Mechanics

SERPENTINE BELT DERAILED, AND BIG FLUID LEAK

1997 Jeep Grand Cherokee • 125,000 miles

Hello:

I'm trying to diagnose a problem with my son's vehicle. It's a Jeep Grand Cherokee, which I'm unfamiliar with. And my credentials are weak: I'm just a weekend shade-tree mechanic.

Anyway, while he was driving he suddenly lost the power assist from his steering. He continued home, looked beneath the vehicle, and noticed a lot of fluid leaking from the steering gearbox area. He thinks about two quarts leaked just while he was watching. It was nighttime so he didn't do much more investigating.

Today I investigated. The serpentine belt is off its track. Not broken, just derailed and dangling; not riding on any of the cogs or idlers. There's a little bit of power steering fluid (I think) on a few inches of it. So somehow it derailed. Nothing is leaking at the moment, but I can see some power steering fluid wetting the area below the steering gearbox. Thats probably the source of the leak my son saw. However, the power steering fluid in the reservoir is at the "Full" mark on the dipstick ! The *only other* signs of leakage are near the radiator overflow port, where it looks like a small amount of coolant has leaked from the overflow hose.

So to me it doesn't add up to a clear root cause. Why did the serpentine belt derail? Did it slip off because power steering fluid leaked onto it? Why is the power steering reservoir full after my son watched "a couple quarts" of fluid pour onto the driveway?

Any thoughts or advice; tips for additional troubleshooting?

Thank you,
Jeff
Avatar
Outriding
November 9, 2013.



Anything is possible. However, most common cause of derailment is caused by a seized pulley. While the belt is off, spin every pulley. (Except crank pulley, it wont turn by hand) the pulleys should all turn freely. As far as this leak goes, did u notice which hose to the steering box was wet? And is it leaking at the fitting, or elsewhere? So far it sounds like the steering pump ran dry, and seized up, causing the serp belt to derail. Start here, and please keep us updated.


Madmike1735
Nov 9, 2013.
Thank you, Madmike.

I'll do some more troubleshooting this afternoon. I'll try what you suggested.

Regarding the leak, I didn't notice any wet hoses or fittings. The leak seemed to be at the bottom of the gearbox, where a shaft exits and connects to the pitman arm.

The power steering reservoir is still at the "Full" mark.

Does the gearbox use power steering fluid, or does it use its own lubricant, like gear oil?

Thanks for your help!
Jeff


Tiny
Outriding
Nov 10, 2013.
It will use power steering fluid. Sometimes however, it may use automatic transmission fluid- mercon 3. Its used for its anti-foaming capabilities. Hope this helps


Madmike1735
Nov 10, 2013.
To make pinpointing the leak easier, try degreasing everything. Once its clean, it will be very easy to pinpoint. Trying to say for sure what is leaking when everything is soaked is very difficult.


Madmike1735
Nov 10, 2013.
Thanks for those tips, Madmike.

This afternoon I checked each of the pulleys as you suggested above, and immediately found trouble with the water pump. The shaft wobbled around, the pulley scraped the housing, and coolant started leaking from the water pump. All the other pulleys (except the crank pulley) spun nicely.

The leaking coolant wetted all sorts of stuff, including the shaft from the steering gear box. So I think the gearbox itself isn't actually leaking; as I thought earlier.

I think it all adds up now. Probably the water pump failed while my son was driving. Then the pulley wobbled around 'til the belt derailled. That's when he noticed the loss of steering assist. When he arrived home ~10 minutes later, the leak he observed was probably pressurized coolant escaping from the water pump. Next day when I looked, I saw no active leak because the pressure had dissipated. I saw the residual coolant on the shaft from the steering gear box, which fooled me into thinking the gearbox was leaking.

So despite the confusing set of symptoms, I think it's just a straightforward case of a water pump failure, plus all the aftershocks.

Many thanks for your answers and your troubleshooting tips!


Tiny
Outriding
Nov 10, 2013.
Glad you found the leak!


Madmike1735
Nov 11, 2013.