mudbog42

I have a 2001 5.3l in my 51 Chevy, but for some reason it never reaches what I believe a normal operating temp should be...

The temp never goes above 160 and while driving it will stay at about 125-130 and won't get any warmer....

This is the second thermostat in there now. I am using the stock temp thermostat that comes up for a 2001 5.3l at the parts store, but it still runs really cold.

Does anybody know why this motor is running so cold? Oh yeah not sure if this would make a difference, but I have no heater core hooked up or a heater period.

Thanks for any help

busta9876

iTrader: (3)

Where do you have the temp gauges sender at? Front head on drivers side?

I had a LT1 a while back, and my coolant temp sender was in the head. They are reverse flow cooling:water enters block and goes to the heads first, then down to cylinders and out to radiator. In winter, the gauge reading in the front of cylinder head would barely get above 120-130. Computer gets its signal from the water outlet on the LT1, it was reading 180.

I've often wondered if the LS series is a reverse flow as well. If you're water temp sender is in drivers front, that would explain a cold reading. Might compare the reading there with reading the PCM gets from the BACK of the passenger side head.

Just a thought....anyone know for sure about the reverse flow cooling?

mudbog42

I have the sender in the back of the passenger head.

I don't believe the LS motors are reverse cooled, but I could be wrong.

I'll have to get my hands on a scanner and try and match it up to the computer readings.

Sizzlenut

iTrader: (1)

What are you using to read the temp? Are you using an adapter that moves the sensor away from the head?

mudbog42

I am using the adapter from S&P to use the mechanical temp sending unit.

Shawn MacAnanny

iTrader: (12)

Mine rarely goes above 150. Electric temp sensor in driver side head, Autometer gauge. I've gotten it to 190-200 before if i leave the fans off and make a few runs.

Stu Cool

iTrader: (13)

Are you using an electric fan or the original truck fan? Is it a clutch fan or pulling air all the time? Did you loop the heater hoses or block them? Does the radiator feel warm? I would do like you said and get a scanner reading, or let it get warm and stick a cooking thermometer in the coolant in the radiator.

Pat

mudbog42

I'm using the original truck clutch fan that came on the motor. I looped the heater hoses. I'll have to pull the car out and check on the temperature of everything.

bczee

iTrader: (12)

Just a few things to ask or check.. doesn't hurt to ask or double check.

Are you sure your sender and gauge are reading correctly ? try taking the sender off and heat it up with either some hot water or bultane torch, just don't heat it too hot all at once.

also, have you made sure you have purged the air out of the cooling system, (yeah, I know, it usually cause over heating, but ??)

Are you sure that the Thermostat is not being bound by the housing or gasket (if one is being used) and not allowing it to closing ?

boy, most of the time, everyone is having overheating problems...

mudbog42

The gauge should be correct, I guess I could double check it, but its the same gauge I used on my last motor and it worked perfect.

I also double checked to make sure it was purged correctly. I'll have to pull the thermostat to check if its stuck.

LUMPY85

that is a very odd problem, my 2000 5.3 heats up very fast, but it never gets hot, i have a flexalite blackmagic fan on mine with a HD 3 core radiator.

98blackSS

I may have to cave and buy one of those blackmagic's myself. I bought a Becool (SPAL) 3150cfm fan which I thought would do it, but I still run hot when I'm rock crawling and on the pedal. I run a AA tripple core radiator myself.

What max temps are you guys seeing?

LUMPY85

i kinda had a brain fart when i installed my temp sensor. i made a brass plug that replaced one on the block that my temp sensor threaded into. it is bored out the allow coolant flow up to the sensors threads, but it on the block not the heads. the max temp i have seen is 190, mind you i am basically checking the water coming from the radiator, it hasnt passed the hottest part of the motor (the heads) until after it passes my temp sensor. i think i am going to mount a new one in the head, and leave the one in the block, if for nothing else, it tells me my radiator is plenty for the motor.

98blackSS

I'd probably buy the BM xtreme fan without the temp sensor/controller stuff since I'm currently using the ECM to control fan on/off. I use the port in the driver head for the ECM's coolant sensor and my autometer gauge sensor is screwed into the pass side head.

I generally run about 205 deg all the time according to the gauge with the OEM 195deg t-stat. But I've seen it go up to 220 when wheeling/crawling under load on a hot day. This seems rather hot to me. Just assumed that the fan isn't keeping up since it's the only airflow my radiator ever gets due to the low speed driving offroad. I rarely drive it on the street.

Are you guys running the stock t-stat?

thunderstruck507

iTrader: (18)

mine runs at 190-195, doesn't kick the fan on until 196 or so...

Just make sure you check the reading through the pcm with a scanner, then compare to the gauge

Monza355

iTrader: (3)

My Monza runs cool as well. Sitting in traffic it may get to 190 but as soon as I roll down the road it will drop to like 150 or so. It always ran hot with the built 355 at like 205 or so in traffic. What's the deal?

Bill

mudbog42

Ok well haven't had a chance to get a scanner hooked up, but felt around the radiator and it feels cold, you can pretty much grab it with your hand, so its definitely not warming up. Put a cooking thermometer in the coolant and it was real close to the gauge reading.

Going to go ahead and replace the thermostat today, since I will be flushing the system.
Someone correct me if I am wrong, but if the thermostat at one point got too hot, say from not having all air bubbles purged from the system at one point in time, the wax pellet would be ruined thus causing it to flow too much....

mudbog42

Ok well just got done replacing the T-stat and running it for about 40 minutes and the temp will not go above 160. The cooking thermometer reads 175 from the water coming out of the steam vent and about 135 from the water in the radiator. The lower radiator hose is cold enough that you can grab it with your whole hand.

Not sure what else it could be...

1BadAction

iTrader: (10)

sounds like an issue with the way the fan is working with the radiator. If the rad has a ton of cooling capacity, the fan doesnt need to be as agressive as it is on the **** ant stock LSx radiator. see what i'm getting at?

mudbog42

I'm using a radiator from an 80's or so suburban. Would that radiator have that much more capacity than the silverado one?