Mod New Blue Hub Fan Clutch?

[Elbert]

has anyone seen any web sites or sources of information for modifing a GM fan clutch to engage sooner?
Have a 5.7 vortec from a 99 GM SUV/pickup in my 60 with matching GM Fan and fan clutch. Need the clutch to engage "sooner".. Wonder if there is a way to adjust the spring in teh center of the front of hte fan clutch or swap teh fluid out. I believ the spring would trigger the clutch to come on sooner, just unsure of how to mod it. I know this ithe 80 section, but its about the only area where anyone talks about "fan clutches".. shoot me a PM if you know of any references on modifing the new GM fan clutch that has the large single threaded nut mount to the water pump pulley.

 

[inkpot]

has anyone seen any web sites or sources of information for modifing a GM fan clutch to engage sooner?
Have a 5.7 vortec from a 99 GM SUV/pickup in my 60 with matching GM Fan and fan clutch. Need the clutch to engage "sooner".. Wonder if there is a way to adjust the spring in teh center of the front of hte fan clutch or swap teh fluid out. I believ the spring would trigger the clutch to come on sooner, just unsure of how to mod it. I know this ithe 80 section, but its about the only area where anyone talks about "fan clutches".. shoot me a PM if you know of any references on modifing the new GM fan clutch that has the large single threaded nut mount to the water pump pulley.

I don't know wht those look like. Is the clutch body similar to the 80 series where it is a clam-shell setup? Does it look like it can be divided in half? Or, does it have a big drain plug on the side of it? I think I have seen that on some chevys. Post up a pic or two and we can look it over. John

 

[Elbert]

I don't know wht those look like. Is the clutch body similar to the 80 series where it is a clam-shell setup? Does it look like it can be divided in half? Or, does it have a big drain plug on the side of it? I think I have seen that on some chevys. Post up a pic or two and we can look it over. John

I don't have a good pic of the side of the fan clutch that faces the engine but see the attached pics. From what little I've seen of some mods (some people claim the spring can be modified).

Other other question for the "wise ones" does it matter if the fan blades of the radiator fan or captured entirely by the shroud or should they stick out of the shroud 25-to 50%? If anyone knows first hand... this gets into V-8 swap business but I need to understand that too. My point is that I wonder if the fan shroud is restricting teh flow of air across the radiator which too would impact the fan clutch in that its dependent on air flow to act. Purely a guess on my part at this time based on other post.

I have another fan clutch around here somewhere...I'll look to see...but from the pics it appears that it's not made to split or be taken apart.

 

[inkpot]

The temp "adjustment" is actually done on the inside of the Aisan units by resetting some screws. The eatons don't have this. Unless there is a removable plug on the engine side, you may be out of luck. John

 

[Kernal]

I have another Eaton apart, checked the valve, first opening is ~120F and fully open at ~160F. Pretty much exactly matching the heat profile that I see for fan demand/need when monitoring fan output temp.

Bringing this thread back as temperatures outside are heading back up.

I have an Eaton clutch and have never heard the roar on start-up but also don't have any known overheating issues; so is a "roar" required to indicate proper function with an Eaton?? When the internal valve of the fan clutch is fully open at 160F does that mean that the fan should be locked up at that temp with the fan pushing a lot of air? I'm not clear on how the fan clutch works internally?? Thanks.

 

[Wheelingnoob]

Well my Blue clutch has been in my truck since 07 from the receipt I got from the previous owner. It was making the normal sound at cold start but would not engage again after that.

The HG has been replace cooling system totally flushed and rad pressure tested and cleaned out totally.

Driving down the hwy I have no issues at all 186-190f all the time even up steep mountain passes. If I slow down and do hills or idle around town stop and go the temp starts to rise. I did a 2 mile 8% grade at 35mph and it hit 225f, I pulled over and was able to stop the fan with my bare hand.

So last saturday I did a drain and re fill with 35ml of 10k cst Toyota fluid. I then went out wheeling on Sunday and had the same problem again, lots of fan noise on cold start and noting after. Every small steep hill on 4lo would result in me idling at the top with the heat on full front and rear to cool it off again. I got out with it at 220f after on hill and again stopped the fan with my hand.

Should I adjust the timing of the fan now and try that or put more 10k CST fluid in?

I'm at a loss and cant afford a new clutch at the moment.

Thanks,

 

[Tools R Us]

My "over the net guess" is; the thermostat valve is stuck.

