Engine/Transmission (1994 - 1998) fan clutch question

[Mhannink]

So my truck has 230k miles and im noticing the fan is kicking on more then normal. Now I know that its been warm out and that I've been running the ac a lot but this summer has been realitivly cool and I just recently cleaned the hell out of my cooling package. I notice the fan is on cause I feel the extra drag when accelerating but what's new is that I can sometimes hear it I mean really hear it. Im wondering do these viscous fan clutches ever fail on? I know they will stop working and not engage propperly but what about engageing too soon?

 

[HEMI®Dart]

I have seen one "lock-up" so it spins at max.



Try turning it by the blade when truck is off. See if it freewheels or moves. Look for silicon fluid leaking. Check for front to back play.

 

[CharlieFoxtrot]

I've read they'e supposed to engage at ~180-190, iirc. That's about when mine comes on, according to the stock gage.



What bugs me is, it comes on at ~180-190, while the truck is unloaded, cruising at 75 on the highway. Outside temps in the hi-80s to lo-90s. AC on full blast. Shouldn't the 75-MPH wind blowing thru the grill be enough to keep it cool??



And FWIW, it does the same thing with temps 10 degrees cooler outside. Maybe not as often...



thanks

kevin

 

[Mhannink]

I have seen one "lock-up" so it spins at max.



Try turning it by the blade when truck is off. See if it freewheels or moves. Look for silicon fluid leaking. Check for front to back play.

i did see some oil on the coil on the front of the clutch, didnt think much of it at the time but i have been wondering if that might be the fluid leaking out. fan spins fine maybe feels tight but ive never really been sure what the viscous should feel like. no "play" that i can detect in any direction though admittedly its been a while since ive checked it.

I've read they'e supposed to engage at ~180-190, iirc. That's about when mine comes on, according to the stock gage.



What bugs me is, it comes on at ~180-190, while the truck is unloaded, cruising at 75 on the highway. Outside temps in the hi-80s to lo-90s. AC on full blast. Shouldn't the 75-MPH wind blowing thru the grill be enough to keep it cool??



And FWIW, it does the same thing with temps 10 degrees cooler outside. Maybe not as often...



thanks

kevin

the ac on will dump enough heat into the clutch to warm it up and engage. mine seems to act fairly normal except its maybe a little bit too often. my other big concern is its way louder then it used to be. i washed out my radiators trying to solve that and it seemed to but only for a short while. my truck sounds like a big truck with the fan on. i mean i can hear it. thats over my engine, exhaust, tires, and music. it is at lower road speeds and higher rpm. just seems to be too loud like its locked in same as an air clutch. ive never heard that before in my truck.



my main reason for asking is over the last 3 years i have owned the truck my mileage has been getting worse. consistently year to year. a couple years ago i put big tires on and so expected the drop. i have since put new smaller tires and narrower rims on and expected to see it return and did but only slightly about maybe . 5mpg. i have done some other major work to the truck. fass and heat sink air to fuel cooler, new overflow valve, new injectors, and draw straw with new sending unit. truck runs better then ever and fuel mileage has come up drastically but its only back to what it was 80k miles ago. im also much more consistent on mileage too. i have not done any fuel mods to the truck since i have owned it except the ones i just mentioned. the engine feels very strong, sounds really good, i dont have any blowby, and dont use a drop of oil in 10k miles. so i dont think its the engine wearing out. a couple years ago i also installed a hamilton big stick cam, and more recently adjusted timing back to what i had before the cam. neither of the mods seem to do much for fuel mileage, though the engine ran very well after.



my theory is that maybe that fan clutch has been slowly wearing out and engaging too soon/often, bringing fuel mileage down, and its gotten bad enough to finally notice.



my fuel mileage 3 years ago averaged for the year 16 and month to month 15 to 17. it dropped from there to 14 for the year and 13 to 15 month to month. i havent had enough time to collect data with the new mods but tank to tank is constent at 15. 5 to 16. 5.

