'99 Rattling/Hesitation/Poor MPG
 

Hey All,

I did some searching and found very little that helped...

There is an intermittent rattling sound coming from the motor. It seems to be louder with the AC on, particularly 1800-2200 RPM. I would also describe the sound as gravelly. The noise comes and goes as I accelerate (rapid on/off sound) and as it is making the noise, I notice a signficant amount of hesitation; as soon as the noise stops, the car surges a tad. Mileage is at 13.5-14 mpg.

Just bought the Blazer a month ago with 76,000, now has 79,000. In the first month, the dealer (under warranty) has replaced the following:

(used) MAF
(used) AC Compressor
cat
fuel filter
flushed cooling system (rust-colored fluid?)
idler/pitman arms
ball joints
tires
power mirror switch
windshield washer
front diff seal
trans output seal
alternator
oil lines
...think that's it

Any suggestions? Should have shelved my patriotism in favor of a 4Runner...

RE: '99 Rattling/Hesitation/Poor MPG
 

I have a 2000 blazer with the same amount of mileage. I have a rattle that has been there since I bought it. I believe it to be either the exhaust or a heatshield under the truck. The sound is the same as yours, but I notice no change in performance. Dex-Cool looks rusty if it's used fluid. It is orange out of the bottle. Your truck uses Dex-Cool (any GM 96 and newer does.).