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Two questions on my 98 GMC Sierra

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New User

Aug 17, 2010, 3:57 PM

Post #1 of 3 (2728 views)
Two questions on my 98 GMC Sierra Sign In

Hello folks,

I just got home from Afghanistan and was given a truck by my dad which I am really thankful for. The truck has some miles on it though and it has a couple of issues that I can't quite figure out so here are the details:

Year: 1998
Make: GMC
Model: Sierra K1500 4x4 SLE Crew Cab
Engine Size: 350 not sure how many liters I apologize
Mileage: 206,321

Alrighty, so I was given the truck with pretty limited knowledge of what has and hasn't been done knowing only that my dad and I changed the oil and the oil filter when I got it. I already plan on the standard changing of plugs, fuel filters, trans fluid and filter and probably the plug wires. I also know it has the K&N Air Filter on it which I need to get the cleaning kit for and clean it up.

Now on to my issues:

1) Whenever I first start the truck after it has been sitting a while whether it is morning or afternoon and hot or cool outside (from what I could tell so far) then the truck wants to stall a little, particularly on a sloped surface. What it does is for the first, maybe 30 seconds I am in motion it sort of stalls and has very little power. Sometimes it will make a loud pop noise as it goes through the gears (at least from what I can tell this is when the noise happens) other times it will just do the stall and take it's time building up power. After this initial period of about 30 seconds then everything runs fine, no stalling or sputtering and it shifts gears perfectly. I've asked people and I get everything from transmission to rear differential to fuel problems as a possible cause. Also, the service engine soon light comes on from time to time but not really on any pattern and I am trying to get an OBD 2 reader now to check out what fault codes I might have.

2) Whenever I turn on the A/C the belt squeals like a banshee until I get the truck up to about 2500 RPMs and then it stops. When my dad put belt treatment on it it stopped squealing though. Also, whenever I cleaned and sprayed out the engine it did it with or without the A/C on. Not sure if it needs a new belt or tensioner but it has a new alternator already. Thank you in advance for any help or advice you can offer.


Veteran / Moderator
Sidom profile image

Aug 17, 2010, 4:16 PM

Post #2 of 3 (2721 views)
Re: Two questions on my 98 GMC Sierra Sign In

A couple of quick checks you can do...

Those are good for bad check valves in the fuel pump, pressure bleeds off and takes a bit to build up. You can check the pressure to confirm this with a gauge or a simple test would be to just cycle the key from the off to on position about 5 or 6 times. Leave it on for a few seconds & off for a few seconds, basically do it slowly. If it starts & runs fine after doing this you are pretty much looking at a fuel problems.

With serp belts, you can't put anything on them. That will actually make it worse. Belt dressing was "meant" for V belts as a work around to replacing a worn out belt....

Clean all the pulleys real good with carb clean and try a new belt with a tensioner.............

(This post was edited by Sidom on Aug 17, 2010, 4:17 PM)

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 17, 2010, 4:48 PM

Post #3 of 3 (2714 views)
Re: Two questions on my 98 GMC Sierra Sign In

Afganvet: My gratitude to you for your service!

Sidom pretty well summed up the areas to be checking. The belt is probably trash and so is the tensioner. Probably hearing belt squeal from alternator trying to rechage up after the start up. It shouldn't. Check battery is strong or it's just working alternator too hard.

350 means 5.7 liter. Same same. If your VIN# has an "R" in it it's the Vortec 5.7.

Own one. Runs new but has no miles. Already ate the intake gasket common to these.

Check front end parts. These are a nightmare to properly grease and many never get touched. Don't forget there's one on the driveshaft to the back.

If this isn't a rustbucket it's worth some investment IMO.

As Sidom said fuel issues are common to but you can get thru those and on to a great running truck.

Good luck. Ask away with any questions you may come across,


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