 

[landtank]

Heat soak the clutch and evaluate the timing per my thread. That should help base line the clutch and hopefully point you in a direction for a solution.

 

[Wheelingnoob]

My "over the net guess" is; the thermostat valve is stuck.

Yeah I tested the valve when I had it appart, a little heat on the spring and the valve opened.

Heat soak the clutch and evaluate the timing per my thread. That should help base line the clutch and hopefully point you in a direction for a solution.

Yeah that's what I will have to try next I guess.

They do no physically wear out do they? The fluid I drained was the same gold color as the 10k Toyota stuff I put in. No signs of wear...

 

[Tools R Us]

Bringing this thread back as temperatures outside are heading back up.

I have an Eaton clutch and have never heard the roar on start-up but also don't have any known overheating issues; so is a "roar" required to indicate proper function with an Eaton?? When the internal valve of the fan clutch is fully open at 160F does that mean that the fan should be locked up at that temp with the fan pushing a lot of air? I'm not clear on how the fan clutch works internally?? Thanks.

Missed this one, was wheeling in Utah.

The Eaton clutches are more civilized, have an anti-drain setup on the reservoir, so don't do the startup roar thing. As long as it is cooling well, I wouldn't worry about it.

 

[Tools R Us]

...but from the pics it appears that it's not made to split or be taken apart.

Correct, most domestic clutches are sealed. That one looks to be an Eaton. The valve can be adjusted, look at the spring in this pic, it is bent where it attaches. Some Eaton open hotter than I prefer, so I bend the spring to bring the first opening is 125-130F ish. I have also observed that some later clutches open hotter 140-150F, likely to save power/mpg?

So it can be cheated, but it can't be opened, so will be a total guess.

 

[Tools R Us]

Yeah I tested the valve when I had it appart, a little heat on the spring and the valve opened. ...

Lately? One of the failure modes is the valve sticking, most often from rust, very rare here. I test/set the valves with a heat gun, hairdryer will work. In this case, simply using a small screwdriver to open the valve and watching for it to close smoothly, should confirm that it isn't sticking, without even needing to open it.

... They do no physically wear out do they? The fluid I drained was the same gold color as the 10k Toyota stuff I put in. No signs of wear...

As the fluid ages it loses it's ability to shear, but this usually takes a very long time. Other than the valve, there are not really any wear parts that would cause your issue. I have heard a couple of reports of hobby store fluid that had very short life, not enough data to be sure.

The other possibility; what is the condition of your radiator? The clutch works on the air temp that it senses from the coolers. If a large section of the radiator is clogged, that area will allow cool air in and may not have enough heat to activate the clutch.

 

[Wheelingnoob]

Lately? One of the failure modes is the valve sticking, most often from rust, very rare here. I test/set the valves with a heat gun, hairdryer will work. In this case, simply using a small screwdriver to open the valve and watching for it to close smoothly, should confirm that it isn't sticking, without even needing to open it.



As the fluid ages it loses it's ability to shear, but this usually takes a very long time. Other than the valve, there are not really any wear parts that would cause your issue. I have heard a couple of reports of hobby store fluid that had very short life, not enough data to be sure.

The other possibility; what is the condition of your radiator? The clutch works on the air temp that it senses from the coolers. If a large section of the radiator is clogged, that area will allow cool air in and may not have enough heat to activate the clutch.

Yeah I just had it open last weekend and tested the valve then, I used a torch to slightly warm the spring till it started moving.....did not take much. I did not tough the valve though I just wanted to make sure it was not stuck or otherwise not working.

The fluid I put in was new Toyota 10K cts, two tubes of it (36ml) not wanting to over fill it as I only drained it for 45min in the oven.

The idea about the rad is a good one and something I had not thought about. The place I took it for cleaning said it had even flow after there back flush and boil over. But maybe its got a few passages plugged, no real way to test it and unfortunately no money to replace it on a whim.

I may open the clutch again tomorrow night and make sure its not sticking then try adjusting it. I may ad a bit more fluid too as I still have two tubes of 10K cts for it.

 

[Tools R Us]

... The place I took it for cleaning said it had even flow after there back flush and boil over. But maybe its got a few passages plugged, no real way to test it and unfortunately no money to replace it on a whim. ...

OK, this is sounding more like a radiator problem:

A: If the clutch roars at startup, the fluid is good, the clutch is capable of delivering drive. If the valve isn't sticking, it should deliver drive when the heat load is there.

