1988 e150 with 302...
I have been watching the overflow tank for a couple of weeks now and noticed the antifreeze level was dropping. I already added more antifreeze once a little over the cold level. The tank is say, 6"x6" square and the level seems to be dropping about a 1/4" to a 1/2" each day after having driven the van several miles and it cools overnight..
A couple do times I saw water on top of the radiator under the overflow hose that runs to the overflow tank. The hose was pretty soft almost rotten so I replaced it today. The hose appeared to have a vacuum on it because it was flat this morning when i first checked it
A couple of questions about this..
First, no one local sold radiator overflow tubing so I had to use a piece of vacuum hose, will that hold up?

Second, I am guessing it is loosing about a cup of antifreeze a day, is that a normal amount to go out the overflow after the engine is turned off?

Should the radiator be full to the top when you take the cap off and the engine is cold?

Ihave only been checking every couple of days but now I will check it daily and see if the hose fixed the problem. Occasionally I seemed to smell antifreeze while driving and wondered if it might be the heater core but it is not a constant smell..
Thanks Anna

 

It should go in and out of the overflow tank.

The heat causes expansion and fluid goes out of the radiator into the overflow. When it cools off it creates a vacuum and sucks it back in.

I would say it was probably your overflow hose leaking, but keep an eye on it. Vacuum hose should be fine for the overflow. Most vacuum hose can also be used for windshield washer fluid and coolant.

Did you recently do anything to the van involving the cooling system that could have caused some air pockets to form? It might be that those are slowly working there way out and eventually your coolant level will stop dropping.

Only other thing would be a leak or the engine burning it. If its leaking you should notice a puddle or be able to smell the coolant dripping on the hot engine and evaporating.

If its burning, you should be able to see some white/gray smoke coming out the tailpipe.

 

There should be no appreciable loss of coolant, it is a sealed system.
Check the hose going to the overflow and the overflow tank itself-is it blocked by sediment anywhere, that could explain the vacuum in the hose. Can you remove the hose from the rad, blow into it and get a good stream of bubbles in the overflow tank? If everything ok there, all connections tight, then I would suspect your rad cap has worn out and needs to be replaced

 

Thanks for the reply's.. Yes recently changed the thermostat, upper and lower hose, radiator cap, had the radiator vatted and roded out, and yesterday replaced the overflow hose. I have been driving it for 3 weeks now since the work was completed so there should be no air left in the system.. No odd smoke or smell from the exhaust

This morning the antifreeze level in the overflow tank was above the cold mark. After driving 5 or 6 miles and letting it sit for an hour or so, the antifreeze level was almost up to the hot line on the tank..

BUT I still see antifreeze on top of the radiator right around where the overflow hose connects.. I have seen some hoses held on with a small clamp, but this hose is new and fit very tight. This is a non pressurized overflow system... I guess I should try a small clamp anyway and "another" radiator cap as this one is aftermarket.. IF that is not the problem then it must be the weld where the tube connects to the filler neck I would think.. If it is the weld, maybe the radiator shop can fix it without having to remove the radiator.. That leak is probably the first thing I need to fix before I will know if I am loosing antifreeze anywhere else.

BTW, the radiator cap has a relief handle on it and it is holding pressure so the leak has to be above the lower seal I would guess.

 

How about having someone doing a pressure leakdown test on your system? It's basically an air pump on the radiator cap flange.

It should be evident where it is leaking if it is where antifreeze should be.

Once you are outside the radiator, there is very little pressure in the plumbing to your overflow tank...it's like pushing antifreeze in and out of the tank down a flex drinking straw.

George

 

Good idea George.. I know how to do the pressure test.. Maybe if I go to the parts store and do it right there in the parking lot, they won't make me go through the whole deposit thing on a loaner tool...

I stopped by today and swapped the cap for another one and when pulling the pressure release, I saw antifreeze leaking out around the little fitting on the neck where the rubber overflow tube connects. Since the tubing was on, and pushed all the way up to the neck, I couldn't tell very well the exact spot of the leak. SO it could be the upper flange on the filler neck where the upper seal on the cap seals it. . Right now we are about to have a ice storm down south here so I am done for the day with it... Perhaps the next time I run the van enough to get it up to temp, if I take the rubber line off and plug the connector with something then pull the overflow release, I will be able to see exactly where it is leaking from..

Thinking, when you do a pressure test, doesn't that adapter seal down inside at the bottom of the filler neck flange?

 

I have not done pressure tests but have had them done.

I am guessing that there is an expanding rubber plug on the fitting for the air gauge/pump and that it may seal around the circumference of the neck. Seems to me I have seen them in kits with multi sized plugs(?)

edit--just checked online and they have kits with gauged rubber plugs but many or most also give you some different sized radiator caps--I am guessing those will seat on the bottom of the neck like the factory cap.

If it's gonna leak, it will leak under pressure. And it's easier poking or feeling around on a cold engine.

Good luck...
George

 

1988 is before my time but our fleet of 06-13 vans regularly sit below the designated lines on the coolant reservoir. I pay no attention and instruct drivers to ignore slightly low levels until they get significantly below the "low" mark, like to where there's not much visible in the tank before they bother me about it.

I've found that we can add coolant until we're blue in the face up to the "full" lines and it just pisses out somewhere. As long as we're a few inches above the bottom of the tank and it doesn't move lower over a few hour drive, I'm good.

That said, smelling coolant in the cabin is a major clue. If you're correct on that, you have some heater core replacement work ahead of you.

 

I pressure tested my moms 78 E100 a wile back before replacing all her hoses.. her radiator is the same as mine. I used one like this:
Cooling System/Cap Pressure Tester at National Tool Warehouse
If i remember correctly I didn't need an adapter. It just twisted on like a radiator cap and you pump it up to the max rating on the stock radiator cap, then wait 10 or 15 minutes and see if it leaks down. There is thumb twist on the top of the tester cap where the line goes in, you twist it and it releases the pressure. The adapter in that kit is for testing the radiator cap itself.

Yes the smell in the cabin makes me a bit nervous but I don't seem to smell it coming out the vents and the windshield doesn't fog up like my Lincoln did.. I did do a search after reading your post Delgriffith, and it doesn't seem like such a bad job to replace it if an 88 E350 is the same.
https://www.ford-trucks.com/forums/1...placement.html

My mothers 78 was very easy and only took about an hour. Just had to take the 2 hoses off, f screws holding the blower motor on, unplug the wire connector, and reach under the dash and remove 6 or 7 nuts (that you can plainly see) and the cover with the heater core inside pulled right off from under the hood..

If it is the original then it is 28 years old! It seems like the older heater cores lasted much longer then the newer ones... If I have to replace it, perhaps I'll try to find a oem Ford one...

 

Update: I drove to the shop that cleaned the radiator and they replaced the overflow tube with tubing designed for the radiator. That solved the problem. Don't let the parts store tell you vacuum hose will work because it will split!

 

Whew! Finally an easy fix to a problem! Yeah, I got bit by that on my bride's Explorer. I found some clear vinyl tubing that shows the coolant in the hose and it seals even better than the black rubber.
jim