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Engine runs to cold??

bablazer73

bablazer73

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runs to cold?? 12/27

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.
 
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I'd bet that either A) the thermostat is bad or B) it got installed slightly offset and is letting cold water leak past. When the temps are really low it doesn't take much extra flow to keep the engine too cool.
 
Try a new clutch fan, mine did the same as yours. I replaced everything you have, and still had the same problem. My clutch fan was running 100% of the time, not allowing the engine to warm up.
 
I would have to go with a stuck open thermostat. my 454's fan clutch is bad right now but still hits 190.
 
opfor2 said:
But he stated that he has a new 195 thermostat, so I don't think it's stuck open...

Dan..
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Not saying his is doing it, but I've had defective one's right out of the box (makes for frustrating diagnosis).

Clutch fan could be the issue, but both my trucks have large extra pitched fans with no clutches (direct drive, constantly turning at water pump RPM). One is on a plow truck and I usually end up wearing a t-shirt under my jacket. Until I get out to shovel the walkways I sit in the truck with just a t-shirt as I keep the heat cranked to keep the windows clear (and usually keep one window cracked for venitilation. The other is on my pulling truck which has an SBC with the largest 4-core radiator I could find and it still gets up to temp with no problems.

Again not saying it is the clutch fan, but who know......

bablazer73: You said you have new water pump, radiator, thermostat, etc. Was there a reason for this? Was there heat before? Did you replace the radiator with a different size?


Side Note: I thought the reason for a clutch fan was to spin less during cold temp situations to help the motor heat up faster, but still be able to "lockup" so that it could keep it at operating temp once it warmed up. I have seen several clutch fans fail and cause overheating (that is how I was able to get NoAngel's blazer so cheap), but never one causing too much cooling (not saying it can't happen, just haven't seen it).
 
Leadfoot said:
Side Note: I thought the reason for a clutch fan was to spin less during cold temp situations to help the motor heat up faster, but still be able to "lockup" so that it could keep it at operating temp once it warmed up. I have seen several clutch fans fail and cause overheating (that is how I was able to get NoAngel's blazer so cheap), but never one causing too much cooling (not saying it can't happen, just haven't seen it).
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I agree 100% !!!
 
Yes to the fan clutch.

Thermostat won't open if the engine is too cold and it's working properly, really doesn't matter what the fan is doing with a closed 'stat, since there isn't a whole lot of heat transfer.

Clutch fans job is mainly to not rob power from the engine, which increases overall efficiency.
 
Clutch fans job is mainly to not rob power from the engine, which increases overall efficiency.
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I have heard this and thought I understood the concept of less drag from the fan blades (due to clutch slip) reducing drag on the motor which would increase efficiency.

I was then told that was not the main function. The main function was quicker warmups and allowing the choke to open quicker (or computer going from open loop to closed loop) and that is how they can advertise increased efficiency as the mixture leans out quicker during cold weather.

It was also stated (not sure of the validity), that a clutch fan does not increase HP or efficiency over a stock direct mount fan (although several companies claim HP increase......similar to K&N thread). The clutch assembly weighs considerably MORE than a direct mount fan and spacer and requires more energy to rotate. Granted the slip allows some of the resistance to be bled off, but not a significant amount to say it's more efficient than a stock direct mount fan (as far as resistance at the crank is concerned).

Now if you compare it to a heavy steep pitched fan.......maybe but even then I think it would be negligable.

FWIW

Henry, when you figure out what it was please post. If, its the clutch fan it would give me alot of food for thought.

TIA :cool1:
 
Ugh, K&N thread. :)

However, like has been mentioned, if you can believe what you read, a clutched fan will ALWAYS make more power than a direct drive clutch fan. Both are "stock", just depends on year and application, but that relates to whether it saves GM money or not, and whether it was required to help them meet CAFE or emission goals and go with a smaller radiator.

Thats simple physics...the clutched portion of the fan, to include the blades, are not directly tied to the engine at all times. When they aren't, the fan isn't trying to move (as much) air, and at higher speeds, isn't impeding vehicle progress (however slight) by blocking airflow through the engine compartment. A non-clutched fan acts like a big plate at higher vehicle/engine speeds, and anything blocking airflow requires more power from the engine to keep forward progress. Besides the fact a fan is absolutely worthless at most road speeds, and if the cooling system works right, will actually hinder cooling.

Warmups on most 80's vehicles (car or truck) are done with the electric choke. Yes, no cooling over the radiator and engine WILL decrease warmup time, but I just don't see it being as important as trying to make a 305 feel like a 350, or trying to keep a larger engine cool with as small a cooling system as possible.

