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My PTO has a slight leak on the transmission mounting, it leaks on the side and weeps out.

If you want to big deal it you can have Cat do the blow by test with a special meter that is attached to the breather to get a specific CFM for acceptable blow by.

I used sensor common, there is some difference of opinion that sensor common is not the same as gnd, but it seems to work for most people. I also had to wire in a relay tied to service brake to give the ecm signal the brake is applied to shut off the cruise control.

Good job, glad you got it sorted. I am sure everyone else with the 3126 is looking forward to this project in the future.

I am guessing when you pull the sensor the ECM just assumes the pressure based on engine RPM and spool valve current. It must use a trend line or a table to estimate the values. Glad you are making progress.

The troubleshooting steps are not much help

Does the value change on ET? My experience with bad sensors is a hard failure, were the sensor produces no computed data usually outside of range or unreasonable data range, intermittent failure give correct/incorrect reasonable values and unreasonable data range. Then the unannunicated failure...

The system description says at least 870 psi, my guess is that starting is inhibited until that limit is reached.

I think each clutch should have a pressure switch, if they are pressurized you should have a code, can you check if you have any transmission codes. a youtuber had a truck that the tranmission was seized and it ended up just getting really hot, another guy on Facebook had a tranmission that he...

Did you make that cover yourself? it does not look like the OEM. The perimeter might have to be bent over to help water sealing. When I made patches on airplanes we would bend the ends slightly to give a slight spring to help clamp the edges.

My hatched leaked, I used 2 layers of butyl tape, and on the outside I used a paintable urethane sealant. I used a rubbing alcohol with a silicone fillet tool to get the sealant to flow well. I never painted over it so the the sealant is starting to weather but it still does not leak after 3...

I installed cruise control on the 3126, I wired in a service brake input using a change over relay, and I had to figure out the cruise control set resume polarity in relation to switch and ecm. If you have CAT ET, you can live view what position the set/resume is. On my truck when the cruise...

The bed removal is not required to remove the transmission, if you can provide the same access as if the bed was installed it is possible. My friend had his transmission replaced at a service shop, and I think the hardest part for them was dropping it, I think the weight and balance was...

when I run the PTO or have the TC stalled the fan does cycle, but I am assuming that is from the tranmission producing heat. When I had the geared hubs the fan cycled quite a bit. Also my fan did cycle when my exhaust brake got stuck closed and I was driving on the highway. The temp needle...

Reading through the recommendations is that you should use the highest viscosity for your temp range CAT seems to think 10W-30 is what is best for my temp range up here in Alaska, 15w-40 is just so common and significantly cheaper than trying to find a different grade. My truck has been run...

Do you think a thinner oil would help reduce restrictions, maybe increase the speed of the fluid moving though the pump? CAT gives specs all the way down to a 5w-40 DEO for the 3126. Most hydraulic oil I have seen run in a similar style pumps have been skydrol a vinyl ester based fluid that is...

I know these style hydraulic pumps are very reliable. A swash plate hydraulic pump are ubiquitous for most aircraft hydraulic pumps. They can go over 10s of thousands hours without failure. Most of the time they fail due to low fluid levels causing it to overheat. Why does it lift, is the fluid...

There might not be an engineering or solution to the puzzle, it could be that the pump for the 3126 is under-built, and may be required to change once or twice in the truck’s life cycle. The failure is hard to predict because the ECM is what decides at what pressures when to fail. Most of these...

Do you think it is a clone of the ford powerstroke, it looks similar sized.

My guess is that it is a variable displacement hydraulic pump, it can deliver a variable flow rate and a variable pressure at a wide rpm range. I think the failure is that the pressure is not adequate for the ECM desired fuel schedule and that is what causes the pump failure. My observation is...