I would do the blue fan clutch first unless you know the radiator is bad.
Builds Chronicles of a Cruiser (1 Viewer)
- Thread starter Dark Knight
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Thread starter
- #42
The reason I’m doing a new radiator is because when i replaced other cooling hoses and had a look in there i saw some buildup. I did a good flush but still believe passages could be blocked. When the temp was rising i was traveling at 35-55mph. That should have been sufficient air movement to keep things cool regardless of the fan right??
I would also do the fan clutch first because it's easier, cheaper and can cause some odd overheating behaviors by itself even if all else is good. Not saying it's your problem but it's at least possible. If you suspect your rad though it could be wise to go ahead and replace it since they are also cheap and I'm of the belief that managing temps on the 1FZFE with their iron block and alu head is important for avoiding HG failure.
It's been a few years since I did my fan clutch testing but I recall that when the fan clutch was not up to snuff that my '97 would run warmest at slow and higher speeds. There was a mid-range speed where there wasn't as much load on the engine and there was decent air flow through the radiator as temps would drop in this range. My guess is that this would have been in the 20mph to 50mph range but I could be 10mph or more off on either end. In any case, it seems that above certain speeds there are air pressure dynamics that reduce airflow through the radiator which causes temps to shoot up at higher speeds. I believe that others have noticed/reported this as well on the forum though I don't recall where.
If your current fan clutch seems to be in ok condition I'd consider just changing the oil in it and setting the opening temps. This has been discussed a lot on the forum, etc. I'll add that if you get a new fan clutch I also recommend changing the oil and setting the temp on it too based on my experience and what I have read from others. In a nutshell I installed a new blue hub that caused the engine to run hot out of the box. I then changed the oil and set the opening temp on that new blue hub and it's kept the 80's engine cool even while towing in Summer/etc.
This is a long thread but it has some good info on the servicing process on the first page:
forum.ih8mud.com
It's been a few years since I did my fan clutch testing but I recall that when the fan clutch was not up to snuff that my '97 would run warmest at slow and higher speeds. There was a mid-range speed where there wasn't as much load on the engine and there was decent air flow through the radiator as temps would drop in this range. My guess is that this would have been in the 20mph to 50mph range but I could be 10mph or more off on either end. In any case, it seems that above certain speeds there are air pressure dynamics that reduce airflow through the radiator which causes temps to shoot up at higher speeds. I believe that others have noticed/reported this as well on the forum though I don't recall where.
If your current fan clutch seems to be in ok condition I'd consider just changing the oil in it and setting the opening temps. This has been discussed a lot on the forum, etc. I'll add that if you get a new fan clutch I also recommend changing the oil and setting the temp on it too based on my experience and what I have read from others. In a nutshell I installed a new blue hub that caused the engine to run hot out of the box. I then changed the oil and set the opening temp on that new blue hub and it's kept the 80's engine cool even while towing in Summer/etc.
This is a long thread but it has some good info on the servicing process on the first page:
Blue fan clutch mod...Thread has gone to hell, read at your own risk
History: On my first drive this summer after replacing my transmission I was having an overheat condition with the truck. On the following weekend while towing a camper it was real severe in the 230* range. After returning I was able to confirm that my Blue hubbed fan clutch was to blame...
forum.ih8mud.com
Jump to more current threads to learn what weight oil and tuning settings folks are using/etc. I'm running the following and the clutch worked great for years on this tune and not run too much or too little per my ear, mpg and temps. I probably could have raised the opening temp a bit and could have squeezed in a bit more oil or even gone with a heavier oil but it's done great with this setup so I'm not going to tune further til necessary.| small hole 50% open at 110 degrees | 45 ml of 15k CST oil |
- Thread starter
- #45
That interesting about airflow at different speeds. I didn’t think of that.
A new OEM radiator is on the way (comes with the foam) and a blue hub clutch fan. I got the non-modified version so i could modify it to my liking if needed.
A new OEM radiator is on the way (comes with the foam) and a blue hub clutch fan. I got the non-modified version so i could modify it to my liking if needed.
Sounds like you'll be set for the long haul.
Yeah, the reduced airflow at high speeds is a little counter intuitive. I read about it and then was able to test/confirm it when running a really puny fan clutch but don't totally understand what's going on or if there is an easy way to improve it. Is it turbulence from the bumper (mine is stock), back pressure in the engine compartment or something else that slows the flow? It's possible that a few easy mods like a well placed air break line could increase airflow at higher speeds. I've had luck with similar mods on other vehicles (air cooled VWs specifically) but on the 80 we can just tune the fan clutch, which is nice and easy, so I've not played with it further.
On a related note, the 80 get's much better MPGs if I keep it below 65 MPH. I'd love to see an 80 put through wind tunnel testing with the smoke trails to see what is happening at different speeds and I bet there is a lot of turbulence/drag at the rear of the 80.
Please share them if anyone has photos of 80 series wind tunnel tests.
