• Steel Soldiers now has a few new forums, read more about it at: New Munitions Forums!

  • Microsoft MSN, Live, Hotmail, Outlook email users may not be receiving emails. We are working to resolve this issue. Please add support@steelsoldiers.com to your trusted contacts.

 

Overheating 🥵

Stevev

Stevev

Member
37
7
8
Location
Dover nh
Good morning and Happy New Year
On my 1989 M998 my fan was always engaged
I replaced my Cadillac valve and now getting 120 psi to fan and it is disengaged all is good runs great but now won’t engage
Temp climbs to 240 and I still have 120 psi
My sensor is also new my truck was running at 160
Before I replaced the valve so I think the
Temp gauge is correct
Any ideas?
Could the tdm be bad? It giving 26v all the time to the valve when running
Thanks
Steve
 
Dock Rocker

Dock Rocker

Active member
980
71
28
Location
Jackson ms
Is it just spinning all the time or is the clutch actually engaged?

Unplug the TDM and take it for a spin. With the TDM unplugged the fan will fail to engaged. When you do this does it run hot?

If it still runs hot I would do a radiator flush and see what comes out. Have you done one lately?


Sent from my iPhone using Tapatalk
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
Dock Rocker said:
Is it just spinning all the time or is the clutch actually engaged?

Unplug the TDM and take it for a spin. With the TDM unplugged the fan will fail to engaged. When you do this does it run hot?

If it still runs hot I would do a radiator flush and see what comes out. Have you done one lately?


Sent from my iPhone using Tapatalk
Click to expand...
Thanks for the replay
It is definitely engaging and disengaging
Now
When I unplug the tdm the fan moves and engages and cools back off
I’m wondering if the tdm can go bad and send 24v all the time? I thought when I changed the Cadillac valve and now getting the fan to disengage my problem was solved...lol
She runs great now tho
Thanks for the help
 
DREDnot

DREDnot

Well-known member
717
430
63
Location
Phoenix, AZ
From what I've read here on SS, the TDM is not known for reliability. It has a reputation as the most likely culprit in overheating issues involving the fan clutch.
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
DREDnot said:
From what I've read here on SS, the TDM is not known for reliability. It has a reputation as the most likely culprit in overheating issues involving the fan clutch.
Click to expand...
That’s what I was thinking
I’m going to drive it for a while and see if the fan kicks in
From what I read it may not kick in in certain driving conditions so maybe it will kick in if I drive it normal without pushing the engine
 
DREDnot

DREDnot

Well-known member
717
430
63
Location
Phoenix, AZ
My first impression driving mine on the road is that they seem to run at what looks like too hot on the gauge. Gave me anxiety the first few times I drove it any distance.

Mine has always kicked on right at the 220 hash mark. It cycles consistently when I'm driving in traffic 40-50 MPH. I found that gives the most consistent conditions to cause the fan to engage and when it does, you know it!

The time/distance it takes to first get to engagement temperature will vary with the outside temps, as will the time between fan engagements.

This is how mine has functioned since I got it a year(850mi) ago. It is still running the fresh and functional coolant it came with.

I've been gathering the parts to go through the cooling system completely and hopefully replacing all the controls and sensors with genuine NOS will give me the maximum cooling capacity that the stock system has to offer.
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
DREDnot said:
My first impression driving mine on the road is that they seem to run at what looks like too hot on the gauge. Gave me anxiety the first few times I drove it any distance.

Mine has always kicked on right at the 220 hash mark. It cycles consistently when I'm driving in traffic 40-50 MPH. I found that gives the most consistent conditions to cause the fan to engage and when it does, you know it!

The time/distance it takes to first get to engagement temperature will vary with the outside temps, as will the time between fan engagements.

This is how mine has functioned since I got it a year(850mi) ago. It is still running the fresh and functional coolant it came with.

I've been gathering the parts to go through the cooling system completely and hopefully replacing all the controls and sensors with genuine NOS will give me the maximum cooling capacity that the stock system has to offer.
Click to expand...
Thanks for the info
I’ve had mine since oct
Just going through it fixing what isn’t working
Even tho it drives me nuts figuring out what’s wrong I love this thing
Lol
 
Dock Rocker

Dock Rocker

Active member
980
71
28
Location
Jackson ms
Just unplug the TDM and drive it. That will have the fan engaged 100% of the time. If it still runs hot you have a radiator problem. If not you need to start trouble shooting.

Also do you know for sure if your gauge is correct? They are not known to be reliable.


