Engine/Transmission (1994 - 1998) The 'ol lift pump ticking...

[JGheen]

Ok, so I know that the lift pump can start to make a ticking sound over time due to the wear on the push rod on cam lobe, but what makes it come and go? I have been hearing my lift pump ticking intermitently just about every other day and sometimes throughout the day. It makes different tone ticking noises as well as seems to effect performance very minimally at times. The noises vary from the typical tick, tick, tick sound to something that almost sounds like the pump pumping fuel, hard to describe that sound. So, I am probably going to change the pump out tomorrow since it will be a big maintenance day for the truck, but I am curious to know about what makes the sound differences as well as it coming and going? Seems to have no effect on whether the engine is warm or cold.



One other thing, does anyone know what size threads the lift pump mounting bolts are? I want to replace them with studs after reading all the pump replacement threads explaining the easy of removal and installation with them.



Thanks, Joe

 

[Johnstra]

Hey, Joe. Regarding the difficulties around installing the lift pump... if you find TDC then bar the engine another 180-270*, you won't have much trouble at all installing the pump using the stock bolts. Not saying studs wouldn't be even easier, but it really is no big deal using the stock bolts if the cam is in the right position.



As to the ticking... I don't know why the sound changes. Mine had begun to tick pretty much all the time so I replaced it and the tick is gone. Has anyone ever checked the condition of the push rod bore in a used pump? Maybe it's just the rod finding different surfaces to slide against.



-john

 

[JGheen]

Thanks John,



On getting the cam lobe in the right position, I thought the engine just had to be at TDC on #1 for the lobe to be on the base circle? I am could be mistaken and the base circle of the lobe is probably found by turning the engine 180*~ past TDC on #1 like you mentioned, but I thought I would just double check that.



I hear ya on the push rod just probably finding it's own happy place everytime you start up and sometimes it ticks and sometimes it doesn't. Just got back home from work and the thing didn't tick at all until I pulled into the driveway and let 'er idle before shut down. Sounded fine when it started up at work, guess it found the happy place during the drive home.



Joe

 

[Johnstra]

Yes, the manual is clear: 180*-270* past TDC on #1. Joe Donnely also posted the same info recently.

-john

 

[DPinkston]

I am gonna take vacation next week and pull maintenance on my truck. Gonna adjust the valves, r&r the prefilter, install 3. 55s gears up front, install 215 injectors. My lift pump is ticking too, at least I think that is what it is. Priced a new one from the local Case/IH dealer at $106. Problem is mines a 97 and I read on here somewhere that this may be a transition year for using the Case pump so it may or may not work. They don't have one in stock and would have to order it. We all know about "special order" items and the "restocking fee" that goes with them so I am reluctant to order one. I'll ponder on it some more... .

Danny

 

[GAmes]

I am gonna take vacation next week and pull maintenance on my truck. Gonna adjust the valves, r&r the prefilter, install 3. 55s gears up front, install 215 injectors. My lift pump is ticking too, at least I think that is what it is. Priced a new one from the local Case/IH dealer at $106. Problem is mines a 97 and I read on here somewhere that this may be a transition year for using the Case pump so it may or may not work. They don't have one in stock and would have to order it. We all know about "special order" items and the "restocking fee" that goes with them so I am reluctant to order one. I'll ponder on it some more... .

Danny

The one I installed was from Case. I had to remove one of the fittings from my old pump and put it on the new one, not that tough.



Joe, I don't remember the size, but I do remember that the length of the studs was 50mm. When you go to the hardware store take a bolt with you.

 

[bkroupa]

Mine had a variable ticking noise for a while before I figured out what it was. My pump had a broken spring that would wind & unwind until one day it finally laid down. My pump had apparently been weak for a while, adding a new lift pump added enough power to make the stock clutch slip rolling on to pass. I don't think the '97 pump is any different, I used a pump listed for a '96 on my '98 because NAPA listed an electric lift pump for a '97 & up

 

[JGheen]

Got the pump changed out....

Well, I got the pump changed out today, haven't started it yet cuz I basically took my time and did other maintenance stuff during the day. Boy, that grommet for unusual fitting on top of the strainer is a weird deal. I hope it doesn't leak, I used an new grommet but I have never seen a fitting for a hard line into a boss like that before.

