4.3 timing chain - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pound41 · 04-30-2016, 06:38 PM

Hello I have a 2003 s10 blazer with 4.3. It has 107k on it and runs ok. The other day I got an intermittent code for a random misfire. It has had the diesel knocking sound since I got it about a year ago. Sound has gotten worse. Upon research I have found extremely common on 4.3 with different answers on serious or not. I am thinking of changing the timing chain set and tensioner.
Supposedly the tensioner is the noise maker. Anyway What is the best stuff to use. AC Delco or a better choice in the aftermarket stuff.
Thanks

95 S_Trucker · 05-01-2016, 06:20 PM

There is not a timing chain tensioner on that engine.

pound41 · 05-01-2016, 07:14 PM

http://www.s-seriesforum.com/forum/s...ad.php?t=75141
Look at the attached link. This is what I have found in many places. I have never taken one apart so I don't know
Thanks

95 S_Trucker · 05-01-2016, 07:29 PM

From the factory, these engines did not have a timing chain tensioner.

As the chain stretches, it can rattle on the slack side.

If the timing chain is the source of the noise, putting a new one on will solve the issue until it stretches again.

Installing the tensioner retrofit will take the slack out of a stretched chain.

It's a big job to get to the timing chain on these trucks as the oil pan has to come off. The means drop the front differential(4wd models) or removing the engine(2wd models)

pound41 · 05-01-2016, 10:59 PM

So is the tensioner GM's answer to stop the rattle. I have 2 2003 blazers. One rattles pretty good the other has some of the sound. I drove dozens before I bought these 2 never heard the sound in any of the others. I know when you got around 100k on older GM's it was good to change the timing chain. What is the life expectancy on these. Son is going to be taking the moisy one off to college in a few months.
Thanks

68C15 · 05-05-2016, 08:38 AM

You're "supposed" to remove the pan but you can use the same cheat method as older SBC's. Snip/grind corners of lip on bottom of timing cover then reseal with silicone

pound41 · 05-08-2016, 04:41 PM

I have done the corner snipping on the older one as well. Is there anything special about the 4.3 or go you just line the marks up on the gears or do you get high compression up on number 1 or is it another cylinder
Thanks

04-30-2016, 06:38 PM	#1
pound41 Registered User Join Date: Dec 2002 Location: Northern Virginia Posts: 1,268	4.3 timing chain Hello I have a 2003 s10 blazer with 4.3. It has 107k on it and runs ok. The other day I got an intermittent code for a random misfire. It has had the diesel knocking sound since I got it about a year ago. Sound has gotten worse. Upon research I have found extremely common on 4.3 with different answers on serious or not. I am thinking of changing the timing chain set and tensioner. Supposedly the tensioner is the noise maker. Anyway What is the best stuff to use. AC Delco or a better choice in the aftermarket stuff. Thanks

05-01-2016, 06:20 PM	#2
95 S_Trucker Registered User Join Date: Oct 2009 Location: . Posts: 2,187	Re: 4.3 timing chain There is not a timing chain tensioner on that engine.

05-01-2016, 07:14 PM	#3
pound41 Registered User Join Date: Dec 2002 Location: Northern Virginia Posts: 1,268	Re: 4.3 timing chain http://www.s-seriesforum.com/forum/s...ad.php?t=75141 Look at the attached link. This is what I have found in many places. I have never taken one apart so I don't know Thanks

05-01-2016, 07:29 PM	#4
95 S_Trucker Registered User Join Date: Oct 2009 Location: . Posts: 2,187	Re: 4.3 timing chain From the factory, these engines did not have a timing chain tensioner. As the chain stretches, it can rattle on the slack side. If the timing chain is the source of the noise, putting a new one on will solve the issue until it stretches again. Installing the tensioner retrofit will take the slack out of a stretched chain. It's a big job to get to the timing chain on these trucks as the oil pan has to come off. The means drop the front differential(4wd models) or removing the engine(2wd models)

05-01-2016, 10:59 PM	#5
pound41 Registered User Join Date: Dec 2002 Location: Northern Virginia Posts: 1,268	Re: 4.3 timing chain So is the tensioner GM's answer to stop the rattle. I have 2 2003 blazers. One rattles pretty good the other has some of the sound. I drove dozens before I bought these 2 never heard the sound in any of the others. I know when you got around 100k on older GM's it was good to change the timing chain. What is the life expectancy on these. Son is going to be taking the moisy one off to college in a few months. Thanks

05-05-2016, 08:38 AM	#6
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: 4.3 timing chain You're "supposed" to remove the pan but you can use the same cheat method as older SBC's. Snip/grind corners of lip on bottom of timing cover then reseal with silicone __________________ Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card

05-08-2016, 04:41 PM	#7
pound41 Registered User Join Date: Dec 2002 Location: Northern Virginia Posts: 1,268	Re: 4.3 timing chain I have done the corner snipping on the older one as well. Is there anything special about the 4.3 or go you just line the marks up on the gears or do you get high compression up on number 1 or is it another cylinder Thanks



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