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Smokes on start up after sitting for a few hours and will stop after 3- 4 minutes?

Tiny
JIM!!
  • MEMBER
  • 1989 GMC JIMMY
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
I have not noticed any oil consumption or water. Before I go to valve stem seals would like second option had a friend tell me I should lock at ECU. It has a faint smell of gas catalytic is new/plugs/cap/rotor/wires/and module are new as well. I passed smog check no problem. Thanks for any advice.
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Sunday, November 6th, 2022 AT 9:36 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

The ECU has nothing to do with this. It sounds like you are on the right path with the valve seals. Keep in mind, with 150,000 on it, the valve guides can cause issues as well, but the seals usually take care of the problem.

When you have the valve covers off to do this, make sure the oil returns in the heads are clear.

Also, I found an old technical service bulletin. I don't feel this is the issue but want you to be aware of it.

Let me know how things turn out for you.

Take care,

Joe

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Sunday, November 6th, 2022 AT 9:52 PM
Tiny
JIM!!
  • MEMBER
  • 4 POSTS
Thank you Joe. I would all like to know if a Chevrolet 350 will bolt up to my 700r4 transmission I have in this GMC. I'm building this for my next project car but can't seem to find anything in my price range I'm thing I need to change distributor and intake cause the GMC is a throttle body set up. And thank you for the first answer.
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Sunday, November 6th, 2022 AT 10:13 PM
Tiny
JIM!!
  • MEMBER
  • 4 POSTS
Smoke problem is with 1989 GMC Jimmy just thinking about changing engine from 5.7 to 350.
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Sunday, November 6th, 2022 AT 10:15 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

It should be the same engine. It's a corporate GM engine used in multiple vehicles. So, yes it will bolt up for you.

Let me know what you plan.

Take care,

Joe
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Monday, November 7th, 2022 AT 6:15 PM

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