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Coolant Leak

Discussion in 'Stock 1991 - 1994 Explorers' started by tmosesjr, July 4, 2012.

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    1. tmosesjr

      tmosesjr New Member

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      I have a 1993 Explorer 4X4. 4.0 Pushrod V6. It has been leaking coolant for a few weaks, so I put some leak sealer in it and it stopped for a couple of days. Now its leaking again, I cant see the leak, nothing hitting the ground. But I do notice , after the engine is hot and I turn it off, a hissing sound like water hitting a hot surface. (Duh). It seems to be around where the thermostat housing is, or on the very right side (passenger) top of the water pump, because I can see a small amount of water on it. Could i just need new hoses? Or is it the water pump? I am ruling out the thermostat because the upper hose is hot. Any suggestions?
       
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    3. mehedgec

      mehedgec Active Member

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      Could be Lower Intake Gasket. Very common in the 4.0
       
    4. R&T Babich

      R&T Babich Active Member

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      Keep wiping things down and see if you can pinpoint the leak.
      You might try replacing the hose clamps with worm drives.
      I had a car once that was leaking coolant and couldn't find it for months.
      Finally on a really hot day after turning off the engine I happened to look under the car.
      There was a tiny stream of mist coming out the side of the lower radiator hose.
      The pinhole right in the middle of the hose could not be seen just looking at it.
      Never had a drop on the ground, but had to keep filling coolant.
      Had a tire once with the same thing, 3 little spots in the middle of the sidewall that a tiny bit of air was leaking out of.
      Found those by dunking the tire in a water tank.
      Also, had a distributor cap that looked perfect, but was cross firing thru a crack.
      It's amazing sometimes how things can look fine, but have flaws.
       
    5. tmosesjr

      tmosesjr New Member

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      I am now starting to see coolant leaking down underneath the car. Same are, just had never made it to the ground before. Been going through about a gallon of water when I drive it. I guess I just need to replace all my hoses and start there?
       
    6. R&T Babich

      R&T Babich Active Member

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      I was just looking at our cars and the thermostat housing is very rusty. I've been wondering for awhile how long it will last before it rusts thru. I have another '92 for parts that had 219k on it and the housing is rusty, but never leaked. The fitting is now 20 years old so it may be a time issue, not mileage for the rust. The thermostat housing seems to be going for around $70. If your hoses are 20 years old like mine it would seem like a good place to start.
       
    7. tmosesjr

      tmosesjr New Member

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      Now there is absolutely no leak. None. I didn't do anything to the car, the leak just stopped. How is that possible? I mean it was leaking at least a gallon of water every time I drove it. And now, not a drop.
       
    8. Comacoz

      Comacoz New Member

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      I just did this job on my 1991 Explorer 2wd, and it was a leaking thermostat housing (along with a bad thermostat inside) spilling coolant all over the top of my water pump, and being flug by the belt all over the intake tube and other parts. I could eventually see and hear steam shooting from the bottom of the thermostat housing and the truck was overheating bad with all the lost coolant and no circulation. It sounds like you're having the same issue since you saw coolant on top of ur pump (the thermostat housing is directly above it) and you were losing massive amounts of coolant. Take off and inspect the upper radiator hose for leaks . If the hose is the problem (you're a lucky sob) and have a quick fix. If the hose is good, you're gonna need to replace the thermostat housing ($24 Compression Works at autozone, comes with paper gasket) and thermostat ($6 Duralast at autozone, comes with rubber gasket attached). Both gaskets are crucial to sealing up that housing chamber. You DO NOT need any sealant.

      Repair: Make sure u have good light, you'll need to disconnect neg battery cable, drain coolant (can reuse if good), remove air tube, you already have upper radiator hose off, remove belt, and you can get to the three housing bolts pretty easy. The bolt on top right and bottom are easy, the top left is a little harder. It sits right up against the belt tensioner (which u DO NOT have to remove) and will require maybe a deep socket with small extension on a small ratchet and some finagling. If it gives u a hard time, dont lose patience. I was able to get that bolt off by having the socket slanted and not even all the way on the bolt. There was also a cable running down to the crankshaft right in between that bolt and the housing pipe that is a pain and will be in your way. You should be able to move it slightly to get a little more room.

