Engine runs to cold??

[imiceman44]

My 88 K5 doesn't ever seem to warm up. I don't get much heat from the vents. I have a new water pump, radiater,and a new 195 stat. It still has the clutch fan, but thats not locked up. at an idle the rad fluid temp only gets to 120. This is my plow truck. Any idea's why?? This is my plow truck, some heat would be nice!! I'm gonna try some cardboard over the front, But I shouldn't be having this problem!! I have never had one run this cold!


12/22
Put another new t stat in today. The engine temp guage came up to 190-210 range on the factory guage, and the temp at the top of the radiater was going between 110 and 135. But still no heat. I'm starting to think I have more than one problem here. I was checking the hoses, The hose that goes into the heater core is hot, but coming out it's warm. I had to quit working on it before I could go further, But it seems that the heater core may be restricted or plugged. I am gonna pull the hose off the outlet side and see what comes out. I may end up changing that out next.

Well did you try back flushing the cooling system?
I used the prestone kit and did a flush and it worked fine after that.
Try it before you take any parts out. if you don't have a leak don't take a heater core out it's too much trouble.

 

[POWERMAD]

It sounds like the engine is operating at normal temp, 190-210. The radiator seems to be at normal operating temp as well. 190-210 engine temps should have the cab pretty toasty.
I would look at the blend doors and check for restrictions to the airflow to the heater core.
It sorta sounds like the heat control blend door is stuck in the cold position.
Or the heater core is plugged.

My K5 used to take forever to warm up but it would eventualy get toasty.
I did find that routing the return from the heater core back to the engine instead of the radiator made for faster warm ups.

But it sounds like yours is not pushing hot air even though the engine is up to temp.
Which sounds like a climate control problem and not engine temp related.

 

[bablazer73]

Well, I already have the heater core. I Plan on putting that in on sunday. I,ve done them before, so I deal with that. Not a huge deal to do.

 

[bablazer73]

I checked all the doors, They seem to open/close fine. Although I can't see inside to see if anything is stopping the blend door. the blower motor itself is strong. I guess since I have the core already, If there is a problem in the box, I'll find it while it's apart!!!

 

[bablazer73]

I have heat now!!

well, The heater core is in and I have heat now!! The heater core was plugged up badly. lot's of rust! Most likely the same reason the rad was replaced before i got the truck. I did find a few things wrong in the heater box, But nothing that would have affected the actual heat. Part of the direction doors was bent. Would not allow the door to close all the way for defroster vents. But not a temp problem. I am on my way to the junk yard to get that piece.

 

[dyeager535]

I guess since I have electric fans and an ECM to check both ambient air temp and engine temp, I can measure how long it takes to warm up the vehicle to a certain temp, both with the fans forced on, and with the fans off.

I suspect warmup time difference with the fans on or off is not going to be significant. One more absolutely worthless test to conduct...I'll try to get around to it just because I want to see how much of a difference it really does make.

OK, this took as long as I expected it would. Got first half of test done tonight. Disconnected both fan relays (scan tool forces fan one on all the time) and fired the truck up from "cold". I had to start it up once previous because it's been sitting for awhile and I forgot I was going to test this, it ran for maybe 10 seconds and was shut off to begin test. Bumped throttle a couple of times during test for the aftermarket roller lifters. Hood closed. All temp readings taken from scan tool.

Starting engine temp was 70.7*
Intake Air Temp was 73.4*
After 13.16 minutes:
engine temp 196.2*
Intake Air Temp 98.6*

I stopped test as soon as engine temp passed 195*, which is my t-stat rated temp.

Next test I'll reconnect the fan relays and ground the secondary fan switch to force both fans on constantly. If anything, I suspect the additional load on the alternator is going to decrease warmup times.

 

[DustinK5]

try flushing out the heater core. Sometimes over time sediment in your coolant can clog up your heater core.
disconect the heater hoses and attach a garden hose to one end of the nipples from the heatercore and turn on the water. You need good water preasure from your garden hose. Once you've done that real good, switch the garden hose to the other nipple and flush it out the opposite way.

 

[Leadfoot]

OK, this took as long as I expected it would. Got first half of test done tonight. Disconnected both fan relays (scan tool forces fan one on all the time) and fired the truck up from "cold". I had to start it up once previous because it's been sitting for awhile and I forgot I was going to test this, it ran for maybe 10 seconds and was shut off to begin test. Bumped throttle a couple of times during test for the aftermarket roller lifters. Hood closed. All temp readings taken from scan tool.

Starting engine temp was 70.7*
Intake Air Temp was 73.4*
After 13.16 minutes:
engine temp 196.2*
Intake Air Temp 98.6*

I stopped test as soon as engine temp passed 195*, which is my t-stat rated temp.

Next test I'll reconnect the fan relays and ground the secondary fan switch to force both fans on constantly. If anything, I suspect the additional load on the alternator is going to decrease warmup times.

Cool. Keep us posted on the findings.

 

[dyeager535]

OK, this took as long as I expected it would. Got first half of test done tonight. Disconnected both fan relays (scan tool forces fan one on all the time) and fired the truck up from "cold". I had to start it up once previous because it's been sitting for awhile and I forgot I was going to test this, it ran for maybe 10 seconds and was shut off to begin test. Bumped throttle a couple of times during test for the aftermarket roller lifters. Hood closed. All temp readings taken from scan tool.

Starting engine temp was 70.7*
Intake Air Temp was 73.4*
After 13.16 minutes:
engine temp 196.2*
Intake Air Temp 98.6*

I stopped test as soon as engine temp passed 195*, which is my t-stat rated temp.

Next test I'll reconnect the fan relays and ground the secondary fan switch to force both fans on constantly. If anything, I suspect the additional load on the alternator is going to decrease warmup times.

As promised, finished my "test":

Starting engine temp was 68*
Intake Air Temp was 68*
After 13.21 minutes:
engine temp 196.2*
Intake Air Temp: didn't get

So, it looks like it doesn't make a bit of difference, or if anything, very, very little whether your fan(s) are on or off for engine warmup. Kind of surprised, the load on the engine was obviously much more with both fans running constantly, but the scanner forces it to run at 1000RPM regardless, so it was an even comparison.

Since I can't think of any other way to measure, I went and grabbed one of those garden wind gauges...the kind with the paddle that is calibrated to MPH readings on a curved surface. Secondary fan was just about 15MPH, primary was pushing 25MPH. Too close to the engine to get directly behind either one, but I guess this is close enough. Of course, fan diameter is a major factor, so just measuring the same with a clutch fan isn't going to be a good comparison.