Fuel leak from top of gear pump head

[SquareOne]

Quick update, fired up the truck, no visible initial leaks. Let it idle (700rpm) till temp began to read on dash, then set cruise to highest idle (1150ish) to bring the coolant temp up to normal op temp.

Coolant temp at the thermostat housing was about 175, temp at the fuel pump head reached 153, no leaks so far. Brought the rpm up to 15-1700 for 5min or so, then let come back to idle for an additional 15min. All in all, it ran for approx 45min with no leaks noticed. Still doesn't mean it's fixed, but is doing better than the original test on Fri whereas it would begin to 'wet' the threads within a few min at operating temp.

Waiting for the computer to charge for a leak down test. If it passes, I will make about a 7hr run today and report back.

[SquareOne]

Alrighttyy, so here's the unfortunate update.....ran the leak down test, got the fuel press up to 29k, shut it down, and lost right at 4k psi in one minute (held solid at 24.5psi - not that it matters). Looked at the pump head and could see fuel seeping from the torx, down the side, and pooling at the head gasket. I think it's safe to say where it's loosing pressure...

Now the fun part, have called a few different places trying to get a new head to no avail. Waiting on responses now. If any of you have some info on obtaining the fuel pump head (new) for a cm2350, please let me know.

**Not sure what that torx plug holds down, but whatever it is apparently isn't happy. I rember reading a post from Mr. Hagg mentioning the relief valve in the head. Supposedly once they've failed, the head needs to be replaced. Is this potentially what it is?

[SquareOne]

Looks like they are backordered, go figure. Would have to be put on waiting list and 'may' come in this week or next according to Cummins near me. Sounds like it depends on what dealer is willing to give up their stock, That price is about $24-$2500 with the head gasket and freight.
- They offer new and reman----before the sentence was finished I said 'NO' to the reman. It's literally only a $450-500 difference. Not worth the risk.


** Now it seems the new is not available. I can get a reman overnight, but damn I don't want reman.

****Spoke with Kaitlyn over at Jerry's shop and it seems they do use Cummins reman high press fuel pump heads. The new heads are apparently unattainable at this point, and with national backorders, the remans are questionable on time at best. Just gonna pull the trigger on a Cummins reman to in order to get this repair started. Will keep everyone updated on the progress ---although sounds like it will be sloowwww.

[tree98]

Gotta take what you can get right now unfortunately, your lucky you can it at all. I'm looking at backorder's going into August and beyond.

[SquareOne]

Quick update....still waiting on the fuel pump head as of 4/23. Hopefully it shows today, but we'll see. At this point, it's not the week off that's driving me nuts or even the cost or lost revenue - it's the fact that this week off was involuntary. It is what it is though and I have to deal with it.

On another note, while doing a little research this morning (going over the torque specs on everything for when the parts arrive), I found a 'cut-away' image of the fuel pump head on Quickserve. Hadn't noticed it before. It looks like beneath the torx plug is a relief valve. When you do the plunger test I believe this is what will allow it to pass or fail. Since the relief valve is not serviceable, once compromised, the head needs to be replaced. The image can be found here:

https://quickserve.cummins.com/rtgraphic...475_lg.png


The valley on the lower right is what is beneath the torx plug which I had the issues. Fuel is apparently blowing past at higher pressures and once it gets through it rapidly increases the amount externally leaked.

[tree98]

Thanks for doing this now we have a good understanding of why these heads can't be repaired

[Waterloo]

Good info here, I like learning about these pumps... The backorder, finding that silly air compressor gasket of mine was a chore, Cummins was out of stock and no clue when more would arrive, so I called around to the dealerships in the area, found one at a Peterbilt dealer, that is not good for such a common part. I think this parts issue is going to be growing exponentially here in the future, especially for these newer motors and trucks.

[SquareOne]

So, after 4 days, 3 stops and about a 250mi round trip, I finally have all the pieces for this damn thing. Here are the part numbers for future reference:

4384373RX - Fuel pump head assembly (reman unfortunately) - (x1)
3046599 - FP 12pt cap screw, long (what's 30 bucks for fresh bolts) - (x1)
3946085 - FP 12pt cap screw, short - (x3)
2872513 - FP head gasket - (x1)
3963990 - Sealing washer for Banjo bolt - (x2)
3963988 - Sealing washer for Banjo bolt - (x2)
2872663 - Gasket (for fuel pump adapter at rear of head) - (x1)

All in, looking at about $2130 in parts. The fuel pump head comes as an assembly with the barrel/plunger assemblies as well as the high pressure fuel fitting (at front of head) already installed.

I'll be installing tomorrow morning and report back with the results. Hopefully there aren't any surprises.

Got it cleaned up and shot a few coats of Cummins red. Here is a couple pics of how they come, minus the blue tape.

Tags:

fuel pump, fuel pump parts, fuel pump head, ISX fuel pump, plungers, tappets

[SquareOne]

Success! Everything went smoothly with the new fuel pump head replacement - no surprises, which is always good. Let the pump prime about 3 times while I was cleaning up, fired it up with no hesitation. Nice smooth idle with no hiccups.

Ran the pressure test with insite, high press touched 29,250psi. After 90 seconds , pressure had dropped to 28,950psi. 300psi give or take 100psi for the numbers bouncing back and forth. Well within the acceptable limit. Engine temp about 150-160, idle set at 700rpm when the test was performed.

* Something to note with the test. May help others diagnose this issue before it has an external leak. When the high press test was performed with the compromised head, the engine began to jump around when pushed past the 22-23k psi mark. Not so with the new head. Very smooth idle all the way through the test (from 10k-29k psi). My engine had about 470k when the FP head failed. If you’re nearing or surpassed that mileage it may be a good idea to run the high pressure test and check for the stumble.

While Insite was connected did a cutout test of the injectors (isolated each injector so that the engine ran on that one only). Other than each test dropping about 40-50rpm, all cylinders audibly were very similar.

I'll report back with any updates if need be. So far it seems like the problem is resolved. Wish there was a way to catch it before it has an external leak, but not sure how much more proactive you can be with this situation. I'll be hitting the road (finally) on Sun for about a 600mi trip so it should be a good test of the repair.