Coolant Below Temperature Threshold

2kwik4u · Post by **2kwik4u** » Thu Feb 15, 2007 4:07 am

I know this has been covered 100 times before from guys running low temp thermostats. However the code appeared in the CC last night. Truck is 100% stock with the exception of the K&N FIPK (and some floormats, but they don't count

).

I've noticed that the truck wasn't getting anywhere NEAR the 210* mark on the guage, and the gas milage has SUCKED lately (last 4 tanks had a HIGH mark of 14.5mpg). With the highs lately being in the teens, and the lows in the single digits, I'm wondering if my clutch fan is broke, and staying on. Seems like I can hear it from time to time, however it also seems to unlock at times as well.

My plan of attack is to put the Efan that I've had sitting around for awhile in, and see if that helps. The truck still has a stock thermostat to the best of my knowledge, so if the efan doesn't help (I can't see how it wouldn't though), I might spring for the 190* low temp unit. Of course with that comes relocating the IAT for the summer months.

Anyone have an comments, or heads up, or thoughts?!?!?

F9K9 · Post by **F9K9** » Thu Feb 15, 2007 7:22 am

It sounds like the Tstat is stuck open.

2kwik4u · Post by **2kwik4u** » Thu Feb 15, 2007 7:35 am

f9k9 wrote:It sounds like the Tstat is stuck open.

I somewhat thought the same thing, but it warms to about 180 degrees or so (the first 1/4 mark on the guage), and then stabilizes there. I might get a new 190* one to put in while I have the truck apart for the fan anyway.

killian96ss · Post by **killian96ss** » Thu Feb 15, 2007 7:58 am

If the clutch fan was stuck on you would probably notice it since it sounds like an jet engine.

When the clutch fan on my CC was engaged it was real loud, but I guess it's possible that yours is quiet when engaged.

If the fan was stuck on your gas mileage would definitely drop.

If the temps where you live are that cold then I would think that switching to a low temp t-stat would only make matters worse.

If you do want to try a low temp t-stat the one you want is 180* not 190*.

Stock is 195*

Make sure you don't get the 160* t-stat since it causes problems.

I ran a 180* t-stat for 84k miles using the factory IAT location and I never had any problems or set any lights.

Steve

2kwik4u · Post by **2kwik4u** » Thu Feb 15, 2007 9:10 am

yes, yes and more yes.

I can hear the fan more often than not lately. Which in cold weather like this had me puzzled. It's been this cold for about a month and a half now, however they are predicting back into the 60's late next week. I have a semi-hatred towards clutch fans anyway, so I'll go ahead and make some plans to replace it this weekend. I'd certainly like to think that a nice 1-2mpg increase would be coming my way from that as well, but I'm not holding my breath

As for the lower temp stat. I was thinking if I'm going to replace the stat, I'm going to get a lower temp one, and try to help head off some of the summer overheating issues I was having, and expect to have again this year. I'd certainly like to think with both the efan, and the lower temp stat, I can keep those in check this coming summer....Check on the 180* though. The Sy/Ty guys run the 160, and I just don't think thats warm enough for a daily driver, however for a performance application it makes sense, especially considering how prone to detonation those trucks are. The vortec heads resist that detonation better, and 180* should be fine I would think.

killian96ss · Post by **killian96ss** » Thu Feb 15, 2007 9:27 am

2kwik4u wrote:The Sy/Ty guys run the 160, and I just don't think thats warm enough for a daily driver, however for a performance application it makes sense, especially considering how prone to detonation those trucks are. The vortec heads resist that detonation better, and 180* should be fine I would think.

A 160* t-stat will work in our trucks, but using one will always cause the CEL or SES light to come on because of the OBD2 emission parameters.

Every engine makes its best power at a specific temperature and I think a lot of people just assume that using the lowest rated t-stat will give them the most power.

This is not true in any way because heat expansion in the combustion chamber is what drives the pistons and too little or too much heat can upset the perfect balance.

I have seen a few V-8's on dynos that make more hp using a 180* t-stat vs. a 160* t-stat.

Steve

2kwik4u · Post by **2kwik4u** » Thu Feb 15, 2007 9:43 am

killian96ss wrote:
2kwik4u wrote:The Sy/Ty guys run the 160, and I just don't think thats warm enough for a daily driver, however for a performance application it makes sense, especially considering how prone to detonation those trucks are. The vortec heads resist that detonation better, and 180* should be fine I would think.
A 160* t-stat will work in our trucks, but using one will always cause the CEL or SES light to come on because of the OBD2 emission parameters.

Every engine makes its best power at a specific temperature and I think a lot of people just assume that using the lowest rated t-stat will give them the most power.

This is not true in any way because heat expansion in the combustion chamber is what drives the pistons and too little or too much heat can upset the perfect balance.

I have seen a few V-8's on dynos that make more hp using a 180* t-stat vs. a 160* t-stat.

