84FLH
Well-Known Member
- Joined
- February 14, 2016
- Messages
- 196
- Points
- 28
- Year, Model & Trim Level
- 2000 Mercury Mountaineer
Hey everyone. Another week. Another Mounty problem.
The big nut in the picture has a very slight weep of coolant, where nut meets radiator. The weeping is at one, and only one, point of the six flats; the point that's at 8 o'clock in the picture.
This is a replacement radiator about 8 years old. Don't know the brand.
This past Saturday I decided to try tightening the big nut. I loosened the small compression fitting behind the nut and tightened the nut about 1/8th of a turn. During that slight movement I thought I detected resistance increasing, so I stopped tightening. Then I retightened the small compression fitting nut.
I used a paint marker to denote new position of the big nut. Then I taped paper under the nut to see if the weeping was fixed or not. Turns out the weeping is much, much less but not 100% gone.
Here's my questions:
- Can I unscrew the big nut from the radiator and use plumber's tape or sealant to stop the weeping?
- Is there an O-ring at the inside end of the big nut ... and if so, what's the chance it'll drop inside the plastic tank before I get it out of the tank?
This all started about a month ago when I'd driven one mile from work on the way home and stopped at a red light. I happened to notice "Check Gauge" was on. Right next to that idiot light my temp gauge was pinned to HOT! As I looked at the gauge in amazement it dropped right back down to the middle where it always is. I pulled over and found the overflow tank almost overflowing with dirty dark brown fluid. I had no coolant or turkey baster with me but since the gauge was reading ok I drove the 20 miles home. Gauge stayed in the middle.
On inspection I found the overflow tank full of brown sludge and brown stuff that looked like ground black pepper. It had to be K-Seal I'd used to patch the Mercury radiator in 2017 for a few months before I decided to have a new radiator installed (also 2017). So now, 8 years later, the K-Seal must've made the t-stat stick closed for a minute or two, then the engine puked all the 8 year old K-Seal coolant into the radiator, where the by now boiling K-Seal coolant went into the overflow tank.
I removed the overflow tank and thoroughly cleaned every spec of K-Seal out. I flushed the overflow hose and ensured air blew through it by mouth just fine. Installed new aftermarket t-stat and new Motorcraft radiator cap (couldn't find Motorcraft t-stat with the bleed hole). Added new coolant and .... kept finding the overflow tank from halfway to 3/4's full all the time. Coolant in radiator was always about 3-4" below radiator fill hole. Rechecked overflow tank and hose and found them both clear of obstructions.
So then I parked on extreme hill with nose up and ran engine with funnel on radiator (well, mostly on radiator) to purge air. Put more coolant in. Still, the OF tank was always half to 3/4 full. I've been working a lot of OT and didn't have time or desire to mess with the Monty. So I kept a full jug of coolant, a turkey baster, and two empty coolant jugs in the truck.
Then one day I noticed some very, very tiny bubbles at that radiator fitting big nut. They were only coming from one of the points of the nut. Then it hit me. That leak was preventing the system from pressurizing. The lower system pressure also lowered coolant boiling point. Boiling or almost boiling coolant was rushing into the radiator and gushing through the OF tube to the OF tank.
So last Saturday I tightened the big nut. After my 40 mile round trip to church the next day, I found some seepage at the big nut. So I tightened it a little more, and put the paint mark and paper on radiator as noted above. Today (Monday) I still found some seepage under the big nut. So before I throw in the towel and bring to a shop I'd like to try plumber's tape or sealant. I just don't know what's behind the big nut!
The big nut in the picture has a very slight weep of coolant, where nut meets radiator. The weeping is at one, and only one, point of the six flats; the point that's at 8 o'clock in the picture.
This is a replacement radiator about 8 years old. Don't know the brand.
This past Saturday I decided to try tightening the big nut. I loosened the small compression fitting behind the nut and tightened the nut about 1/8th of a turn. During that slight movement I thought I detected resistance increasing, so I stopped tightening. Then I retightened the small compression fitting nut.
I used a paint marker to denote new position of the big nut. Then I taped paper under the nut to see if the weeping was fixed or not. Turns out the weeping is much, much less but not 100% gone.
Here's my questions:
- Can I unscrew the big nut from the radiator and use plumber's tape or sealant to stop the weeping?
- Is there an O-ring at the inside end of the big nut ... and if so, what's the chance it'll drop inside the plastic tank before I get it out of the tank?
This all started about a month ago when I'd driven one mile from work on the way home and stopped at a red light. I happened to notice "Check Gauge" was on. Right next to that idiot light my temp gauge was pinned to HOT! As I looked at the gauge in amazement it dropped right back down to the middle where it always is. I pulled over and found the overflow tank almost overflowing with dirty dark brown fluid. I had no coolant or turkey baster with me but since the gauge was reading ok I drove the 20 miles home. Gauge stayed in the middle.
On inspection I found the overflow tank full of brown sludge and brown stuff that looked like ground black pepper. It had to be K-Seal I'd used to patch the Mercury radiator in 2017 for a few months before I decided to have a new radiator installed (also 2017). So now, 8 years later, the K-Seal must've made the t-stat stick closed for a minute or two, then the engine puked all the 8 year old K-Seal coolant into the radiator, where the by now boiling K-Seal coolant went into the overflow tank.
I removed the overflow tank and thoroughly cleaned every spec of K-Seal out. I flushed the overflow hose and ensured air blew through it by mouth just fine. Installed new aftermarket t-stat and new Motorcraft radiator cap (couldn't find Motorcraft t-stat with the bleed hole). Added new coolant and .... kept finding the overflow tank from halfway to 3/4's full all the time. Coolant in radiator was always about 3-4" below radiator fill hole. Rechecked overflow tank and hose and found them both clear of obstructions.
So then I parked on extreme hill with nose up and ran engine with funnel on radiator (well, mostly on radiator) to purge air. Put more coolant in. Still, the OF tank was always half to 3/4 full. I've been working a lot of OT and didn't have time or desire to mess with the Monty. So I kept a full jug of coolant, a turkey baster, and two empty coolant jugs in the truck.
Then one day I noticed some very, very tiny bubbles at that radiator fitting big nut. They were only coming from one of the points of the nut. Then it hit me. That leak was preventing the system from pressurizing. The lower system pressure also lowered coolant boiling point. Boiling or almost boiling coolant was rushing into the radiator and gushing through the OF tube to the OF tank.
So last Saturday I tightened the big nut. After my 40 mile round trip to church the next day, I found some seepage at the big nut. So I tightened it a little more, and put the paint mark and paper on radiator as noted above. Today (Monday) I still found some seepage under the big nut. So before I throw in the towel and bring to a shop I'd like to try plumber's tape or sealant. I just don't know what's behind the big nut!
