Started running sluggish and the idle was up and down and would shut off?

Tiny
ZAKKARY
  • MEMBER
  • 1998 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 100,000 MILES
It started running sluggishly and the idle was up and down and would shut off sometimes when you drove it. But I replaced the timing chain and sprockets because it jumped time just a little bit and crankshaft sensor and distributor/camshaft sensor and re-tuned it with a jet performance tool. I also ran seafoam through it. It will start but it squeals while idling or driving which is probably my powering steering pulley and has a rough idle that goes up and down. Also sounds like a knock in the bottom end I was just curious if it could be something simple before I switch the engine. (Was told the engine and transmission was basically new when I got which it did look clean)
Wednesday, April 5th, 2023 AT 8:52 AM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,397 POSTS
It sounds like you could have low compression on one cylinder, a broken valve spring or vacuum leak. Can you please shoot a quick video with your phone so I can hear the noise? That way I can tell for sure what's going on for sure. You can upload it here with your response. Also, this guide may help:

https://www.2carpros.com/articles/stall-at-idle

And use this guide when the engine is cold only:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Was this
answer
helpful?
Yes
No
Wednesday, April 5th, 2023 AT 9:49 AM
Tiny
ZAKKARY
  • MEMBER
  • 4 POSTS
Here.
Was this
answer
helpful?
Yes
No
Wednesday, April 5th, 2023 AT 10:05 AM
Tiny
ZAKKARY
  • MEMBER
  • 4 POSTS
You can also hear the vacuum idle up and down, but you can barely hear it in the video.
Was this
answer
helpful?
Yes
No
Wednesday, April 5th, 2023 AT 10:09 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,397 POSTS
Thanks for the video, it helps. I would remove the serpentine belt and start the engine for a few seconds to see if the squeaking noise goes away, if so, spin the front accessories to see which pulley is making the noise. Next, I would do a compression test because you may have a head gasket blown between two cylinders. Please use this guide:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and report back.
Was this
answer
helpful?
Yes
No
Thursday, April 6th, 2023 AT 11:07 AM
Tiny
ZAKKARY
  • MEMBER
  • 4 POSTS
I'll look when I get the time thanks for the assistance!
Was this
answer
helpful?
Yes
No
Thursday, April 6th, 2023 AT 8:16 PM

Please login or register to post a reply.

Sponsored links