1994 F150 2x4 4.9L I6 5 speed, no A/C

first problem was that the engine temp gauge wasn't registering as warm as normal.. Used to get into the NOR zone, but was barely getting past into the first section of the gauge.

Also, when the truck was off, the gauge actually moved up into the normal zone. It would zero out again, as soon as I started the truck (when cold).

Read the blinkin' dash code - think it was a 32.. Not sure if this has any bearing on temp gauge. EVP low voltage ?

yesterday, put in a new thermostat (failsafe), replaced coolant, then the temp gauge showed somewhat warmer, but still not into the NOR zone.

Went out today, and the sonofabitch, ran well into the warm zone (the L of Normal), then blew a leak at the bottom hose of the rad. I think it was just a loose clamp on the hose. When I put heater on full heat and fan, to see if temp would go down, it just blew cold air.

Truck is sitting in driveway, waiting for me to get off work, so I can play with it again.

I'm going to refill with dexcool coolant, bleed the air, check for leak at bottom rad hose. And see what happens. Any other ideas or things I should look for/replace ?

If someone could confirm the following, mucho appreciato..

1. when installing new thermo - the gasket goes onto the engine, then the thermo goes onto/into the removed housing, with the longer spring end going into the engine opening.

2. where is the single wire temp gauge sensor on this engine ? (single red/white wire)

3. does the code 32 (EVP low voltage) have anything to do with my temp gauge problem ?

4. which way does water flow when the thermo is closed, and then when it opens ?

5. is the valve gate that sends hot water through the heater core hoses, electronic or mechanical ? (I'm wondering why I wasn't getting any hot air from the heater)

Answer what you can as you see relevant.

thanks to all mechs.

 

Sounds like you've got a plugged radiator, but check your temp sender first. It should be right next to your water neck for your thermostat. Get a test light and hook it ot the hot wire for the temp sender. Ground it. If your gauge pegs hot, then it's good, and your sender is crap. If the gauge dosn't move, then it probably needs replaced. You'll know your on the hot side wire if you get a light when you ground the test light. The next thing is to do a flow test on your radiator. Fords are notorious for popping emission lights such as your 32. Spring goes down into the block. We glue the gasket to the water neck with Super Weather Strip Adhesive(monkey snot) from napa, never had a leak that way. Usually the t-stat has a recess in the block, but I've had them with the recess in the neck too.

 

Were you running dexcool before? When did you switch and was the cooling system properly flushed. It's funny stuff that doesn't mix well with others. Sludging is a common problem which could point towards plugged radiator.

On a lighter note, it may have been just the stuck thermostat. After replacing the thermostat, did you burp the cooling system completely? Air in the system will keep coolant from flowing to the heater core.

Hope that helps.

 

You shouldn't use Dexcool, the engine wasn't designed to use it. Us regular Prestone green. Only use Dexcool if it came from the factory with it.

Why you ask? Dexcool needs to completely cover everything in order to protect it (ie - there can be no air in the system) Our engines weren't designed to get all the air out, there are no bleed off points. There will always be "some" air in our systems and Dexcool will sludge up because of it. Also Dexcool required an additive be put in yearly, it just not worth the extra hassle and expense. Leave Decool to the GM boys....

my $.02
Tim

 

Firetruck..

looks like the coolant temp sensor is bad. When engine/cooling system is cold I get a 5.3k ohms reading across the sensor contacts, and after running it for 15 minutes (hot), I only get a 5.36k reading. I'm going to replace the sensor.

When speaking with Ford, they advised to use same type of coolant the truck had in it when it was sold new.. Being a 1994, I guess that means the good old green stuff..

But I've already put the Texaco Long life (Dexcool compatible) in the system.

Should I leave it in, or flush it out (again), and re-fill with green ? Is anyone else using orange without problems ?

 

1994 4.9l I6 No A/C

1. The coolant temp gauge sensor is the two wire found on the housing
for the thermostat, but where is the single wire sending unit ? Manual says somewhere below the intake manifold (the left side if yor standing in front of the truck with the hood up, looking at the engine)

2. my temp gauge actually moves up into the NOR area when I turn the truck off.. When I turn it on, it goes to the left and stays there ?

3. Not getting the normal sauna level heat from my cab heater.. Is this indicative of air in the cooling system ?

 

I think that your temperature sensor is located on the right rear of the engine's cylinder head.

Lou Braun

 

arghh..

I did the gauge test by removing contact wire from coolant temp sender, grounding it out - the dash temp gauge needle moved to far right.. Looks like the gauge is fine.

Drained the coolant (again), and replaced the coolant temp sender with a new one.. filled the system back up using method described to ensure no air, put the wire back on the sender, and NOTTA ! The gauge still doesn't budge.

Interestingly, the gauge does move up to the NORmal area when I turn the engine off. Almost like it works when the engine is off ? Is there anyway the polarity on a single point connection can be reversed ?

??????

 

I'm having a similar problem (95 302)after replacing t-stat and water pump. My temp gauge barely moves enough to reach the N of normal. I have good heat and I see the gauge gradually move from cold as engine warms. I even see when the t-stat opens b/c the temp drops and comes back up. But never past the N of normal. Also replaced gauge sending unit with no change. All was normal before the pump and stat change. What is up?

 

update - reviewed all that I had done in troubleshooting my original problem, and repeated. When I got to the t-stat, I removed it and found that it had stuck in the open position - it was brand new, from CdnTire. How'd that happen ? Replaced it with a Ford OEM, (about the same price), and things are all back to normal - nice hot heat in cab, and the temp gauge is working like a charm.. All is good..

Interesting (to me, anyway) that the temp gauge didn;t even budge, even after hours of driving, when/with the t-stat wide open. This made me believe the temp sender was faulty (which it probably wasn't), because the short-out test on the gauge indicated the gauge worked fine.

Does anyone need a working/used temp gauge sender ?