Removing it was the easiest thing, just took the starter off and got it out since the truck is 3' off the ground. :-laf Putting it back on was another story. #@$%! BUT. . I went to Orchard supply and got me some 30mm M8x1. 25 socket head bolts(the thread size of the bolts for the lift pump if anyone is interested ) as well as some 25mm(actual bolt length). The 30mm bolts threaded in nice and gave me 5 more mm of bolt length for bolting up the pump. Checked them before install and they didn't bottom out, so they worked great! Oh yeah, I was lucky and when the engine was shut down last, the pump ended up on the base circle of the cam, so I didn't have to roll the engine over any to get the pump back on! Oo. But it still was a pain to get it back on, took a bit of manuvering under the truck and trying to reach way up into the side of the engine from the ground. Got lots of new hand scars. :{

Hopefully this fixes the ticking and maybe gives me a bit more power if the other one was slightly faulty. Still looking for a proper fuel pressure checking gauge.



Joe

 

[MLee]

Joe;

Did you change out the heater to pump hose? Some say it needs to be longer. Would you do your change this way again or try from the top? on mine it looks like a pain to do it either way, just to much stuff in the way. Your 98 is easier to work on.

Marv.

 

[JGheen]

Marv, I did change out that hose and I had to cut both ends of it a bit cuz it was too long. I only took about 1/4" off of each end and the pump sat more flush against the fuel heater housing.



Joe

 

[MLee]

Thanks Joe, Is it a dealer or a Cummins part? being that it is formed. Do you have a number?

Marv.

 

[JGheen]

It's a Cummins part#3921680

 

[bkroupa]

easier access

I did mine without removing the starter or getting under the truck at all.

I removed the left front wheel & the inner fender (not neccesary on a 4wd). You can reach the lift pump through the wheel well opening very easily & get straight on the bolts with a long extension. I had no trouble pushing the pump straight in & starting the original bolts. I trimmed the inner fender like the 4wd's so I could easily change he pump on the side of the road if it ever happens again.

 

[MLee]

Thanks Joe.



bkroupa;;

The inner fender that you cut, was it the metal to gain a little more access? Looked at mine in that area and that would be all I could get through there would be be the extension with out doing a mod like that.

Marv.

 

[bkroupa]

No metal, just the plastic while I had it off.

I'd never done one before, but if I had it to do over I'd do it the same way.

 

[MLee]

Sounds like there is less metal in that area on the 98. Mine has about 2" above the frame of open space for access. Maybe that is why some guys grow arms 4' long when working on these trucks. access was not a word the design people new.

Marv.

 

[bmoeller]

Ok, so I know that the lift pump can start to make a ticking sound over time due to the wear on the push rod on cam lobe, but what makes it come and go?

The noise doesn't come from wear on the plunger and cam lobe. It is from the spring on the other end of the plunger. What happens is, they get tired over time. They get so that the spring will not return to full length when the lobe is on the base circle. That is what happened to mine. The length that is was short, was the amount of the plunger stroke.



Since there is no longer spring contact at all times keeping the plunger against the lobe, it makes the ticking noise.



The noise changes with the fuel pressure. Higher pressure, less noise. Less pressure, more noise.

 

[Johnstra]

Thanks for the explanation, bmoeller. That makes good sense.

-john

 

[Cooker]

If you have vacuum in the fuel tank it will create undue stress on the LP and cause the LP tick to come and go. On two trucks now I have fixed the intermittent LP tick by eliminating the vacuum in the fuel tank.



As mentioned the Case LP is the same but there is one fitting that is different on the Cummins LP. On some LP this fitting can be swapped, on some it cannot. On my 96 the fittings were not interchangeable. I posted some pictures some time back so you can identify if if you have the fitting that cannot be swapped.

 

[JGheen]

If you have vacuum in the fuel tank it will create undue stress on the LP and cause the LP tick to come and go. On two trucks now I have fixed the intermittent LP tick by eliminating the vacuum in the fuel tank.

So what was wrong with the tank? Did it have a good air leak on top of it somewhere to cause this vacuum?



Joe