1996 Roadmaster fan belt tensioner pulley

[robert graham]

1996 Roadmaster fan tensioner pulley bearing is warn and causing belt to squeal....new pulley is unavailable/not produced....it's a special grooved metal design unique to the trailer towing package/heavy duty cooling systems equipped cars.....my resourceful mechanic suggests to replace mechanical fan/ pulleys/ belt/etc. With an electric fan that would run all the time when engine is running....Any of you guys with any experience or ideas on this conversion before I pay the mechanic $300 to do this?....Any other ideas?....I've been to lots of dealers and parts houses looking for replacement pulley with no luck at all, so I'm going to need to do something on this....Thanks Folks!...

 

[HotZ28]

Does Item #8 tensioner/pulley below look like what you are looking for? The pulley alone looks exactly like the pulley used for an idler pulley for the PAU supercharger belt drive. Here is a pic and the dimensions on that particular pulley:

Number of Grooves 6
Material Thermoplastic or metal
Contact Surface V-Ribbed Grooved
Pulley 1 Flanged Yes
Outside Diameter (mm) 76
Bearing Bore Inside Diameter 1 (mm) 17
Width (mm) 25
Contents Pulley
Number of Pulleys 1

http://www.amazon.com/ACDelco-10186...automotive&vehicleId=2&vehicleType=automotive

http://parts.nalleygmc.com/showAsse...1996&ukey_category=19395&ukey_trimLevel=14752

 

[robert graham]

Well, it looks a lot like it but how can I be sure without taking the old one off?....Any thoughts on the electric fan conversion?...With the fan and pulleys removed it would leave plenty of room in there for the electric fan but I wonder if the electric fan moves enough air to keep it cool?...

 

[robert graham]

Yep, that's exactly what I need....does Rock Auto have it?....

 

[HotZ28]

You would actually have to verify the dimensions by removing the pulley. The link below should help answer any other questions you may have about the conversion & cooling ability of the electric fans.

http://gmlongroof.4umer.com/t57-mechanical-fan-delete

Here is a diagram of the duel electric fan combination used in my '96 RM. The RP0/SPID code is KNP - COOLING SYSTEM,TRANSMISSION,HEAVY DUTY HVY DUTY TRANS CLG SYS(KNP)

http://parts.nalleygmc.com/showAsse...1996&ukey_category=19395&ukey_trimLevel=14752

 

[robert graham]

Well, I'm not exactly sure what my mechanic has in mind for the fan but he said it was no big deal, just removal of all the mechanical stuff, mount the electric fan and a relay.....do we need a fuse/breaker and an on/off switch mounted under the hood?.....He said the fan was $85 plus labor to equal $300 total....seems reasonable?...

 

[buickwagon]

It's not enough to add the relay. You also need to have the PCM reprogrammed to activate the fan -- the option is there, but turned off in the tow-pack cars.

I forgot to mention: if it is just the bearing, it is often possible to press in a new bearing into the existing pulley assembly. However, before bothering with that you should check the tension and verify that the spring is still serviceable.

 

[robert graham]

It's not enough to add the relay. You also need to have the PCM reprogrammed to activate the fan -- the option is there, but turned off in the tow-pack cars.

My car has a small thermostatically operated electric fan on it already...in addition to the main belt driven fan....what's required to have PCM reprogrammed and what is it?...I believe he intends for the new fan to just run continuously whenever the motor is running...that sound O.K.?

 

[buickwagon]

The fan will normally be controlled by coolant temperature. The reprogramming requires some software and the appropriate cable. I'm not certain exactly which software is best for the 96 -- it has OBDII and I seem to recall you have to pay for TunerCat and that TunerPro does not support post-95 models. Someone else may have a cheaper option.

I see you posted just before my edit, above. I added that you can often replace just the bearing in many steel tensioner pulleys if the spring is still OK. Dayco makes a nice inexpensive belt tension test tool you can check the tension with before making a decision.

