Running hot at highway speeds!?

[chumwon]

Hello everyone, I know heating issues have been discussed but im wondering if anyone else has trouble at high speeds but fine cruising or at idle? It's has a banks system, IP isn't up very high, new radiator, thermostat and fluid. I'm thinking it's the gearing and smaller tires (215/85/16) that don't help rpms. With 4.10s doing 70 is close to 2500rpms...she'll see 220 or more if i let it go on, aftermarket gauge if ac on with a load. As soon as I'm getting on the off ramp and back down to 55 she'll go to 190..just curious if I have another problem or time to change tires and gearing. Thanks!

 

[franklin2]

You have done everything like I did, and I had the same problem. My problem turned out to be the fan. Yep, I could not believe that all that air going through the radiator would not cool it at 70mph, but I locked my fan and the problem went away. You could probably get a new fan clutch and it would fix yours also.

 

[snicklas]

Another thing to check, when the engine is up to temp and the thermostat is open. Have someone hold the throttle at "highway speed" and go look at the lower radiator hose. Ih had a couple vehicles in the past, when the hose would get old, or the spring was missing, the hose would suck shut and cause an overheat. At low speed and rpm there wasn't a problem.

 

[chumwon]

You have done everything like I did, and I had the same problem. My problem turned out to be the fan. Yep, I could not believe that all that air going through the radiator would not cool it at 70mph, but I locked my fan and the problem went away. You could probably get a new fan clutch and it would fix yours also.

That is the last thing I wanted to do but can't tell if it was bad but I've came to the conclusion I never hear this "jet plane" noise of it ever coming on fully!

Another thing to check, when the engine is up to temp and the thermostat is open. Have someone hold the throttle at "highway speed" and go look at the lower radiator hose. Ih had a couple vehicles in the past, when the hose would get old, or the spring was missing, the hose would suck shut and cause an overheat. At low speed and rpm there wasn't a problem.

I didn't think of this but have had that happen in the past where a line would collapse, I'll be double checking that! Thank you

 

[m67tang]

Same trouble here- it was fan clutch! Once replaced it stopped.

 

[chumwon]

Well it's sounding like a clutch fan is in my future then! I just priced it out at $125!!...figures theres two that are offered as there is a mid year change.. but ill make sure it's not other things before I tackle that. I still have time before the warmth sets in here up north

 

[idiabuse]

better check that lower radiator hose if it has no spring inside the IDI coolant pump inlet will suck it closed at 80mph ask me how eye know.

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[catbird7]

You have done everything like I did, and I had the same problem. My problem turned out to be the fan. Yep, I could not believe that all that air going through the radiator would not cool it at 70mph, but I locked my fan and the problem went away. You could probably get a new fan clutch and it would fix yours also.

I agree with Franklin2 & m67stang, had same symptoms and new fan clutch fixed it. My original clutch felt fine, didn't wobble or anything like that, I simply changed it because all of the other new parts (t-stat, alum rad, hoses, coolant, timing adjusted by Mel) didn't make a difference on temp. New clutch was night & day! Make sure you use loctite on new clutch.....

 

[Kizer]

You can drain and refill the clutch. Drill a hole, drain, refill and plug.
Here's a link to photos of the process described above:

https://goo.gl/photos/3hHCBjd7mjNwBLWb8
For some reason I can't get pics to post today?

I used Honda DPF for oil. Others have experimented with heavier oil but I found that the DPF worked great...I think it's just fancy hydraulic oil.
Search "fan clutch modification" or some such ... several others have used "trick".

 

[chumwon]

I agree with Franklin2 & m67stang, had same symptoms and new fan clutch fixed it. My original clutch felt fine, didn't wobble or anything like that, I simply changed it because all of the other new parts (t-stat, alum rad, hoses, coolant, timing adjusted by Mel) didn't make a difference on temp. New clutch was night & day! Make sure you use loctite on new clutch.....

Ahh thanks for the loctite reminder, don't want that girl taking off on me!

You can drain and refill the clutch. Drill a hole, drain, refill and plug.
Here's a link to photos of the process described above:

https://goo.gl/photos/3hHCBjd7mjNwBLWb8
For some reason I can't get pics to post today?

I used Honda DPF for oil. Others have experimented with heavier oil but I found that the DPF worked great...I think it's just fancy hydraulic oil.
Search "fan clutch modification" or some such ... several others have used "trick".

I'll be looking into this, I don't see how it can hurt anything since it's junk now and it'll save me a bunch of $ an I don't have to take it off! Keeps sounding better an better. Thanks Kizer!!

 

[chumwon]

I guess I do need to get it off to make sure I do it the job right but that's fine. I also see people have changed the springs final set place so the fan would engage slightly earlier, anyone ever experimented with that before?

 

[icanfixall]

etter look at both sides of the clutch. If you see ANY dirt or moisture around the shaft or spring.. Than clutch has gone bad and NOTHING will fix the seals so refilling it will do nothing for you. Yes... Changing the length of the spring will make the clutch lock up sooner so the temps remain lower but please look into this modification. Its not difficult. Just research how its done. MS Tech of Babylon New York does this to the fan they sell for over 200 bucks and from first hand experience it really does work. I have pulled heavy loads up both grades out of southern cali and actually saw my temps going DOWN as I climbed these grades. Yes, the roar of that fan pulling so much air starts like a tornado sound and it can scare you a bit. Once you hear it you never forget it.

 

[chumwon]

etter look at both sides of the clutch. If you see ANY dirt or moisture around the shaft or spring.. Than clutch has gone bad and NOTHING will fix the seals so refilling it will do nothing for you. Yes... Changing the length of the spring will make the clutch lock up sooner so the temps remain lower but please look into this modification. Its not difficult. Just research how its done. MS Tech of Babylon New York does this to the fan they sell for over 200 bucks and from first hand experience it really does work. I have pulled heavy loads up both grades out of southern cali and actually saw my temps going DOWN as I climbed these grades. Yes, the roar of that fan pulling so much air starts like a tornado sound and it can scare you a bit. Once you hear it you never forget it.

Alright thank you sir I'll be looking more into it then! Gotta love not having to worry about over heating issues! And I'll make sure the seals are still worthy in the original one before I attempt to revive it.

 

[OLDBULL8]

Why don't you just block off the rad with some cardboard, even at idle and see when or if the clutch kicks in at what temp. anywhere from 220*F to 240*F.

 

[Kizer]

I'll be looking into this, I don't see how it can hurt anything since it's junk now and it'll save me a bunch of $ an I don't have to take it off! Keeps sounding better an better. Thanks Kizer!!

You're welcome. I'd take it off of the truck for mod.