3406B 7FB series cam into the shop yesterday leaking fuel around the #3 injector pump, nobiggy do a bonnet seal ring... still leaking... rats maybe I screwed up the oring… Install another... Now its worse and nothing was wrong with the first, no nicks or cuts from threads on the bushing. Maybe the injector line is leaking under the nut even though the line seat looks ok. Nope still have a leak with a small "pulse". Is there a place where the barrel can get a hairline crack and leak? The seat in the barrel looks good, no garbage under the bushing nut. This is driving me crazy. I guess tomorrow I pull the compressor off to get a better view and pull the # 3 pump to get an even better view. I bet I've done 75 bonnet seals with out an issue. Did 3 on a 3306 once in 20 minutes... On a hot engine.
Don't go completely nuts, I have a call into my top Cat-Cat injector pump rebuild man, the best one I've ever run on to. So hold on when I get a call from him I will call you. Truck Shop
Thanks, I figured you would know the right guy. The dealer guys I talked to weren't much help.
Check the sleeve on the injection line I've ran in to a lot of leaks on these that were cracked ,dished etc. Bob
I forgot to mention that I did install a new line too. No difference.
This spring a guy I have lunch with said I smell diesel in my van. so I looked and #3 injector line nut was leaking at the nozzle adaptor on a ISB Cummins .I backed it off and retightened it ,quit leaking. About a month later I was helping the local Cummins guru we replaced all 6 lines and adapters when we resealed the front of the motor.Number 3 leaked and we put the old line back on and ran it. Three new lines later it is still running the old line ,Cummins has no idea why all the new lines leak? We are waiting for a new line from a different manufacturing batch. Bob
Yeah, I did the "back off and progressively retighten" thing here too. no change, put the original line back on, no change... Gonna pressurize the gallery chamber with about 60 psi tomorrow and see if that makes the o-ring leak. If not, then pull #3 pump and get a close up inspection. That barrel is so thick I really cant see it cracking through the threads or even having any other hairline crack anywhere else. The other thing I cant find out is if there were any variations on the o-ring part numbers, maybe different thicknesses of O-rings? Cat has done this hole before, 2 weeks later it was seeping, they replaced the o-ring again, 2 weeks it was seeping again. Something is not right here.
Change the bonnet.. They will get corroded &/or crack at the sealing surface.. The barrels will crack.. but its more likely the bonnet..
It's fixed, hairline crack at the injector line sealing cup on the bonnet, almost impossible to see. I imagine the new injector line spread the crack more than the old line. Borrowed a bonnet out of a junk 3406C (rod through the block) and life is good again.
Told ya.. happens all the time.
It was a first for me...
Wonderful... this thing is coming back next week. Now #2 and 4 are seeping fuel. Supposedly Cat did this entire housing off the engine a year ago. $3000 bill. The one bonnet I changed had been lapped on the bottom with the roughest lapping job I have ever seen, I would scream if it was a hydraulic pump with that lap job. Guess I'll order up a couple bonnets and see. Oh, I found out that Cat had redone a couple of seals since they did the pump and now "its out of warrantee". P.S.... Customer is not mad at me, He would just like the issue cured.
A suggestion. You've done #3 already. It's coming back for #2 & #4. Why not do #1, #5, & #6 while you're at it to save you the headache of it coming back again with one of them leaking..? T'would be easier to do them all at once would it not..?
That's my plan this time. But my point is that the Cat dealer has been in this thing twice and now it's stuck on me to get it right. Less than a year since all was "redone" by them.
Order MORE ORINGS than u think u need.. & find the CORRECT torque setting..
Brought it in yesterday, checked the torque on the other 5 bushings, took more than several degrees of turn to hit the 160 lb ft click. So far 4 trips and no seeps. My manual says 160 and its fairly old. Is there a newer spec. ?
160 is it. Truck Shop
That's what I thought +/- 10? these were probably around 150 or so. Should have got out the dial type to see where they started to move. Oh well, no leaks for now.
Bob, Three conflicting torque settings here ........... 160, 170, or 180. All values +/-10. Take your pick. FWIW the one with the most recent date on it says 180.
When I had my hands on 1.. I torqued them to 160-170 ftlbs. IF you "floogle" it.. theres a SB from Dipaco, an aftermarket co., that changes "their" torque setting to 190.. BUT that's for THEIR oring.. {aftermarket}
Thanks Nige, I'll keep that in mind on the next one. 160 has always worked for me in the past.