      My old housing
      [​IMG]
      As you can see, the thermostat housing was seriously in need of replace, the top had corroded so bad and when i took it off, it was bulging in a couple of spots, and there wasn't even a paper gasket on it! There musta been some kind of silicone sealant instead. :/

      Now once u have the housing off, you'll see the themorstat poking out. PAY ATTENTION to how it is installed, with the the small hole (air relief valve) at the top and the bar on the thermostat horizontal, as u want to install the new one the same way. Try rotating the thermostat with small flat nose plyers, or something u can grip the bar with, to loosen it up a bit (spray a lil wd40 on the rubber edges of the thermostat , it'll get in there and help u rotate it). Take a small screwdriver and put it behind the bar on the thermostat, tap the screwdriver with a small hammer or something to pry and pop out the thermostat

      Old Thermostat
      [​IMG]
      You can see the rubber gasket that goes around the thermostat is pretty much gone, and just nasty. And it is all rusted up from years of running water periodically in the cooling system.

      After you have that old thing outta there, stuff a rag in the engine opening, and clean off any gasket or rust residue with a degreaser and a gasket scraper if necessary. Also a good time to clean off any coolant residue that got on ur pump or any other parts of ur motor while you have good access in there. When ur finished cleaning, put a lil wd40 on the edges of the new thermostat and install with Air Valve at top, make sure its nice n snug in there. Install your new Thermostat housing with paper gasket. The gasket might require some patience. It was easiest to insert the top right bolt through the housing with the gasket on and attach to engine, screw it in slightly with ur fingers, and align gasket with other holes and put other two bolts in slighty with fingers. Screw them in nice n slow, you don't want to rip that new paper gasket. Tighting down bolts evenly and torque to 10 ft lbs. If you dont have a torque wrench, just make sure they are nice and tight. Take a moment to admire the new nice looking thermostat housing you just put on and pat yourself on the back, if you will. Reinstall your belt, upper radiator hose, intake tube, add your coolant back , and reconnect battery. Double check your connections before you start it back up. Your leak should be solved!

      Total cost should be about $30-$50 bucks for parts and coolant, maybe 3-4 hours depending on the cleaning required. I ended up replacing the upper radiator hose, and belt while i was in there, as they were badly worn as well, as well as cleaned all my pulleys before i put on new belt (I was using belt dressing for awhile and that stuff gunks up all over them). And buy some latex gloves for $2!

      P.S. If your upper hose was hot, that confirms the water pump is working. And your leak probably stopped because of that leak sealer u added before. I guess somehow its working at the moment. It has been 4 days since i did this repair and everything is cooling great and I have no more leaks. I'm going to eventually replace the thermostat sensor also. If you have any problems or need any more help message me. Good luck!
       
      Last edited: July 17, 2012
    9. Tony H

      Tony H Well-Known Member

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      I agree with this.
      And it stopped leaking again because the stop leak found it's way in there again.
      It's very hard to get an eyeball in there but look under the solid upper radiator hose by the Temp Sensor. that is where the Intake gasket is the thinest and is likely to leak. The small amount of coolant drips down the front of the engine and runs down around teh passenger side of the Water Pump.
       
    10. tmosesjr

      tmosesjr New Member

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      @Comacoz, Thank you. I did this repair last Sunday Morning, and so far, so good. Not one drop of water has leaked out. Changed out the thermostat, (which still looked decent, except for the rubber ring around it looked bad.) The old housing just looked old, couldn't find or see where it may have been leaking from, replaced anyway. And a new upper hose and clamps. All seems great now, needle never goes past the middle mark, even stays a little on the cool side. And that's hard to do in 100+ degree heat. Lol. Thanks for the pics and help.
       
