Hidden Coolant Leak in 1999 4.0 V6 OHV

[davydude]

I really need some knowledgeable input with my problem before it gets too expensive. Try and make a long story short. Got stuck in the snow and after getting out truck wound up having a bad coolant leak. I could never see good enough to tell where it comes from. Have successfully replaced the following: water pump, fan clutch, a freeze plug in the front face of driver side head(behind ac bracket), the thermostat and thermostat housing, and the coolant temperature sensor. Before putting ac compressor and power steering assembly back in place, I inspected as much as I could while lacking a mirror or able to run motor to look for leaks. Still is leaking and looks like somewhere behind and below the thermostat housing, somewhere between intake manifold and ? There shouldn't be a bypass hose like on a SOHC. Doesn't list one anywhere for OHV in manual. I can see another sensor on bottom of block, which may be leaking or dripping from being sprayed on from leak above it, either way it is not the main leak. Anyone familiar enough with a 1999 Ford Explorer 2 door 4.0 V6 OHV Engine that could give me something else to go on would be a great help. Thanks

 

[MuNkY6913]

Hey man. I just went through this same thing.I didn't replace nearly as much. I was having coolant leaking from somewhere. I originally thought it was that little sensor on the bottom drivers side of the engine it ended up being about a half turn to lose. After that I noticed it was just getting dripped on from higher up. I went to the water pump. Every where around it was dry and the bolts where tight. I could see coolant dripping from the bottom of it though.I could see the block behind it was wet. So I went to the thermostat but that was dry all the way around it as well. Directly to the right of the thermostat housing I could see a little puddle of coolant back in behind the housing. So I determined it to be coming from there. The lower intake manifold gasket.so after taking off the upper manifold and the valve covers, I get the lower manifold off. The gasket had deteriorated to almost nothing right where the leak was coming from. I replaced it and haven't had a leak so far. Only went on a test drive cause now it runs rough and has no power. I messed something up and have to find it. Might as well replace the valve cover gaskets while your in there.

 

[koda2000]

if you don't want to mess with it right now, try an 8 ounce bottle of a product called K-Seal. Just make room for it in the radiator, shake the bottle well and pour it in, then let the engine idle for about 30 mins. I just stopped 2 pretty good leaks with this product. it worked instantly. amazing stuff and it's supposed to be a permanent fix. if it will hold until spring i'll be happy.

 

[davydude]

Thanks to everyone, who did, for your input. I'm also beginning to think it's the manifold gasket as well, always did really because of where the leak is located. Although everything I replaced was in very poor condition and in need of replacing, none have been the source of the leak. So I guess I'm gonna learn how to do the manifold on a '99 Ford Explorer like the rest of it! I have to say that it is one of the easiest cars, so far, that I have worked on. And a pretty tough little motor. Hopefully the manifold is as easy to do as the rest of it was. Because the manual (Chilton) makes it sound rather daunting. As though you basically do everything twice. Last thing I want to do is take it to a shop.

 

[MuNkY6913]

It seems kinda bad but it's not as hard as it looks. It would have been easier if I didn't have to stand on a stool to see in. Didn't even know there was a gasket in the egr tube. Found it on the floor when I backed out and it was running really rough. I found a pretty good thread somewhere on Google that's got some good pictures and directions. Good luck man.