3.2 runs cold, currently stumped

[GM Ontairo]

I started taking my truck to the track and decided to upgrade the cooling system to eliminate the clutch fan and allow more room for working on the motor.

I purchased a griffin rad and some dual e-fans. Completely overkill but it's what I now have and am trying to make it work.

Ever since installing the new cooling system the truck runs cold constantly. It will come up to temp when sitting. However as soon as I start driving and getting airflow through the rad it cools right back down.

So first thing I tried was swapping out thermostats for another 192F motorad that I bought brand new.



Nothing changed. The truck would come up to temp and then go further until the e-fans came on. As soon as I started driving it, it would drop right back down to 160f. I shot the thermostat housing and just below the intake with an infrared thermometer to ensure my gauge was working properly. All temps were verified with the infrared thermometer.

I thought maybe coolant was just simply bypassing the thermostat around the sides because there seemed to be a little bit of play in the intake recess for it.

So I made up this little rubber gasket just to ensure this wasn't the problem.







Nothing changed. 160f cruising temp all day.
I then pressure tested the rad and changed out the rad cap. No leaks, pressure held at 15 psi for 20 mins. Rad cap is functioning properly.

I now decided to throw in a jet 180f thermostat to see if anything changed. No change, 160f cruising temp.

So now I started trying to overcomplicate the problem. I began to think, well maybe the water pump is spinning in reverse??? I changed from a v-belt drive to serp to accommodate the supercharger.
I started looking at the way 2.8l water pumps were spun with the serp belt and holy shit it was indeed spinning backwards?? ****ing eureka! When we put the blower on and switched to the serp drive, I just simply reversed the pump.

(other 2.8 for belt routing reference)


So that was the problem all along. The water pump was pushing the water the wrong way and just blowing it right through the thermostat...

Then came the moment of holy shit how do I set about rerouting the serp belt to spin it the other way. I was looking at all kinds of different options and then had a brilliant moment where it came together really nicely.

http://www.s10forum.com/forum/f106/how-to-remove-delete-smog-pump-430782/

Thank you so much to built2rail_1 for this how to. It gave me the idea of rerouting it this way.


So we reclocked the tensioner.





This is the old set-up


With the old set-up the way the tensioner was position was less than ideal. We were only utilizing the last 20% of it's sweep.


With this new belt route The blower sees a little more wrap. The the tensioner is actually working very well and I can now looking into dropping pulley sizes. Oh and the water pump is spinning the right way!




Took it for a drive and now no belt slippage at all. Wait but the temp is still the same 160f??!! what that was for sure the problem,????!!!

or maybe not??



So yup did all of that and it didn't help solve my low temp problem at all. I mean there was definitely some positives but not the outcome I was after.

So I then started researching motorad thermostats and found a lot of bad reviews about how the springs are weak and they prematurely open and run motors cold. So I went out and bought a stant 195F the next day. I was so sure this was the problem. Nothing changed 160f cruising temp.

I also pinched off the heater core lines to make sure nothing foul was happening there, no change. Then tried flipping the thermostat for curiosities sake. No change either.


I would love to get some fresh eyes on this problem. I feel like I'm having a can't see the forest for the trees moment.

Is it possible the thermostat is cracking a touch or the air bleed is letting enough coolant through to drop the operating temp?

[45es]

When ever you change something and a new problem begins, go back to the last thing you did before the problem started. You will usually find the cause. In your case, you answered your own question as to why you are running cold. Re-read the second and third paragraph in your first post. You even say, "complete overkill".

[robertisaar]

you can have a radiator the size of a semi, it won't prevent the engine from running at the thermostat temp unless the stat is in some way open or being bypassed.

[GM Ontairo]

45es, I hear you loud and clear. I don't really want to buy a new thermostat/shroud and put the clutch fan back on. I can't see why I won't be able to get this to work.

Robertisaar, This is exactly what I've read time and time again. I can't for the life of me figure out how it is being bypassed though? Does anyone know which directional these water pumps are designed to spin? Or are they uni-directional? I've thought about putting a flow restrictor inline to see if that may help.

[Guest]

The serpintine water pumps are meant to spin in reverse or anti-clockwise. As long as the water pump pulley is contacting the outside of the belt (smooth side) the water pump will rotate in the correct direction, regardless of which way you wrap the belt onto it as you see from your drawings.

If you used a water pump originally designed for a V-belt set-up and simply swapped the serp pulley on to it, you have an issue, though that usually causes overheating, not overcooling. When you swapped the serp belt system in place of the V-belt system, did you swap the front cover and water pump at the same time?

[GM Ontairo]

Thanks for confirming that Raven,
Yes I switched over to the newer pump and timing cover specifically designed for the serpentine belt set-up.


I also meant to add that I tested all of the thermostats in boiling water. Brought the water to a boil slowly and watched each thermostat individually for the temp they opened at and closed at. They were all operating correctly. I think this is just a matter of coolant bypassing somewhere.

[GM Ontairo]

Any ideas?

[robertisaar]

GM's troubleshooting steps aren't very helpful here... they keep coming back around to the thermostat. I understand why, but I can't see you getting that many junk thermostats in a row.

GM's steps:

check/adjust coolant level
inspect for/correct blockages in cooling passages(radiator/heater core/heads/manifold/block)
and back to the thermostat.

where is your coolant temp sensor and/or sender located? if they're in any way moved from a stock location, unexpected changes in the signal they produce can occur. for that matter, how new are those sensors/senders?

[GM Ontairo]

Thanks for the input Robert. Coolant sensor is in the original location. Without looking at the truck I can't say with 100% confidence but I believe its on the front of the drivers side head. It's oldish? but I've checked the temps with an infrared thermometer on the thermostat housing and just below on the intake. The gauge reads 160ish and the infrared thermometer would read 160-164 temps.

I'm kind of at a loss. Would love to figure this out. I'm trying to think of a way to stop the air bleed on the thermostat. I can't see that little bit of coolant bypassing the thermostat cooling the motor 35*f below the thermostat rating? but I've been wrong many times on this problem already.

[45es]

Just a quick review.

You said you wanted to eliminate your original clutch fan and stock radiator. In doing so, you installed electric fans and Griffin Radiator. At that time, did you change anything else? What was the operating temperature before the new components?

You said you have tested all the thermostats in water and confirmed they are opening at the correct temperatures. That eliminates the possibility of receiving several bad thermostats.

You have checked the water side of the system pretty thoroughly and have not found a cause for the cool temperature. I know the thermostat is the engine set temperature controlling device in the system. Here is what is confusing to me. You said, "So first thing I tried was swapping out thermostats for another 192F motorad that I bought brand new. Nothing changed. The truck would come up to temp and then go further until the e-fans came on. As soon as I started driving it, it would drop right back down to 160f." When the engine reaches operating temperature and before the electric fans come on, does engine rpm (vehicle not moving) have any effect on temperature? It makes no sense that the only thing you have noted that has an effect on the operating temperature is air flow thorough the radiator.