Overheating issue

blk99 · Sep 1, 2014

I tow very heavy (30k + at least 4 times a week) over mountain passes and in the last few weeks on hot days it overheats about halfway up the mountain.... it doesnt seem like the fan is working at full speed but sometimes it does AND, only sometimes, if i click on the AC or the Defrost, the fan will kick in and roar..... and when the fan is working full speed and i take some load off (feathering for EGT's) it sounds like it disengages and i hear a squealing noise....

Tensioner is less than a year old and belt is less than 2 months old.

I can figure out if i should replace the fan clutch, or tensioner or everything??? I would rather figure out the issue than throw parts at it....

Thanks

gnxtc2 · Sep 1, 2014

How fast are you going up the mountain?

And towing 30K on a daily basis, look into a medium class truck.

Billy T.
[email protected]

Arisley · Sep 1, 2014

If it was the tensioner, your A/C and Alternator would be griping about it also. I am betting your fan clutch is bad. How old is your thermostat?
Overheating issues on these trucks are really rare.

blk99 · Sep 1, 2014

gnxtc2 said:
How fast are you going up the mountain?

And towing 30K on a daily basis, look into a medium class truck.

Billy T.
[email protected]

40-45mph....2nd gear 2500ish rpms

Truck has handled it perfectly for the last 3 years....

blk99 · Sep 1, 2014

Arisley said:
If it was the tensioner, your A/C and Alternator would be griping about it also. I am betting your fan clutch is bad. How old is your thermostat?
Overheating issues on these trucks are really rare.

For years i have turned off the AC when pulling big hills cause it makes the fan pulsate (kicks on and off every 5 seconds or so) and the belt squeal.... but thats been going on way before the new tensioner or belt....

Thermostat is a couple years old....

I know they are, thats why im baffled....

On cooler days or in the evenings it seems to do fine.... but on second thought, the fan seems to work better when the ambient is cooler, too...

EDIT: i'll watch the volts next trip and see if they drop.... i noticed the other day it was only at 13.5 but i think i was just sitting still not pulling...

TERRCO · Sep 2, 2014

Check temps across your radiator surface with a laser thermometer. Over the course of a year I noticed my temperature gauge slowly start running warmer and warmer till it ran straight up . My gauge always ran about an 1/8 up. I threw parts at it including flushing the radiator. My best friend who is a mechanic suggested I put a new radiator in it. He checked the surface temps and said that only part if the radiator was flowing. I put in a new radiator and that problem was solved.

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TARM · Sep 2, 2014

My guess is your fan clutch is going out. It sounds like its the viscous clutch is not staying engaged like it should be. Regardless if you are overtaxing your engine or not with that load the fan clutch should not be disengaging if the air temp is over 205F so unless that fan is roaring and you are still overheating then I say the fan clutch. It works independent of all other systems strictly on temp for lockup. It should be fully locked up as air temps coming across it thru the radiator reach 205 F at which point it should be at full song and roaring like a freight train considering it along is using something around 27 HP!! That is moving some serious air.

The other possibility if you have not already replaced it is the T-stat. If its not fully opening it could be possible to have rad temps much lower while engine temps soar. Obviously a tstat is super easy and cheap so I would change that just to be on the safe side. But you could always do a rough test of yours in a pot of water to see when it opens. It should at least start to open within 4 degree of its rating usually 195 so say by 200 and should be fully open by 220.

If that checks out than I would strongly suspect the clutch. Which sucks as they are not cheap. Maybe look at a salvage yard

Here are the instructions for testing the fan clutch, both minimum and maximum speed tests:

Fan Clutch Test

NOTE: The following test does not apply to the 6.0L diesel. For the 6.0L diesel, refer to the Powertrain Control / Emmisions Diagnosis (PC/ED) manual.

Spin the fan blade (8600) by hand. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Fan Clutch Test — Minimum Speed Requirement

Use a suitable marker to mark the coolant pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).
Connect a tachometer to the engine.
Install a throttle adjusting tool.
Connect the Digital Photoelectric Tachometer.
WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation.

Start the engine and run it at approximately 1,500 rpm until the normal operating temperature has been achieved.
Operate the strobe light at 3600 rpm for 7.3L diesel engines, and aim it at the coolant pump pulley. Adjust the engine speed until the light flash and the coolant pump pulley mark are synchronized.

Aim the strobe light at the fan blade bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade bolt (the fan blade appears to stand still).
The fan blade speed must not be greater than 2,000 rpm on 7.3L engines.

Turn the engine off.

If the fan blade speed was greater than 2.000 rpm on 7.3L diesel engines, install a new fan clutch (8A616).

Fan Clutch Test — Maximum Speed Requirement

Perform Steps 1 through 5 of the Fan Clutch Test—Minimum Speed Requirement.

NOTE: The temperature of the air hitting the fan clutch should be above 96°C (205°F) for maximum fan speed.

Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200). This will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.

Place the climate control function selector switch in the MAX A/C position and the blower motor switch in the HI position.

Adjust the strobe to 3,600 rpm for 7.3L diesel engines.

WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation.

Start the engine and adjust the engine speed until the strobe light flash and the coolant pump pulley mark are synchronized.

Aim the strobe light at the fan blade retaining bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade bolt (the fan blade appears to stand still).

If the fan blade speed is less than 2,850 rpm on 7.3L engines, install a new fan clutch.

blk99 · Sep 2, 2014

Got a 25% off coupon for NAPA online so i ordered a fan clutch today.... my gut feeling was the fan clutch but i didnt know.... i reckon we shall find out!

CSIPSD · Sep 2, 2014

Order a 180* stat from RiffRaff buddy...

blk99 · Sep 3, 2014

Thats not too cold?

CSIPSD · Sep 3, 2014

For a stock truck... Sure.

Your not stock anymore.

HBDELUX · Sep 3, 2014

Interested to hear if the new fan clutch resolved the issue for you. I know the sounds you described and subsequent overheating. I have had the exact same problem towing the mountain passes the last month.

blk99 · Sep 4, 2014

I didnt pull the big mountain today but watched volts today and noticed: in the morning when still semi cold, 14.2v.... ran around empty for 30 miles or so to get loaded, volts slowly dropped to 13.9-14v..... hopped back in the truck and took off and volts were at 13.9 and slowly dropped to 13.5 over 20 miles or so and stayed there all day.... hit 13.4 once while pulling a small hill but it was brief.

Is this a completely unrelated issue??? And could it be causing mild EGT issues? I noticed the truck has been kind of slow to react off the line when towing....

CSIPSD · Sep 4, 2014

Doubtful... Didnt you just put a new alt in? or was that a starter?

blk99 · Sep 5, 2014

Both... alt was first.... year or so ago i think.... napa lifetime one...

OBS-Addiction97 · Sep 6, 2014

Most part store alts are junk ....

gnxtc2 · Sep 6, 2014

X1000 ^^^^^^^^

Billy T.
[email protected]

TERRCO · Sep 8, 2014

So still getting hot?

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Jomax · Sep 8, 2014

blk99 said:
Both... alt was first.... year or so ago i think.... napa lifetime one...

I'm on my 4th napa alt lifetime premium aswell. . This one is dying too, 13.1volts a 2k rpm.. at idle it holds 12v.. they're junk. I have an autozone alt, lasting longer.

Sent from my SM-N900V using Tapatalk

lincolnlocker · Sep 8, 2014

Jomax said:
I'm on my 4th napa alt lifetime premium aswell. . This one is dying too, 13.1volts a 2k rpm.. at idle it holds 12v.. they're junk. I have an autozone alt, lasting longer.

Sent from my SM-N900V using Tapatalk

im on number 6 for an advance auto lifetimer... and it is dying now. im gonna find a large case e series alt or go with a large case 6blow alt and either mod the mount or make spacers for it to fit.

live life full throttle