So, since buying the truck ('89 302 4x4) in Aug, I have been plagued with numerous drivability issues....ranging from crud in the fuel system that plugged the filter and 2 injectors, many vacuum leaks, loppy idle when cold and most recently, I discovered the knock sensor was unplugged. I am happy to say I have sorted the majority of these issues with the assistance from this board.
I have noticed that the PO installed many parts 'oversize', like for instance, the alternator. It is as big as a soccer ball!! The truck must have been geared up as an off roader at on time (although there is no indication of any aftermarket light wiring harnesses).

Since the weather turned cold, I noticed the dash temp gauge would not get very hot. The temp in the cab would barely get warm enough to defog the windshield. Yesterday I changed the t-stat with an OEM 195er. The problem persists. My buddy has a '92 Bronco plow truck, which I peeked under the hood to see if I had the serp belt routed properly around the water pump. I just wanted to confirm if I had mine turning the right direction. I did, but that is when I noticed how small his radiator is. Mine is a 3 core, and it is huge! After driving it for 45 mins, the bottom hose is still cold to the touch. I cut a piece of cardboard and slippeded it in front of the rad and it still does not come up to temp!! I have never seen a radiator work so well! The truck has always ran extremely rich, and I believe this to be the primary cause....the engine can't get up to temp and the EEC thinks it's cold and fires more fuel in.
I am not overly concerned, but I thought I would toss this out to see if there has been any BTDT's or possible solutions (other than the obvious replacing the radiator).
BTW, the water pump is pumping well, good circulation visable when the t-stat is open and good flow through the heater hoses.

Dan

 

are you sure the new thermostat is opening and closing? If so, cover some more radiator (you can always slip it back out if it gets too hot). we've got about 25 fahrenheit (probably barbeque weather for you) and mine warms up slow.

Good Luck.

Dave

 

If your thermostat opens and you are getting flow then the engine is operating at 190-200 degrees. No heat in the cab is a blower or heater core issue, the core will clog up over time, a simple fix is to pull off the heater hoses at the firewall and force water through the core from a garden hose. If this doesn't cure the heat problem pull the core access cover off(in behind the glove box), and make sure the diverter doors are operating properly when the controls are operated. Finally, the dash temp gauge has it's own sensor in the drivers side lower intake towards the front, it's small about the size of a dime and a single wire pushes on a stud sticking out the top. Corrosion here will result in a low reading, and sometimes the sensor just needs replacing.

 

is your top rad. hose warm or hot after you make a trip or has been running for a while. if the bottom on is cold that isnt going to tell you if the t-stat is working or not. If the top one is hot then your t-stat is working properly then you need to check your heater core.

Is your fan blowing alot of air when on high. check this with your bubbies bronco

 

Thanks for the replies.
I took the truck for a 15 mile spin at highway speeds this afternoon and the gauge finally climbed to read between the N and O in 'normal". After I left the highway, the temp dropped somewhat but still maintained temps just below the N. After getting home, the cooling system finally burped itself, as both the top and bottom hoses were hot and hard, indicating the system was fully pressurized. I suspect it was airlocked after the t-stat change, even though I replaced about 3 quarts of coolant (same as what came out) yesterday. Still doesn't explain why I never had heat to start with?!
I still do not have decent heat in the cab. I have verified that the mixing flap is moving, to say when the glove box is removed and I slide the lever, the the arm moves. I can hear it come hard against the stops in both directions, so in my simple mind, that indicates to me that all is ok there. I have all 4 speeds on the blower. Incidently, when the truck is up on heat, the faster the fan speed, the cooler the air becomes......I think the next move is to flush the heater core, which I'll do soon. The PO installed one of those flushing kits on the heater hoses, so it should be easy to do.
Will report when I get that far.

Cheers, Out.

Dan

 

Glad to hear it bud...Trade ya rads.....Later On

JR

 

You can't really go by the sound of the blend door hitting the stop.
I had that sound in mine too, but when I pulled the heater core cover to replace the core, I found it was really hitting a long deck screw that had fallen down thru the defrost vent. The door was open just a little, but a little cold air really knocks down the output of the heater.
Changing the core was really easy, fast, and cheap. If you think it needs a new one, don't put off doing it or you will feel like kicking yourself latter.
Good luck Frank

 

pull core and use the old eyeballs to see what is what.

 

Yea make sure you burp that cooling system every time you open it up. My bronco is always in between the N and O on NORMAL and when i first bought it i thought something was wrong. Maby it is a sensor? Ended up thinking it was my thermostat and turning a easy 5 minute job into a 4 month job and still waiting for a lower intake in the mail LOL Use anti seize But thats a whole different can of worms

 

mine always runs about the N but then again I have the lower temp t-stat but heater still works great

 

Again, thanks for the replies.

Well, I have heat in the cab now. I decided to blow (about 30-40 psi) through the heater core, vice flushing, as it was -15C this morning and I didn't want to freeze my a$$ off doing that. I captured as much coolant as I could and it was pretty chunky..no smoking guns though. I decided to re-check the mixing flap and it seemed to operate OK, but I opened up the air box anyway, to have a look. Again nothing obvious, no mouse nests or dried up snake skins!! The core, while not looking very new, was in good shape visably....I have seen worse. So I buttoned it back up, adjusted the cable, reconnected the heater hoses, and bam, I had heat. Not sure what I did, but the heat is more what I would expect. I'll wait to really jump up and down until later tonite or tomorrow morning when it is good and cold...I'll see what it will do then.

BTW, I have a 4 core aluminium radiator in the truck!! I cut a piece of cardboard which completely covers the entire face of the rad to allow the poor old girl to heat up. Still never gets hotter than the N in normal. I can't think why someone would have installed it in a 302 4X4. Anybody know what radiator the diesels run?

Dan

 

Your large rad is a good thing. better than not enough capacity. On my 96 there was a super cool option with AC (4 core). The coolant capacity difference is around 3 liters more than standard. strangely enough the 302 has a little more capacity than the 351. Not sure if thats what you have, or if it was available in that year. maybe you just have a different rad.

 

good you have some heat.

could be towing package radiator.

 

Thought I had a 4 tube radiator, until I tried to order a new one and found only 1 and 2 tubes are available. Ask about it at a radiator shop. Guy showed me one without tanks. The tubes are about 1 inch wide. I was used to older style radiator with 1/2 wide tubes. I actually have a new 2 tube radiator and it is about 2.5 inches thick. A 4 tube would be close to 5 inches thick ( ya know about 1/2 the length of your manhood) and that is one hell of a radiator, and would not fit in a 4.9 liter engine truck.
Frank

 

The replacement radiator for my truck with the super cool option is a 4 core 27.5 x 18.5 at only 2 5/8s thick. Its also more than twice the price of the regular rad.