Hi guys. I have an issue with my 2000 Blazer 4x4 that I just can't figure out. It's not really a drive-ability or mechanical issue, just annoying. Basically, the engine is very loud, has a certain tone, before 3k RPM. If I rev it up in park past 3k RPM, the engine noise changes tone and gets much quieter, and then it stays quieter even under 3k RPMs. It will stay this way for maybe 5-10 minutes, and then go back to being louder. I can reproduce this while driving too, just needs to be on highway or from dead stop to get the car over 3k RPM, where the tone of the engine will change to something much quieter. I bought the blazer with about 120k miles on it, and it's done it ever since I've owned it. Now has over 183k miles on it, and still makes the same issue. I'm a pretty decent home mechanic and can usually diagnose most things, but I am completely stumped as to what makes the noise. The only thing I can think of is that it is related to the transmission in some way. I've had plenty of different vehicles with 4L60s, 700-r4s, and 4L80s in them and none have ever made this type of enigmatic noise (but they were all 5.7s). I've even had a K2500 4x4 and the transfer case didn't make this type of noise. I'm attaching a video of it so you can hear what I'm talking about. I've never had the privilege of driving another s10 so I do not know if maybe they all sound like this? I'm thinking that's unlikely however because this forum would be littered with complaints from drivers over the years.

Also the blazer is mechanically sound, transmission works great (put in a transgo shift kit somewhere around 130k miles to get rid of a tranny code where the converter would not stay locked). No misfires, new distributor, cam retard perfect, replaced intake gaskets, brand new walker exhaust including cats from engine exhaust manifolds back (1 month old). It's been bugging me for 6 years as to why the engine sounds the way it does. Hopefully you guys can provide some insight!


You can really hear the tone change after about the 20 second marker.

Also I never realized the speedo moved while revving the engine in the driveway until I watched the video...huh go figure.

 

I can't really make out what the sound is but it looks like you have great oil pressure.

 

Sure it's not just the fan clutch?

 

I never thought about the fan clutch. I'll pop the hood and check, but I have my doubts. Why would the clutch disengage after a certain RPM, and stay disengaged?

 

They wear out, mine roars for the first few minutes

 

So it totally is the fan clutch. checked this morning and it stay 100% engaged through start up and stays engaged the whole time even if the engine completely warms. It will only disengage if I speed the engine up past about 3200 RPM. And then it will reengage during driving and reengage about 10 minutes later.

I've been putting up with it for years, never had an inkling it was the fan clutch. At least I've never had an overheating problem with the blazer!

I guess it's an easy enough fix. I've seen threads on converting to electric fans, is it worth the hassle? I can get the fans from an intrepid for around $50 used and I would need a controller for about $80 to make it pretty much hands off. The blazer is pretty much used only by the babysitter, so I want no chance of this car overheating and stranding the kids somewhere because she forgot to flip the fan switch.

 

Thats up to you. the stock fan will always work

 

I do not know what it is with the fan clutch in the Blazer....have had noise issues with both Blazers I have had along with reading about others. Even before I watched/listened to the video I suspected the fan clutch was the problem.

As far as putting electric fans in....I would not especially how your Blazer is used. Replace the fan clutch and be done. From living in the desert southwest the Blazer's cooling system has never been a problem and works good...so why take a chance and mess this up...again especially how your Blazer is used.

Just my $0.02 worth.

 

Mine does that too, only lasts for a couple of blocks though.

 

$50 for an intrepid fan sounds rather steep. I got my fan for like $19 at a u pull. I like my e-fan set up even though it took me a while to get it to work just the way I wanted.