COOLANT

[teano]

I own a 91 Explorer,4.0,4x4,auto w/AC.
I have been having a coolant leak problem for several weeks.
It started out w/ having to put in about a half gallon every two weeks. I looked an looked but could not find a leak. Then my altenator went up and upon replacing it after i had removed the hose from the aircleaner to the TB I saw antifreeze under the thermostat housing, so I assumed that the thermostat gasket was leaking.I replaced the stat and gasket,upper and lower hose's as well as the heater hoses.
Now it spews antifreeze, from where I dont know... I dbl and triple checked all the hoses and everything I replaced is not leaking. The weep hole on the water pump is dry. the upper parts of the engine is dry also. after taking it out and parking it again Ill see coolant all over the front axel and under the engine.
PLEASE HELP

 

[ERIC]

Drive it, park it, shut the engine off, lift the hood, and patiently stand there and watch for the leak...especially around the radiator cap. If you have a plugged return line to the overflow reservoir, you will get fluid running out at the cap.

If it isn't the cap, you'll still find the leak with this "procedure." Good luck.

Do you have a flushing attachment on the heater hose? If so, pay close attention to that too.

 

[NAVAJOMATT]

Nother option would be to take an old cap drill a hole in the center stick an old tire valve stem in there and pressurize the system with air at about 14 psi you should get a nice solid stream from where the leak is unless there is something in the way in which case you can just follow the water trail........Have a friend who did this with his 93 RX7 the dealer vcould find no leaks but he sure did when he ran this setup. Good luck

 

[ERIC]

An excellent idea, Matt. But remember this technique will not test the radiator cap that was being used, nor will it test the path to the overflow reservoir. And we have seen those two items be a problem in the past. In fact, I had a plugged inlet at the reservoir once, which caused the fluid to push past the cap and dribble down the radiator. This was not visible to a casual exam, but it was losing me just about the same quantity of fluid per week as teano is losing, so it needs to be looked at. This path can also be checked by pulling the tube off the radiator fill inlet and blowing into it....bubbles in the reservoir indicate it's clear...but then ya gotta check the overflow outlet too!!! Yep, even that little place can get a clog.

However, I am going to make up a cap the way you suggested just to have it on hand for testing. Chances are i'll eventually need it.

 

[teano]

Thanks for all of your ideas. I borrowed a stant cooling system pressure tester today, funny thing...it held 17lbs of pressure for 20 mins and no leak.... drove around all day and no leaks.... Then I took my daughters out to their Grandmothers and it started leaking its a#% off. Of course it only leaks at nite when you cant see anything. I crawled under the truck again... coolant is all over the place...
I'll try again tomorrow...

 

[teano]

Well, I found the problem.... It's the intake manifold gasket leaking from the right front corner....
I still don't understand why the pressure check held 17lbs for more than 20mins yesterday... Could be that the gasket was expanding and contracting with the heat of the engine.
Picked up the lower intake set from the local FORD dealer for $27.00 with my discount... Unfortunatly they were out of the valve cover gaskets, so I had to go with an aftermarket set which luckly came with the upper plenum gaskets ($32.00 cork&rubber) that dealer was also out of. Since I dont have proper tools for this kind of job, and for the fact that I threw out my back some how under the truck yesterday, I'm paying one of my neighbors to install them for me. I think he gave me a good deal, as long as I supplied the parts he needs, he will only charge me $200.00.

Thanks for your suggestions,
TEANO