Engine/Transmission (1994 - 1998) 98 12v 4x4 annoying ticking noise during idle

[UhhhDawson]

i bought a 98 12v 2500 4x4 a couple months ago with 144k on it. it seems to be doing fine, but the engine or something close to it makes this INCREDIBLY annoying ticking sound when it idles and also when it revs but it is harder to hear because of the engine itself and the turbo. anyway, it isnt a knocking sound, it sounds like a piece of thin metal that is spinning brushing something. when i stand beside the truck while it is running the sound seems to come from underneath the drivers side, but when i actually get under the truck it seems to be coming from up in the engine compartment at the back of the engine close to the firewall. sorry this is so long-winded, i would appreciate any suggestions!

 

[trucknut]

Mechanical Lift Pump!

My 98 12v did the same noise that your describing. It also made a strange noise on the down shift. After changing out the lift pump the noises disappeared.

 

[Ol'TrailDog]

As a reminder the valve lash adjustment interval on the 12v is every 25k.

 

[Bobcat698]

My 98 12v did the same noise that your describing. It also made a strange noise on the down shift. After changing out the lift pump the noises disappeared.

To verify that the lift pump is indeed the culprit, with the engine running & the ticking noise occuring, push on the rubber primer-plunger on the lift pump. If the ticking subsides, that is your problem.

 

[San Felipe Bob]

overflow valve

Sounds like the overflow valve.

Check the fuel pressures.



SFB

 

[TPCDrafting]

It's the lift pump, mine has done it off/on for the last 6 years. More so when it's cold.

 

[FDavid]

Its just the nature of the lift pump. I had that ticking sound too so I checked my fuel pressure and everything was right on spec. I went to cummins anyway and got a brand new lift pump and overflow valve and its still doing it. The tech there explained to me not to worry about it and that its just the nature of some lift pumps.

 

[Matthug]

Sometimes people don't do the valve lash adjustment on the 6th cylinder since it's so far back in there... sometimes the 5th too.

 

[bmoeller]

When the lift gets some miles on it, the springs get tired. Mine was ticking very loudly, and replaced it. When swapping 2 fittings around, I found that the spring was no longer going back to its original length. Was almost as short as its amount of stroke.

 

[WMonroe]

Mine ticks pretty loud also. Most noticeable when standing at the drivers door. The lift pump was brand new in december. I'm not too worried about it.

Will

 

[RHARVEY]

Mine has been getting louder over the last couple of months or so. The ticking I am hearing sound like its coming from the fuel tank. I can put my ear up against the tank and I can really hear it. .

Looks like I will be doing a fuel pump. . this one has approx 120k on it... What would cause it to tick like that???



Thanks

Rick

 

[JTEdieselram]

I have had the same problem, IT IS the lift pump, as soon as I swaped mine out with the FASS system the noise went away. I know how freakin' anoying that sound is! I will say that the lift pump on my truck never quit working, it just drove me crazy, hope this helps you!