CAT HEUI issues, failures and fixes

[biscuitwhistler37]

What we're trying to achieve here is a more intricate understanding of how and why these things fail, with a focus point on the 3126B, which seems to have the highest failure rate.

I have not been able to find a rebuild kit for this, if someone knows of one please post it here.

I understand that the core charge of this unit is astronomical, but if someone has a trashed unit they can donate or knows where to find one, that would be a huge help.

Linked below is a thread here on SS detailing symptoms of a failing HEUI, and fantastic advice on how to diagnose it.

HEUI Troubleshooting - Injection Pressure Desired and Actual Mismatch

Anyone have any experience with this? I have a 2000 M1088A1. The CEL light came on the other day and with CAT ET hooked up, it showed code 164-11 and/or 164-2. Looking them up reveals a somewhat generic trigger of mismatch between desired and actual injection activation pressure on the HEUI...

www.steelsoldiers.com

I will be updating information as I come across it and hopefully we'll be able to find why they fail so often, and in some cases, so quickly.

 

[biscuitwhistler37]

https://www.irv2.com/forums/f124/interesting-heui-discovery-481583.html

I know links from outside websites are generally frowned upon, but since there's so little information or pics on a teardown out there I hope it will be forgiven, also just in case the link dies I downloaded the pics so we'll always have them in the event a junk HEUI is unobtainable.

This HEUI is off a 3126E, which from what I gather is the same engine as the 3126B, with an electronics upgrade. A search for an HEUI pump for both engines yielded the same result.

 

[Skyhawk13205]

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 that the pump failure is not catastrophic but latent a degradation of performance before the ECM derates or refuses to schedule fuel.

 

[Keith Knight]

My recent encounter with the HEUI pump failing.
Early signs were, steady on the throttle and an occasional increase of RPM for just a fraction of a second like a blip. Driving it the next 2 days it became more noticeable and more often till it through a check engine light and a code.
After speaking with a couple members from SS. And watching a YouTube video of adept ape.

Everyone continued saying the pressure sensor is rarely the problem and because the solenoid comes on the new pump I decided to just move forward with replacing the pump.

 

[Keith Knight]

I’m putting together the list of parts missing the receipt for a couple of the orings. I get them Monday when I return the core.

 

[hike]

Looking at CAT SIS2.0 It looks like the pump group includes transfer pump and solenoid, reman for about 15% less than new. Also, the reman is on the shelf at our local CAT Truck location, new would be order (1-2 days)—

134-0467

 

[hike]

I’m putting together the list of parts missing the receipt for a couple of the orings. I get them Monday when I return the core. View attachment 943498

Is this the list with your o-rings?

 

[Keith Knight]

Yes it will include o-rings and seals.

 

[GeneralDisorder]

https://www.irv2.com/forums/f124/interesting-heui-discovery-481583.html

I know links from outside websites are generally frowned upon, but since there's so little information or pics on a teardown out there I hope it will be forgiven, also just in case the link dies I downloaded the pics so we'll always have them in the event a junk HEUI is unobtainable.

This HEUI is off a 3126E, which from what I gather is the same engine as the 3126B, with an electronics upgrade. A search for an HEUI pump for both engines yielded the same result.



View attachment 943479View attachment 943480View attachment 943481View attachment 943482View attachment 943483View attachment 943484View attachment 943485

Negative. That is the C7 style pump (probably used on the E variant). The B pump looks nothing like that. It's much smaller (probably half that size) and the piston cylinder block is yellow metal. That thing looks like a beast compared to the 3126B pump - which looks like a childs toy inside.

 

[Keith Knight]

 

[Skyhawk13205]

Negative. That is the C7 style pump (probably used on the E variant). The B pump looks nothing like that. It's much smaller (probably half that size) and the piston cylinder block is yellow metal. That thing looks like a beast compared to the 3126B pump - which looks like a childs toy inside.

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

 

[biscuitwhistler37]

Negative. That is the C7 style pump (probably used on the E variant). The B pump looks nothing like that. It's much smaller (probably half that size) and the piston cylinder block is yellow metal. That thing looks like a beast compared to the 3126B pump - which looks like a childs toy inside.

Of course. Can't be that simple . The hunt continues. Thanks for clarifying that

After poking around in more RV forums, can confirm the square style pump was part of the 3126E update.

Another search says the E pump and B pump are interchangeable, researching more on that now.

 

[biscuitwhistler37]

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

Not quite, the Ford 6.4 and 6.7 pumps look like tiny V engines.

The 6.0 looks closer, 7.3 even more so, but none are the same as the cat engines.

 

[GeneralDisorder]

Here's some pics I found from the 3126B pump I managed to "take apart"

It is also a swash-plate piston design. Just REALLY puny and sad looking.

 

[Skyhawk13205]

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 trucks are over 20+ years old, and most of the pumps are prob original. My ECM data shows I have over 680 idle hours which is quite a bit of equivalent miles. Maybe to prevent a breakdown on the road the Huei pump replacement should be a preventive item for persons with 50k equivalent miles. My truck would qualify for that replacment.