Sent from my iPhone using Tapatalk
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
The fan was always on when I bought it
I tested the psi at the fan clutch and it was 50
New Cadillac valve fixed it psi is now 120
But the fan clutch is getting 24volts still from the tdm when the temp is 220-240
 
DREDnot

DREDnot

Well-known member
717
430
63
Location
Phoenix, AZ
Stevev said:
But the fan clutch is getting 24volts still from the tdm when the temp is 220-240
Click to expand...
Another possibility is the fan switch in the crossover being bad. Check for continuity when cold, and again when over 220. It signals when to engage the fan

DSCN8757.JPG
 
Last edited:
REF

REF

Active member
Steel Soldiers Supporter
100
107
43
Location
Porterville Calif
Don't forget about the micro switch on the throttle lever, it's sole purpose is to kick the fan off when fording. if the switch sticks it will prevent the TDM from allowing the fan to come on.
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
REF said:
Don't forget about the micro switch on the throttle lever, it's sole purpose is to kick the fan off when fording. if the switch sticks it will prevent the TDM from allowing the fan to come on.
Click to expand...
Good call thanks you
Can I just leave it unplugged
I won’t be going through any rivers lol
 
REF

REF

Active member
Steel Soldiers Supporter
100
107
43
Location
Porterville Calif
If memory serves the switch is normally open so unplugging should work, I haven't tried it BUT look at it first. It's just a small micro switch on the side of your injector pump with a lever that pushes the switch when the throttle is pushed wide open. push the lever with your finger make sure it moves freely and if so listen for a click when you push the lever. If the lever is free and the switch clicks then unplug the leads and put an ohm meter between them and check to see if the switch is opening and closing. You mad just need a little oil on the lever.
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
REF said:
If memory serves the switch is normally open so unplugging should work, I haven't tried it BUT look at it first. It's just a small micro switch on the side of your injector pump with a lever that pushes the switch when the throttle is pushed wide open. push the lever with your finger make sure it moves freely and if so listen for a click when you push the lever. If the lever is free and the switch clicks then unplug the leads and put an ohm meter between them and check to see if the switch is opening and closing. You mad just need a little oil on the lever.
Click to expand...
Thanks bud I’ll do it tonight
 
REF

REF

Active member
Steel Soldiers Supporter
100
107
43
Location
Porterville Calif
The nice thing about the switch is that anytime you need full power, like passing a car ( LOL) . it will kick the fan out and make the freed up HP available to the wheels.
 
Milcommoguy

Milcommoguy

Well-known member
Supporting Vendor
1,652
2,095
113
Location
Rosamond, CA
Not the "sole" purpose, but important when going for a swim. More importantly IMO... It is also tied to the kick down solenoid on the TH400 transmissions. Probably fines more use there when passing. Still disengages fan for that added extra 20 seconds of boost.

Just saying: As with anything they do go bad. If not closing at WOT, it will not trigger TDM to start fan disengage timer and transmission KDS. If jacked up and closed all the time, fan won't cycle and transmission will not shift out of first. Switch is N.O. and closes when WOT. It is a special switch assembly and could be modified with a micro switch type. Not worth the headache. Go OEM.

Hummwv fans make poor boating propellers. CAMO
 
Stevev

Stevev

Member
37
7
8
Location
Dover nh
Milcommoguy said:
Not the "sole" purpose, but important when going for a swim. More importantly IMO... It is also tied to the kick down solenoid on the TH400 transmissions. Probably fines more use there when passing. Still disengages fan for that added extra 20 seconds of boost.

Just saying: As with anything they do go bad. If not closing at WOT, it will not trigger TDM to start fan disengage timer and transmission KDS. If jacked up and closed all the time, fan won't cycle and transmission will not shift out of first. Switch is N.O. and closes when WOT. It is a special switch assembly and could be modified with a micro switch type. Not worth the headache. Go OEM.

Hummwv fans make poor boating propellers. CAMO
Click to expand...
I just tested the micro switch on the throttle
The switch is normally open and makes continuity when you peg the throttle
So I assume the fan should be engaged at 220degees or more when the engine isn’t wide open
I just ordered a new TDM mine seems to give 24v all the time to the Cadillac valve keeping the fan clutched and the psi stayed at 125psi
I tried to follow the TM on testing the TDM and it seemed to ohm out much lower then what it should
Hope the new one does the trick
Thanks for all the help 👍
 
A

avman

Member
70
9
8
Location
Tampa, FL
Stevev said:
Good morning and Happy New Year
On my 1989 M998 my fan was always engaged
I replaced my Cadillac valve and now getting 120 psi to fan and it is disengaged all is good runs great but now won’t engage
Temp climbs to 240 and I still have 120 psi
My sensor is also new my truck was running at 160
Before I replaced the valve so I think the
Temp gauge is correct
Any ideas?
Could the tdm be bad? It giving 26v all the time to the valve when running
Thanks
Steve
Click to expand...
There are pads in the fan. Everything worked fine on my hmmwv and was overheating. Replaced these pads and no more overheating issues. You will see small screws on the back of the fan. They are easy to replace. Got my new pads off of eBay a few years ago
 
You must log in or register to reply here.
108,262members
163,587threads
2,301,843posts
1,012online users
Top
✖
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks