I am noticing coolant missing from my 1993 Explorer without any signs as to where it is going. Approximately a quart per year is lost. There is no weeping at the water pump that I have noticed with 90,000 miles on the original pump. My oil is not milky from moisture, nor have I noticed any other problems. Please Share! Joe

 

A quart per year isn't too bad.
One common place to loose coolant (and/or oil) is through the lower intake manifold gasket. The bolts come loose, allowing it to leak either internally or externally. It's so common, I make a practice of periodically tightening those bolts as preventive maintenance.

 

Thanks! I am from the old school/technology. You use it or lose it and use it usually means problems.

 

I had a leak in my radiator, up high and out of sight. I could smell antifreeze, but no drips etc. I didn't loose much fluid, but what little I did loose ran down the radiator and vaporized from the heat and fan action...a very small leak, but a leak.

Maybe you can have someone pressure test your system and use the soapy water trick to find the bubbles? Or see how long it holds the pressure.

 

my head gasket leaked out the exhaust didnt go in the oil but after a while it got worse and you could see it through the exhaust clouds of white smoke grew bigger and bigger. and if your heater core has a leak in it you may not notice either

 

4.0 has Alum. heads very prone to warping and cracking if every over heated. Yours might be just loose head bolts. Don't let it go to long. Critical to use a torque wrench and tighten the head bolts to proper torque.

 

Since my initial post (very bottom) I have lost more coolant and recalled or noticed the following related to questions.

1. I have a coolant or hot coolant smell in my garage “After Some Trips Not All”. The smell comes from the engine area but there are no signs of steam or leaking coolant. Would the loose intake bolts allow this smell? Where would signs of loose intake bolts most likely show? Are the bolts easily accessed? I have the torque sequence and specs in my Haynes Manuel plus I have torque wrenches. How often do you torque the bolts? Do you find them very loose?

2. I feel the coolant is possibly moving down to a certain level and holding. This could mean a high pin-hole in the radiator that soap should detect, Right? Are there other possibilities of a high leak or areas that I should look for if the coolant is holding at a certain level? This came to mind when I noticed the coolant is always in sight and needs about the same amount each time. Which is probably more than the quart per year that I initially reported but not over 2 – 3 quarts per year.

3. Last, the loss is erratic or related to certain driving. I might check the coolant for a month w/o any changes in basically the same Hot Texas Temperature. Then it seems to suddenly drop but I am not tracking highway vs in town driving. Please Share Again, Joe


Initial Post:
I am noticing coolant missing from my 1993 Explorer without any signs as to where it is going. Approximately a quart per year is lost. There is no weeping at the water pump that I have noticed with 90,000 miles on the original pump. My oil is not milky from moisture, nor have I noticed any other problems. Please Share! Joe

 

The highest pressure is seen in the first few minutes the engines is cut off. If you do not find a leak under hood or underneath the engine, then most likely it is leaking across the head gasket and evaporizing in the exhaust.

 

I had a similar problem, on my 96 and it turned out to be the heater control by-pass valve. Never saw a leak or puddles until I was jump starting my other truck and happened to catch a drip comming from the bottom of the valve. Check it out.

 

I have a 97 and had a similar problem, slow loss of coolant with no signs as to where it was going. I checked the t-stat housing bolts, they were OK; noticed a drip on the heater control valve, replaced it; but still lost coolant. Slowly but surely I developed the telltale fog from the tailpipe, heavy coolant smell. Last weekend I tightened the lower intake bolts and that seems to have stopped the fog and there's no smell. The coolant level has been steady so I have my fingers crossed.

 

Vicv, Your troubleshooting was along the same lines that I have planned.

1. With the strong coolant smell in my garage I started looking for leaks. Mainly after seeing the work of getting to the intake bolts and not seeing any sign of leaks on the intake. Will I see any sign on the intake leaks and were the bolts noticeably loose? I noticed one sign of coolant close to the thermostat housing but not directly related yet (a good engine cleaning is needed to remove the old residue). I did replace the thermostat about 5 years ago. I still have factory hose clamps and my sign of a leak is on the front and top of the engine without getting a drip but sign of residue.

2. The dealer replaced the intake gaskets about 5 years ago looking for an oil leak that was the rear main that was never solved. The intake gaskets appeared to be rubber impregnated or rubber coated which I felt would seal good without constant torquing. I am hearing and feeling this is not the case, nor am I seeing it recommended as schedule maintenance. My intake area is dusty from the lack of cleaning but no signs of blow-by or a leak.

All recommendations are welcomed and when the rain allows, I'll get busy.
Thanks, Joe

 

A pressure tester is the easiest way to find a leak. Some parts stores will rent a pressure tester.

AFAIK the 91-99 4.0L OHV engine has IRON heads but they are prone to head gasket failure. Annual use of a stop leak will help seal small leaks. According to my books the aluminum head OHC 4.0L was introduced in MY1997.

A quart of coolant per year is easily lost thru evaporation.

 

Is it possible to get to all of the lower intake bolts on the 93 Explorer with the 4.0L V6 engine without removing the upper intake manifold? I have completely built a number of engines. Mainly before the fuel injection and turbo systems which makes this look a little Fuzzy. This is in my search for coolant missing from my 1993 Explorer without any signs as to where it’s going. I'll also check to see if any smell of coolant is coming from the tailpipe. Joe

 

I do my lower intake bolts with the upper intake in place. The first time I did it, it took a while figuring out how to get a socket on some of those bolts (driver's side against the firewall was real fun. Don't like the one next to the fuel injector underneath the upper radiator hose either), but having done it once, it isn't too bad the second time around.

 

Wickware, I removed the upper intake unit as I didn't want to chance breaking anything fumbling around for the manifold bolts. After removal I did not notice any external signs of leakage. In my case, given all the steam and coolant smell in the exhaust I was sure the leak was internal. The manifold bolts were not "loose", they were snug but could be tightened without much effort. It's almost as if the gasket shrunk and got thinner. I printed out a set of directions provided by a fellow user, I'll have to look for the link and will post it for you.