A bit of newbie question but my time to mess around with my truck has been really limited lately, so I'm looking for some opinions before I tinker...

My trucks heat has been climbing lately. At first it would just occasionally build a bit when it was first warming up, then drop to normal. I just figured it was the thermostat finally opening and didn't worry about it.

About a month ago, I adjusted my valve clearances, and the carb float. After I bought a rebuilt carb, the fuel level was always all the way up to the top. I finally adjusted the tabs, and now it's in the middle, which should be good.

After doing this and adjusting the valves (did it all at once), my engine is much louder once it's over 2k or so rpm's. Also, the heat is hanging out up closer to the red line that I'm comfortable with. It seems to always drop, but it's not just doing it when it warms up for the first time driving it that day.

Anyway, the louder engine might be a totally different issue from the overheating. I'm definitely going to throw in a new thermostat just in case, but could improperly adjusted valves cause the engine to be louder, and run hotter?

 

Mine was doing something similar.. It was the fan clutch. ~$35 at Autozone and about an hour of time to R&R.

 

x2 on the fan clutch, you should actually hear the fan running it might also put a drag on the motor too, when you first start it in the morning, after about 20-30 seconds if that you should hear it turn off and your rpm come up a bit.

 

Ok, I'll check it. It was brand new back when everything was brand new on the truck...about 3 years ago, but that doesn't necessarily mean it's working.

Thanks.

 

Anytime time you replace a fan clutch.... go OEM. anybody that doesn't... don't come askin why you got a overheating problem. if you still have this problem after the thermostat... probably your fan clutch. go buy an oem one if it is the culprit. if your last one wasn't oem... i would start pointing the finger there already... and are you using red coolant? for some reason it is supposed to be better..lol

i hope you can find the problem before any damage happens.

 

Yes, I always go OEM or better.

Well, tell me if this answers the question or not, but after driving from work to home on my lunch break, I popped the hood, and the fan was spinning.

 

yea.....X 3 on the fan clutch. if i get hung up in traffic (at idle) my temp starts climbing. i know for a fact that the fan clutch is the culprit because when the truck is just idling I can grab the fan and stop it from turning.

Disclaimer: I had to drink a couple beers to get the nerve up to grab a spinning fan.

 

So this is not normal? Sorry I only know so much...I've replaced pretty much everything on my truck but that doesn't mean I understand how it all works. How does this tell you the clutch is bad? If mine is spinning while I'm idling, it seems like it working correctly...

 

Normally when idling or doing a lot of stop and go driving, the clutch should be engaged, so you shouldn't be able to stop the spinning fan by hand.

In my experience the fan always spins a little because there is always a little bit of drag created by the clutch, even when it is disengaged. Whether or not the clutch was engaged or disengaged likely depends on what type of driving you were doing.

As I understand it (and somebody please correct me if I'm wrong here), the clutch is disengaged when the engine is cool or when you are driving on the highway and the fan is not needed for cooling. When the clutch is disengaged, the fan more or less freewheels. When the motor starts to heat up, such as idling or stop and go traffic, the fan clutch engages, forcing the fan to spin (not entirely sure on the specifics of how this works, but I think it has a bi-metallic strip on the clutch that expands and contracts with changes in temperature which controls the flow of silicon liquid inside the clutch, which is what engages and disengages the clutch).

I recently had some issues with my temp gauge reading hot and after replacing the thermostat, fan clutch and trying 3 different sending units I concluded that the gauge was malfunctioning (my radiator was basically new, so I could rule that out). I ended up putting in an aftermarket temp gauge in place of the worthless ammeter. The gauge reads in degrees and gives me a better idea of what is actually going on with the temp. I think the stock temp gauge is designed to stay in the middle of the gauge over a fairly wide range of temps.

 

Thanks for that, it seems to make sense. I'm going to find a little time this weekend to re-adjust my valves and look over some things, so I'll check out my fan, too, and maybe replace the thermostat. I'll get a thick leather glove or something and stick my hand in the fan.

