LQ4 Running Too Cold!

Ok, have a ques for the forum nobody seems to be able to shed some light on so far. Have a 2000 Sierra that won't get up to temp. Gauge sits just above 160, infrared on the water outlet says the same thing. Have tested and installed 2 additional thermostats, each open at 190 or so and close at 180. No change in the vehicle. Water pump and radiator were replaced 9 months or so ago, no problems until recently. Temp will occasionally reach "normal" on the gauge, then drop randomly, mostly on the highway. The engine is physically running cold, and the mileage has suffered as a result. After sitting with the engine off and heat soaking, the temp rises to 174, then after 20 seconds of running, it drops to 155 or so. Any ideas?

electric fans?

Fan clutch?

thats what im thinkin but u would know it if it was the fan clutch cause u could hear it.

I have the engine driven fan, it doesn't roar like the clutch is locked up, and even at idle the heat won't build.

Is it cold where you live?

My truck does NOT heat up in winter. I have the entire radiator covered with cardboard, and it still takes 20 minutes of driving before the OD will engage. I have a 160* stat in, and I barely even hit those temps. I have electric fans, and NEVER use them in the winter. Just something I've learned to deal with.

I'm barely hitting 160 myself this winter in the truck I bought.

Granted, I've changed the water pump and radiator since last winter, but there was no issue with heat at all. Gauge was always rock solid one needle-width below 210. It was just fine in the cold (30-40deg) until the last few weeks. I don't think living with a condition like this is acceptable, something has gone wrong and needs to be addressed. Even in the "Snowmageddon" the local whiners have been whining about here last season didn't faze the heater, so I am certain there is a new development of which I am presently unaware.

Probably had a restriction in the old radiator that was letting it get up to temp. Now you have a more efficient system and it is doing its job. Try blocking off a portion of the radiator with cardboard to get the temps up.

30-40 degrees isn't cold. At all. You shouldn't be having any trouble. Even when it's -20 my truck gets up to temp, it takes a while, but it does.

Right, has been in the 20's the last few days... And so far it seems anyone with an issue has developed a work around using cardboard over the radiator instead of actually fixing the problem. I can't be the ONLY ONE who has this issue and wants to actually fix it. Am I ?

Quote:

---

Originally Posted by Frenchy

30-40 degrees isn't cold. At all. You shouldn't be having any trouble. Even when it's -20 my truck gets up to temp, it takes a while, but it does.

---

dam -20. when it gets down to 20 here i can barely stand it

You did get the proper thermostat correct? One that opens too much and flows too much can cause a vehicle to do 1 of 2 things.

1. Over heat cause coolant is not given enough time to cool when passing through the radiator

or

2. Run colder because the coolant is not heated as thoroughly when passing through the block at a faster rate.

Just trying to eliminate any possible fault.

Yes, tested the 2 new ones I pulled out. In a pot of water, they both open at 190, close at 180 or pretty close. By 200 they were both open pretty far, and closed fast when dunked in cold water. Used a meat thermometer instead of infrared.

Quote:

---

Originally Posted by Hambone!

Right, has been in the 20's the last few days... And so far it seems anyone with an issue has developed a work around using cardboard over the radiator instead of actually fixing the problem. I can't be the ONLY ONE who has this issue and wants to actually fix it. Am I ?

---

Yup. I've spent a bunch of time/money to make sure mine runs cold in the summer when I'm spraying/towing/etc. Cardboard works just fine for me in the winter. Put a honda radiator in it if you want it to heat up faster.

Have we run out of steam here? It's an odd feeling to be the only one trying to actually solve the problem rather than develop a work-around. No idea what would cause significant coolant flow through the upper hose when started cold (32deg)? Anyone have an engineering diagram of the water pump or cooling system for an LQ4?

Just out of curiousity, have you verified engine temps on a scanner of sorts such as HPT? Both my trucks run at around 190* on a scanner but the gauge is always off by 20* or so.

do you use 50/50 antifreeze?

CTS data matches what I get from the infrared, still below the rating of the thermostat. The mix may be heavier on the glycol than water right now, but even so, wouldn't the heat transfer properties be fairly close?

Quote:

---

Originally Posted by Hambone!

Ok, have a ques for the forum nobody seems to be able to shed some light on so far. Have a 2000 Sierra that won't get up to temp. Gauge sits just above 160, infrared on the water outlet says the same thing. Have tested and installed 2 additional thermostats, each open at 190 or so and close at 180. No change in the vehicle. Water pump and radiator were replaced 9 months or so ago, no problems until recently. Temp will occasionally reach "normal" on the gauge, then drop randomly, mostly on the highway. The engine is physically running cold, and the mileage has suffered as a result. After sitting with the engine off and heat soaking, the temp rises to 174, then after 20 seconds of running, it drops to 155 or so. Any ideas?

---

Quote:

---

Originally Posted by Hambone!

CTS data matches what I get from the infrared, still below the rating of the thermostat. The mix may be heavier on the glycol than water right now, but even so, wouldn't the heat transfer properties be fairly close?

---

not neccessarly, in our case we use glycol for cooling, which in terms aborbs the heat instead of dissapating the heat which would be used in heating. you mentioned this started happening, i read you changed the water pump and radiator, to try and solve your issue, just asking here but i take we are sure we have a 195 thermostat or 190 whichever, remember youre testing this in water only and your radiator is filled with antifreeze, so is it cold in your area as of now, did it just start doing this during the cold months? reason im asking is this could be do to, to much glycol? and its keep the engine cooler than normal? maybe try and use less glycol?

undersatand what youre saying and i probably dont have a lagit answer for ya, just trying to maybe help ya solve the issue ;)

Yes, this started becoming more of an issue as the weather got colder. Presently, there is the new design (04 up) pump, thermostat and water outlet brand new from GM, and system has more water in it than before. Similar results, unfortunately. Temp comes right up to 1/3, never drops, then after a few mins on the highway, its at "normal". Normal is almost straight up on the gauge (1/2 of scale), just shy of the 210 marking. This is a real pisser......

I'm having the same exact problem with my 4.8. I changed my tstat, but that didn't change anything. So, I took the clutch fan off and that seemed to help some, but not much. The radiator is new (I hit a deer) but I had the same problem with the old radiator, too and the gauge it reading right. My temp stays around 180* when it's around 40* outside and will get to 210* on a day that's about 60* while letting it idle for 20 minutes or so after I've been driving a while. When it does get up to operating temp, the heater blows really hot. On those low teen temp mornings when I get off of work, it's a really cold ride home and the truck will stay in the "cold temp" shift pattern all the way home, which is a 30 minute ride. I don't know what to try next. Anyone have an idea? :help: