my(86) bronco ii wants to overheat. Ive replaced the waterpump, thermostat(190), fan clutch. it holds pressure no leaks. it seems the harder i run the engine(highway only) the temp gauge rises. the real guestion is, does everyones fluctuate this much? mine nearly gets to the red and only cools back down at sloweer speeds. mainly it stays in the normal range. this fluctuation makes me nervous. Its not really even hot yet here in missouri. my gas mileage is about 16mpg is this normal? I only ask becuse my timing on the engine is guestionable Ive set it 10 degrees out with that mushroom plug out. what makes me think its wrong is that its a wee bit hesitant at starting. some times it takes two tries, also if it is causing the engine to run hot. Im currently running flush threw the radiator. Prestone brand for neglected engines. maybe the radiator just cant keep up?

 

I started having overheating problems when I modded mine. I went to an Explorer radiator (3 times thicker and bolts right in). It cost me $150 brand new. If you can afford one with aluminum tanks they will cool better than plastic. Even the fan shroud bolts up to it. It added a whole extra gallon of coolant capacity and even down here in the hot southwest I don't have overheating problems any more. I don't know if the factory fan would be a little too close or not 'cause I got a flex fan years ago. A flex fan might help you too. Only other thing you'll have to get is an Explorer lower rad hose. I run a 165 'stat. It also helps keep it cool in summer. Yeah I know it might run a little rich because the computer might think it's not fully warmed up yet but it runs close to 180 or so in the summer anyway. It still blows warm air in the winter too so no problems there. I'd at least consider going to a 180 'stat.

Sorry but I can't comment on your performance/mileage issues. I used to get 20mpg stock but now only 13 or so hiway but I usually trailer it. I get 10-12 on long trails and consider that OK with my mods. What mushroom plug are you talking about?

 

the mushroom plug allows the computer to advance the timing 10' from what ive read, and it does. mine comes out of a wiring hareness in front of the distributer. did your temp fluctuate alot(before)? i wunder how hot its getting when the gauge is in the red maybe 220?

 

What you may also have is an air pocket in the cooling system. When you drain and refill the system, fill it as far as you can, leave the radiator cap off, turn the heat all the way up, then start the engine and let it warm up. Watch the radiator fill and you will notice that it will start sucking down... add coolant as this happens, and repeat until it will not take any more coolant. Put the radiator cap back on, then drive it around for a little bit and watch your temp gauge to see if it is still "running hot". You may also have excessive buildup on your temp sensor / sender. I would not go with anything lower than a 180 degree thermostat unless you put a higher capacity radiator in there, preferrably one out of an older Ranger (copper/brass, 3-row -- don't have the part # handy, but you can order one from www.lmctruck.com if you can't find a usable one in a junkyard) or an aftermarket all-aluminum one. Explorer radiators will work, but you might as well snag the water outlet off the engine block (I don't recall it being an issue to swap the water outlets, I'll have to double-check) and use an explorer top and bottom radiator hose if you do that swap, IMO.

I had a similar situation until I fixed some leaks, replaced the radiator cap and flushed and refilled my cooling system. Hope this helps some.

 

thanks for the info everyone. Im trying the easy fix first. flushing aand such. It seems to me that if this radiator came stock it should work as intended. did they intend for the temp. to flucuate? I f it doesnt overheat it must be alright. the gauge on mine might be sensetive. theere are no numbers on mine but the thing has a very large quadrent that reads (NORMAL) sometimes mine reaches the (N). I wonder if they (engineers) realy entended fluctuation so exstreme.

 

The early brass 3 row radiator has a different mounting system that the others. If your BII has brackets that bolt from the top down in to the core support and the brackets have a "C" with a rubber liner that goes over the top of the tanks to hold it in the early brass 3 core will work. If your radiator has bolts that go from the engine compartment forward into the core support then the larger 2 core aluminum 4.0 radiator is the up grade to use.

Others have gone with an after market temp gauge to find out how hot the engine is really getting. As some say the problem can be with the BII gauges. On my 89 I could never run the AC in Denver in the summer when I went to Colorado to wheel. Just not enough air in bumper to bumper traffic.

Try using a hose to flush the exterior of the radiator from the back. Could be you have a lot of bugs and stuff that is restricting air flow through the radiator. But you might just be beating a dead horse trying to get that old thin one core radiator to cool the engine.

10 degrees is correct on the timing with the spout (mushroom plug) removed. Then the computer should be able to advance and retard the timing enough to keep it from pinging with the plug replaced. If it is I would suspect the computer is not able to adjust the timming for some reason. I'd first remove the spout and check the timing again and if it is correct, replace the spout and check for engine advance retard through the rpm range.

 

wow, what an amazing amount of knowledge everyone has. you all must have been with your trucks a very long time.
my history of my bII is that its set in a field for about 4 years. which is or has caused alot of its problems. The funniest thing that i found is that a valve rod on the #1 cylinder had popped out, unharmed (very wierd). Does anyone think a lifter colapsing could cause this? because im affraid with the temp getting hot, it causes my lifter rods to knock. also the oil flow under the valve cover is very minimal. the heavy oil slows flow, but the light oil causes tapping. If my valves are adjusted wrong, could it cause extra heat in engine?
one more thing I gave someone a jump over the weekend and it messed my computer up. at first the high pressure fuel pump wasnt working. Pinned it down to the relay. I got a new relay and still did not work. I tested relays and found the correct voltage going threw the relay, but not enough amps to activate the switch. My solution is to ground one wire on the relay instead of having to pull a jumper wire in and out. Im wondering if this will or could really ruin my CPU. right now it causes my rpm gauge to read about an average of 500 to hi. also im wondering if the computer regulates the pump some how? mine is on all the time now when the key is on.

 

Man oh man are these things hard to figure out. Even worse on a board like this when you can't look at stuff. I'm lost on electrical problems. So I'll leave that part to someone else. Sounds to me like you have a tired old truck.

Good luck.

 

Really its a strong runner i might think it has 180,000 I saw it has alot of potential, the enterior cleaned up really nice and only one small rust hole on front drivers rear quarter panel. At first I was hoping the motor would just blow, so I could put a different motor in it. but of all the crap ive put it threw it seems to be bullet proof. no oil burning and as clean as a whistle. toot... toot.

 

Man I don't know what to tell you on the fuel pump problem. I've replaced mine when it went out but that's it. When I went to the Sploder radiator I didn't swap the water outlet or upper hose. The new rad works with the factory 2.9 outlet and 2.9 upper hose. You just need to go with a Sploder lower rad hose. That's it.

A pushrod falling out could very well indicate a collapsed lifter. Bad news is on the 2.9 you can't replace lifters without removing the heads first. If you go as far as replacing the lifter, do them all. More are sure to go soon. I don't think having a slightly loose pushrod would generate much extra heat if any. But if your exhaust pushrod popped out, who knows how that would affect things - not being able to evacuate the cylinder after the power stroke - if the cylinder even functioned at all. Seems like it could mess things up and cause overheating and hot gasses to mix with incoming fuel in the intake manifold. NOT good. You would have a dead cylinder if the intake pushrod popped out.

 

well yes the intake one was popped out. I forfot to mention I put it back in and the truck runs fine. I just want it to be right the problem is its getting to hot I think. I guess i will find out this weekend just how hot I can get it. If it gets to hot I can drive it into the lake. meow..