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.
 
opfor2 said:
But he stated that he has a new 195 thermostat, so I don't think it's stuck open...

Dan..
Click to expand...
I had a "new" for 6 months thermostat stick open on me , darn gauge wouldn't get close to thermostat temperature . It would flow slow enough to heat transfer , but would never get hot enough for good heat out the vents . It was like all the old southern California hot rod guys used to do to flathead Fords and put washers in place of the thermostats :xmas:
 
The new rad was in the truck when I got it. The truck ran "hot" when I first got it home, but that was BECAUSE the t-stat wouldn't open!! I ALWAYS put a NEW Heavy duty water pump on my plow trucks. For no other reason other than... because!!! I usually don't run clutch fans. I usually remove them And install a fixed heavy duty fan. Since the plow blocks the air flow to the rad, I use a fixed fan to pull more air. I have NEVER had one run this cold!! It was -3 this am. I let the truck run for awhile and it couldn't even melt the ice on the window!! I am gonna play with it more on thursday. I have the day off. I haven't put the truck on the road yet. But I need too!!! Soon!!
 
bablazer73 said:
The new rad was in the truck when I got it. The truck ran "hot" when I first got it home, but that was BECAUSE the t-stat wouldn't open!! I ALWAYS put a NEW Heavy duty water pump on my plow trucks. For no other reason other than... because!!! I usually don't run clutch fans. I usually remove them And install a fixed heavy duty fan. Since the plow blocks the air flow to the rad, I use a fixed fan to pull more air. I have NEVER had one run this cold!! It was -3 this am. I let the truck run for awhile and it couldn't even melt the ice on the window!! I am gonna play with it more on thursday. I have the day off. I haven't put the truck on the road yet. But I need too!!! Soon!!
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I second trying another thermostat, I have had so many new one stick open, they are not the best quality even the GM ones.
 
stats are cheap, it would be worth the couple bucks to throw a new one in, just to be sure. this thread reminds me, i gotta change the stat on my 91...
 
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.
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Now that I think about it..... The coolant in the block just sits there (within reason) until the block warms up and the thermostat opens allowing fluid to circulate through the cooling system. I would assume neither type of fan would significantly change that time. That is in regard to the first time the thermostat opens, once coolant starts to circulate and the thermostat begins to cycle (open/close open/close), fans would play much more of a role as BTU transfer in the radiator is much more significant than at first startup.

As you stated, air moving through the rad at high speeds is much more than a stock fan can pull (CFM) and there is a difference is volume (delta), but does the fan actually impede it? If the clearance with the shroud was tight and the air could only be moved by the fan blades, logic and physics would say yes, but most manufacturers leave a gap around the edge of the fan and shroud (where pressure is greatest due to the bottle neck effect of the shroud), which is a build in bypass. My bet (could be wrong as never tested), is that at 75 MPH the fan has negligable effect on cooling (good or bad).


Wouldn't hurt to experiment though, but it might be tough trying to find consistent cold weather temps for true cold start tests...
 
Wouldn't hurt to experiment though, but it might be tough trying to find consistent cold weather temps for true cold start tests...
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Well, the beauty of injection is that I can make sure that ambient air temp and engine temp are consistent for both tests through the ECM. Really doesn't matter what ambient temp is, but it will be easier to see the difference the larger the gap between ambient air temp and engine temp.

It's been pretty much settled that an electric fan not under power (or even under power) doesn't impede airflow much (fan will just spin as fast as the incoming air "pushes" it) but with a clutched fan locked, or a non-clutched fan, the air that would turn an electric fan (or non-locked clutch fan) is now working against a fan that is physically coupled to the engine. If the fan can't pull more air than is trying to get through it, then it HAS to be a restriction, no?

I've thought of this before, I'd like to try to measure at least airspeed behind the stock clutched fan and electric fans, but I don't have anything that could do it effectively. Of course, physical diameter of the fan itself is important, but knowing the velocity of the air would be a step towards knowing what kind of CFM the stock clutch fans can pull, which no one seems to know. Going off on a tangent here... :)

If this wasn't significant, you wouldn't see non-locked/non-powered fans of any type spin up with increased airflow through them, nor would there be speed controlled fan off settings in newer vehicle programming IMO. No point in coding that in the PCM if it wasn't an issue of some sort.
 
i currently have a locked up fan clutch, and its 14 degrees right now, takes about 10 minutes of driving to reach 200 degrees, then the cold antifreeze circulates and it drops down a bit. so doesnt sound like its the fan to me.. unless your in like alaska or something...

update: yeah i didnt see this second page of posts, so my post doesnt make much of a help, but 2 of you i believe were interested in how long it takes to get warm anyway, so here ya go...
 
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