Topic: How to test the fan clutch

[83MT]

I've been overheating a little bit lately, and had someone suggest the fan clutch. It doesn't do it as much at highway speeds (although I've been avoiding taking it on the highway lately), but it will climb up towards the red while driving around town. It will climb, then drop, then climb again, so I don't think it's the thermostat, though I'll probably replace that anyways.

I see nothing in the FSM about how to test the fan clutch. I took someone's advice and checked to see if it was spinning, and if I could stop it. It's definitely spinning, but I can stop it by shoving an old radiator hose in there. Does that tell me anything? Just hoping it's not a larger problem..

This is my 83 22R. Basically stock, rebuilt about 20,000 miles ago. I feel like it started doing it out of the blue. I guess I should try flushing the radiator, too.

It seems to me that this started when I adjusted my valves and my carb float. The engine was a LOT louder up over 2,000rpms. I adjusted them again and it's quieter than before, but still louder than at first. I don't think I'm running lean; the sight glass is actually a little more full than ideal.

Any ideas? Thanks.

[1980yota]

How old is your radiator? Sounds like a partial stopped up radiator. If the temp is going up and down and up and down then the thermostat is hunting and therefore is not working right. This could be due to flow being blocked going through the radiator.

If you cant stop the fan from turning and if feels like it is pulling a decent amount of air then it is probably engaging fine.

[jmac]

"climb, then drop, then climb again" I think your thermostat is sticking and would replace it first....easy and cheap.  I've seen the third gens stay cool on highway but not in town when thermostats start failing.

Not trying to highjack, but I think I got some fan clutch issues going right now myself.  Thought it was a the lifters ticking but got louder and was not "rheumatic".  Noticed my fan can wobble a some and figure that where it coming from.  Anyone know if you can replace bearing without doing whole clutch?

[83MT [OP]]

Thanks guys. I'll flush the radiator and replace the thermostat. Just to reiterate: I can stop the fan by shoving an old radiator hose in it. Could probably just grab it with my hand but I'm not that brave...

jmac- not sure but I don't think the clutch is all that pricey.

[junya92toy]

Put it in boiling water, see if it locks up

[Rocksurfer]

Can also use the boiling method on the t-stat to see if it opens.

[83MT [OP]]

Alright, thanks. I'm guessing it must open, because the temp does eventually drop, even with in town driving. But maybe it's getting a little sticky. I went ahead and ordered a new fan clutch and thermostat. I'm going to flush the cooling system on Thursday, and replace the thermostat and fan clutch on Friday. Hopefully that does it!

[2manytoys]

Flushing the system is OK for getting nasty old coolant out of the system but, it isn't going to clean out your radiator if tubes are plugged up. You usually can't see it by looking in throught the cap either. They usually plug more towards the bottom.

Usually when fan clutches go bad, you can spin the fan freely by hand. Not running of coarse. New ones will turn by hand but have resistance. Not keep spinning.

[83MT [OP]]

Yeah, and especially since I'm in the market for a camp trailer, it's probably time to just upgrade to a slightly later model radiator anyways. Probably will want more cooling capabilities once I start towing. But for now...I just want my truck to not overheat during the rest of camping season, and hunting season..

Thanks!

[emsvitil]

Turn engine on.

Reach down and stop blade with your fingers.

If blade stopped and you still have your fingers, clutch is BAD.


If you chopped your fingers off, clutch is GOOD


 

[1980yota]

Yeah, and especially since I'm in the market for a camp trailer, it's probably time to just upgrade to a slightly later model radiator anyways. Probably will want more cooling capabilities once I start towing. But for now...I just want my truck to not overheat during the rest of camping season, and hunting season..

Thanks!

I highly recommend Daves all copper radiator if you decide to go that route. It was only about 20 or 30 higher than a new chinese aluminum and plastic radiator from the parts store. He has 2 and 3 core as well if you want to upgrade as you said. I went with a 2 core because of depth constraints with my electric fan and it has done great for me. No worrying about seals leaking between the aluminum core and plastic tanks. Just my .02

[83MT [OP]]

Thanks ems. Yeah...I wasn't brave enough to stick my fingers in there, but an old radiator hose stopped it pretty easily. I think it smoked a little, though...

Dave's Offroad? I'll check it out. Thanks.

[83MT [OP]]

I did a minor flush of the coolant system last night. Replaced the thermostat and fan clutch and put in Toyota Red coolant. When it heats up later today will be the test...

The lower radiator hose never got hot...but after a little searching this morning, it looks like that's not abnormal? I spent a good amount of time bleeding the system but wasn't brave enough to stick my hand in between the fan and alternator until after I shut the engine off. Only noticed then that the lower hose wasn't hot.

If everything seems fine driving around today, I'm going to replace the spark plugs and take a little camping trip. Huckleberries are out!

My coolant overflow reservoir had some serious dark, dirty water in the bottom....Not sure if it's oil or what. The coolant in general had a little dark hue, but was overall fairly clean. I drained it into an old gallon jug so I'll need to pour some into something else so I can see it better, to see if it looks oily or anything.

As far as letting it idle and burping the system, it never did overheat, but it was pretty nice & cool last night. And I now realize...if you forget to take the old rubber gasket off the old thermostat and put it on the new one, it won't seal and you'll have coolant circulating the system right away...and it will take a LONG time for that temp gauge to start rising.....