"Cold Start Diagnosis"

mandirigma01 · 02-04-2003, 12:15 PM

See my original thread "'01 to "02 Yukon Denali". Anyway, I brought my Denali in to have a Cold Sart diagnosis done on the vehicle and the service rep. just called me back this morning and told me that I do have a knocking sound. Possibly a piston problem. I suggest ALL yukon owners to get this diagnosis done ASAP BEFORE their regular warranty expires, unless you have an extended warranty. The person that I met who had this same problem got a brand spanking new engine from GMC.

You may ask yourself why wouldn't this be a recall? IMHO it would cost too much money for GMC. If only a handful of people found out about this problem it wouldn't cost as much as a TOTAL RECALL! I'll keep everyone updated on this forum.

jhermiz · 02-05-2003, 08:05 PM

As I stated before this is not a problem with all Yukon's. My Yukon SLT has no such noise. So yes it might be wise to investigate...no this is not a recall. GMC would get sued if it were a true diagnosis on all vehicles.

Jon

bowtiebandit · 02-05-2003, 09:52 PM

I'm suprised your advisor didn't tell you the real story on this. If it is the normal piston slap noise that most of the Generation 3 engines have I bet you it goes away when warm. What causes this is a few differnt things. 1. The engine was designed with minimal piston skirts to achieve the performance that everyone is after. 2. Todays gas. 3. What actually causes the noise is carbon buildup on the piston surface and sides. I have seen pictures of engines with 200 and 300k on them that all have had documented noise concerns. GM had given these customers new engines just to see how they where doing and when torn down the cylinder walls still had crosshatches and the bearings where obviously worn but not spun. I know they had looked into teflon coating the piston skirts for newer vehicle's only for customer satisfaction.
I have personally taken 3 apart and cleaned the surface of the pistons to remedy this, it works great but only lasts about 15k. You may want to try going to your local parts store and look for a product that can clean this without tearing your engine apart. GM has a product called Top Engine Cleaner that does a damn good job of it. If you noise does go away when warm thats probably it, as they warm the carbon softens or decrystalizes and stops making noise.

lynndeeh · 03-22-2003, 02:00 PM

I am looking for information. I have a 2001 Yukon that has what I would call a 'knocking' noise. Actually, it is more of a loud ticking sound. When the car was new, it only did it on a cold start. Now, with 34,000 miles on it, the noise is constant. The dealer says there is nothing wrong, "they all do that." My guess is that if they all did that, it would be listed as a feature of some sort.......

bowtiebandit · 03-22-2003, 07:07 PM

There are a couple 0f issues GM is looking at for possible areas of concern with the Gen III engines.
1. Needle bearings from the rocker arms coming apart and ending up in the oil pan.
2. Oil pump pickup tube O'ring splitting aerating the oil.
3. Piston issues from excessive carbon buildup on the ring-land sides.

Most engine noises on initial startup are not " issues " with these engines but a continuing noise is a problem.

lynndeeh · 03-22-2003, 08:26 PM

BoeTieBandit - Thank you for the info. I'll take it back to the folks that tell me 'they all do that'. I'll let you know what happens.

lynndeeh · 03-22-2003, 08:30 PM

bowtiebandit - next time I'll get your name right. Sorry about that.

lynndeeh · 04-09-2003, 07:04 AM

BowtieBandit - I finally got my Yukon back to the dealership and got the same answer to my complaint - they all do that. I presented them with the printout from this forum and they had to confer with GM on what to do. They had me bring the car in and did the 'de-carbon' routine and replaced one spark plug. That, to the surprise of the dealer, made the noise go away.
I forgot to mention that this particular Yukon is a bi-fuel vehicle. I have a propane conversion on it and run on propane about 90% of the time. I am surprised that there is a carbon buildup running on propane.

DMC12 · 05-07-2003, 08:10 PM

Wow! If the de-carbon treatment actually works, then this thread should be "stickied" in any GM forum where this engine appears (hint, hint: Suburban forum) for all to see

imatexan · 07-22-2003, 10:54 AM

I have a 2002 Yukon with 25K miles on it and it has been making this noise. I have had it checked by the dealer and they gave me a printout of the statement that was noted earlier in this chat thread. However, the noise has not been going away after the engine warms up. GM states that the noise usually goes away a couple of minutes after startup, but I have found that that is not the case. It is a really bad sounding noise for a gas engine to make and even noticeable by individuals with little or no automotive mechanical aptitude who even make a statement that "something sounds wrong".
I am planning on taking the Yukon back in to another dealer for a second opinion.

DMC12 · 07-22-2003, 11:38 AM

Quote:

Originally posted by imatexan
I am planning on taking the Yukon back in to another dealer for a second opinion.

Let me know how it goes... the dealers out here blatantly denied the existance of the knock.

Barton17 · 08-02-2003, 06:12 PM

I too have a Yukon with the "clicking" sound. It has 33,000 miles and has had the full time clicking sound since I bought it @ 20,000 miles. Now it has an additional clicking sound only on cold start that goes away in less than a minute. The original sound remains. I brought it in to 2 different dealers at least four times over the past year to document the complaint. I also was given a copy of the document saying that this was normal. I have owned cars for 40 years. Most reached over 150,000 miles. Ones that made such a sound, and was not a diesel, had a problem.
Is there any info on engine failure as a result of this "normal sound"? Failed pistons, valves, etc.? I suspect that this is a real problem, but GMC's plan is to deny it, knowing that is cheaper to fight it out on an individual basis than to have a recall.

fxef84 · 08-14-2003, 10:50 AM

Regard General Motors Top End Cleaner to correct the problem of engine ticking on start up. I have a 2001 Chevrolet Lumina (car) 3100 V6 that had all of these symptoms and similar dealer stories. I tried the Top End Cleaner recommended by bowtiebandit, and although it didn't make the noise go away entirely it did minimize it to the point of not being outwardly noticeable. It now goes away in a few seconds, rather than in minutes. More over this is an amazingly quite engine once it's warm and believe it or not it's a bit quieter now at full temperature. I also switched from 5w30 oil to 10w30 which is OK per the owners manual. Not sure if this did much, but I believe an oil change after such a procedure is a must. What's interesting is that the dealer recommend some "sort of chemical engine cleaning" for over $100 dollars to solve my particular problem. GM's Top End Cleaner sells for $7 at my local dealer. Just find a vacuum port that allows the stuff to enter the manifold directly. On my engine the throttle body is lower than the intake plenum so it doesn't work well using their directions. Hope this helps some of you.

DenaliMCD · 08-21-2003, 08:46 PM

@ 60k miles mine still has the knocking. But if you say that the Carbon cleaner works i will try it and hopefully it will fix the problem. Thanks for the sugestion

lukefx · 11-08-2003, 04:42 PM

The noise is called pinging. If you put Super Unleaded in the vehicle it will go away. They are teasted with fuel that is alot better quality than we get at the pumps, try another gas station too. On older vehicles you can correct the problem by slowing the timing down.

POST REPLY TO THIS THREAD