up at CAT to get the right one.