Cold engine clicking

chase777chase777 Member Posts: 2
edited March 2014 in Chevrolet
I have a 1998 6 cylinder Astro LS. Last year when the weather got cold my engine
would make a clicking noise until it warmed up. I took it to the dealer service
center and they stated due to the age of my van this is normal and advised me to
change the oil to a synthetic. After a few weeks the clicking went away.

On 01/24 I had the oil changed (somewhere else) and told them I needed a
synthetic, and was told they use a synthetic blend. Two days ago the clicking
came back even louder. Again as soon as the van warms up it goes away. I called
the dealer and they stated "you can bring it in if you want" like there was
really nothing wrong. Has anyone else had this problem or do you have any ideas?
I am thinking of having the oil changed again to 100% synthetic (if that is what
the dealer used).


  • spike99spike99 Member Posts: 239
    Sounds like "piston knock" (or in its early stages "piston ticking") to me.

    This is a known problem with GM 4.3L engines. Especially when the engine endures lots of miles. As a suggestion, do use 100% synthetic engine oil. Some folks like Mobile 1. Others like Amsoil. Use what brand of oil and rating based on your comfort (and weather location).

    Will "piston slap" create long term problems? Some say YES and some say NO. Jurry is still out on this question. As a suggestion, continue to use 100% Synthetic engine oil - even if only piece of mind (about long term engine damage question).

    For lots of info engine knocking, do a google search of "4.3 piston slap". Lots of info to review yourself. Or, click q=4%2e3+piston+slap

    Hope this helps...

  • spike99spike99 Member Posts: 239
    Here's an info extract from one of the sites found by google...


    From Piston Slap!

    Are you a GM truck owner experiencing from loud knocking or excessive engine noise? You are not alone! 1000's of other consumers are also reporting these symptoms. What you may be suffering from is the now infamous phenomenon known as Piston Slap.

    What is Piston Slap?

    Piston slap is caused when there's too much space between the piston and the cylinder wall. The piston moves up and down in the cylinder and the extra clearance results in a greater amount of rocking in the cylinder, producing a loud knocking noise. Vehicles with the engine knock problem include 1999 - 2002 GMC and Chevy pickups and sports-utility models with 3.1, 3.4, 4.3, 4.6 (Northstar), 4.8, 5.3, 5.7(LS1), 6.0 or 8.1 liter engines. Specific models include (but may not be limited to): Chevrolet Silverado, Tahoe and Suburban, GMC Sierra, Yukon and Yukon XL. The 2002 Cadillac Escalade SUV also reportedly suffers from the problem.

    Can Piston Slap damage my engine?

    GM spokeswoman Deborah Frakes states: "the only known effect of this condition is an audible sound that typically occurs during the first five to thirty seconds after starting" and that "the condition does not create any degradation of durability, performance or safety." In fact, in several of their Technical Service Bulletins (TSB's), GM claims that the "Cold Start Knock" is normal.

    Consumers have differing opinions. GM truck owners complain that piston slap damages the engine and causes excessive oil and fuel consumption. Many consumers suffering from piston slap report that the knocking is constant, lasting well beyond the initial start-up, and appears regardless of the temperature. Additionally, consumers argue that the problem lowers the value of their vehicle when they try to sell it or trade it in. In a recent article in the Detroit Free Press, Charlie Vogelheim, an executive from Kelly Blue Book, said " a knocking engine could lower the value of a vehicle by $4000 to $6000 at trade-in."

    Is There Anything I Can Do?

    If you would like to know whether or not a legitimate claim for recovery under the lemon law is available to you, take a moment to read through this web site or contact any of the attorneys listed. There is no cost or fee for doing so.

    The website has been used as a source for some of the information above. is an excellent resource for additional in
  • chase777chase777 Member Posts: 2
    Thanks....that confirms it and explains why the GM service center wants to dismiss this problem as nothing. I will get the oil changed and go with the 100% synthetic ASAP. I only have 61,000 original miles on this van and I am the original owner. I have always had the oil changed every 3000 miles or sooner. Thanks again for the info. I did not know what to call it other than clicking.

    One thing I just thought of....when my van was 6 months old some of the oil lines were put in the wrong place and burned through, causing it to leak out a lot of oil. They fixed it under warranty and I caught it before all the oil ran out. About 2 years ago it started missing and they thought it was the fuel pump after $850.00 It was still missing. Then they found out it was the coil, dist cap, pluges, etc..basically a total tune up plus some, Ended up costing me over $2000.00 (the fuel pump would have been fine) I should probably goto another GM service center.
  • spike99spike99 Member Posts: 239
    Over time, the factory oil lines do leak - regardless of how they are installed. To me, the piping material of the factory oil lines must be different. Proper galvanized steel piping (instead of soft aluminum) and its rubber should be double layered - like hydronlic hose. If you shop around, some piping / machine shops create much better piping. Simply bring them your original leaking oil lines (ya, your vehicle may have to site for 7 days or so) and the shop will "clone them" to create much better piping. And, its often 1/3 the cost that GM charges. Something to think of - if you see your new oil lines starting a slow leak.

    My local auto shop "wasted my dollars" chasing down a brake problem as well. Master cylinder, new front rotors (thinking the first set were warped) and new pads. In the end, they discovered it was a bad front wheel sensor - and its computer wasn't registering an error code. Its unfortunate that even "the best of the best" mechanics have difficulties chasing down certain problems. Luckily, my van was finally fixed as well. Only you can decide if you want to re-visit your local GM auto (or non-GM) shop. Good luck on what ever you decide...

  • biker70zbiker70z Member Posts: 1
    I have a 5.3 chevy and it calls for 5W-30. I found that running Mobil1 5W-20 will eliminate this problem. Royal Purple and other pure synthetic oills won't help as I have tried. It is very annoying to hear knocking noise coming from expensive engines as you all know. I heard it is caused by an oil pickup tube issue that was a poor design. My thought are GM should have recalled this issue, but thats GM. Anyways, try that oil and please let me know how it worked for you.
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