Erratic fan clutch

[Ron & Dee]

My big radiator fan clutch has been acting strange lately

While traveling on vacation this summer the fan doesn't know when to come on or when to go off. The normal operation for my fan has always been; cycles on around 211 and cycles off about 206 or below, except for a hard pull. Now, sometimes it comes on at 211, 213, 215, and on a hard pull it doesn't come on until 226 or 228, and by that time I start sweating The cut off varies also.

Is it time to change the fan clutch?

Thanks,

Ron

[M&EM]

Quote:

Originally Posted by Ron & Dee My big radiator fan clutch has been acting strange lately Is it time to change the fan clutch? Thanks, Ron

Ron I went thru this kind of issue end of last summer and spent the following six months testing everything, well almost, Finally bought a new fan clutch in Jan. Three months later, I still got same symptoms. A 2nd clutch replacement didn't improve much. Finally discovered root cause to be the fan shroud which had separated from the radiator along the top side. I repaired that and every thing was back to normal. The fan clutch is expensive so check other possible causes first. My original is most likely still good and is a spare now. Make sure all the air dam material is in place. Then check that fan shroud, top and bottom halves and the side pieces. By the time I was all done I had replaced thermostat, radiator cap and flushed out the cooling system inside and out. None of these helped, but were all on my list of maintenance any way. Just my 2 cents .

Marty

[max49]

[QUOTE=Ron & Dee;926434 Now, sometimes it comes on at 211, 213, 215, and on a hard pull it doesn't come on until 226 or 228, and by that time I start sweating The cut off varies also.

Is it time to change the fan clutch?

Thanks,

Ron[/QUOTE]

226 or 228* ? Is that from your scan gauge? I thought my 214* was cooking. If it wasn't for the burnt wires, I guess 214* is no big deal. I've already started tearing out some of my "air dam" on the problem side. There's no rhyme or reason to my fan clutch either except it come on often with the AC on, sometimes it's on at 190* and goes off at 211*, but not for long. It obviously does'nt get it's info from the same place as the scan gauge.

[M&EM]

As I have found out over the past 9 months, the fan clutch thermostat feels the air temperature coming thru the radiator. If there is any air bypassing the radiator such as due to a loose or separated fan shroud or in my case also a fan blade milled slot at the top of the shroud, then the fan clutch will see a lower air temperature mixed with the radiator air and not engage until high enough temperatures at the radiator brings the mixed air to the required level for fan clutch activation...

[kennersonf]

I just finished a 5900 mile trip today. Prior to going on the trip I found the plastic around the top screws of the fan shroud had broken off and the shroud was not secured at the top. This resulted in a 3/8 inch gap. I used flat washers under the screws and was able to secure the top of the shroud. I also plugged the hole in the bottom shroud that was caused by the fan hitting it (I had fixed the cause of this years ago). The shroud repair resulted in a cooler operating temperature then earlier trips. This trip the engine ran consistantly between 197 and 200 degrees. Before it was at 202 degrees. The fan clutch also kicked in around 205 degrees as compared to 210 before the fix. I did not have time to buy a new shroud before the trip but plan on buy both upper and lower shrouds and installing them. To make a long story short, check your fan shroud.

[Ron & Dee]

My operating temps are read from my ScanGauge. The manual says the normal operating temperature is from 190 degrees to 240. I have never reached 240 but come close to 230 several times.

Are there more than one sensor that determines when the big fan comes on?

Thanks,

Ron

[Clay L]

If the fan clutch setting is the same as the one on the 454 engine it is supposed to come on at an air temp coming through the radiator of 165 degrees.

[M&EM]

Quote:

Originally Posted by Ron & Dee My operating temps are read from my ScanGauge. The manual says the normal operating temperature is from 190 degrees to 240. I have never reached 240 but come close to 230 several times. Are there more than one sensor that determines when the big fan comes on? Thanks, Ron

Ron, the only sensor that controls the big fan is the spiral thermostat spring built into the front of the fan clutch assembly. It controls the fan clutch viscous coupling by allowing more or less silicone oil to be introduced between the clutch plates. The spiral spring rotates a small valve inside the clutch. It is a mechanical sensor.

When your scan gauge shows close to 230F, what does the dash gauge indicate?

Marty

[Ron & Dee]

Marty,

My dash gauge is screwy.



The green mark is 204 degrees and the red mark that I have put on the gauge is about 228 degrees. I assume the 210 degree mark is getting pretty close to 230 degrees.

Ron

[MegaRoadie]

GM just doesn't seem to get temp gauges to work right or someone along the way changes parameters and screws them up.

