thunder550

iTrader: (70)

The fans are not speed controlled by the PCM. It just acts as an on/off switch. The a/c also acts as an on/off switch. I have the Nelson harness, so they work like this:

A/C off, PCM trigger off: Both fans off
A/C off, PCM trigger on: Both fans on low
A/C on, PCM trigger off: One fan on high, one fan off
A/C on, PCM trigger on: Both fans on high

PCM is set to on at 200, off at 190

Like I said, I can't hear the fans while I'm driving, but I have pulled over to check them and they have been running like they were supposed to (a/c was on, and both fans were on high). Also turned the a/c off and both fans went to low, so it seems like they are doing what they are supposed to.

As far as the air pocket goes, I will have to look around and see if I can find a bleeder valve...hopefully that's the problem. If that doesn't work, it's a new t-stat, and if that doesn't work....**** I dunno then. I don't want to go back to the cluch fan but I might have to.

thunder550

iTrader: (70)

Does this keep the radiator from filling in from the top?

jps_2001

just a question but have you pulled a plug. I am use to old trucks, when one leans out it runs hot. Since you are running radix it might be that. I really don't know about these new trucks.

budhayes3

iTrader: (19)

Not sure that I understand your question...

I fill at the overflow, and it'll bubble and gurgle a bit, then level out in the overflow. Next I grab the upper hose, and kind of squeeze slowly and push it toward the engine block a bit. while I'm doing this the overflow will gurgle more and the level will actually go down. I do this over and over until the gurgling stops. Then I start it up with the cap off and let it run until the t-stat opens and the level goes down (it will fluctuate up and down as the engine warms up). I top it off some more, turn on the heat and make sure it's hot and that there's flow through the heater core, and top off again if necessary.

desTRUCKtive

I have never seen a bleeder valve. Emperor makes a good point, this is how I bleed my system when I installed my T-Stat. I cannot remember exactly how I did it. But I think all it was, is a series of heat cycles.

1st Let it cool down a little
2nd run the truck at about 2000rpm with cap off till it reaches about 195, (right when the thermostat opens). Wait about 2 minutes after water is flowing through the thermostat and put the radiator cap on. Turn off Vehicle. let it cool down a little

3rd Do the same process over, repeat it about 2 to 3 more times, and add radiator fluid after each cycle if needed.

I think this is how I bleed of my system, I will try to search for some directions.

BigTex

iTrader: (16)

I severely overheated my truck last year once. I had the PCM triggering my relays. It had been working fine for months, but one day in heavy traffic, the PCM didn't trip the relays. By the time I noticed it and made it off, it was in reduced power mode and boiling over coolant. I know it was the PCM trigger that failed because I cut that same wire and manually grounded it to turn on the fans. So don't put 100% trust in the PCM.

Now I just run all the time with the fans manually tripped on low speed and haven't had any problems.

budhayes3

iTrader: (19)

That's good to know...Bryan at PCMforLess has my fans set to come on at 180* and turn off at 173*, so I figure that once the 95* weather rolls around they'll be running most of the time (although I'll probably have my a/c on so they'll be on high)

one03sierra

iTrader: (1)

when i did cam swaps i bleed the system by cutting an old hose. i took an old upper rad hose and cut it in half. i then turned it straight up from the rad. i installed the new hose on the connection at the water pump and let it sit on the core support. i would fill the cooling system till full and coming out of the hose that was attached to the water pump. then removed the cut hose and attached the new one. kept filling till full and let it run till warm without the rad cap on it. then put the cap on and took it around the block. let it sit for a minute and then slowley rmoved the cap to bleed.



also!!! is this a new or used rad you just put in there?? there is a hose that goes from the rad to the overflow/fill tank. top right hand if in the seat. remo0ve it from the rad and see if the hole is blocked. mine had only a pin hole in it. i drilled it out to 3/8 and reattched it and had no further problems.

good luck!!!!!!

thunder550

iTrader: (70)

OK I tried the squishy hose thing, didn't get any bubbles only solid coolant flow. Also did the heat cycle, didn't have to add anything. I'm gonna put a manual switch on the fans so I can turn them on just to make sure the PCM isn't flaking out.

The radiator was brand new...I'll check the overflow hose as well and make sure it's no blocked. Thanks for the help guys.

thunder550

iTrader: (70)

Ok I just had a thought...tell me what you guys think.

Allen told me to set the fans to Aux Fans in HPT, but we had already set them to 2 fans, stage 1 on at 200 off at 190, stage 2 on at 210 off at 200. What I'm wondering is if when stage 2 temp hits, the PCM shuts off stage one. This would mean that once my engine hit 210, my fans (stage1 ) would turn off because the PCM thought it was turning on a second stage fan.

This would explain why I never see high temps around town, cause the engine never hits 210....but pulling a 6000 lb trailer up hill I can see it hitting 210 and shutting off the fans, that would explain why it takes so long to start to rise, but once it starts it goes up really fast.