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Thermostat leak on 03 Explorer


Buick35
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I know it's not really old but my son bought a Ford Eplorer in great shape for $400 except for a small leak at the thermostat housing.It's an 8 cylinder. Turned out not to be the housing but the plastic intake manifold has a crack where the housing attaches. Why would they make a plastic intake? Anyway we changed the thermostat and "o" ring and J.B.Welded the intake and will let it cure overnight, hope it will hold. Plastic,Really?

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Because it weighs less, doesn't corrode, and is less conductive of heat. Ford is not the only one, those have been around for years now. Fords do seem to have more trouble with them than others. A friend had to replace the one on his (2004?) Crown Victoria when replacing the steel coolant tubes under the manifold. The plastic manifold needed replacement at the same time. I don't remember why. It was a common enough replacement that aftermarket ones were available (Dorman, etc.).

Edited by Bloo (see edit history)
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Is the engine in your Exploder a 4.6?  This was an issue on earlier Panther Platform cars like my '96 Lincoln.  When I bought it as an eight year old car I replaced the intake as a preventative measure.  My understanding is the problem with these first started showing up on Police Interceptor models.  They would fail under hard acceleration and the front, integral, coolant crossover tube would split.  It started showing up later on regular passenger models with many people experiencing failure accelerating hard at interstate on-ramps.  On the extreme end, inattentive drivers suffered catastrophic engine failure when they ran low on coolant.  Ford settled a costly class action suit over the issue.  The solution was to redesign the intake with a separate cast aluminum coolant crossover.  My car still had the original when I got it and I replaced it as a preventative measure.  

 

I think with passenger cars the designed was changed by 2001 but I can't speak to trucks.  It's also possible they continued to used the all-plastic design on other engine models.  I sourced a used FoMoCo replacement with the aluminum crossover when I did mine and haven't touched it since.  I also did someone else's with a Dorman unit and it was every bit as good as the Ford manufactured intake.

 

   

ford_4.6L_intake_manifold_problem.jpg

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I had a crack along the seam of a plastic radiator top tank. I cleaned it off with lacquer thinner and scuffed it up with sandpaper and mixed up some J B Weld. That was five years ago and it's still holding. Give it a try, you have nothing to loose.

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7 hours ago, 46 woodie said:

I had a crack along the seam of a plastic radiator top tank. I cleaned it off with lacquer thinner and scuffed it up with sandpaper and mixed up some J B Weld. That was five years ago and it's still holding. Give it a try, you have nothing to loose.

You are the first person I have heard of having any success with that type of repair.  
Good to hear of something that might work

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On 3/23/2020 at 11:03 AM, W_Higgins said:

Is the engine in your Exploder a 4.6?  This was an issue on earlier Panther Platform cars like my '96 Lincoln.  When I bought it as an eight year old car I replaced the intake as a preventative measure.  My understanding is the problem with these first started showing up on Police Interceptor models.  They would fail under hard acceleration and the front, integral, coolant crossover tube would split.  It started showing up later on regular passenger models with many people experiencing failure accelerating hard at interstate on-ramps.  On the extreme end, inattentive drivers suffered catastrophic engine failure when they ran low on coolant.  Ford settled a costly class action suit over the issue.  The solution was to redesign the intake with a separate cast aluminum coolant crossover.  My car still had the original when I got it and I replaced it as a preventative measure.  

 

I think with passenger cars the designed was changed by 2001 but I can't speak to trucks.  It's also possible they continued to used the all-plastic design on other engine models.  I sourced a used FoMoCo replacement with the aluminum crossover when I did mine and haven't touched it since.  I also did someone else's with a Dorman unit and it was every bit as good as the Ford manufactured intake.

 

   

ford_4.6L_intake_manifold_problem.jpg

 

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26 minutes ago, Buick35 said:

Thanks,Its got the 4.6 motor. I told my son if he bought the intake Id  change it for him to keep me busy. Hope it won't be too hard.Greg

 

It is an unbelievably easy job, at least on a Lincoln.  No doubt there is a tutorial on another forum or a YouTube video out there in the event you don't have the service manual.  The suggestion below to check the coolant tube laying in the valley is a good one.  I don't know if trucks are the same, but on cars there is a coolant tube that is mostly formed steel and replacing it necessitates removing the intake to do the job, so unless it has been done recently, it's a given that you do it at the same time.


Whatever the case, replacing the intake is the smart money.  If you chance it with epoxy and have to rollback the thing home, you just spent as much on the ride as you would have for the new intake.

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  I’ve done a half a dozen of those in  pickups with 5.4’s. Coolant tubes were always rusty. Just bypassed tubes with heater hose routed OUTSIDE of intake valley.

  Ford assembly line heater core quick connects at firewall a pita to disconnect and usually rusty and have destroy to remove. I just replace with hose clamps.

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