• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Electric Fan clutch

I don't think 200* is too hot even sustained, and I prefer to measure that at the rear and control my fan from the rear. As fast as these motors heat up there is more opportunity for temps to get out of hand and cause harm, and a side note, most every head gasket I've seen blown was on the rear of the head where the oblong passage is... Heat related maybe ?

We will agree to disagree....
 
Twisted Steel Performance said:
I don't think 200* is too hot even sustained, and I prefer to measure that at the rear and control my fan from the rear. As fast as these motors heat up there is more opportunity for temps to get out of hand and cause harm, and a side note, most every head gasket I've seen blown was on the rear of the head where the oblong passage is... Heat related maybe ?

We will agree to disagree....
Click to expand...
I’m enjoying the right rear cylinder head gauge, enjoying even more that electro viscous fan clutch system.
I have seen the head temp get as high as 200* and the temp control is set to kick on the phan at about 198* and thats at the temp sensor reading aCcording to the Autell Maxi Pro 200 reading.
 
Twisted Steel Performance said:
I don't think 200* is too hot even sustained, and I prefer to measure that at the rear and control my fan from the rear. As fast as these motors heat up there is more opportunity for temps to get out of hand and cause harm, and a side note, most every head gasket I've seen blown was on the rear of the head where the oblong passage is... Heat related maybe ?

We will agree to disagree....
Click to expand...
I agree with all this 100%.
My only thought is- if the temp peaks at the rear of head just barely enough to kick on the fan at 195/200. But it drops temp by time it gets to thermostat and the stat is closed - having the fan run doesn’t help.
It isn’t until the stat is open and that hot water gets to the radiator to be cooled that the power robbing fan will do any good.

Now if running the fan a little bit earlier doesn’t hurt your feelings- then heck yeah let the fan get an early start. My version of doing it is by trying to keep temps in 180-185 range. And when there is enough radiator to do that you can avoid fan use more.

I know- “how would the water be cooler at the stat”. In monitoring it - it happens, that why we know it is the hottest spot.

Even the “balanced flow” is not 50/50. That passenger's side still gets a little less flow and heats a little more. Thats even with a centermount turbo or n/a. Now pickups have the added ambient heat of the turbo effects as well.
If there ever was a case for individual thermostat per head design in a pickup this is it. Many large diesels do just that. Series 60 Detroits, the ol 71 series Detroits, many big caterpillars and cummins. I am still in consideration of doing the individual block off thermostats that I posted up here years ago just because of it. To be honest I am surprised no one else has ever done it before, but maybe not so many people have ever put two temp gauges in the top of the two rear heads (where folks were adding the rear head hose kits). This would eliminate the crossover- only ties the two together if both stats are open and water on the way to the radiator from both sides.

The only drawback to fan on too early- mpg /power loss. And more work for engine. But err on the side of caution is never bad.
 
Last edited:
Just an update, still running the Mishimoto controller until a new fitting arrives that will allow me to use the Flexalite controller sender in the t-stat housing. Going to add a tee with a bleeder valve too so I can ensure that the system is properly air purged. Should be able to install it this week.

I have been having very serious belt stretching issues since I put the electro clutch and dmax fan on. It led me to buy a shorter belt than I normally run - and then catastrophe struck when my powermaster alternator left the chat while doing 70mph on I-95. In a construction zone (no shoulder). Got over as soon as I could and shut her down. Been driving it for about two weeks since and there doesn't seem to be any damage - other than to my psychological condition. After running the normal length belt I usually run since then, I changed back to the shorter belt because I was getting chirping at start and idle. If I damage another drive accessory, I may have to use some washers under the A/C compressor to make the longer belt work.

