2005 Chevy Trailblazer sounds like a diesel

Hi everyone. I am brand new so bear with me. I am in desperate need of advice, and remember too that I know practically nothing about automobiles. I have a 2005 Chevrolet Trailblazer LS L6 4.2L 4X4. In the past year it has developed a clacking sound and everyone asks me if it is a diesel. It seems to drive okay, though is a real gas hog. Several told me it sounded serious so I finally took it to a Chevy dealer nearest to me. They have had it in the shop for about 10 days. They gave me an initial estimate to replace a cam in which the lobe had significant wear, thus causing the noise, priced at $2900. Called few minutes later and said they could not locate a 2nd cam so decided to replace the head for just $200 more. Okay, 10 days later they call and say that this, as well as switching out a piston, did not stop the noise. Now they want to put in a rebuilt engine for nearly $8000. Holy Moley. Had initially thought I would trade it in, but the trade-in on it was only $6K. But now a new engine will be more than it is worth. I feel stuck and want your advice. I have a feeling it is something simpler, but they are not finding it. I have read that a power steering pump or pulley can cause noises but don’t know if they would be a “diesel” sound of not. Also, what are my options about accepting this replaced engine or not? Can I ask them to put the old parts back on as they apparently were not bad after all since it didn’t stop the noise? Then do I pay them for all their labor? Comments very welcome.

If someone complains about a “diesel” sound, my first suspect would be some kind of exhaust problem. The exhaust sound is not being properly muffled. This sound can vary, from like firecrackers going off, to a put-put-put sound. It depends on where it is sourced, and how open the sound is to the environment. So I’d start probably by suspecting a bad muffler, next, a cracked exhaust pipe or cat, next, a cracked exhaust manifold, or finally, a problem with an exhaust valve not working properly.

It sounds like your shop did some initital tests, presumably ruled out most of the items above, and decided it to be a valve problem. At the point they said they couldn’t locate the proper 2nd cam, to me, that would be a red flag. It shouldn’t be difficult to find a used one using the junkyard computer network.

I guess if this were my car, the first thing I’d do is tow it away from the dealer shop asap. And tel the tow driver to take it to an inde mechanic for a second opinion. A dealer shop is good at warranty repairs and diagnosing drivability problems in out of warranty vehicles, but isn’t the best choice for actually doing major engine repairs like this. You’ll get better results at an inde mechanic. Ask friends, co-workers etc for a recommendation.

And if you are looking at $8,000 for a used/rebuilt engine, unless you are confident that the rebuilder has the experience, tooling, and testing to insure the rebuild job delivers a “new” engine, you may well decide based on cost considerations it makes more sense to send this vehicle to the recyler, and buy a new one.

Thx for your reply. I will ad that I did take this to two other independent mechanics. The 1st said to trade it off as it sounded like pistons or valves and very expensive. The 2nd thought it was the timing chain, but never got back to me. This was when I decided to use the Chevy dealer thinking that they could pin-point exactly what the problem might be. I have copied your reply hoping it might be useful. Thx again.

Is there a reason why the engine might have serious problems? A 2005 Chevy wouldn’t usually have major engine problems as you describe. Has all the routine engine maintenance been kept up to date? Has it ever been run low on oil? Has it ever overheated? How many miles on the engine?

fyi, A shop mechanic can use a a tool called an “auto-stethoscope” to narrow down the source of a noise. I’ve used just a length of rubber garden hose for this sometimes when diagnosing noise sources on my car. I was able to pinpoint a noise which sounded at first like a timing belt problem, but instead was just the alternator.

No, no reason. It has had a few semi-serious problems. The fuel gauge sensor, an idler pulley, etc in the past couple of years. I did not buy it new, as it had around 40K on it when I bought it. It has 65K on it now. As I said, it seems to run fine, just this doggone noise. I will certainly ask about the auto-stethoscope testing when I see them on Monday. Thx.

Just my 2 cents, but based on what you’ve posted I think the entire thing has been a misdiagnosed fiasco that was not handled correctly from the start.

Starting at the point where they found a worn cam lobe the question they should have immediately asked themselves is “why?”.
A worn cam lobe in almost every case is caused by irregular oil changes, chronic low oil level, or very high miles on the engine.
With a worn cam lobe the assumption should be that the entire engine is worn.

To go in and replace camshafts, cylinder head, and even a piston on a fishing expedition is ill advised to put it politely.

The sticky question is what to do about that massive outlay of money so far. Legally, you probably can’t get it back but drawing a line in the sand might get at least a partial refund.

My gut feeling is that the vehicle was damaged goods when you bought it. A common recommendation by car makers is to extend oil change intervals and odds are that it may have only had a couple of oil changes at most by the 40k miles mark. The end result is a prematurely worn engine which may have timing chain and cam lobe wear along with everything else.

Sorry I can’t be more helpful but another 8 grand? No way.

Thx for your input. I of course don’t know the history before I bought it though it was in like new condition all over. Plus, until the last year, I have had no major problems with it. I have had it the last 6 years so I don’t put many miles on my cars. It has always had regular servicing since I have owned it. To explain further, the $8K (I exaggerated a little as it was 7200 plus tax) was for all the work they have done on it thus far included. Not that this helps much.