-I bow to your superior experience level. You have worked on many more than I have. It just seems that around here the first thing that people always suggest is the supposedly "frequent occurrence" of an airlock. I never had one but then I did not put thermostats in upside down. I have seen them installed upside down but the effect is immediately apparent after the person does it and it does not matter whether the radiator cap is on or off as in this case.

I have only seen the one failed impeller. Much more common is a failed seal and bearing long before they get to the rotted impeller stage. Of course with 20 years you may have seen more of the **** poor quality new replacement parts around nowadays that would explain the loose impellers.

I have seen a number of the debris between the radiator and condenser problems but that does not stop water circulation, -just airflow, and again will not make the difference if the cap is on or off like the original question but more probably just the opposite.

In fact my 1991 Explorer had a history of AC problems and hot running that had been to the shop many times to repair by the PO with those nice "no trouble found" designations. When I inspected the vehicle it took about one minute to see the source of that problem. It did of course lower the price of said vehicle considerably. I did spend a few hours that afternoon picking the sand grains out of the condenser fins that blocked about 25-50% of the space and re-combing them. Then removing the grass clippings that filled the bottom half of the space between the condenser and radiator. The AC worked quite well after that and the engine ran cool as a cucumber. The PO liked to follow sand trucks out on the highway... It did explain the condition of the windshield etc which also lowered the price.

Note- Locksmith lock pick tools work extremely well to pull sand grains out from between the fins of a condenser or radiator.

 

CG,

Could you define “boil over”. What exactly do you see happening?

<OWith the cap on, is coolant coming out of the overflow, if so when (running, idle, off)?
..................And if so……….a little bit or is it blasting out like a steam engine?

When you remove the cap does the coolant kind of roll out or does it explode?

If you filled the rad to no closer than an 1 ½ “ less than full, put on a new cap, drive the rig to operating temp then just let it set …….what happens?

<O

 

Torque, the best one I ever had I think was a saab with twin electric fans, we got it from a body shop that had just repaired the front end. We couldn't charge the AC cause the high side would go right out of site with half a charge. After screwing around with it all day I finally condemned the condenser figuring it had to have an internal problem, I pulled it out cut the the loops off both ends of the tubes so I could look straight threw it and the damn thing was spotless. Put in a new condenser, fired it up and it did the same thing. So I'm leaning over the front of the car totally discusted with myself not being able to figure it out and I've got my cigarette in my hand leaning on the rad support and the smoke coming of the cig is going in the right fan and out the left fan, the body shop had wired one of the fans backwards.

 

well lets see...as far as overflow bottle is concerned i just thought there must have been one at one time. it has that little metal tube on the neck of the radiator fill that you attach a tube too. boiling over means its boiling just like you would boil a pan of water on the stove. if the cap is on it shoots out the overflow tube. no steam just hot as heck water/coolent. if i pop the cap off the water is boiling over like a too full pan of water on the stove. it does it with the truck on or off. obviously when its turned off the water cools down. the one time i let it run for probably 15 to 20 minutes, idling with no rad cap, it didnt boil at all and the temp gauge was normal (well, its always normal, and im pretty sure its working correctly) but when i shut if off it burp/boiled a pretty large amount of water out. it may have been more of a burp though. the hood was hindering my view. i cant mess with it till this weekend. when i leave for work its dark and when i get home its dark. i dont really wanna play with hot water in the dark =)

 

No hurry........Hot water BAD........Just tryin' to help ......again......

If you filled the rad to no closer than an 1 ½ “ less than full, put on a new cap, drive the rig to operating temp then dont do anything, just let it set …….what happens?

 

They say that most "discoveries" are made by accident. That has been my experience almost 100% of the time! The fact that you are able to use that nice high performance PC is in part due to an accidental discovery of mine. It seems to happen that way all the time.

 

I read somewhere that anti-freeze expands about 30% more than water when hot...and that is why the expansion tank is on new cars.You run the tank or leave room in the radiator for expansion.How much anti freeze are you running?What cap did you put on? The old style cap held everything tight to a point.The new ones are designed to bleed back and forth. Try just water and see what happens.(I use distilled water...)The higher the AF mix, the higher the expansion .You really only need enough to keep from freezing and to protect all the different metals in the system from electralisis.Water has a lower boiling temp. than anti-freeze,but did you know that water exchanges heat FASTER? I read a lot of stuff when I can't sleep...and my truck had a heat problem once, hence the reading subject.

 

Running a sealed system with an overflow tank also lowers the amount of corrosive oxygen entering the system. A special cap with dual seals is required for an overflow tank system. Distilled water is the preferred mixing agent. Straight water with a rust inhibitor is used on some diesel engines. A 45/55% mix of AF and water is listed as the OEM recommended minimum level of protection. When you consider Ford could have saved a huge bundle of $$$ using a 40/60 mix but they did not tells the story! A 50/50 mix is preferred. Some extremely cold areas use a different mix.

 

ok now my heads starting to spin. so you guys are saying dont run an overflow bottle? dont use alot of antifreeze. dont fill to the top because with expansion it will just shoot out the overflow tube. ive got two more days till the weekend. im going to poke the hole in the thermostat. i will make sure the radiator isnt filled to the top. i wont put an overflow on it (for now). when i go to the part store what cap should i ask for? lol..this is getting complicated but im learning alot...so thanks

 

I would go with a 13 lb cap, as far as recovery or not, it's up to you. Personally I like the recovery system because you can keep the rad full to the top and it's not as apt to spit if you slightly overfill it.

You can use the recovery cap on a non recovery system so go with that incase you want to add the bottle later.

 

My 78 F250 did not run an overflow bottle. Just a hose out the bottom of the truck. I can't help you with a radiator cap number for an overflow system. However an overflow bottle system cap will work on either system. I think 50/50 AF mix will work anywhere in the US.

 

your cap should be a prestone "X"29. But I want the credit when this 6 dollar fix works

 

The early 80's truck came with a 2 section plastic container.
One for expansion/recovery of the cooling system & one for the Windshield Washer Fluid.

That's what I am putting on my truck this year (not that I need it)



Once you get the recovery bottle get the Motorcraft RS-50 cap.


*Note: I want the credit when he figures out he has filled the rad too full

 

Dennis, do they even use wiper fluid up there in the frozen northland? Doesn't it just make tiny stalagmite icicles if/when it squirts out? -hehe

 

Yes but NOT Today

It hit + 7*C .....melting snow & ice all over the province.