 

You are a braver man than I. No way I'd stick my hand near the spinning fan (I like my fingers too much ). I think you could get an idea of whether or not the fan clutch is working properly by shutting off the truck and immediately spinning the fan to see how much resistance you get (I think the clutch fluid is fairly viscous, so it will take a little while for it to transition from engaged to disengaged). It should spin noticeably harder when the clutch is engaged and relatively easy when it is not engaged.

Also look for leakage around the clutch as this would indicate that it is going bad. Good luck - I know firsthand how frustrating it can be trying to track down the source of the problem.

 

Yes...and I was planning to do this just hours before I have a show playing banjo!

Maybe I'll skip the fingers in the fan part of it...

Anyways, thanks. I'll check some things out, and see if the FSM has any advice for testing the fan clutch.

 

Probably just a fluke, but it wasn't overheating this weekend. I re-adjusted the valves, and it quieted down the engine a little. Didn't make it to the dealership before the weekend so I didn't replace the thermostat yet. I'll still check the fan clutch and thermostat before moving on. FSM has no proceedure (that I can find) on testing the fan clutch, so I guess I'll find something to jam in there when it's running, or try to remember to see how easily it spins by hand right after turning my truck off.

 

Update. Like I mentioned above, I readjusted the valves and the engine quieted down a little, but not as quiet as it used to be. I readjusted the float. Still some slight overheating. Now I have a question for more people:

What is the correct procedure for checking the fan clutch?? I stuck an old radiator hose in there yesterday and it stopped it. But it started to smoke a little when I did this...Does the fact that I can stop the fan mean that the clutch is bad? Or does the clutch work that way? I'd like to get one ordered right away if that's my problem. Thanks!

 

Hey Zach, the fan clutch should have more resistance than that, even at idle. Keep the hose on the fan and raise the idle to 3k, if the resistance doesn't built that's probably it. You need to do this at operating temp..Also is it a stock 30 year old radiator? If so, you might want to have the inside refurbished.. A lot of rust has probably built up over the years..The radiator might not be cycling the water correctly/ enough because it's impeded..With that said maybe it's the water pump. Start with the fan clutch, when the water pump goes you'll know it... good luck

 

Ok, thanks a lot. I had the radiator tested when the engine was out. But it may have just been pressure tested, I'm not sure. Probably could use an upgrade, but it's been fine so far. Rust isn't too much of an issue around here.

Water pump is new with the rebuilt engine (about 20,000 miles ago), but I know that's not necessarily a reason to rule it out.

I'll check the fan clutch again, thanks!

 

What specs are you adjusting your valves at?
I'm only asking because I just adjusted mine to the factory specs hot and they are louder than I'd like, so I plan to adjust them cold at .001" tighter than I did before and see if that helps with the noise. People on here have said that the cold adjust and a little tighter setting gets them quiet.

 

Interesting...I'm using the FSM hot engine specs.

I don't know engines really well...but this isn't like a valve clacking noise or something, the engine just sounds like I'm revving it a lot higher than I am, if that makes sense. No ticking, just loud.

Thanks. For some reason I assumed that I had gone too tight, and that's why it got loud. You're thinking maybe not tight enough?

 

Mine gets loud on occasion. I've found that my LC Engineering header comes lose from the head. No fault of the header though. My head is in pretty bad shape as far as the exhaust studs are concerned. The aluminum seems to be giving up and applying the propper torque values to the exhaust manifold bolts, just pulls the studs right out of the head. So I've got other issues.. I've also got their poly motor mounts so things are quite stiff and transfer a lot of vibes.

But to get back on topic and address your concern with the increased noise.. I'd look at a exhaust manifold leak. Mine sounds like I'm at 3-4K when I'm at 2-2.5K when I have a leak.

20R head needs get put on..

 

Great, thanks Justin. I'm used to sounding like a Harley when I have a manifold leak, so that wasn't something I was thinking of. I'll see if the torque is right on it.

Hopefully Thursday I flush the radiator, and a new fan clutch and thermostat should be in in time for the weekend. I want my truck for the rest of camping season and in time for hunting season!