B: A flush and boil will only somewhat work on a lightly/freshly plugged radiator. When it first starts to plug, the material is jelly type stuff. Once the flow stops in a core tube, the sediment that builds is solid, think cement and must be mechanically removed, called rodding. This is only somewhat successful, but a flush/boil is rarely successful.

Obviously it is difficult/imposable to diagnose this type of failure over the net, but try a couple of tests. With the motor warm/hot, so the thermostat is fully open and running, attempt to measure the temp of the core tubes. The best way is using a quick acting bead type thermistor and touch each tube near the bottom tank, access from the front below the condenser. If that isn't available, a IR thermometer will work, but will be measuring tube and fin temp. The idea is; all of the tubes should be warm and close to even temp, any that are cool are plugged.

When the motor gets warm, somewhat hot, roll down the windows and switch the A/C to max, allow it to run a bit, then pull over and check the fan. The heat from the A/C should engage the fan and may somewhat reduce motor temp. If it does, it is very likely the problem is the radiator.

Use a wired thermometer, (one of the ones that I use is a cheap home unit, that has a long wired probe for outdoors) tape the wired probe to the front of the motor with the probe in air (not touching the motor). This will read fan output temp. At relatively low speed 20-30ish mph) and the motor hot (200F ish) you should be seeing 150f+ fan output temps.

 

[Wheelingnoob]

OK, this is sounding more like a radiator problem:

A: If the clutch roars at startup, the fluid is good, the clutch is capable of delivering drive. If the valve isn't sticking, it should deliver drive when the heat load is there.

B: A flush and boil will only somewhat work on a lightly/freshly plugged radiator. When it first starts to plug, the material is jelly type stuff. Once the flow stops in a core tube, the sediment that builds is solid, think cement and must be mechanically removed, called rodding. This is only somewhat successful, but a flush/boil is rarely successful.

Obviously it is difficult/imposable to diagnose this type of failure over the net, but try a couple of tests. With the motor warm/hot, so the thermostat is fully open and running, attempt to measure the temp of the core tubes. The best way is using a quick acting bead type thermistor and touch each tube near the bottom tank, access from the front below the condenser. If that isn't available, a IR thermometer will work, but will be measuring tube and fin temp. The idea is; all of the tubes should be warm and close to even temp, any that are cool are plugged.

When the motor gets warm, somewhat hot, roll down the windows and switch the A/C to max, allow it to run a bit, then pull over and check the fan. The heat from the A/C should engage the fan and may somewhat reduce motor temp. If it does, it is very likely the problem is the radiator.

Use a wired thermometer, (one of the ones that I use is a cheap home unit, that has a long wired probe for outdoors) tape the wired probe to the front of the motor with the probe in air (not touching the motor). This will read fan output temp. At relatively low speed 20-30ish mph) and the motor hot (200F ish) you should be seeing 150f+ fan output temps.

Awesome thanks for the trouble shooting guide! I will try this out tonight and report back.

 

[Wheelingnoob]

Turned out 12"-14" of my rad in front of my clutch is ice cold with the engine temp at 225f. Looks like my rad is sludged up even though the rad shop back flushed it and boiled it over.

I'm now pricing out a OEM 3 core brass rad......ouch.

 

[Tools R Us]

Turned out 12"-14" of my rad in front of my clutch is ice cold with the engine temp at 225f. Looks like my rad is sludged up even though the rad shop back flushed it and boiled it over.

I'm now pricing out a OEM 3 core brass rad......ouch.

That would do it! Was there also hot spots in the radiator? My first choice would be a plastic/alloy, but it likely doesn't matter, run what you are comfortable with.

 

[Wheelingnoob]

That would do it! Was there also hot spots in the radiator? My first choice would be a plastic/alloy, but it likely doesn't matter, run what you are comfortable with.

Out side of that 12-14" of sludge rad core it was very hot like 225f hot. That is defiantly my issue. I have ordered a 93-94 OEM 3 core rad to replace it with, will have it next week.

 

[Tools R Us]

Out side of that 12-14" of sludge rad core it was very hot like 225f hot. That is defiantly my issue. I have ordered a 93-94 OEM 3 core rad to replace it with, will have it next week.

That is what would be expected, sounds like a good confirmation of the problem.

 

[TX Cruiser]

Your going to need a black hub fan clutch to keep the condenser cool. Remember, there is going to be more surface area to cool it down (radiator, 2v3 row) the cooler the radiator, the less the clutch works, the less the a/c cools. Of course this is at idle, in traffic.

Our a/c systems are quite adequate, when there is flow across the condenser. 134 is picky.