Steve

I agree, that lowest is not always best. However in a boosted application, the lower the coolant temp the more resistance to knock you have. Cooler is generally better in that application.

I also totally agree that the 160 will work in ours, but without tuning software, I dont' want to fight the SES light all the time, and all the other madness that comes with it. Maybe when I get some software, but for now....not so much.

kwalsh · Post by **kwalsh** » Thu Feb 15, 2007 10:05 am

Did you just say it will warm up into the 60s???

I consider it warm when it is above 15 with the wind chill factor included.

Post by **HenryJ** » Thu Feb 15, 2007 3:46 pm

I am sure you guys have figured it out already, but a fan being stuck has no bearing on engine temperature. The thermostat controls engine temperature.

Sub zero temperatures should still be fine and not set the MIL. The PCM uses reading from the ECT and IAT to determine the amount of time required to reach the temperature threshold. How cold it is outside is part of the equation.

A stuck fan would kill performance and perhaps mileage, but not effect operating temperatures.

A sticky stat sounds like the problem if the ECT and IAT readings are good. Connecting to a scan tool might be a good idea, just to check some sensor readings for accuracy.

Clear the code and see if it repeats is a good idea too.

The only option you have for a choice of stats is the Jet 180 or stock 195, IMO. Retaining the bypass valve is important for those seeking to maximize cooling in the summer heat.

2kwik4u · Post by **2kwik4u** » Fri Feb 16, 2007 7:15 am

Yes and no.

The fan does control temp to some degree. If you pull more air over the same surface area, you increase the cooling effeciency of the radiator, and make the coolant cooler. When mixing the hot coolant from the engine with the cold coolant from the radiator, the difference in temp is what determines the final temperature.

With that said, the t-stat is the controller of how fast that coolant is mixed.

With the symptoms I have I'm leaning towards a combination of both. I'll replace the T-stat first, and see what happens. The fan needs to go anyway in the quest for more MPG's, so I'll wait to get it changed, but it'll still happen.

Post by **HenryJ** » Fri Feb 16, 2007 10:17 am

2kwik4u wrote:...The fan does control temp to some degree. If you pull more air over the same surface area, you increase the cooling efficiency of the radiator, and make the coolant cooler. When mixing the hot coolant from the engine with the cold coolant from the radiator, the difference in temp is what determines the final temperature.

You have the right idea, but perhaps some misconceptions, or just the opportunity for someone else to get the wrong idea. I just don't want the latter to occur.

Yes, the fan does control the temperature to some degree. But only after the thermostat is fully opened and the radiator is unable to dissipate the heat without the assistance of increased airflow. The radiator does not get "cooler" . Its efficiency is indeed improved and a greater amount of heat is transfered to the airflow. That is just mincing words. I just want the process clear.

The thermostat does open and close to control the temperature. It alone controls the temperature until the full open position is achieved. After that point airflow and the radiators ability to transfer the heat are the controlling factors. Ideally the radiator and fan should be sufficient to never require the thermostat to be in the fully open position continually. That would be operating too close to the edge and the potential for overheating might exist.

Could you use the fan to control the temperature alone? Yes. Race cars use a restrictor in place of a thermostat sometimes. The fan is used to control the temperature. This is a very controlled situation and not subject to the rigors of a street driven vehicle.

Would I want to rely on fans to control temperature? No.

The whole system needs to work together. It feels a little ridiculous to argue that the fans do not control the temperature, but when we are referring to the low side and low coolant temperatures, the fan really does have no ability to make changes. the thermostat is the only temperature control on the low side.
Consider a boat. It has no fans and a reservoir of , sometimes extremely cold coolant. The thermostat is the only temperature control.

2kwik4u · Post by **2kwik4u** » Fri Feb 16, 2007 10:27 am

I agree on the low side, the thermostat is the primary control. I also agree that the entire system needs to work together, and further agree that controlling the temp solely based on the fan is a bad idea.

I had cooling problems this past summer (overheating in traffic with A/C on, and ambients in the high 90's), I'm going to guess the T-stat was close to failing then, and has now completely failed. I also attribute alot of that problem to the lack of airflow from the clutch fan at idle. Of course my luck it won't lock in the summer, and won't unlock in the winter. Stupid POS is getting replaced anyway, this is more of a good reason than it is the cause of the SES light.

Post by **HenryJ** » Fri Feb 16, 2007 10:41 am

IMO, the stock cooling system is undersized for a hot climate.
I had the very same issues. The fan is not the root of evil. It does a very good job and is much more efficient than any electric will ever be.
Now, that is the fan. The clutch does a good job of combining performance and cooling, but is not adjustable and locks way too late to head off an overheating situation. If a lower temp clutch was available, or at least a few ranges to choose from, then perhaps it would be the best option.