But, the mishi keeps the engine nice and cool. It fully engages by the time the engine temp hits 201 or so and then keeps running until the temps are well into the 170's. And thats the problem. It runs too much below the 180 tstat closing when its don't literally nothing but draining my power. Hopefully the Flexalite will be able to resolve this. Here's a shot of the torque dashboard after a highway trip towing the M1102 with the A/C on max.
1720375690838.png
1720376008598.png
 
Running a serpentine belt I assume, when I did this conversion using the spin-on style water pump I didn't have any issues with belt lengths. my only issue I had was when water hit the belt when I went though puddles it would jump off the back side of the tensioner. I finally chalked that up to an aftermarket tensioner with a narrower than OE pulley. of course mine is a 95 that uses the infamous pancake ac compressor mounted on the drinkers side.
 
smokymtn65 said:
I have considered swapping my controller over to an inkbid PID temp controller. You can set ramp up, and the temp spread real easy. I have one on my powder coat oven and it think it would make it sweet to tighten on the spread / temp differential. Using the same a @ak diesel driver now.
Click to expand...
are these made for 12 and 24vdc applications? I did a google search and only came up with 110-220vac units.
 
I installed the Flex-a-lite controller yesterday and confirmed its operation. In the process of tuning the engagement point as its still running when the t-stats are closed. I put it in an aluminum project box since the area I mount these controllers is rather exposed (above the front driver tire) and its not altogether clear from Flex-a-lite whether the unit is waterproof (I suspect not as they have a unit that is specifically advertised as waterproof).

WIP pic:
1720625388998.png

New sender setup. Much better as I know that I can purge my cooling system.
1720625461364.png
 
@CursedH1 just to note on the location of your sensor probe for the controller. it will have a slow heat up with a fast cool down. the brass tee sticking out like that will cool faster than the water jacket when the fan turns on possibly not completely cooling the engine before it turns off.
unless the probe is sticking down into the water jacket past the tee you will have to compensate for this and for the temp differences (maybe 5 degrees)

I would recommend drilling and tapping a new hole in the water jacket so it will be more accurate.
 
Beginning to think that this change isn't going to work for my rig. I got the engagement temp to the point where I can hear the fan engaged when my ECM-read temp hits about 201-203. However, once the temp drops below 180, the fan will stay engaged for 5 more miles or about 10 minutes before it goes off. Not ideal. The OEM fan would disengage nearly the point where the t-stats closed up and hot coolant stopped flowing through the rad.

It doesn't really make sense to me why it'll engage at 202, but it won't disengage at 180? I realize it's not going to be immediate, but 5 miles is just... not acceptable. At all.

This is absolutely killing my performance - and its started to have a slight vibration at idle when the fan is engaged. Overall I'm considering ditching the whole thing and swapping over to the ModMafia cooling system I had on my last P400 which worked great.
 
dbrannon79 said:
@CursedH1 just to note on the location of your sensor probe for the controller. it will have a slow heat up with a fast cool down. the brass tee sticking out like that will cool faster than the water jacket when the fan turns on possibly not completely cooling the engine before it turns off.
unless the probe is sticking down into the water jacket past the tee you will have to compensate for this and for the temp differences (maybe 5 degrees)

I would recommend drilling and tapping a new hole in the water jacket so it will be more accurate.
Click to expand...
See my post above. It's actually acting completely opposite of that.
 
CursedH1 said:
See my post above. It's actually acting completely opposite of that.
Click to expand...
do you have a light setup in your dash to see when the controller is on or off? something I noted on mine is even after the controller turns off the fan will stay engaged for a short bit until the little coil cools as well as it needed at least 2k of rpm to break it free. when my fan clutch was new it stayed on longer. as it breaks in it will be quicker to release.

EDIT: I also first had an off-brand fan clutch installed I got off rockauto which would not release at all once engaged. I literally had to tie one of the fan blades and start the engine to get it to break free. later I replaced it with a delco clutch which still had to be broken in before it would release properly.
 
dbrannon79 said:
do you have a light setup in your dash to see when the controller is on or off? something I noted on mine is even after the controller turns off the fan will stay engaged for a short bit until the little coil cools as well as it needed at least 2k of rpm to break it free. when my fan clutch was new it stayed on longer. as it breaks in it will be quicker to release.

