Greetings,

I have a 98 Blazer 4wd auto with a 4.3 engine with 135,000 miles. If I start the truck on a cold morning- say below 25 degrees, it makes a grinding sound (sounds like grinding gears) immediately upon start up for about a second. The noise goes away and everything seems to work fine.

If I start the truck later in the day the grinding noise does not emerge. However when I let it sit for more than say 8 hours in the cold, the noise emerges upon start-up again. This noise does not appear with warmer ambient temperatures.

This has been going on for years now and I have replaced the following:

Starter- ring and starter gear were in good shape when I took it off. Had it rebuild anyway.
Alternator (new Napa premium)
Waterpump (new acdelco)
Belt (gates)
Belt idler pulley (gates)
Bet tensioner assembly (gates)
fan clutch
timing chain
rod and main bearings
inspected the oil pump- in good condition

The only thing I can think of is the p/s pump. However it operates normally and does not make any noise. Engine has great oil pressure since I replaced the bearings. The noise has been there since I acquired the vehicle.

I know a good way to pinpoint the noise would be to remove the drive belt and start the engine and see if the noise goes away. Since I've replaced about all the accessories besides the p/s pump, then I think I've narrowed it down. However I just wanted to see if anyone else has experienced this.

Thanks,
Joe

 

Solved! Flushed the system and replaced the pump. The grinding sound is now gone upon cold start up. For added assurance, I installed a magnetic P/S filter on the return line.

Cheers,
Joe