 

[HEMI®Dart]

I would put a new Thermal fan clutch in. You should be able to get the fan & clutch out together without removing the shroud. As long as the top rad hose is cool.

 

[Mhannink]

thats what im thinking im going to do but i dont know yet. im gonna run a little longer and see. it has been hot and my dads powerstroke and other buddies of mine are mentioning the same things. maybe we are all just noticing it for once.

 

[Texis]

You can't really clean the raidators without taking them out and using a strong solvent IMHO. I cleaned mine fairly often and recently had to buy a new one (cracks on the end reservoirs) I was amazed at how much crap was packed deep down in the radiator. "Looked" clean from the front and back, but basically was 75% blocked off with dirt, etc. Surprised it was cooling at all. I picked up one from O'Reillys for $285 (life time warrantee).



I'm extremely pleased, 105 degrees with the AC on max, pulling a low boy with a tractor/bush hog and I can't get it above the themostat setting of 180. The truck has been flirting with the heat for the last couple of summers... I should have replaced it years ago!



I did a new fan clutch at the same time. Mine had gotten to were I never heard it come on at all? Now it is the correct tone and comes on only on rare occassion, for a few seconds. (supper hot outside & heavy load)



I suggest you pull that radiator and have a look, I think you will be surprised at the blockage. A blocked radiator would also explain why Charlie's fan clutch is still coming on at 75 mph.

 

[Mhannink]

also just a thought does anyone know where its possible to get a mag clutch that would fit our trucks? i dont mind switching to a different fan provided it fits if thats what is required. mag would be nice since it wouldnt spin at all untill its needed.

 

[Mhannink]

You can't really clean the raidators without taking them out IMHO. I cleaned mine fairly often and recently had to buy a new one (cracks on the end reservoirs) I was amazed at how much crap was packed deep down iinto the back side of the radiator. Looked clean from the front, but basically was 75% blocked off with dirt, etc. Surprised it was colling at all. I picked up one from O'Reillys for $285 (life time warrantee).



I'm extremely pleased, 105 degrees with the AC on max, pulling a low boy with a tractor/bush hog and I can't get it above the themostat setting of 180. The truck has been flirting with the heat for the last couple of summers... I should have replaced it years ago!



I did a new fan clutch at the same time. Mine had gotten to were I never heard it come on at all? Now it is the correct tone and comes on only on rare occassion, for a few seconds. (supper hot outside & heavy load)



I suggest you pull that radiator and have a look, I think you will be surprised at the blockage. That would explain why the fan clutch is still coming on at 75 mph.

i have found that its very effective if to clean the radiator in chassis if i use water and soap. spray simple green or even dish soap on the rad. really saturate it. then with engine speed up around 2k start hosing it out till the soap is long gone. then repeat a couple times. takes me a couple hours and its spic and span. i have pulled radiators later after cleaning like this and they where definately clean. also ive inspected the radiator with the fan and shround off. going in for other things its clean and spotless so i think my method works very well.



first time i did this on a 1/2 ton dodge soaked the radiator with the engine running got in the cab and reved it up i could hear the water get pulled through the radiator and hit the fan. sounded like someone sucking through a straw and then you hear the splat as the water hit the fan. worked on equipment even better since the are full time fans. rev it up to top engine limit and start washing. between the heat, air pressure, vibration, and the water i could clean them out in no time at all. made my boss really happy.

 

[CharlieFoxtrot]

A blocked radiator would also explain why Charlie's fan clutch is still coming on at 75 mph.

Yup, except my rad is only a year or so old. Fan clutch acted pretty much the same with the original radiator, which sprung a leak.



If it never came on, or never shut off, I'd absolutely replace the clutch. But it seems to come on and shut off at the correct temps. It just gets to those temps more often than I'd like.



This _is_ my first diesel, and the first thing I've driven in years that's not expected to run at 195-210 degrees, so maybe it's just me...

