skoob

I own a 1992 DLX with a 22re motor. I recently did a head gasket, timing chain job on the motor. Ever since I have been seen a slight increase in temperature on the gauge. At first it was very erratic so I put in a two stage thermostat which helped a lot. I will see the needle swing up from time to time about 50 percentage the gauge travel. When the vehicle moves forward it drops quickly down to almost 15 percent of gauge travel. It was suggested it may be the fan clutch. I am curious how I can be sure this is my issue. It may also be time to replace anyway, the vehicle has 160,000 miles and was in a front end collision several years before I worked on the motor( I just wasn't ready to retire this incredible truck).

Rerunn

Try to spin the fan by hand. If there is little to no resistance you need to replace it. If there is it should be OK. That what it sounds like to me tho

Kiroshu

Temperature drops with engine speed increase or vehicle speed increase..?

Fan shroud missing...?

As stated above check fan clutch fluid coupling verify its feel.

If when cold it is very easy to spin significant wear may be present.

A more generic feel test: should be hard to turn when cold/easy to turn(with some resistance)when warm/hard to turn when hot. There are specific temperatures for clutch lock but I don't see this information in the FSM.

Check air flow when the engine is running/do you feel good air flow behind the fan..?

Check for any damage or leaks. If damaged or silicone leakage present replace the fan clutch fluid coupling.

Is the clutch loose...?

Fan installed correctly..?

RAD4Runner

Unfortunately, tests mentioned in the forums are by feel- hence subjective - at best. How little is little resistance? How much is a lot of resistance? Little force to a piano mover may be a lot of force to the pianist whose forte is nocturnes.

The FSM does not have a practical test, either. Only inspection.

A practical, measurable test of function would be:

1. Use optical (non-contact) tachometer and compare rpm of fan with the rpm of pulley,OR
2. Use a scale, tie to fan at known exact spot, measure pull of fan upon starting when cold. Record pull force and RPM. Then, do same upon arriving home from a long enough drive so engine is at operating temp.

Compare above with readings from other trucks of same year-model.
Compare to readings from other trucks with brand-new clutches.

I plan to do above on my 86, 22RE. Will post results on my build thread.
If anyone has done any of the above, please chime in with your results.

scope103

We deal with enough myths; I love it when someone tries to be scientific.

But I don't think the fan clutch senses engine temperature at all. Rather, temperature of the air as it exits the radiator. So if you're driving across a frozen lake in Alaska, the air coming through the radiator will be pretty cold no matter what the engine temperature, and the fan will not be driven. But in Redding, CA in mid-summer, that fan will probably engage immediately even with what passes for a dead-cold engine there.

So I think the best test would be to put a remote thermometer (any cooking store has cheap ones) right behind the radiator, listen for the increased fan noise when the clutch engages, and try to correlate those two. Just a thought.

RAD4Runner

Agree. so I'd just have to do it in the morning when cold air from radiator combined with 70-degree San Diego air blows across the fan clutch and upon getting home in the afternoon when hot air of radiator combined with 70-degree San Diego air blows across the fan clutch

Compare with readings from brand-new fan clutch.

wireguy

A guy at an excellent local radiator shop showed me the fan clutch on my '86 with 22R could be restored to like new by simply disassembling it and refilling it with silicon grease. Mine went right back to perfect function and has been fine ever since, a couple hundred thousand miles. He praised that fan clutch as well designed.

RAD4Runner

Yep, they use various weights of silicone oil to control engagement. I believe 4crawler explains the process.

Agree. Very reliable. That's why owner of shop I use who used to race 22RE's in Baja says, that while Electric fan is OK for performance, Better to stick with mechanical fan clutch for reliability.

BTW,
If this could be indication of amount of coupling...
As soon as I get home, I counted number of seconds from time I shut off engine to the time fan stops turning.
Fan stops after approx 8 seconds.
Theoretically, if there is 100% coupling (same as fan mechanically/directly mounted to pulley), fan will stop as soon as engine stops.
I haven't observed coupling upon starting in cold morning, yet.

scope103

http://www.4crawler.com/4x4/Docs/FanClutch.pdf

skoob

Thanks for the tips. After driving home 20 minutes I turned off and opened the hood the fan easily spun. I am sure that is my problem. When I get the part I will give a update.

skoob

I just completed putting on the new Asin(ordered from Autohauz) fan clutch. I have just turned up the heat and drove around town for about 20 minutes, stop and go traffic. Temp gauge never exceeded 30% of total. I think that did it a and I do not have to worry about overheating my truck. Only took 1 hr of time and was quite easy. Once again thanks for the input, Autohauz was a vendor I located here on this site, their part was legit and saved me money.

