Running hot and out of ideas.... (1 Viewer)

[alvarorb]

About three years ago, I took my 96 FZJ80 to a garage inSouthern California for service. On my way there from Norcal, I kept an eye on engine temperature. I always do. The truck ran at 198°F all the time. Even while going up the grapevine. While at the shop, they told me that my radiator was leaking, so I had them replace it with a Denso radiator. When I got the truck back, I noticed the truck would run hot on hot days. Sometimes as hot as 220°F. I only run the truck about 500 miles a year. And when it's cool outside, this is not an issue. Having said that. I need to fix this.

Since then, I’ve taken several steps to fix the issue:

1. Changed the fan clutch.
2. Changed the thermostat, OEM.
3. Changed the temperature sensor, OEM.

Despite these efforts, the truck still runs hot. Before the radiator was replaced
At this point, I’m considering whether to change the water pump or replace the radiator again. Any advice you can offer would be greatly appreciated.

 

[LC4LIFE]

What type of fan clutch exactly, and has it been modified? Modding a blu-hub fan clutch seems to nearly always yield positive results.

 

[alvarorb]

Regular fan clutch. No mod

 

[ChargedSHOTaco]

Was the water pump replaced?

 

[alvarorb]

Was the water pump replaced?

No. The water pump has not been replaced

 

[Fosters]

Do you have your fan shroud?
Blue hub fan clutch
Drain and flush coolant

 

[alvarorb]

Do you have your fan shroud?
Blue hub fan clutch
Drain and flush coolant

Yes to fan shroud. And I’ve replaced the radiator coolant

 

[ChargedSHOTaco]

No. The water pump has not been replaced

I’m thinking this is your problem.

 

[jpoole]

On my '97 I replaced the Eaton fan clutch with a new Aisin blue hub and it would run hot pretty easily with that out of the box blue hub. I then adjusted the opening temperature and changed the oil in that new fan clutch and it's not run hot since.

When it was running hot (220ish which would shut-off the AC) I found that it would occur at idle after a hard push or at higher speeds (70+mph roughly). At 20-40 mph (very roughly) it wouldn't run hot because of airflow from forward motion. At higher speeds I think that airflow slows or stops without the fan pulling it through the rad based on what I would see on the odb2 temp sender.

As part of baselining my 80 I also cleaned (replaced actually) the AC condensor and added foam between the core support and the radiator to help ensure that the air flowing through the radiator was mostly from outside of the engine compartment. I added the foam before changing the Eaton clutch and the foam alone didn't make much of a difference though I assume it helped things once the blue hub was modded and pulling air.

I'd mod the fan clutch regardless of what else you plan to do and I wouldn't run one of these rigs without a modded clutch. The temp at which oil starts to be sent to the clutch to drive the fan can vary a lot and have a big impact on the range of operating temps that the cooling system allows.

 

[CivicFerio]

@alvarorb It is an airflow through the radiator issue. My 80 also exhibits the same exact issues despite having have a new blue fan clutch, koyo rad, toyota thermostat and waterpump. At my wits end, I bought the latest fan clutch colored gray from a 05-06 105 Series for a 1FZ sold in middle east markets but it performed about the same as a blue clutch with a 10K cst silicone oil. I even stuffed in a 12 inch 30 amps SPAL paddle blade fan but it only puts a small dent in ECT in stop and go situations.

Last years southern California heatwave about 110F, I experimented a back to back runs with my modded 10K CST blue clutch vs locked up fan clutch. With the modded clutch up the grapevine it will see 220F easily even with AC off but with the locked up clutch it stayed 195F and AC stayed really cold but could barely go up the hill due to the immense drag caused by the fan spinning. I also lost 1.5 MPG and it was quite loud inside the cabin with the fan at 1:1 to input shaft speed.

I would mod your blue clutch to a 20K CST fluid and see how it goes. Leave the valve opening temps stock so it won't engage in cooler conditions and improves efficiency.