 

[cerberusiam]

What bugs me is, it comes on at ~180-190, while the truck is unloaded, cruising at 75 on the highway. Outside temps in the hi-80s to lo-90s. AC on full blast. Shouldn't the 75-MPH wind blowing thru the grill be enough to keep it cool??

Under those conditions, no. The coolant is shedding that heat as is the AC condensor. Sounds like it is working just as it should.



Its entirely possible the clutch is getting ready to lock completely. Thats better than just free wheeling like the new ones and overheating things. As long as you coolant temps look good don't think you have a problem.

 

[GOlsen]

My fan spins all the time. Is it supposed to do that? With the truck off, the fan spins (got some drag on it though). But as long as the engine is running, the fan is spinning, even when cold.

 

[Mhannink]

My fan spins all the time. Is it supposed to do that? With the truck off, the fan spins (got some drag on it though). But as long as the engine is running, the fan is spinning, even when cold.

yes the fan always spins. the viscous fluid design does that. its hard to tell looking at it but its not spinning engine speed. at least not at higher rpm, maybe at idle. that drag you feel is the viscous fluid inside the clutch. the clutch progressivly engages harder and comes closer to engine speed as the tempurature coil on the front warms up. the idea is its works like an on/off clutch that is self controled.

 

[GOlsen]

Ok, cool. Thanks for the reply.

 

[BGlidewell]

I had a fan clutch go out on my 96 1500. I think one of the diagnostics was to see if it would spin freely with the engine OFF. If not, it was bad.

 

[Vaughn MacKenzie]

The clutch on my '96 progressively engaged more and more readily to where it was often fully engaged when only 90 outside. I bought a new one from Auto Zone and it wasn't much better, so I sprung for a new one from Dodge and it works great, problem solved. It doesn't engage aggresively until it's closer to 100 outside (which it's hardly done since this has been the mildest summer ever).

 

[Mhannink]

so the clutches do fail to the on postion or at least can?

 

[GAmes]

so the clutches do fail to the on postion or at least can?

I had one fail to the engaged position, a few years ago, but it never disengaged like yours is doing. A couple months ago I heard my fan engaging while unloaded which is not normal. I bought a new OEM and the new clutch worked the same, so I reinstalled the old one and put the new one in my parts box. I have put another 10k on it and so far it has not failed. For the last week I have been operating in the northern states and the only times the fan has engaged fully was while pulling a trailer up an incline. I think yours is fine.

 

[Mhannink]

I had one fail to the engaged position, a few years ago, but it never disengaged like yours is doing. A couple months ago I heard my fan engaging while unloaded which is not normal. I bought a new OEM and the new clutch worked the same, so I reinstalled the old one and put the new one in my parts box. I have put another 10k on it and so far it has not failed. For the last week I have been operating in the northern states and the only times the fan has engaged fully was while pulling a trailer up an incline. I think yours is fine.

mine is engaging while unloaded too. when i notice it the most is leaving school. i get there early in the morning, which is about 60 degrees outside, and a 45 minute drive on flat ground. ill get in the truck after about 2 hours and the engine temp is just above 140. start the truck take off and for the first 1/4 miles or so i can hear and feel the fan running, then it shuts off. the fan shouldnt be kicking on at the point. low ambeint temps low engine temps and no ac on. as a note to this i mentioned earlier ive never heard the fan before. add to that it used to be very difficult for me to feel then fan as well. now i feel it really easily.



on another note. does anyone have a source for a good fan clutch. i dont want to go to the dealer and would like a horton or similar clutch. i would love to set up an electromag clutch if anyone has a source for one.

 

[cerberusiam]

so the clutches do fail to the on postion or at least can?

That is a more typical failure than going into freewheel on these clutches. When they fail they lock solid. The 1st and 2nd gens have always done that to me where the 3rd gens just don't pull enough becuase the electrical part fails.