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05-25-2010 12:23 PM #1
Hurst... STOP !!!! It might not need a Valve job... I was a GM line tech in the 80's-90's and 00's. The 94 engine used a Linear EGR valve that gave us a fit. Sometimes the valve itself would be bad, OR a hunk of carbon would get hung up in it and stick it open. Now, it gives the syptoms of a fried valve. So, pull off the EGR, check it for chunks of carbon stuck in the printle valve. If nothing there, then get the valve checked. Also, if there is a hunk of carbon in it, pick it out, then cap the hole going to the intake side and start it up with the valve off, this will blow any other loose carbon out. then reinstall valve. It would also explain the sooted up spark plugs. It can cause, low power, bad or no idling, excessive black tailpipe smoke, and a miss. The problem was so bad, a service bulletin was issued to address it;
( I stole this off another site )
Repeat failure
Repeat failure is a common problem. You can recommend a top engine clean to the customer and attempt to clean loose carbon from the upper intake. GM has noted the problem and come up with a software update for the PCM. Essentially, what the update does is periodically command the EGR to 100 percent opening to prevent or flush out carbon chunks. The new prom numbers were in a "special policy" procedure bulletin and not a regular TSB. The special policy number is 96067(A). It refers to '92-'94 S/T, M/L and C trucks with the 4.3 V6 engine and linear EGR valve. The bulletin number is 67-65-38. It refers to '95 C, S/T and M/L trucks with the 4.3 V6 engine and linear EGR valve.Last edited by Weasel Diesel; 05-25-2010 at 12:35 PM.
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05-26-2010 12:23 AM #2
Weasel Diesel,
Thanks for the information. I have not seen the truck for almost a year. I was planning to have a look at it later this week. I would not have just yanked it apart without checking it though. No way I would take someone's word for something like that, too much work.
If I pull it apart it is because it needed it.
I was unaware of the bulletin that GM had put out on the 4.3. It has been several years since I worked for GM. It was far enough back that we were not called Techs.
I certainly appreciate you taking the time and trouble to post this information, it will give me a heads up and I will check it first thing.
I have always found this to be a pretty decent site to find information.Ed in Jeffersonville, IN
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