Hey,

So I bought my beautiful 2006 MC LTZ with about 80k miles on it about 2 months ago (stole her out the door for just over 7k with taxes!) but this car has little problems that baffle me.

-First off, starting her up when she's cold she idles smoothly, no knocking or tapping from the engine at all, but after she's been running for lets say 30 minutes or so, and the temp is settled it starts to tap. It's an unmistakable faint tapping coming from the engine compartment somewhere, it is steady and is drowned out by acceleration of the engine, but at idle is fairly evident if there is no other noise within the car. Just replaced spark plugs and wires so I don't really think that is the issue, but I just find it weird that it only happens when warm.

-Next, is the transmission/engine. When driving it runs completely fine (except a moderate shake only between about 60-70mph, had wheel bearings and suspension completely replaced, still there, although the tires are on their way out with about 1/4 tread left), but when I slow down to a stop, if I'm rolling about 1-5mph with the breaks unapplied it shudders, almost shivering, but it is not rhythmic at all, it just shudders to a stop. However if I apply the brakes while stopped it stops as well. Release the breaks and it starts to unmistakably shudder just slightly as it rolls along until it hits about 7-8mph then the shudder completely disappears. The transmission sometimes downshifts at odd times, but I figured that was just the collateral damage of having a 4spd tranny paired with a 3900.

If anybody could help diagnose either issue I'd be super grateful. Thanks!

Matt

 

Well... if anyone cares to know the outcome, I took it into a great local shop (just found myself a new mechanic!), its a place called Circle Auto Repair in Fairfax VA. Well anyways, took the car in and got it back out the same day, and here was the verdict...


- Leaking crankshaft oil seal
- Leaking transmission cooler lines
- The resulting oil dripping on the belt was causing slippage - causing an unsteady feeling
- The oil ate through the rubber motor mount, causing the jerking and harsh acceleration
-Leaking transmission fluid was causing rough shifts, and setting off sensors.


All in all, had all the work done for $1000 bucks. Not too bad for having it all done in 6 hours from the time I dropped the car.

 

Sorry we wernt able to help. Thoes sound like some of the rarer problems with the car. Thanks for the update and adding to some info that could be helpful to future members of the forum.

 

Glad you got it fixed, I had the mount replaced when I got the tranny re-build.

 

I'm just worried, because they flushed the tranny o.O I really hope I don't start seeing slippage. I put a little bit of Lucas Oil Trans Conditioner in the fluid to hopefully help but.............. it's 84k on the original tranny and I don't have money for a rebuild

 

I'm not sure if they did just a pan drop or an actual full flush though...

 

I have 87000 on my 06 ss and was thinking of flushing the tranny, is it really that risky to do?

 

Definitely say just drop the pan, and refill with fresh fluid instead of the full flush - from what I've read it flushes out too much friction particles from the fluid which causes slippage...