92 F-150 cooling system question

As the engine gets hot, the system pressurizes, and coolant is pushed out of the radiator and into the recovery bottle. As the system cools when the motor has been turned off, coolant is sucked out of the recovery bottle and back into the radiator. The recovery bottle will have a hose that leads overboard so that in the event the recovery bottle over flows, the extra coolant will be be spit out somewhere where it won't hurt anything.

A typical arrangement will be a hose that goes from the radiator cap/neck to the bottom of the recovery bottle. Coolant goes back and forth from the bottle and the radiator from the bottom of the bottle. If the bottle overfills, then the extra coolant will flow overboard through a hose connected at the top of the bottle. Some systems have a hose inside the bottle that reaches to the bottom, and this hose is connected in some manner to the radiator. In a system like this, the hose may get an air bubble inside, but this is not a problem because when the radiator gets hot, the air is pushed out as the coolant is pushed into the bottle, then when the motor is switched off and cools, the coolant in the recovery bottle will be sucked back into the radiator.

I can't think of the function of a tee in the line at the top of the radiator. Pressure builds in the radiator because of the cap and the sealing surface (rubber ring) on the bottom of the cap. The radiator has to pressurize to a degree greater than the spring rate on the cap in order to push fluid into the recovery bottle.

yes I am following you and I agree that that is what I expect. the one fitting is actually below the sealing surface and the other is above. I would expect the one above to be for the bottle. I looked at my friend's truck today and that is how it is plumbed, but he doesn't have the lower fitting or the tee in the heater hose. I'm just going to assume that this is the issue and swap the hoses (to put the one for the bottle above the sealing surface) and see what happens.

nate

First, there are heater hoses and there are other hoses. The hose connected to the fittings I am talking about are not heater hoses, they are much smaller, more along the lines of a fuel hose for size.

On my '95 Bronco (5.8L V8), there is a hose at the filler neck that goes directly to the bottom of the recovery tank. There is another "hose" below that on the tank of the radiator that leads to the intake manifold, and is not part of the systems I am trying to describe to you. On my Bronco, the hose to the recovery tank is right at the sealing surface. When the pressure cap spring is pushed up by expanding coolant, the result is a flow into the hose that goes to the recovery bottle. There is another hose that is connected in the neck of the filler hole, but this hose is connected to a hard pipe that goes to the intake manifold, and looks like it will heat the intake manifold.

The hose to the recovery bottle is the first hose right at the radiator cap.

If you connect the recovery tank hose that way, where does the remaing hose go?

You should have a hose from the throttle body to the radiator neck below the cap seal such the it returns coolant to the pressurized side of the system. The hose to the bottle is above the seal to catch expansion. The hose from the throttle body helps reduce coking and prevents icing of the throttle body as well as keeping air purged from the engine.

Lugnut

Here, if a pic is worth a thousand words, I just wrote you a short story.

y'see what I meant now? Are the two hoses simply reversed (like someone replaced the rad. and didn't hook it back up right) or is there some serious misrouting going on here?

thanks,

nate

Yes, that's backwards.

Put the top hose on the next nipple down, and move the hose on that nipple to the top.

The hoses are connected to the wrong nipples.

My Bronco hasn't got the tee fitting like you have, but I have the same hoses otherwise. On my truck, the hose to the tee fitting that you have goes directly to the intake manifold.

You are indeed venting the radiator to the outside world the way the hoses are connected right now.

Looking at your pics. Don't know why I missed the 300 engine part. I responded based on 5.0/5.8L engine on throttle body part. Your hoses are reversed in their attachment which will prevent pressurizing the system and cause it to overheat under some conditions. Reverse the hoses so the one from the hose tee goes to the bottom connection and make sure the rad cap is holding pressure. You should see an improvement.

Lugnut

Yes, the hoses are reversed.

Well, I did it, and drove it a short distance this AM to a job site just to see if it was better. It's still overflowing on heat soak - apparently the zip tie I used in lieu of a mini clamp on the overflow bottle hose is not sufficient to prevent leakage :(

The good news is that the system apparently did pressurize, with a lack of white smoke, and the amount of overflow was minimal.

nate

If the system has passed a pressure test and the rad is clean, you may want to consider replacing the thermostat and water pump. If the system treatment - coolant - has not been maintained for corrosion prevention, it is possible that the water pump impellar is rusted away to nothing and not pumping water. Another thing that can happen along the way in older vehicle is installing the wrong rotation water pump. It will work but, not nearly as well as it should. Keep in mind that is a rather long engine and needs a good pump to push coolant all the way back. Also, it may not have all the air purged from the system causing it to burp for a couple of heat cycles.

Lugnut

You probably need a new cap.

The Overflow hose can be connected with a zip tie, although there are better ways. This hose is not pressurized, and any good mechanical fit is all that is really needed.

The hose to the intake manifold (and all of the other places it might go) must be connected with a hose clamp. This is a pressurized fitting, and a zip tie is not nearly strong enough.

that's where it was leaking... apparently the two nipples are slightly different sizes, and the hose was a little stretched out from being pushed on the wrong nipple. A clamp was cheaper than a roll of new hose (or worse yet, the correct molded hose from the dealer) so that's what I did. I felt underneath the bottle and what felt like the remains of an old Oetiker clamp disintegrated in my hands so I put a new mini clamp on that too just for insurance.

right, I understood that bit...

I think I'm ready for this weekend's haul, we'll see if it's all good then. I checked the level again this AM and it's back down to where I filled it yesterday, so it's apparently both pushing coolant out into the bottle and sucking it back in. life is good. Spent the afternoon dunging out the interior, now it's almost presentable inside. Painted the wiper arms, too, makes a big difference to the appearance of the truck (yes, semi-gloss black, not yellow or fluorescent orange ) I don't know why but that seems to be the first part that weathers on any older vehicle.

Getting somewhat off topic, I've been told that the E4OD has a converter drain plug, true? I have half a case of Red Line D4 that I was planning on using for a trans fluid change, but I'm guessing if I drain the converter too that it won't be near enough, yes?

nate

that is correct. if you drain the converter and the pan, you'll need 17 with a 4x4 and 14.5 with a 2wd.

Last update... moved a load of yard debris to the dump on Saturday, and then another load of car parts on Sunday. No pukage. If it didn't puke then, it's not going to, because merely standing in the sun was enough to cause massive sweating (to the point where it was dripping off my nose, chin, eyebrows, etc.) on Sunday. good stuff... love that functional air conditioning, too...

nate