    11. Tony H

      Tony H Well-Known Member

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      So which was it? Thermostat Housing Leak or intake manifold?
       
    12. R&T Babich

      R&T Babich Active Member

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      Found the thermostat housing for $35. (Four Seasons 84883 Water Outlet - Amazon of all places)
       
    13. tmosesjr

      tmosesjr New Member

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      Thermostat Housing and Hose.
       
    14. tmosesjr

      tmosesjr New Member

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      Well, on day 8, it got hot again, after 7 days of absolutely no issues. Now, it's getting hot, but not losing any water. Could it be the water pump going out? Maybe the Fan? Or maybe a faulty thermostat?
       
    15. Comacoz

      Comacoz New Member

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      Autozone sells one for $24
       
    16. Comacoz

      Comacoz New Member

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      Hmm well we know where the leak was coming from and you fixed that, if its starting to overheat again, could be a possible faulty thermostat. What brand is that thermostat and how much was it? Mine was $6 duralast and is working good, but I have read that the cheaper ones can malfunction if the wax inside them gets too hot. If you run the truck, and you see the fan spinning, i would rule that out. If you run the truck and squeeze the upper radiator hose and hold it for a few seconds, then release it, you should feel a surge of coolant go through, that will confirm the water pump is working. Im not sure if there are other ways to test the pump, but see if you can find out before removing it. Im thinking its a bad thermo though (which sucks cuz you just replaced it!), or maybe a bad thermo sensor. If you do end up removing the thermostat again, you should be able to exchange it for a new one for no extra cost. The thermostat sensor is around $5-6 also, might want to consider replacing that as well. I have to replace mine, as my needle tends to fluctuate to hot, and back to normal. Let me know what happens. Worst case scenario, u can take it a shop, usually they'll offer a free diagnosis of the cooling system, and can tell u exactly whats wrong, then u just fix it yourself.

      Oh and double check ur coolant lvl, i know sometimes air pockets can get in the coolant and cause problems. Doesn't hurt to top off the coolant
       
    17. tmosesjr

      tmosesjr New Member

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      I just checked under my hood again, and noticed little pieces of rubber all over the engine compartment. Upon further inspection, I noticed wear on my brand new serpentine belt, and that the Idler pulley wasnt turning. A mechanic told me to replace the pulley, and it should be fine. With the pulley locked up, its not turning the water pump good enough to cool the car. I hope this is all it is.
       
    18. Comacoz

      Comacoz New Member

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      @moses, oh wow the idler pully wasn't turning? I wonder if its rusted up or something, that's the last thing i would have thought of, and that idler pulley has literally no resistance with that belt off, i'm surprised it would seize up on you like that. I don't think that pulley is too expensive. When i was doing my repair and had the belt off, i inspected, cleaned, and turned all my pulleys by hand. And they all spun pretty nice and free. But it sounds like an easy fix man, so that's good. Let me know how it goes
       
    19. tmosesjr

      tmosesjr New Member

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      Yeah, it was locked up solid. But that didn't fix it. I think its the fan clutch, because I noticed as long as I am moving, it does fine. But when I stop is when it heats up. So when I got home, I opened the hood, and there is hardly any air coming off the fan. And it doesn't seem to be moving very fast. And I hear a noise from that area. Is this a hard thing to replace? I did one a long time ago on a 76 el camino and it was easy. But this is a 93, so im sure it's a pain. Probably need special tools and all.
       
    20. tmosesjr

      tmosesjr New Member

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      Still Leaking

      Ok. Here is a tough one. My 93 was leaking real bad, but have never been able to pinpoint where its coming from. Noe its at the point where it will go a month with absolutely no loss of coolant. NONE. Then suddenly, like today its leaking like crazy. And it probably will anytime I drive it today. But tomorrow, it won't be leaking and not leak for another month. HOW IS THIS POSSIBLE? It leaks bad for a day, then nothing for at least a month. I am truly at a loss here. All I hear is a hissing sound coming from somewhere on top of the engine. And the water is leaking middle to right (passenger) side. Any suggestions? I have replace both hoses, thermostat, thermostat housing, fan clutch. The only thing left would be water pump or heater hoses. But wouldn't those make it leak constantly?
       