I think the extra capacity radiator is a must do. Things settle down really well after that upgrade.
Then a cooler stat for those in the warmer climates. The stock stat operates in a range that is just too close to the edge for me.
Now that you have a cooler stat , you need to match the fan engagement. Since lowering the clutch fans engagement point is not an option, electric fans are the next step. They allow me to choose the engagement temperature and are sufficient to maintain operating temperatures for the conditions I have tried thus far.

One mod leads to another

Rad>stat>fans>alt>etc

Once the whole system is in place, it really does work well. I have been very pleased.

2kwik4u · Post by **2kwik4u** » Fri Feb 16, 2007 12:08 pm

Again, we are on the same page.

Stock fan locks too late, and not nearly often enough. I also concur with the "if you give a mouse a cookie" syndrome of mods following each other.

I disagree that the stock fan is efficient. high flow once locked and at a decent RPM, yes, efficient NO. For the amount of air they pull, and the amount of energy they consume, you simply can't beat an eFan IMO. The adjustability, and added control is simply icing on the cake.

F9K9 · Post by **F9K9** » Fri Feb 16, 2007 5:14 pm

HenryJ wrote:.......The fan is not the root of evil. It does a very good job and is much more efficient than any electric will ever be...............

I gotta go with Brule on this one. Under ideal conditions it works fine. I just couldn't find those conditions for myself.

I remember some member joining up awhile back that couldn't believe that there was an overheating issue with our trucks. If I recall correctly, that member had a roommate with a 4.3L that didn't seem to have a problem with overheating. I think I explained all the steps that I had taken and that my setup still wasn't bulletproof. If, I put my ancient mind to the task, I may think of who that was

2kwik4u · Post by **2kwik4u** » Wed Feb 21, 2007 3:56 am

Couple of warm days and the SES is off again. Guess I'm still going to swap thermostats and fans this weekend though.

cpgilmer · Post by **cpgilmer** » Sun May 13, 2007 2:47 am

Does Hypertech offer a stat for our trucks now?? Part number 1027?? I seen a few on e-Bay?? Which is better?? Hpertch or Jet??

Post by **HenryJ** » Sun May 13, 2007 3:48 am

cpgilmer wrote:Does Hypertech offer a stat for our trucks now??

For our trucks, No. They do have a 160 stat, but that was designed for earlier models. They also have some stats with out the bypass valve. I think running without the bypass valve is a mistake. The part number you listed (Hypertech 180° Powerstat Performance Thermostat #1027) does not have a bypass valve. If your plan is to go without, spend $5 on a stat at the local parts store.
That makes Jet your only real choice for a colder thermostat. They are the only one to make a 180 stat with the bypass valve.

cpgilmer · Post by **cpgilmer** » Sun May 13, 2007 5:17 am

Thanks for the info.....would you by any chance have an address of the best place to order one?? Thanks

Post by **HenryJ** » Sun May 13, 2007 6:49 am

I bought mine locally. Summit may have the best price, but the handling charges double the price.
If you have a Shucks, Checker, or Kragen, they are very competitively priced.

EDIT: They will not stock the Jet stat , but can order it and be pretty close to other mail order catalogs. Most times they will not charge freight.
Sometimes you can order it online and pick it up in the store: Shucks online (PartsAmerica)

cpgilmer · Post by **cpgilmer** » Sun May 13, 2007 1:08 pm

No luck....bought it from JEGS off of e-bay...now the fun begins putting this stuff together!!

cpgilmer · Post by **cpgilmer** » Wed May 23, 2007 7:37 am

Jet 180 installed, guess we will see if any issues develop....

2kwik4u · Post by **2kwik4u** » Wed May 23, 2007 7:49 am

I'll be picking one up myself on the way home....well not a jet but a stainless 180* from NAPA

killian96ss · Post by **killian96ss** » Wed May 23, 2007 8:25 am

2kwik4u wrote:not a jet but a stainless 180* from NAPA

Does this one have the bypass valve?

Steve

2kwik4u · Post by **2kwik4u** » Wed May 23, 2007 10:33 am

Don't know.....to be honest I'm not terribly concerned if it does or doesn't. There are pros and cons to both. I'll let you know how it works out.

Post by **HenryJ** » Wed May 23, 2007 12:49 pm

2kwik4u wrote:Don't know.....to be honest I'm not terribly concerned if it does or doesn't. There are pros and cons to both. I'll let you know how it works out.

The only pro for one without the valve is that is cheaper.
I don't see any cons for one with the proper bypass valve other than it costs more for a lower temperature unit.

2kwik4u · Post by **2kwik4u** » Fri May 25, 2007 4:34 am

I was misinformed.....NAPA did not have a low temp stat, nor did they have a stainless one. I'll be checking at AutoZone this afternoon for one. Hopefully with better luck.

I still have an eFan sitting around, and need to grab a tranny cooler as well.....Maybe I can get all that done this weekend?