Re Clutch Fan Assy

[cmd]

Has anyone experienced a rattle that sounds like a bearing noise comming from the fan assy, this only happens when the vehicle is warmed up and at 1500rpm is very noticable.

Thanks

[AHels]

Are you sure it's the fan assembly?
I had a rattle coming from under the hood a few months back, started at around 1500 and at 1900 it sounded like my wife had the food-processor going. Turned out to come from the AC compressor/clutch assy - still not 100% certain of the cause, but I changed the AC drive belt and away it went.

[cmd]

Is this when the ac is in the off position? I did change my belts around 10k ago.

[HUMMERcustoms.com/TAZ]

Get a hand on each side of fan assembly and try to wiggle back and forth cold engine. If it moves even the very least You are most likely looking at the problem. This unit is tight and normally has no slack at all in it. Once trying it cold warm engine up to temp that noise normally comes in at and then shut down engine and try wiggling fan assembly again. This will verify if you do not get wiggle at cold temp.

The A/C clutch assembly can make the noise but, normally only if the bearings in the shaft going into the A/C compressor are going bad or clutch is worn and slipping. You can get noise from A/C if just something inside A/C compressor crashs inside but, normally it will lock up and then burn A/C belt off. Should by strange chance that A/C compressor fails be very sure that You insist that dryer/accumilator is changed. Most Tech's that know and care about what they do will change it. Some think that with A/C failure they can leave it off to hold price down. Dryer is like an oil filter and cleans bad stuff that can float around in freon namely shavings just as the compressor wears out over time. Change it You will be glad You spent the extra money since tech will have to flush system I hope and pull vacumm. Even if he flushs the system all it is doing is filling up the dryer faster and over time if it plugs up You will be wondering why is My A/C not cooling as good. It will not be moving as much freon and that does not allow enough of the heat to be removed from system fluid, freon.

You could in fact have a bad belt and get strange noises as they will slip. But, as recent as you changed Your belt i would be looking at it last.

Hope it helps You find problem. Oh also You can have an altenator going bad and get funny noises if bearing fails in front of housing where pulley is but, not likely.

If You have odd noises and can get a mechanics stethiscope (spelling?) which do not cost much at chain auto stores You can put probe with engine running on some systems like altenator and hear grinding noies. I have a real long screw driver that i use where i can reach easily and just place My ear on handle end and metal shaft will tranmit odd noises. i use it especially mentioned diagnostic tool to listen to heads or a cyclimder wall to see if i'm beginning to hear a rod nock and figure out which cylinder it is.

Caution much be used obviously when You try to use any method that causes you to be close to running engine. Techs scopes are real long so they can stick long narrow probe into running ares hard to reach. I have used a long metal rod with a piece of rubber vacumm line hose stuck on one end and held it to My ear and can hear noises inside. Used are drag stri many times in the day when i could not affor the pro tech tool.

If I messed up and did not make it clear please let me know.

TAZ

[cmd]

Thanks, I will be checking this out. if i do not find play in the fan assy, can i disconnect the drive belts and run the vehicle? will it run ok for a few min with no accessories running so i can listen for noise.

[HUMMERcustoms.com/TAZ]

You can with caution. It takes 5 or 10 minutes running to reach overheat. Watch temp guage and shut down at 230 or 250. Heat will still build up after shut down. Be very careful and at own risk. Just offering info. Heat causes rings to loose tension and they after overheated enough times will allow oil to remain on walls of cylinder and thus an engine smokes. Old cars is just because of wear from age. It would take a long extreme overheat to do permanent damage but, be cautious. You should hear something before overheat so listen and fast under a no cooling situation.

If overheated for very long time will completely remove oils ability to lubricate and things sieze up.

TAZ

[cmd]

took the truck to my mechanic buddy's shop and took off the belt, same noise, sounds like it is comming from the piston area? ive heard of piston slap but i thought this only occured when the engine is cold. I guess i live with it or get rid of it, i dont think i can live with the rattle however, i will never be at ease :confused:

Thanks