Overheating problem

[77mustard40]

I’m wondering just how accurate my dash gauge really is. The engine itself is not showing any sign of overheating, like bubbling in the overflow tank or anything. I wish the coolant sensor on the block, was easier to get to.

The stock dash gauge is nothing more than a decorative piece, they have a bad flat spot in the middle such that once you see it rising above the midpoint you are likely already overheating. Many of us have installed aftermarket sensors or computers to display accurate data.

 

[Malleus]

The flat spot on the upper radiator hose fitting is the spot to insert a temp probe.

 

[flintknapper]

The stock dash gauge is nothing more than a decorative piece, they have a bad flat spot in the middle such that once you see it rising above the midpoint you are likely already overheating. Many of us have installed aftermarket sensors or computers to display accurate data.

^^^^^



In my 80 series:

In my 100 series:

 

[SpenserAK]

I can't imagine having a vehicle without a scangauge anymore.

 

[Marvelicious]

When I opened my new blue hub, I only got out about half of what I put back in. Plus, it was MUCH thinner.

After the 56 ml of 15K, I have roaring and so far it has not exceeded 192°F. But I have not had any hot, hard working days on it yet. Just long road miles.

Did anyone ever distill all the various versions of this into some kind of shorthand for what works? I've gone into the thread linked in the FAQ about 15 times and get bogged down every time. There's about a 20 degree variation on setting the valve and around 20000cst of variation on the different fluids people use. I do see at least a little bit more consistency of fluid volume around 50ml being roughly the common number.

 

[landtank]

Did anyone ever distill all the various versions of this into some kind of shorthand for what works? I've gone into the thread linked in the FAQ about 15 times and get bogged down every time. There's about a 20 degree variation on setting the valve and around 20000cst of variation on the different fluids people use. I do see at least a little bit more consistency of fluid volume around 50ml being roughly the common number.

Everyone has an opinion. If that is my thread on modding the fan clutches I would have deleted it years ago if I was able to.

 

[BILT4ME]

Everyone has an opinion. If that is my thread on modding the fan clutches I would have deleted it years ago if I was able to.

Yes. That is the thread I used as a guide.

I could see a significant difference in the location of folks doing the work.

Those in the West and more desert used thicker fluid and adjusted it more. Those in the Midwest and East used thinner fluid.

The amount of fluid is close and that could be determined by how patient you are to fill the hub and the viscosity of the fluid being used. With the hub sitting on its mounting flange, it appears natural to fill it to the machined surface, letting it flow into and around all the parts.

The temp settings can be subjective, as I did not have a clean way to monitor temp and spring movements. My water heater is set to 120*F, so I used that in a large pan filled with water and an IR gun to see where it roasted at what temp. Then I made a wild ass judgement call, on the "aggressive" side and it works, albeit there is probably a more accurate method, but this is my DD and I needed to finish and I'm not going to take it apart again. I wanted to do it once.

Thank you, @landtank for pulling it together in the first place. I know you did it based on your research and you build and sell new hubs. It's not as accurate as you want it, and there's a lot of polluted information in there now, but it's still useful.

@Marvelicious that is the thread I used as a guide.

 

[TomH]

Did anyone ever distill all the various versions of this into some kind of shorthand for what works? I've gone into the thread linked in the FAQ about 15 times and get bogged down every time. There's about a 20 degree variation on setting the valve and around 20000cst of variation on the different fluids people use. I do see at least a little bit more consistency of fluid volume around 50ml being roughly the common number.

Being in Seattle, weather here is probably similar to yours. I've never modded one of my fan clutches. Drain, refill with 10K cst, and go. Never had a temperature problem.

 

[jpoole]

@Marvelicious

There is not a definitive thread on the fan clutch settings but there is a lot of good info scattered around the forum on the subject. One reason that there may not be a newer thread on the subject could be a nod to those that pioneered the research and sell modified clutches at a reasonable price (thanks @landtank ) . For many, just buying a clutch that's setup is the best option. For those that want to modify their own, they need to run a search and spend a little time reading to get a good understanding of the options before diving in. Once you have a good understanding of what you are doing I think that this is easy and satisfying work. There are ways to get the fan clutch in/out quickly and the only slow part of the process is the draining and filling of the oil as it's slow-moving stuff.

