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logan.d122

Member
Joined
July 18, 2012
Messages
13
Reaction score
1
City, State
MI
Year, Model & Trim Level
2007 Mercury Mountaineer
Hi everyone. Over the past few months I noticed a very small amount off coolant on my driveway when the vehicle cools down after a long drive. It was never a concerning amount and due to the vehicles age I was not too concerned. I monitored the reservoir and it never reached a low level. However, the other day I drove to the store, around town, and back home and after the car sat for a few hours in roughly 45 degree weather I noticed a large amount of coolant leaking under the vehicle, and the reservoir was empty. I rented a pressure test kit from Advance Auto and noticed that when pressurized to 20 psi (like the radiator cap says) coolant begins dripping at a steady pace from behind the compressor pully. The engine is dry on top and none of the hoses seem to be leaking. I removed the alternator to get a better look at the water pump, and the weep hole was clogged, but dry. The leak is in the center and drips on the frame from behind the large compressor pully.

Could this be a bad water pump seal/gasket? I cannot get a good look at the lower side of the water pump without removing the fan (which is next on my list). I have checked the intake manifold and it doesn't seem to be cracked or leaking. I don't want to replace the water pump if that is not the issue. Hoping someone has had a similar issue before and can point me in the right direction. Vehicle was purchased with 112,000 miles and now has 166,000. I have not had the water pump replaced and from the looks of it, it seems to be the original. I am skilled enough to replace the pump myself, just want to see anyone can shed some light on the problem before proceeding with a "fix".
 


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Explorer_PL

Elite Explorer
Joined
November 16, 2007
Messages
2,903
Reaction score
197
City, State
Rockland County, NY
Year, Model & Trim Level
06EB V8
I am not by the car right now so can't visualize the engine bay :), but did you check heater hoses and clamps ?
 




logan.d122

Member
Joined
July 18, 2012
Messages
13
Reaction score
1
City, State
MI
Year, Model & Trim Level
2007 Mercury Mountaineer
I did. I followed all the heater hoses and looked at all the clamps, joints, and connections..... and none of them are leaking. When I pressure test I can see the coolant dripping from behind the compressor pully, but I can't see the bottom of the water pump which is right above the compressor pully. I can see the top of the water pump and it looks fine, add the intake manifold also looks fine, which is why my suspicion is a leak from the gasket at the bottom of the water pump.
 




3C24

Member
Joined
October 2, 2019
Messages
17
Reaction score
4
City, State
CA
Year, Model & Trim Level
2009 XLT 4x2
I had the same issue. Mines was the radiator. You just can't see where it is leaking from because it is so tight in there. When I pulled it out, it was obvious where the leak was from. I got a new Spectra one from Rockauto and replaced the 20 PSI cap with a 16 PSI one. That was 3 years ago and so far no problems.
 




logan.d122

Member
Joined
July 18, 2012
Messages
13
Reaction score
1
City, State
MI
Year, Model & Trim Level
2007 Mercury Mountaineer
After pulling off the fan, reservoir, shroud, alternator, and belt I was finally able to see the problem. Mine was leaking from the bottom of the water pump. The coolant was running right behind the AC compressor pully so I couldn't see the leak before. The gasket was completely degraded. But it was also the original factory water pump and the vehicle has 162K miles on it, so I am slightly impressed it lasted that long. The water pump was a pain to get off. Had to hit it with a hammer for about 30 mins before it finally came loose. I got a replacement pump from O-Reilly's and it installed with no issue. A thing to keep in mind if anyone who has an 06 or 07 4.6L Explorer or Mountaineer, the water pump impeller was changed mid-year 07 according to O'Reilly's so there are 2 different styles. Be sure to pull the pump and see before going to the store. I ended up with the wrong one at first. But after the pump change there is no more leak and my cooling system is holding pressure just fine. The heat is also working a lot better now too!
 




Explorer_PL

Elite Explorer
Joined
November 16, 2007
Messages
2,903
Reaction score
197
City, State
Rockland County, NY
Year, Model & Trim Level
06EB V8
Great, thanks for the tips !
 




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