    21. Anime

      Anime EF YEAH!! Elite Explorer

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      Hissing could be pressure releasing from the hoses as the engine cools. If you have worm-drive type clamps on the hoses, they stay the same size, while the hoses expand when hot and contract when cold. So sometimes the hissing may turn into leaking when the hoses get cool enough. The few times it's leaked may have been cooler nights.

      The best clamps to get for the coolant and heater hoses are constant-tension/constant-torque clamps, either the original factory kind or spring-controlled. They aren't cheap, but they don't allow leaks.

      If it's not the hoses there are plenty of other places where the system can leak, the water pump gasket, head gaskets, etc. Sometimes water pumps can even leak out the weep hole every once in awhile when they start to go but haven't completely failed yet.
       
    22. tmosesjr

      tmosesjr New Member

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      I had a mechanic do a pressure test on the system yesterday, and he TRIED to make it leak. And couldn't. And, it is still not leaking again. Very, very strange.
       
    23. NavyS27

      NavyS27 New Member

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      93 XLT 4.0 Coolant leak

      Sorry to bring an old post back from the dead, but I'm having a very similar issue except that it is a consistant leak. Tmosesjr, did you ever get it fully repaired and if so, what was the fix?

      Here's my story...after parking one night and getting out of the vehicle I smelled coolant a heard hissing coming from the engine area. Looked under the engine and noticed a stream of coolant flowing out and large pool on the ground. After the engine cooled I topped off with water and was able to drive home.
      I pressure checked the system and found that a hissing sound was coming from the thermostat housing area more on the drivers side. I've replaced the thermostat, upper and lower radiator hoses, and water pump gasket. I inspected the thermo housing, heater hoses and temperature sensor, all look good. After putting everything back together today I filled with water and was going to pressure check again but water was flowing out still. Its coming from the drivers side of the engine where the screwdriver is inserted (see photos). I have no idea what else to look at other that head gasket or intake gaskets. Thanks for your help.
       
    24. NavyS27

      NavyS27 New Member

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      Photos

      I'm having trouble posting the photos right now because the computer I'm on. I'll get the photos up as soon as I can.
       
    25. Ramblinwilly

      Ramblinwilly Member

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      Ok, here's my standard leak check list.

      Hose1: top of radiator to thermostat.

      Hose2: bottom of radiator to water pump.

      Hose3: this one is often overlooked. it's about a 3/4 inch diameter hose near the thermo housing/water pump.

      Hose4 &5: Heater core hoses.

      Freeze Out Plugs: Leaky plugs can be tough to find since they are usually buried by some other component like exhaust manifolds. They first develop pin holes and can leak fluid in places where the fluid evaporates leaving no trail.

      As a last resort, you can purchase an inexpensive leak detection system which consists of a fluid that's added to the coolant that illuminates under a UV light. Kit includes everything you need. But I don't think you will need this since you can see and hear your leak. My first bet would be that 3/4 inch hose I mentioned above and next I would suspect a freeze out plug. Hope this helps.

      Might be best if you repost all of this in a separate thread. Good Luck!!!
       
    26. NavyS27

      NavyS27 New Member

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      Leak fixed!

      So thanks to this forum, I was able to diagnose and fix my vehicle. THANK YOU! Sorry I wasn't able to chronicle my progress as it happened but I can post the photos now. It ended up being the lower intake gasket.

      Zoomed in to show where the leak was coming from. This is the driver's side.
      [​IMG]

      Zoomed out
      [​IMG]

      Zoomed out further
      [​IMG]

      FOUND THE PROBLEM!
      [​IMG]

      Gasket off the engine
      [​IMG]

      Bonus photo...teaching him early
      [​IMG]
       

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