Hi Guys,

I did a tire rotation on my '07 LTZ yesterday, and noticed that both the front shocks had a wet oil build up around the lower part of the orange shock body, and (mostly) around the lower spring coil and mounting plate. The oily build up is quite wet, and of course mixed with road dirt now. At the lowest part of the spring mounting plate, on the engine side, there was a small dew-drop of clear light oil. I've tried to embed a picture here - hope it comes out ok.

Is this most likely to be shock oil? I guess if it is, the condition is not normal and the shock seals must be leaking. I've never had this on a new vehicle before - my LTZ has 6,500 miles on it.
I'd be grateful for your opinions before I take it in to be looked at.

Thanks -- Shearwig

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Shearwig......Have you been off-roading, or maybe jumping curbs?

Whether or not you have,the shocks are both leaking (which is unusual) at the shaft seal. The dealer should replace them under warranty. They're pressurized with about 150 psi of nitrogen (look up "de carbon shock absorber" if you're interested in why and how) and this makes a seal defect continue to leak even when the vehicle is stationary.

Many people consider the OE shocks to be nothing but suspension spacers and upgrade to more robust units right away. I always replace at least the fronts on any new or used vehicle that I buy. I've had good luck the best Monroe units that I could find. Sears has them often on sale for about $30 ea. I think.

As the oil leaks out, the nitrogen pressure decreases as it displaces the oil. Eventually the shock piston will have a portion of its travel uncovered with oil and that means no damping for that corner of the vehicle. It won't happen at the same time (ie. side to side) and so you'll have some unsettling gyrations in the front. I'd get them replaced fairly soon.

Hope this helps.

LT4Steve

 

LT4Steve,

Thanks for your reply.

No off-roading or jumping - unless the wife is getting adventurous in her old age! The biggest workout the shocks get are the neighborhood speed bumps.

I guess I'll be taking the Tahoe into the dealer to get the shocksreplaced under warranty. As the LTZ has Autoride, I was also wondering if this setup brought any other components into the system that might cause a fluid leakage.

Shearwig

 

The electronically controlled shock absorbers found on the LTZ will exhibit this type of oil seepage; it is normal and no cause for alarm.

 

ZX,

So as the fluid must be put in the shock absorbers to perform a function in the first place, will it get to the point where they need to be recharged with fluid to perform properly ?

Mine are basically dripping fluid off the back edge of the spring retaining plate. It seems that this amount of fluid loss would affect shock performance somehow.

Thanks -- Shearwig

 

It is my understanding that this condition is normal and that if the shock is cleaned and dried thoroughly you will notice that it does not reoccur or does not continue to be a chronic problem.

Shock performance will not be diminished even though common sense would make most people skeptical. The reason for this seepage is something to with the shocks design, I don't have all the details on this issue in front of me but I do drive an LTZ and have noticed the same thing.

Dealers have been provided with the technical data and are instructed not to replace these shocks for seepage.

What I would do if you are concerned is clean the oil off the outer shock housing with carburetor or brake cleaner and dry with paper towel making sure that you remove all the oil then keep an eye out for more seepage and/or degrading shock performance and take it from there.

 

Thanks ZX, I'll give 'em a cleaning and see what happens.