That big fan clutch is mechanical, working off viscosity of silicon fluids inside the clutch shroud. It either works or it doesn't but no electronics so it is a bit more reiliable, IMHO

Would be extremely careful removing any of the air dam materials, in fact I suffered an idiot lying chevy garage truck shop moron leaving my air dam off and trying to say that Work Horse had a tech bulletin out to remove it to try to cover up their screwup. It is a violation of federall law to modify or remove the air dam, look at your work horse owners booklet ! My new "home made" dam works to quiet my cab noise levels, and directs air flow where it should be so now my fans noise levels are dramatically lower !

I do NOT suffer from mental illness, but rather enjoy it daily !

[M&EM]

Quote:

Originally Posted by Ron & Dee Marty, My dash gauge is screwy. Ron

Ron, I would suspect the ECT, (engine coolant temperature), sensor. My Shop manual shows 3 wire go to it. There are two sensor elements in it.
It appears that one sensor module is used with separate outputs for the pcm and the dash gauge. The pcm is what supplies info to your scan gauge via OBDll.

I think on later model years using the Actia instrument panel, the dash gauge is also driven by the pcm. In the newer models, the pcm makes the dash gauge stay in mid range as long as ECT is within about 180 to 230F. Above that it will move the gauge upscale pretty quick. So around mid range the my scan gauge does not replicate the dash gauge.

Marty

[max49]

Quote:

Originally Posted by MegaRoadie Would be extremely careful removing any of the air dam materials, in fact I suffered an idiot lying chevy garage truck shop moron leaving my air dam off and trying to say that Work Horse had a tech bulletin out to remove it to try to cover up their screwup. It is a violation of federall law to modify or remove the air dam, look at your work horse owners booklet ! My new "home made" dam works to quiet my cab noise l I do NOT suffer from mental illness, but rather enjoy it daily !

That's pretty funny Roadie.
I wonder if they are paroling other felons to make room for air dam tamperers.
Everyone here seems to blame the SP wire burning on the body builder for restricting the air flow. Then they say keep that air dam tight so all air goes thru the radiator and none around the engine.
Well duh,
Having plenty of experience with burnt wires on 2 different 8.1s, I'm betting the tight air dam is contributing to or causing it.
People on this forum told me I was missing some of my air dam on the passenger side just a couple weeks ago. I put some rubber material up to dam it up even tho I didn't think it was ever there before. On my first trip I burnt 2 wires on #6 cylinder, the passenger side, which is the first time with the new engine, and my 1st engine always burned #5 wire on the driver side.
Since I only see 214 degrees and others are reporting 230 degrees I think I'm going to share some of that air with the spark plugs

[Clay L]

Quote:

Originally Posted by max49 That's pretty funny Roadie. I wonder if they are paroling other felons to make room for air dam tamperers. Everyone here seems to blame the SP wire burning on the body builder for restricting the air flow. Then they say keep that air dam tight so all air goes thru the radiator and none around the engine. Well duh, Having plenty of experience with burnt wires on 2 different 8.1s, I'm betting the tight air dam is contributing to or causing it. People on this forum told me I was missing some of my air dam on the passenger side just a couple weeks ago. I put some rubber material up to dam it up even tho I didn't think it was ever there before. On my first trip I burnt 2 wires on #6 cylinder, the passenger side, which is the first time with the new engine, and my 1st engine always burned #5 wire on the driver side. Since I only see 214 degrees and others are reporting 230 degrees I think I'm going to share some of that air with the spark plugs

Max, is it possible that when the engine heats up there a small exhuast leak that is burning the wires?
Having two engines with exhaust leaks seem improbable but since the hot spot seemed to move when the engine was replaced it makes me wonder.

PS. If you get over here to Palisade before too long you can take home some peaches. We are in the middle of harvesting 3000 trees.
(Well not really "we". I have a hip replacement set for Sept 1st and am sitting on my hind end this year watching it all. )

[MegaRoadie]

Kinda wondering who spit in your cheerios there Max !!!!!

One thing the forum should teach all of us is to SHARE info and not necessarily sling a handful at someone with a different idea or approach to a percieved problem.

Had you bothered to ask before leaping, I would have told you that my Itasca has the WorkHorse Cooling Ducting Package installed to boost airflow over the sparkplug areas. That comment, misguided as it was, now paints your comments at a much reduced status IMHO and I would hope it was just a bad day or a childish attempt to lash out. My air dam being removed allowed cab noise levels that inhibited conversation due to road and fan noises and replacing it was not only well researched and thought out but also an individual decission that I take offense that you saw fit to be childish and attack. NUFF SAID

Be safe, enjoy the Open Road, and Thank a Veteran for your freedoms (even if some choose to be childish in exercising them)