I have a 97 Trooper with 175k miles. Great vehicle. Over the last several months I have noticed that the engine when turn off stop suddenly. No, not because the key has been turned off but quickly as if the motor was in drive or there is still some load on it. While running, the engine makes a whinning sound something like the fan clutch when the cooling fan turns on, not this either. I have tried taking the surpentine belt off to eliminate all devices on the belt, no help. Engine runs great, Mileage is 20 on the highway. I am suspicious of the timing belt, water pump or something more serious in the motor. I have tried oil additives (Prolong) with not effect on the noise. Motor has always used oil. I have read some of the posts, seems like I can help this problem.

Any Ideas, Thanks
VMI07

when was the last time that the timing belt was replaced?

Never.. Am I runnig on borrowed time?

VMI07

I wonder if that sound is a water pump bearing?

Anything over 120k on the timing belt and water pump is pushing it a bit.

At 175k I would for sure have them replaced if you are planning on owning the truck a couple more years.

The noise does sound like its being generated in that area. Thanks for your input. The car is in great shape and I do plan on keeping the vehicle several more years. Sounds like I shoud just chalk it up to preventative maintenance and replace the timing belt and the water pump..

Are the parts available aftermarket? I have suffered through the ISUZU parts counter before. Also is there public information for the repair. Its a 98 not a 97.

thanks again,
VMI07

make sure you replace the timing belt tensor too.

If you are looking for OEM parts, the cheapest place to buy them is St. Charles Isuzu (see the FAQ's for their number).

I wonder if it might be the fan clutch, assuming it has one!

Thanks everyone ! It was my alternator. Apparently its been going bad for 20 to 30,000 miles. The noise must of been a bearing. Funny thing was the noise sounded like it was comming from the other side and back of the engine. Anyway, now the issue seems to be the replacement alternator. Battery will not charge from alternator. Trickle charger gets the battery back but within several hours of driving the voltage drops dash lights flash, tach and speedo goes crazy, then engine will not crank. Off to the local Autozone to see if the replacement is bad. No other ideas here, any there?

Thanks everyone ! It was my alternator. Apparently its been going bad for 20 to 30,000 miles. The noise must of been a bearing. Funny thing was the noise sounded like it was comming from the other side and back of the engine. Anyway, now the issue seems to be the replacement alternator. Battery will not charge from alternator. Trickle charger gets the battery back but within several hours of driving the voltage drops dash lights flash, tach and speedo goes crazy, then engine will not crank. Off to the local Autozone to see if the replacement is bad. No other ideas here, any there?
And so begins the remanufactured alternator saga...
It is well documented, on this and many other Isuzu forums, that Isuzus (certain years) for some reason or another do not like remanufactured alternators. It more than likely has to do with the fact that sometime in mid-1996 or so Isuzu did something in the ECM programming that tells the alternator to stop chaging the battery when the engine is under load. It could be that the replacement Voltage Regulators don't like this set-up or it could be the wrong VR in the reman alts. Who knows, but the fact remains that you may end up having to go through two or three remans before you find one that works properly (despite the AutoZone telling you they work fine). :2cents:

Steve,
thank you for your reply. Your suggestions make sense.
Althought the charging system is not working the idiot light on the dash is off indicating the charging system is fine. Battery gives out in about 2-3 hours but recharges fine. If the PCM does not see the fault the dash light may not be triggered. Autozone is more than happy to work with me on the alternator but it seem that you are are suggesting to stay factory. Any suggestions where to buy. The dealer wanted $680 for the replacement.

thanks again !

Steve,
thank you for your reply. Your suggestions make sense.
Althought the charging system is not working the idiot light on the dash is off indicating the charging system is fine. Battery gives out in about 2-3 hours but recharges fine. If the PCM does not see the fault the dash light may not be triggered. Autozone is more than happy to work with me on the alternator but it seem that you are are suggesting to stay factory. Any suggestions where to buy. The dealer wanted $680 for the replacement.

thanks again !
You can call St. Charles Auto (their number is 800-727-8066) or you can try and find a Bosch alternator. I personally got my replacement from the dealer and paid nowhere near $680 ($200-ish maybe?) but I remember some owners having good luck with Bosch.