Yeah, the reduced airflow at high speeds is a little counter intuitive. I read about it and then was able to test/confirm it when running a really puny fan clutch but don't totally understand what's going on or if there is an easy way to improve it. Is it turbulence from the bumper (mine is stock), back pressure in the engine compartment or something else that slows the flow? It's possible that a few easy mods like a well placed air break line could increase airflow at higher speeds. I've had luck with similar mods on other vehicles (air cooled VWs specifically) but on the 80 we can just tune the fan clutch, which is nice and easy, so I've not played with it further.
On a related note, the 80 get's much better MPGs if I keep it below 65 MPH. I'd love to see an 80 put through wind tunnel testing with the smoke trails to see what is happening at different speeds and I bet there is a lot of turbulence/drag at the rear of the 80.
Please share them if anyone has photos of 80 series wind tunnel tests.
- Thread starter
- #47
Im real curious to see if the blue hub has any benefits in stock form along with this new radiator. I’m fearful that it could be buildup in the block passages. The engine had a head gasket job a couple years back and the deposits in the radiator i saw could have been from some crap sealer someone put in there from initial head gasket leak. My engine currently leaks no fluid and doesn’t burn oil, so thats a positive.
It should work well.
As noted above, my blue hub was insufficient out of the box. Somewhere on this forum I've heard that one of the folks that was selling the upgraded blue hubs regularly finds new ones with low oil and possibly mis-tuning, etc. I don't remember exactly what they reported but it roughly matched my findings as the blue hub I was shipped was opening at too high of a temp and was a little low on oil. It was Summer and my AC was shutting off after driving up hills (220+ degrees), etc. with that new blue hub. All that to say, I'd personally go ahead and change the oil and check/set the temps on that new blue hub before install.
As noted above, my blue hub was insufficient out of the box. Somewhere on this forum I've heard that one of the folks that was selling the upgraded blue hubs regularly finds new ones with low oil and possibly mis-tuning, etc. I don't remember exactly what they reported but it roughly matched my findings as the blue hub I was shipped was opening at too high of a temp and was a little low on oil. It was Summer and my AC was shutting off after driving up hills (220+ degrees), etc. with that new blue hub. All that to say, I'd personally go ahead and change the oil and check/set the temps on that new blue hub before install.
- Thread starter
- #49
Jpoole. When was your blue hub clutch purchased?
May 2018. I would expect the inconsistency to be possible with any fan clutch, regardless of when purchased, based on what I've read. In any case it's so easy to check/tune one I would personally always take that step given how important correct functionality is.
- Thread starter
- #51
I read about doing the clutch mod. Im going to have to read through it another time to make sure I fully understand.
I got mine about the same time and it seem to work fine 
- Thread starter
- #53
White knuckle sliders fit like a dream. These are the full length 20 degree version.
The powder coat leaves a bit to desire. I had been spoiled by the crazy good powder coat shrockworks offers.
The powder coat leaves a bit to desire. I had been spoiled by the crazy good powder coat shrockworks offers.
Last edited:
- Thread starter
- #54
New radiator is in with the blue clutch fan. It seemingly cools so good i had a hard time getting to temp for the thermostat to open and bleed the system. We’ll see what happens when i take it up the mountain. Hope it keeps nice and cool now.
- Thread starter
- #55
Is there a market for a used radiator? The one i took out is in great condition, no leaks but would definitely need a professional flush to get it in top condition again.
- Thread starter
- #57
After a trip up the same mountain pass today with the new radiator, peak temp was 30 degrees cooler. Max was 190 with AC blastin. WIN.
Ordered parking brake parts and rear axle bearings/seals from cruiser outfitters. Exceptional service as usual.
Ordered parking brake parts and rear axle bearings/seals from cruiser outfitters. Exceptional service as usual.
Last edited:
- Thread starter
- #58
Incoming. Dissent bumper and comeup winch ordered.
- Thread starter
- #59
Am I missing or have overlooked good instructions on how to properly wire up an “air on board” switch to a set of driving lights?
Particularly interested in the backlight feature of the switch. It lights up when pressed on, what wire do i connect to behind the dash to get the standard backlight? I should be able to piggyback from one of the switches in the center stack above the stereo. But, it would be much easier if i could piggyback of the dimmer switch which is directly next to the blank spot I’ll use for the new switch.
Particularly interested in the backlight feature of the switch. It lights up when pressed on, what wire do i connect to behind the dash to get the standard backlight? I should be able to piggyback from one of the switches in the center stack above the stereo. But, it would be much easier if i could piggyback of the dimmer switch which is directly next to the blank spot I’ll use for the new switch.
- Thread starter
- #60
This is what i have. Red/green/blue/black
I emailed aob because their instructions do not match the pigtail supplied. Their response,
“red power in from fuse box
green power out to activate the relay
blue is for dash lights (optional)
black to ground”
Still leaves me wondering where to connect the blue wire.
I emailed aob because their instructions do not match the pigtail supplied. Their response,
“red power in from fuse box
green power out to activate the relay
blue is for dash lights (optional)
black to ground”
Still leaves me wondering where to connect the blue wire.
