2000 MounTger side: suggestions? | Ford Explorer Forums - Serious Explorations

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2000 MounTger side: suggestions?


Well-Known Member
February 14, 2016
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Year, Model & Trim Level
2000 Mercury Mountaineer
314,000 miles on orig engine. Runs, shifts, drives good.

Dashboard coolant temp gauge had been reading dead cold for some time, months, actually. The vehicle never overheated that I know of during that time. So I replaced t-stat last week using Motorcraft t-stat bought from dealer. I didn't know about burping system, so it wasn't done. After replacing t-stat I topped off radiator with 50/50 and drove it all week. Dashboard coolant temp gauge was good all week: needle was about 1/3 way up from "cold". Perfect.

Last night after driving 20 mins on highway I stopped at store. Smelled coolant when I got out of vehicle.. Checked under front of vehicle. Found coolant heavily dripping from radiator drain area (passenger side of radiator). It was all over lower control arm, tie rod end, etc. Checking more carefully, the leak appeared to originate on the plastic side of radiator (passenger side) about 3" from top of radiator. From there it had dripped down to the radiator drain plug, and was blown back onto lower control arm, etc.

I didn't fill the radiator there in the parking lot, even though I had some 50/50 on hand, because I hoped the leaking would stop once coolant level dropped below where the leak appeared to originate from on the radiator. I drove another 20 mins home and looked under vehicle front. Coolant was once again dripping from radiator drain plug area, and again I noticed the leak appeared to originate on plastic part of radiator, about 3" from radiator top.

Could a defective rad cap over pressurize the system and cause massive leaking from what was previously a small leak?

Did not burping system cause/aggravate this problem?

How can I tell if there's any coolant in the engine or radiator?

Will the leaking stop once coolant level is below suspected origin of leak?

Now that it's daylight I'll be looking closer to find exact origin of leak (if possible), and checking oil for signs of coolant.

What else should I check?

I'll be bringing vehicle to shop next week. Maybe at 314,000 miles it's time for new radiator.

Suggestions welcomed!

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Time for a new radiator. The system is pressurized and must be sealed, so, no it will not stop leaking until it is fixed.

Two of my 2000 5.0 V8's needed to have their radiators replaced because the side tanks began leaking in exactly the same place as yours. They had around 200,000 miles on them when this happened. If you were still running your original radiator at 314,000 miles you certainly got your money's worth out of it. Time to replace it.

Ah, koda, was hoping to hear from you. Should be Yoda instead of koda. And thanks to you also, Turdle, for answering my question. I can see exactly what you're saying. The pressure forces liquid out of the hole, crack, etc.

Today I called a mechanic who has done work for me in the past. He said to drive over (10 miles away) to his shop. He put K-Seal in the radiator. I was hesitant because I've read horror stories about stop leak stuff. But I've read good things about K-Seal. Plus, the radiator was leaking pretty heavy. Lot of drips in rapid succession. 10" diameter puddle 10 mins after engine shut off.

He added the K-Seal, told me to bring it in day after Labor Day for rad replacement, and said if the K-Seal didn't work he'd try to get me in this week.

I drove 8 miles to Stop & Shop (that's how this all got started, a ride to the food store). Parked. Looked under radiator.
Ground was bone dry. WOW!

Title of this thread was supposed to be 2000 Mountaineer Leaking Radiator: Suggestions?

Thanks again Turdle and koda.

I'm a big fan of K-Seal for cooling system leaks, but not for radiator leaks. I doubt it will do anything and its not cheap at $12-$14 for 8 ounces. It wont hurt anything though. As long the leak is high up on the side tank (you stated about 3" from the top), I'd just let the coolant seek it's own level below the leak. It should be okay to drive it this way for a while. Just carry a jug of coolant with you and keep an I on the TEMP gauge. When I first discovered the leak on our 2000 Mountaineer V8 that's what I did for about a month before I replaced the radiator. It never overheated or leaked once the coolant level got below where the leak point was.Later I did the same thing on my 2000 Explorer V8 when I found it leaking.