 

[jpoole]

Leave the valve opening temps stock

Not checking the opening temps implies confidence that they were correct when delivered and are correct "stock" now. My experience says this isn't always the case and that checking the opening temps is a good exercise. When checking the same clutch over time for instance I've seen the opening temps change and I assume it was due to heat cycling aging of the bi-metallic spring. Checking temps is possibly an annoying extra step but heavier, plentiful oil will not solve the problem if the ports are opening at too high of a temp.

Anyway, I'm all for folks doing what they want but checking the opening temps is possibly the easiest part of the whole job once you have figured out what temp you want to use. The point I'm trying to make clear is that you really can't be confident with the opening temps that Aisin Blue Hubs are shipped with, at least based on my limited, first-hand experience. I've also read from others on the forum that they've also found inconsistent oil levels and/or opening temps on new blue hubs. Given what may result from running hot I recommend that everyone check both temp and fill level of their fan clutch, particularly if they are running warm, though I'd do the checks with any new clutch before install.

 

[RiverCityDave]

Yeah this is all valid, but the radiator portion of the cooling system in the cruiser is also designed to be “sealed” around the edges. When I did mine, it made a difference.

The factory radiator had closed cell foam that you may have some remnants of sticking around. I’ll see if I can find some photos of it, but it came pre-installed on the factory radiator for a while, though not anymore. Lot’s of folks just pick up weather stripping at a big box shop and use it. The purpose is to push as much air as possible through the radiator rather than letting it leak around it.

Foam Discussions

Another

 

[TheBussman]

lots of good points here, although the waterpump is very unlikely the culprit unless somebody put a very low quality aftermarket one on that isnt designed right or something. One of the most common things I is the foam missing around the radiator, its very likley they just put the new radiator in with no foam on it, should have some on the top and bottom and this forces more air though.

 

[LC4LIFE]

Regular fan clutch. No mod

I'd start here. Mod the fluid and opening temperature. It will improve airflow, then work to the next thing.

 

[alvarorb]

I went to my local Toyota dealer and they are out of the blue oil/silicone. I did however watch a YouTube video where the person replaces the factory oil for an oil he got at a hobby store. My dealer won't have the oil for a week. Any ideas what the oil from the hobby store is?

 

[alvarorb]

lots of good points here, although the waterpump is very unlikely the culprit unless somebody put a very low quality aftermarket one on that isnt designed right or something. One of the most common things I is the foam missing around the radiator, its very likley they just put the new radiator in with no foam on it, should have some on the top and bottom and this forces more air though.

No foam around the radiator.... Any ideas of where to get it?

 

[LandCruiser65]

I went to my local Toyota dealer and they are out of the blue oil/silicone. I did however watch a YouTube video where the person replaces the factory oil for an oil he got at a hobby store. My dealer won't have the oil for a week. Any ideas what the oil from the hobby store is?

Amazon.com

 

[jpoole]

Here's an example of the oil, note the variety of weights available:

Team Associated Silicone Differential Fluid (2oz) (30,000cst) [ASC5457]

This is a 2oz bottle of a bottle of Team Associated Silicone Differential Fluid. Made in the USA exclusively for Team Associated by Lucas Oil Products.... ASC5457

www.amainhobbies.com

You can use whatever foam you feel comfortable with. I'd go with higher quality and resistance to heat/uv/etc. so that it lasts longer and is less likely to break down. The foam isn't exposed to too much though so quality may not matter that much.

 

[LandCruiser65]

No foam around the radiator.... Any ideas of where to get it?

Amazon.com

 

[TheBussman]

if you

No foam around the radiator.... Any ideas of where to get it?

it comes with a genuine radiator, napa sells different foams and I'm sure hardware store do also. Make everything really clean before trying to stick it on. sometimes I need to use some superglue too.

here's a diagram of the foam try to make it look like that. the piece on the bottom is even taller then it looks in the picture.