EDIT: I also first had an off-brand fan clutch installed I got off rockauto which would not release at all once engaged. I literally had to tie one of the fan blades and start the engine to get it to break free. later I replaced it with a delco clutch which still had to be broken in before it would release properly.
Click to expand...
Ahhh... this might be the culprit then. Definitely a rockauto clutch - listed as "GM GENUINE" although I have no idea if that means AC Delco or not. It does disengage but its on for far too long. Perhaps the issue is the lack of airflow through the H1 grille hitting that coil to cool it off sufficiently....

As for a light - no ... I don't have anything in the cab that tells me if the clutch is getting power or not. I was thinking about putting together something temporary, but given its a PWM arrangement - I was more interested in just using the built in hall sensor in the clutch - finding an off the shelf display for the hall sensor was challenging - finding a 12V driven display that takes 5V reference (iirc) was something that amazon didn't have readily available - and I don't know anything about arduino to do something like that myself.

EDIT: Tomorrow I'll take the tee out of the tstat housing and just put the 1/4" to 1/8" NPT adapter in. That will submerge the probe completely.

Also looking at the P400 crossover. Anyone have experience with these? They're practically giving them away (half the price of the original dual t-stat crossover)

1720652161932.png
 
Last edited:
CursedH1 said:
Also looking at the P400 crossover. Anyone have experience with these? They're practically giving them away (half the price of the original dual t-stat crossover)

View attachment 88583
Click to expand...

I'll look through the parts my 2 hummer customers sent, I think one of them asked me about that one, I'll dig out what he sent and look at it.... I really can't see what "P400" would have to do with anything unless being in a H1 might have something to do with clearance of something.... I'll dig it out today....
 
CursedH1 said:
Ahhh... this might be the culprit then. Definitely a rockauto clutch - listed as "GM GENUINE" although I have no idea if that means AC Delco or not. It does disengage but its on for far too long. Perhaps the issue is the lack of airflow through the H1 grille hitting that coil to cool it off sufficiently....

As for a light - no ... I don't have anything in the cab that tells me if the clutch is getting power or not. I was thinking about putting together something temporary, but given its a PWM arrangement - I was more interested in just using the built in hall sensor in the clutch - finding an off the shelf display for the hall sensor was challenging - finding a 12V driven display that takes 5V reference (iirc) was something that amazon didn't have readily available - and I don't know anything about arduino to do something like that myself.

EDIT: Tomorrow I'll take the tee out of the tstat housing and just put the 1/4" to 1/8" NPT adapter in. That will submerge the probe completely.

Also looking at the P400 crossover. Anyone have experience with these? They're practically giving them away (half the price of the original dual t-stat crossover)

View attachment 88583
Click to expand...
if you have clearance I would eliminate the 1/4"-1/8" adapter as well what size thread is the probe for the controller? mine was 1/8" I drilled and tapped into one side of the crossover coming out of the head. the mor-less flat area above the stats I would be curious if there is clearance to drill and tap there for the sensor and keep your bleeder in it's original location.

even if the clutch is a GM one, it too might still be needing to break in before it starts releasing sooner. It's the light weight plastic fan blade that also plays a part in it's "slow to release" air flow through the stack can also have an effect too. on my truck when it's locked in and I rev it in the driveway it's got more blower power than a leaf blower at clearing the driveway!
 
Something I also just thought about, since your controller is a PWM style, I wonder if once it sends enough power to lock up the fan it also ramps down in the same fashion by slowly reducing voltage. curiosity is if the low voltage the PWM is providing is enough to "maintain" fan lockup well beyond what it needs. you might run a couple of temporary wires from the clutch where the voltage is sent in and connect them to a digital meter you can place in the cab while you drive. see how long it takes to release the fan under load as the controller reaches 0 voltage.

another aspect for testing is to bypass the controller and connect a direct switch you can turn on or off in the cab. drive and see if the release time is sooner once turned off under load.

you should also be able to use a multi meter on the other wires to the clutch seeing the "slippage" or RPM signal from it, that also will tell you if the PWM controller is able to control the fan as say mid lockup as well as mid release once fully locked up.
 
You must log in or register to reply here.
Back
Top