RAD4Runner

Awesome! I'm obsessed with the cooling system because most major problems I've had with my vehicles had been related to it, and such a simple system that can be maintained easily could easily kill an engine worth several thousands if not taken care of.

Thanks for the update Skoob. We could all learn from your experience, and I hope you cdoul share what you've found out about your old and new fan clutch.
I have been so busy I haven't done any measurement but:

• I feel more resistance to hand-turning the fan when engine is cold than when engine is hot.
• Upon starting cold in the morning, I would turn off ignition and the fan would stop right away.
• Upon arriving home, I'd turn off engine and watch the fan keep on spinning for another 8 seconds.
• So it looks like fan follows engine/pulley speed more closely when cold than when hot, when it should be the other way around

Skoob, How does your new fan compare to your old one and from what I've observed? Any special tip on removal and replacement?

RAD4Runner

Hi guys,
So...

Observations:
When engine is cold and stopped, there is more resistance to hand-turning the fan.
When engine is hot and just turned off, there is less resistance to hand-turning the fan.

I took a video of my fan clutch operation when cold, upon starting up in the morning, and then at normal operating temp upon arriving home.
[YOUTUBE] [/YOUTUBE]

• When cold, as soon as engine is shut off, fan stops turning within 2-3 seconds
• When hot, as soon as engine is turned off, fan keeps on turning for another 6-7 seconds.

Above seem contrary to how I understand the fan clutch should work such that:

• When cold, where not much cooling is required, there is less coupling; meaning fan does not follow pulley speed as closely. So when pulley stops, fan should keep on turning longer.
• When hot, when more cooling is required, there is more coupling; meaning fan follows pulley speed more closely. So when pulley (engine) stops fan should stop turning sooner.

Skoob and Redeth, and other folks with new, known-good fan clutch, would you please observe how your fan clutches work now, compared to mine on video?

skoob

I removed the fan shroud and fan with clutch together. Then I transferred fan to new clutch. Reversed it when I put it back in. Their were four 10 mm nuts to loosen. I also removed the power steering belt to get more room. I still have to see if the fan turns when I turn the vehicle off. If it does my guess is it needs to cool the radiator more due to the vehicle no longer moving to cool down the vehicle.

RAD4Runner

Thanks a lot, Skoob!
I also hope to do my force gage measurement this weekend.

skoob

Further update I am using the heater more the gauge still moves around. My drive to work and back is only 15 minutes and halfway I see the gauge go to 40 percent then suddenly plummet to 20 percent. It is strange that some days are better than others. The truck heats up steadily and then goes down. I still feel the motor is safe from overheating but I still want to understand what is going on. When I turn down the heat the temp goes down rather quickly.
I am thinking there is a problem with the heater core. Anyone have any ideas?

RAD4Runner

Sounds quite the opposite of normal. When you turn up the cabin heat, the engine temp should go down because now the heater core is helping remove the heat from the coolant.

Still no one chiming in on how their known-good or brand-new fan clutch operates compared to the 28-year old one on my video above?

skoob

Ok ran the tests on spinning fan. When cold fan spins for 2 seconds after engine cuts off. When engine hot it spun for six seconds before stopping. ( these results on new clutch)

scope103

As i said before, "engine hot/engine cold" is probably not the right question. On my '94, the fan will spin about 1 revolution when the engine is switched off -- hot OR cold! It's not the temperature of the coolant, but of the fan clutch itself. If you're cruising down the road at 40mph, the radiator has plenty of air flow no matter what the coolant temperature (or, as a practical matter, the air temperature). The fan should be essentially disengaged. But if you stop at idle (with the A/C on) for a few minutes, there is so little air flow through the radiator that the clutch will get quit toasty, stiffen up, and start pulling air through with the fan.

My sense is that if you sit at idle for about 10 minutes, at some point you will be able to hear the fan start laboring as it is pulling air through the radiator. Otherwise, no.

RAD4Runner

Thanks, Skoob!
But Scope makes sense...

I tried the "cold" condition before even moving the truck, but I did the "hot" as soon as I stopped from running 50mph on road.

This time, I will now try the "hot" condition as follows:
After arriving home, let it idle for maybe 5 minutes, or until i hear any straining - meaning fan has more engagement.
Turn engine off and see how long fan remains turning. IF engaged in "hot" mode, good fan clutch should stop in less than 8 seconds.

Will keep you guys posted.