Noisy GM 4.3 V6 at startup

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nomochevys

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Truck had been sitting for a long time and I fired it up yesterday and it made a clack clack clack noise that it has never made before. Then it quieted down after a minute or so gradually. Same thing this morning. It was about 40 degrees outside.

This engine was neglected at one point and the oil had not been changed in a few years and when I drained it sludge came out in clumps. The filter was a mess and at least did its job. The old truck is was just not used much but now its going to be back on the road full time. I think I have a mess on my hands.

What is making the noise at startup? Lifters? I have all kinds of little problems with it to try to sort out. It does not use or leak oil at all and runs great for what it is.

One more question. How hard is it to change the serpentine belt on these? This one is original and 17 years old. It looks ok but I dont want to trust it too far since I will be driving this truck a good ways each day from home. Thanks.
 
My 98 doesn't get a ton of use. The only time I've ever had this is when running a Fram and a super tech filter. Using regular delco, the delco ultra guard gold, and the new Fram ultra, no issues.
 
I'd start by Changing the filter again.

I've seen lots of cold start issues with clogged filters in older cars.
They sound terrible until it gets enough pressure/lubrication to everything.

If you haven't changed the oil in a few years, do that again also.
Moisture builds up in the oil if it isn't run up to temp regularly.
A few years is all it would take to make a oil/water emulsion that could really hurt an engine.

What is the 4.3 V6 in?
Make and Model?
 
Could have been the lifters. Could have been the lower end. In that scenario either would make sense. Without having been there to hear it myself it's tough to say, but I'd bet it was lifters. If it has stopped making that noise on start up then just chalk it up to not having been started in a long time.

I would be more concerned with cleaning the engine out by using an oil that is known for it's cleaning abilities. A cheapish conventional would be Pennzoil yellow bottle, Pennzoil Ultra is better yet, reportedly, but more expensive. There are other oils that will clean aggressively, but Pennzoil is good. This is a situation where a larger filter could be beneficial, like the AC Delco PF52 versus the PF47. It will hold a little more of the extra gunk that will be flowing through the oiling system while the PYB is cleaning things up. And short OCIs would probably be a good idea for awhile.

The belt is easy enough to change. If there is a diagram under the hood be sure to check that it's right, and if there isn't one draw one out before you start.

I don't know if KY has Safety or Emissions testing but if so you might want to get that done before spending money in the wrong places.
 
Not uncommon for 4.3 or and GM small block V8 to have lifter noise and it's rarely serious .

If the oil needs a change I would do that and monitor how it looks . A few good runs will likely cure the noisy lifter if it's used regularly .

I have a 97 GMC with a 4.3 BTW and it rattles a little if it's been sitting which it does a lot .

Also.....lower end noise does not go away , maybe some piston slap when cold but certainly not con rod noise !
 
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Originally Posted By: JHZR2
My 98 doesn't get a ton of use. The only time I've ever had this is when running a Fram and a super tech filter. Using regular delco, the delco ultra guard gold, and the new Fram ultra, no issues.


+1 on the filter train.
After sitting for a while the oil will drain out of the top end causing the noise at start up.
If it was neglected I suggest a few quick oil change intervals with some mmo then a synthetic with a good filter with a known quality anti-drain back valve.
A syn should finish the clean up started with the mmo and a quality filter will help keep oil in the top end eliminating the start up noise.
 
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Just changed the serpentine belt on my 4.3 last week and I believe it was original too . Not hard to change , you should have a routing sticker right there under the hood and the belt tensioner has a spot where you can put a ratchet in it to use as a release lever , A bit of fun getting around the fan/fan shroud but just check and make sure it is on all the pullys correctly and not on the edge of one .
 
I have a 96 with a 5.7, it sure does love a Wix filter and I believe it runs the quietest on 10w30 Castrol GTX HM, but I've been running Valvoline NextGen Maxlife 10w40 since i still have about 50 quarts of it left, which it's a little bit louder on.
 
have to consider if its been sitting for awhile some of thos lifters have been at rest with the valve spring compressed and the lifters may have bled down. give it some time and a new filter and oil it'll probably quit doing it soon.
 
Thanks for all of the replies and its a 96 Gmc Sonoma. I checked the oil this morning and it was clean and full but I have to look at my records to see how long ago time wise I changed it. I know for a fact the truck has never had anything but delco Pf52 filters. I may out to change that out and add a quart first to see if it does any good.

This truck has issues but I dont think any of them are terminal. Once the thing gets warmed up its smooth and quiet as can be. I am going to china mart sunday to see about getting some pennzoil dino oil for a quick change also. The real problem here is that the truck needs to be used more instead of sitting.
 
Originally Posted By: ram_man
have to consider if its been sitting for awhile some of thos lifters have been at rest with the valve spring compressed and the lifters may have bled down. give it some time and a new filter and oil it'll probably quit doing it soon.


I have a feeling you are right. I just not ever heard this before out of this truck. I dont think its bottom end or I would hear it all of the time or at least hear it some. With cold weather coming on and since the truck has to sit outside I will paranoid for sometime to come.
 
98 Astro awx w/205k. has cold start up click and clack was told the engine is "tsb'ed" for piston slap. my brother pays no attention. after 85+k..

ken

these motors are bulletproof. I run whatever is is setting around at 7-10k. will out last the van.Vande
 
GM V6's can have loud lifters sometimes, its not a problem. They will bang around for thousands of hours, turn the radio up. I was in a 2013 the other day with 5k on it that did it, its just what they do.

With that vintage of 4.3 watch the coolant level, the intake manifold gaskets were all bad from the factory. They didn't sort that out to the 2000's.
 
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Originally Posted By: hattaresguy
GM V6's can have loud lifters sometimes, its not a problem. They will bang around for thousands of hours, turn the radio up. I was in a 2013 the other day with 5k on it that did it, its just what they do.

With that vintage of 4.3 watch the coolant level, the intake manifold gaskets were all bad from the factory. They didn't sort that out to the 2000's.



Just put in a new thermostat today. I hate to do it but I probably really should do a UOA on this thing to make sure I dont have an intake leak. It clattered around this morning again but didnt seem as bad or as long. I also put in some PYB today with a new filter. I am glad to hear this is not the end of the world. The engine is really quiet once it gets warmed up. I am just trying to get it in good shape to be dependable.
 
I wouldn't waste the money, just see if it burns coolant. If it does change the gaskets.

Remember nothing will run poorer for longer than a GM.
 
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Originally Posted By: hattaresguy
I wouldn't waste the money, just see if it burns coolant. If it does change the gaskets.

Remember nothing will run poorer for longer than a GM.


Well, it was a tad low in the radiator and the over flow tank did not have a drop in it. I topped both off this afternoon. I will keeep an eye on it. I am actually scared to death the heater core may have suffered from the dexcool that came in these things way back when. Heater is working ok though and I dont smell anything .
 
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Originally Posted By: Blkstanger
Sounds like you are on the right track. Worst thing for a vehicle is to let them sit.


Its not sitting anymore. I put 120 miles on it yesterday! Other than being loose and rattly like many Gm's were from that era it is running good. Just trying to get the basics sorted out. I think the drive train has a lot of life left in it. I noticed yesterday it didnt make the clacking noise at start up hardly at all. I think driving it more is helping if that makes any sense.
 
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