 

[robert graham]

Well now, if the mechanic just wires the new electric fan to run continuously while the engine is running that would bypass the thermostat/computer....right?

 

[HotZ28]

Well now, if the mechanic just wires the new electric fan to run continuously while the engine is running that would bypass the thermostat/computer....right?

If you want to go with an aftermarket electric fan set up, you can install a temp sensor to control the fan so it does not run continuously with the ignition switch ON. Several options are available.

My car has a small thermostatically operated electric fan on it already...in addition to the main belt driven fan....what's required to have PCM reprogrammed and what is it?.

If you have that option, the replacement fan can be tied into the PCM ground to the existing relay. That ground from the PCM should activate the new replacement relay. Spend some more time reading the link Here.

 

[robert graham]

If you want to go with an aftermarket electric fan set up, you can install a temp sensor to control the fan so it does not run continuously with the ignition switch ON. Several options are available,

I'm fairly confident my mechanic is thinking of an aftermarket fan....maybe I should just get him to pull the tensioner off and I'll go see about having new bearings installed....maybe NAPA Auto or similar could do it?....then get my mechanic to pop it back in there?....What would you do?...

 

[HotZ28]

If I were in your position, I would go for the replacement bearing! Bearings are cheap and are fairly common in many different dimensions. It may be difficult to remove the existing bearing, but I am sure it could be done.

 

[(insert name here)]

If you are unable to repair the old tensioner pulley, you could also try acquiring one from a junkyard. Someone else correct me if I'm wrong, but I would assume that Fleetwoods, Caprices, and Impalas would all have the same pulley as the Roadmaster (assuming they also had the towing package) which means it shouldn't be too hard to find the part you need (unless perhaps the towing package was particularly uncommon).

 

[robert graham]

Update: my mechanic replaced my belt driven fan with an electric/thermostatically controlled unit- seems to work very well and engine/fan/belt noise is greatly reduced!....for $300 total I'm real happy with this.....so far...

 

[robert graham]

Update: well, that took care of the cooling fan, but now my serpentine belt is starting to squeal....mostly when I turn the steering wheel....guess that could be the tensioner/pulley warn or bad bearings?....or maybe something else like the power steering pump???....I'll be heading back to my mechanic next week for a look-see....Any ideas about this?....Thanks!

 

[HotZ28]

IIRC, the mechanical fan tensioner bearing was the original problem and the unavailability of that part was the reason for installing the electric fan. Did the mechanic remove the original mechanical tensioner/pulley and all fan componants? (The mechanical fan tensioner and the electric fan tensioner are two different animals)! In the diagram below, you will see both. The foreground shows the mechanical belt drive fan which you had & the background shows the electric fan belt drive tensioner/pulley which is Item #7 Part #12552509 and is still available both from the dealer & RockAuto. You may have a bad bearing in the accessory belt tensioner, or the belt is worn out & stretched. I would replace both. http://www.rockauto.com/catalog/raframecatalog.php?carcode=1022218&parttype=11659

http://parts.nalleygmc.com/showAsse...1996&ukey_category=19395&ukey_trimLevel=15026

 

[buickwagon]

Read this: http://www.daycoproducts.com/diagnosing-misalignment-and-belt-noise

 

[robert graham]

The existing mechanical fan tensioner and bracket all remain on the front of the motor....the fan, pulley and belts were removed.....engine is noticeably quieter now and temperature gauge stays right where it's always been and I have not thus far seen or heard the new electric fan come on...but the weather has been cold and we're mostly on the interstate/highways. I'm just wondering if the spring tensioner on the serpentine belt has grown weak and need replacement?....we checked the tensioner pulley and the bearing is smooth and the belt is new....

 

[buickwagon]

And what happens when you spray the ribs with water? As the link above describes, if the noise gets worse, it's inadequate tension, if it disappears, the issue is pulley misalignment (eg: worn bearing, bent pulley, misaligned accessory).