Regarding the oil weights they started low and have crept up over the years. I think the Toyota oil weights that people were originally using were in the 5k to 10k range (per memory at least) and folks started from there but eventually learned that the much higher weights that you could get from hobby providers worked better, etc..

I've shared on setting up these fan clutches multiple times over the years and my take is primarily based on what I've learned on this forum and then tested and learned on my own 80. The quick summary of important points, in my opinion are:

• these fan clutches need an adequate amount of fluid in them to perform correctly over a long time
  • there is some wiggle room per my tests but too little oil will lead to quicker breakdown of the oil and poorer performance in extreme temps
  • With the clutch split and drained (overnight) I just fill to the top of the fill/larger ports a few times, turning the clutch body/hub periodically to help the oil work it's way in, until the clutch stops readily taking more oil. I don't spend hours on this, and just get it mostly full with those ports full and then move on.
• 15k cst to 40k cst is probably a decent range of oil weights to choose from
  • the weight of the oil has seemed like a softer tuning adjustment in my tests but I don't have access to the temps/conditions that some see like dessert wheeling in the SW US
• setting the clutch opening temps is an essential step, per my tests
  • my experience is limited here but the new Aisin blue hub I installed couldn't keep engine temps below 220 in moderate conditions, even with new oil, until I changed the port opening temps
  • I use a boiler and candy thermometer so that I can know for sure the temp on the clutch face (temp spring). A double boiler or spacer of some kind to keep the clutch off of the bottom of the pan is needed so that temps are accurate. This should be easy to setup. I typically will use a few thermometers to make sure one isn't out of whack, and since I have them around.
  • I think that the bimetallic springs can be a little imprecise over time but that's based on imprecise personal observation and not scientific evidence. As they cycle through temps though I think they slowly change position for a given temp which over time can cause the port opening temps to shift a relevant # of degrees.
• you can remove the fan clutch, and reinstall it without adjusting the belts
  • remove the 4 nuts from the fan clutch hub
  • remove the bolts holding the fan shroud to the radiator
  • gently push the fan shroud away from the radiator and work the fan and fan clutch up and out through the gap between shroud and radiator on the passenger side
  • don't hit the radiator and bend the fins, a piece of cardboard against the rad may help here
  • once you get comfortable with this removal/install approach you can get the fan clutch in or out in just a few minutes.

More information along those lines from myself (post #s shared) and many others:

• #9 - on setup - What kind of fan clutch do I have? - https://forum.ih8mud.com/threads/what-kind-of-fan-clutch-do-i-have.1284720/
• #4 - on setup, #14 - on functionality - Fan Clutch Oil Change - https://forum.ih8mud.com/threads/fan-clutch-oil-change.1221954/
  • some nice photos on page #2

I also recently changed the oil/temp in my fan clutch and shared photos/etc. but I couldn't find that post. The above have links to other posts where you can see good photos that help you know what you are looking at and lots of good info from forum members.

 

[ChaseTruck]

The flat spot on the upper radiator hose fitting is the spot to insert a temp probe.

This is what’s on our ‘93 - sender for a Koso temp gauge resides there.

Initially I had the sensor in a coolant hose insert. But then both my wife and the late Tools R Us (RIP Kevin Patterson, can’t believe it’s 4 years already) declared that a solution, so the sensor got moved…

Our trucks live in the AZ desert, so the fan clutches are adapted to that. And the S/C’s.

 

[77mustard40]

I used very little science after plowing through the good and bad of the @landtank thread. I ran a new blue hub unmodified for a year and a half before deciding to mod it. I picked a perfect 108 degree day to adjust it and refill it with 15K (we had a lot of those days last summer in TX) so I didn't bother taking a temp since it was sitting in that heat draining. Performance has been great since the mod, rarely saw temps as high at 195 in the heat.

 

[Marvelicious]

Being in Seattle, weather here is probably similar to yours. I've never modded one of my fan clutches. Drain, refill with 10K cst, and go. Never had a temperature problem.

