Mav’s M1088A1 Conversion

[RRaulston]

ALSO DO NOT BUY A C7 PUMP FOR A 3126 WITHOUT FIRST VERIFYING TEETH COUNT!

the cogs are different for both the drive gear and the pump gear on the used one I purchased.

3126 pump - 30/43 teeth
C7 pump - 23/34 teeth

so... now what??

 

[Mavcaster]

so... now what??

I ordered another pump with the correct number of teeth so will get it installed next weekend hopefully.

 

[RRaulston]

wow, I thought the same pump fit all 3 engines...

 

[Mavcaster]

wow, I thought the same pump fit all 3 engines...

I’m not saying they’re not but this one was advertised as being removed from a C7 and it was almost identical besides the gears.

 

[Buck69]

It almost looks like the pump broke first and the gear teeth were damaged when it jumped out of alignment. Did you open the old pump up to see if there was any indicators that something possibly entered into it? If something passed through the pump, you may find it in the old filter if you still have it.
I would make sure to toss all the related mounting bolts for the pump and gear as they surely saw stresses outside of what they were intended to.

 

[Ronmar]

It almost looks like the pump broke first and the gear teeth were damaged when it jumped out of alignment. Did you open the old pump up to see if there was any indicators that something possibly entered into it? If something passed through the pump, you may find it in the old filter if you still have it.
I would make sure to toss all the related mounting bolts for the pump and gear as they surely saw stresses outside of what they were intended to.

Or something fell thru the gears and the pump housing was the weakest outlet for the gear displacement…

 

[Buck69]

Or something fell thru the gears and the pump housing was the weakest outlet for the gear displacement…

Ya, that was my first thought, but he said there was no other debris in the pan.
I have twice repaired 5.9 Cummins with the drive end of their camshafts snapped off. On both engines, the same screw for the gear case had backed out and landed in the bite. The crunched screws were hard to miss in their pans. I always loctite those screws. Cummins didn't.
To add. If you look at the damaged gear that drives the pump, it appears it had walked up the prior teeth to the one that broke.

 

[Ronmar]

So maybe something stalled the pump… You are not the only owner of this truck. The offending component may have left with a previous oil change…

 

[GeneralDisorder]

Can you still install it? Different number of gear teeth just means it turns at a different ratio/speed - like change gears on a lathe...... That might be by design - we know there were several iterations of the pumps. Literally every listing for aftermarket pumps says 3116, 3126, C7.

That's really odd.....

 

[Mavcaster]

Can you still install it? Different number of gear teeth just means it turns at a different ratio/speed - like change gears on a lathe...... That might be by design - we know there were several iterations of the pumps. Literally every listing for aftermarket pumps says 3116, 3126, C7.

That's really odd.....

No it would not fully seat to the bottom of the block.

 

[Mavcaster]

So the losing streak continues with these ebay pumps. Here you can see the bushing for the idler gear is completely toast. What I ended up doing just swapping the almost new idler gear and shaft from my broken pump to the ebay pump housing. It’s going back in today. Moral of the story is, stay away from ebay if you can.

 

[Buck69]

Good catch!
You have to watch out for the jobbers as well. I had to eat a 9k repair bill after Maxi-Force passed this off to me as a new "OE" pump for a 9 liter Deere engine. It was manufactured in South America. Shaft end play was within spec but the internal driven gear had .012" of end play. Even the cover had a step due to poor machining which was not visible of course until disassembly. Oil pressure remained within spec until dropping to idle at operating temp which is when it quickly allowed the bearings to be wiped. They only offered to refund the cost of their pump.

 

[Mavcaster]

Good catch!
You have to watch out for the jobbers as well. I had to eat a 9k repair bill after Maxi-Force passed this off to me as a new "OE" pump for a 9 liter Deere engine. It was manufactured in South America. Shaft end play was within spec but the internal driven gear had .012" of end play. Even the cover had a step due to poor machining which was not visible of course until disassembly. Oil pressure remained within spec until dropping to idle at operating temp which is when it quickly allowed the bearings to be wiped. They only offered to refund the cost of their pump.
View attachment 893879View attachment 893880View attachment 893881View attachment 893882

Dang yeah good point on that too. I saw a ton of chinese pumps for these engines on ebay and wanted no part of that.

 

[Mavcaster]

Made some good progress today, got the “new” oil pump installed and pan back on. Filled it up with oil and now just need to get the trans cooler reinstalled and new coolant added then can fire it up and start working on this oil actuation fault code again.

Also was able to get all the 5th wheel lock nuts cut off today and lifted off the truck. That thing was pretty heavy.

 

[Mavcaster]

Another small victory…

I can confirm that if your check valve off the front glad hand is full of crud and gets stuck open, the parking brakes will not release. Thanks to @Ronmar video I was able to get a better understanding of how all that works and because I will be deleting the front glad hands anyway I removed and plugged the emergency glad hand feed line from the 2 way check valve under the cab and then capped off the faulty check valve behind the bumper. That fixed the issue and now by brakes can release. I’ll hopefully get to fully remove that system this weekend.

 

[Mullaney]

Another small victory…

I can confirm that if your check valve off the front glad hand is full of crud and gets stuck open, the parking brakes will not release. Thanks to @Ronmar video I was able to get a better understanding of how all that works and because I will be deleting the front glad hands anyway I removed and plugged the emergency glad hand feed line from the 2 way check valve under the cab and then capped off the faulty check valve behind the bumper. That fixed the issue and now by brakes can release. I’ll hopefully get to fully remove that system this weekend.

.
Just remember,,, Keeping those front glad hands will help the wrecker driver if you ever need a tow. There are caps that should be on a chain up front that keep bugs and critters out of those air lines. Special caps that allow the air system to "breathe". Purpose of the glad hands up front is to provide braking power while being towed...

 

[Mavcaster]

.
Just remember,,, Keeping those front glad hands will help the wrecker driver if you ever need a tow. There are caps that should be on a chain up front that keep bugs and critters out of those air lines. Special caps that allow the air system to "breathe". Purpose of the glad hands up front is to provide braking power while being towed...

Yeah I’ve wrestled with this idea and have decided that I will be mounting a winch in that location like others have done. I may play around with the idea of just relocating the glad hands as well, not quite sure yet.

 

[Mavcaster]

On top of the stock alternator of the A0.5 trucks (as I think @Ronmar likes to call them, am I missing a lead on the left terminal or is this only needed for a dual output gauge in the cab?

 

[Ronmar]

That wire to the AC terminal on the reg feeds RPM info to a LBCD, which the A0.5s dont have(no LBCD, remote or manual battery disconects)... so no youvare not missing anything if you dont have a LBCD...

 

[Mavcaster]

Ok awesome thanks for the clarification, still working over everything. I have an intermittent high voltage fault for the IAP sensor so a replacement on the way, hoping that fixes the issue. Was unable to find any broken or chaffed wires between the sensor and ECM. I did find the wires going into what looks like the water temp sensor frayed and hanging on only by a few so will need to replace that as well.