Rick 12v CTD

a very very realistic look at why those seals fail me thinks

wheelieking71

interesting stuff! my truck has 245,000mi on the odometer. the pump has been off, and apart before (the paint seal on all the screws was broken). but i have no idea how long ago. the throttle linkage at the pump (the part with the rotary spring) was so worn out it had almost failed. i cant imagine anybody rebuilding the pump, and not replacing those parts, so i am guessing it has been together in its current state for a long time!




i am going to try and get the pump out in the next day or two. and then i will know for sure if it "blew" the seal, or physically pushed it out. if there is room for a snap-ring, i will most definitely be adding one. i am willing to bet, if there is a snap-ring, the pump can handle the pressure! my research tells me the high pressure lift pump maxes at around 50lbs? properly retained that seal should have no problem holding that pressure. i have guaged crankcase pressure in lots of chainsaw engines way above 50lbs, and never lost a seal in one of those. all of which are only held by friction.

apwatson50

There is not enough room to put a snap-ring in the case without first milling the seat deeper so the seal goes in further.

wheelieking71

thanks for the info. that will not be a problem (as long as there is room to go deeper).

1st921stgen

k im new to diesel. got a 92 cummins 12v how do i crank the pump up a little. dont care about the smoke i just want some more pep for towing.... it has a cold air and straight pipe. up the fuel pressure is all i want to do next... help is greatly appriciated

dieselJon

Check out the 1st thread/post called the Sticky. Look under there and rear all the links related before adjusting,

Rick 12v CTD

I can't really see the second gen pump getting to 50psi although I suppose it's a possibility.

I'll find out soon enough when I get everything together and have my gauge installed as well.

Also, wheel yeah my ip still on my motor had wear like that. I got a local shop to silver solder it so it would be ok. Seems to have worked ok too. Getting them to silver solder it was about $10. The cost of the parts from the local bosch shops were WAY more than that.

wheelieking71

yea, the shiny parts in this pic:



cost me well over $200!! and the bottom part (that actually splines to the shaft) is obsolete.

Rick 12v CTD

oh I know. It was the bosch dealer I went to when I was looking for those parts that told me to just silver solder it and save myself a ton of money.

So did the seal blow out or get pushed out of it's bore?

wheelieking71

noy sure yet. i should know tomorrow! the pump is just about ready to come out:



injector lines, fuel line, oil fill tube, gear nut, pop the gear, 3 mounting nuts, and its on the bench.

Rick 12v CTD

ima bump this as I hope and wait for the true issue with the front seal.

wheelieking71

the seal was still in its bore, but the added pressure "de-vulcanized" the rubber from the metal seal case:





i had intentions of somehow mechanically retaining the seal. but its not going to happen this go-round. first off, the snap ring is out. its not that its not "doable", but it would compromise the length of the bushing. or, i would have to "groove" the maximum diameter of the seal-land. not sure that would work either. then i thought about drilling and tapping the front of the pump, and bolting a plate to the front of the seal-boss. but im not sure how much room there is between the gear, and pump. so, i just pressed the new seal in, and reassembled the pump. i will be back here soon anyways, as i unfortunately discovered my main pump body is essentially garbage. i doctored it up, and am going to run it untill i buy a better pump. but it is definitely not a permanent fix. https://www.dieseltruckresource.com/...t295801p2.html

so, the plan now is to just regulate the fuel pressure. i already bought the regulator, fuel line/fittings. i just want to get my truck back on the road! LOL

Rick 12v CTD

hm bummer... so it seems that it's not so much the fuel pressure pushing out the front seal but the pressure ruining the front seal and leaving it in it's more.

I mean, I'd assume your front seal is as old as your truck is so that might have played a role in it's failure.

In any case this is good info. Looks like I'll be using my regulator after all. I'll probbaly just run it at 20psi though. I've heard of a few guys running 18-20 psi and have never seen or heard of any front seal failures from that.

In all honesty, I wouldn't be surprised if the front seal sees 40 or 50psi from a second gen pump. I know a second gen can get 40+ and the fuel return is very different and capable of returning a lot more fuel than a VE. That and there is no return on the inlet which is a distinctly different part of the pump than where the actual return is located under the AFC housing.

It's almost tempting to run a second gen pump just for a few minutes unregulated to see what kinda pressure I see...


Which regulator did you settle on?

wheelieking71

i went with the Mallory 4307M for a regulator. you could spend up to about $300 if you wanted to, but this one was $110, and i think it will accomplish the job just fine. and, i dont know if the seal in my pump was original, or not? the pump had definitely been into before (by somebody who definitely shouldnt have been there!) but that doesnt mean they replaced the front seal. and, it wouldnt surprise me in the least if they didnt. rather than replace the pump to timing housing gasket, they gooped it up with "blue-goo". i will say it again, some people should not be allowed to use tools.

Rick 12v CTD

yeah that's too bad... it's amazing the dumb stuff people do to save a couple bucks. I don't get why someone wouldn't do it once, and do it right. For their own sake, as well as for the sake of anyone who might own it after them. I even know a few people like that. Super cheap and try to fix things by jimmy rigging it. It's not my style, that's for sure.

And I went with the same regulator as you. the Mallory 4307M through Summit.