Load roar from engine...

[cps68500]

Ok, I am a nOob here, but I've been searching for days and have questions that I can't really find to my liking of the answer I suppose...

I drove cross country in my 99 silverado 5.3 1500 4x4. I was towing a small trailer (sad, my whole life of 23 fit in here) and about halfway I noticed a loud roaring noise comming from the engine compartment. I also had a severe loss of power. I ran at all times with the trailer in tow/haul mode. My loss of power and the noise almost seemd like an old chrysler van I had where the tranny slipped a bit, but the truck never jerked like the van had. My thoughts were of the trainy itself, so I checked fluid as normal but it was where it should be. As being halfway, and not much more than first months rent and gas to get out there, I decided to press on... taking it easy on the truck. Well, I got out here, and working from home I didn't use the truck much more than 100- 200 miles a month and within the first month, the noise dissapeared.... no power loss, no noise. Now, I must make the trip back, and 2 weeks ago the noise, and power loss is back... My searches, have lead me to think of the fan clutch. My problem is how do I know which type I have - Thermal, NON-Thermal... and how for each one do I find out if it is bad... Someone told me if I turn it more than once, it was bad.... at a dead cold, after 10 hours of sitting, I can turn the fan with some resistance ( not that it flys around 100 times ) and it spins freely.... I drove it 5 mins down the street and 5 back, and I can spin it just the same (the temp guage was at 200 after 10 mins of driving...) so I am left to believe the clutch is working!?!?!

Sorry for the long post, thought you could use the extra info...

thanks in adv.
Chris

[desertmike1]

Chris,
A thermally controlled clutch fan, once engaged makes a loud whirling sound, this is not your case.
(a) it's winter time and your not pulling much weight.
(b) If the fan engages, there is typically very little power loss.
(c) Fans typically engage while climbing mountain pass's in the summer months when the ambient temps get above 80-90deg.

I drive the mountains of Southern Ca in a 14 passenger chevy Express VAN POOL, and like the fords and dodge's of the past we only hear the (fan) kick-in while climbing the pass's. Never on the flat lands!

I would take a close look at the air ducting for (leaks) between the MAF sensor located next to your air cleaner box, and the throttle body at the intake manifold for loose clamps, rips, tears etc etc.
This may not be the problem, but it's a no cost good start.

Good luck!
-Mike

[cps68500]

I could see mountain driving, but this is not the case. This is full time, all the time... just to the store and back, or down somewhere on the highway.... As for the airflow leak, I actually just pulled them all off to replace the belts and put them back on, so I know they are snug now...


Still searching...

[cps68500]

On a quick second note, I suppose I could always remove the fan for a quick drive up and back to the store. This would give me a definite answer if I am looking in the right place... No?

[okie-chevy-man]

watch that temp like a hawk. process of elimination iu guess

[desertmike1]

Pulling the fan would definitely give you an answer one way or the other!

But I would restore the serpentine belt pully back onto the water pump with shorter bolts to allow all the accessories to function normal, and allow the water pump to pump coolent.

Watch your temps!

This should be a good test.

-Mike

[cps68500]

Thanks guys, I wound up having to rent the tools to take off the fan, and said... well I am here I might as well just buy the part anyways and put it on to test it out. Well I get it on, started her up and the same sound occured.... Well, I thought....it's not warmed up yet yer bonehead.... So I drove half a block....and about a min later.... no more load roar, and very very nice acceleration....

So, Im all great now...

But I have a few more things now.... front pinion seal, speed sensors... this truck is sad and needs some luvin.... anyone have the procedure to remove and replace the front pinion seal??

[desertmike1]

Glad to hear you got one of your problems fixed!

I replaced a pinion seal on my 1990 truck rear end, and it was pretty straight forward. The key is the pinion nut has to be returned back to it's original position or you will have a noisy 3rd member.

Jack up the front end to releave drive train loads, so that you can remove the drive shaft
I used a caliper to measure the distance from the top of the pinions threaded end down to the top of it's retainer nut, I then used a torque wrench to measure the brake-away torque of the nut it-self, record the readings so you don't forget. The seal was easily replace by popping it out with a screw driver, and then gently tapping the new one back in.
Install the pinion nut and torque it to the value you recorded earlier and re-measure the exposed pinion threaded end.The caliper measurment is your FINAL adjustment.

I forgot to mention after I removed my drive shaft I used the parking brake to hold the ring&pinion solid to facilitate removing the nut, you might need somebody to hold the brake or gently rest the front tires on the ground, what ever it takes to prevent the pinion from turning.

This might be a good time to change lubricant!

-Mike