The way I understand it, calling adjusting the timing "a mod" is a bit of a misnomer. There's some adjustment built into the housing to allow for differences in the springs, so it's just a matter of adjusting and confirming where the valve starts to open. I suspect Aisin just slaps them together and calls it good.

Thanks to everyone who shared. That mostly confirms what I had pieced together. Buying one that has been done seems like a great plan if you're the sort of person who pays someone to wash your car and change your oil. I mount my own tires sometimes, so I'll be doing it myself. Removing the clutch from the engine sounds like more work than the actual fluid change and adjustment to me.

 

[surfpig]

I can't imagine having a vehicle without a scangauge anymore.

Our newer cars don't even have a temp gauge.

 

[landtank]

The way I understand it, calling adjusting the timing "a mod" is a bit of a misnomer. There's some adjustment built into the housing to allow for differences in the springs, so it's just a matter of adjusting and confirming where the valve starts to open. I suspect Aisin just slaps them together and calls it good.

Thanks to everyone who shared. That mostly confirms what I had pieced together. Buying one that has been done seems like a great plan if you're the sort of person who pays someone to wash your car and change your oil. I mount my own tires sometimes, so I'll be doing it myself. Removing the clutch from the engine sounds like more work than the actual fluid change and adjustment to me.

Hey, I started that thread because myself and others were seeing high temps in the summer and I like to FK with stuff. I was the first to use hobby oil because the factory stuff was limited and pricey.

A lot of skeptics on using that stuff. Now it’s just the obvious choice. And nobody has burnt out an engine using it.

 

[surfpig]

Everyone has an opinion. If that is my thread on modding the fan clutches I would have deleted it years ago if I was able to.

How many times did I go through that thread!

I settled on about 15K for the fluid, and the critical thing to do is adjust/calibrate the temp at which time the valve opens up.

 

[Marco Lau]

Fan clutch!
My elec. fan setup is keeping my engine cool. It is sub 180F at stop and go traffic. I need to dial it up a bit to get the engine warmer @ 187 F. Having the ability to adjust temp is a luxury .

 

[lumbee1]

^^^^^



In my 80 series:

View attachment 3500623

In my 100 series:


View attachment 3500624

Yes! I cannot recommend ScanGaugeII enough. My temps fluctuate between 181 and 186 in the summer and 179 to 182 in the winter.

 

[Marco Lau]

Yes! I cannot recommend ScanGaugeII enough. My temps fluctuate between 181 and 186 in the summer and 179 to 182 in the winter.

those are good numbers!

 

[mendozart]

So, I finally had some time to get back to the LC. I did notice that no coolant was pulled from the reservoir when I initially ran the car. This goes back to when I was topping off the reservoir when my radiator was leaking, the level had stopped dropping. The hose going into the reservoir was very loose, so I’m going to replace all those hoses, and probably the cap. I opened the radiator cap, and the level was low, hence it wasn’t pulling coolant into the radiator. I filled it up and ran the engine, and it burped up quite a bit of air. Installed the cap after it stopped burping. Also, when I shut the engine off, my fan free wheeled for at least 5 to 8 seconds, so I will for sure be replacing my fan clutch.

 

[flintknapper]

So, I finally had some time to get back to the LC. I did notice that no coolant was pulled from the reservoir when I initially ran the car. This goes back to when I was topping off the reservoir when my radiator was leaking, the level had stopped dropping. The hose going into the reservoir was very loose, so I’m going to replace all those hoses, and probably the cap. I opened the radiator cap, and the level was low, hence it wasn’t pulling coolant into the radiator. I filled it up and ran the engine, and it burped up quite a bit of air. Installed the cap after it stopped burping. Also, when I shut the engine off, my fan free wheeled for at least 5 to 8 seconds, so I will for sure be replacing my fan clutch.

Yes, do ALL the hoses to the reservoir cap as well. And check that the cap isn't plugged or replace it.

IF it is plugged (or the radiator cap malfunctioning) when your engine cools and pulls a vacuum the upper radiator will collapse a bit. A sure sign something is amiss.

You've done a good job troubleshooting the issue and its apparent you understand the cooling system is just that (a SYSTEM) and all components need to be working correctly.

I believe if you replace the fan clutch and inspect the reservoir cap and hoses, you will realize cooler operating temps.