4.6 thermostat change problem

I have a 2000 merc Grand Marquis with the 4.6 engine. The garage I go to has tried to twice to change the thermostat but have been stopped dead, fearful, that the bolts going into the plastic intake manifold are
going to snap off. If that happens they say that it would require a new manifold and lts of expensive labor.
I have been in the garage on two other occasions when they have not been able to remove the bolts on two 4.6 engines to change the thermostat.
What a lousey design problem in my estimation. Has anyone else had this problem with those damned plastic intake bolts for the thermostat?
Thanks
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Have them try removing the bolts when the engine is DEAD cold, which means an over night stay at their shop. JR
Wegge wrote:

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4.6Ls and never had a bolt break. Of coarse this is no garantee that yours wont. Is the thing overheating or what? Its not the bolt that is plastic, its the intake itself.
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I live in far northern Minnesota where we've come off a few weeks of -35 below with wind chills of -55 to -60 bewlow. Thermostats are often changed up here to keep engines warm and not from overheating. I was referring to the metal bolts snapping off making it necessary to perhaps remove the whole intake to drill them out if that should happen.
Scott M wrote:

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The bolt bosses are metal inserts. Generally the bolts do not break but the inserts come loose and spin in the plastic. It is rare but can happen. There is a good side to this. If that were to happen, the manifold is very easy to replace labor is less than for the manifold on a 5.0. The manifolds are also less expensive than a manifold for the 5.0.

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Thomas Moats wrote:

I haven't had to deal with this yet (dealer *did* replaced manifold at 65K) but I've noticed this subject here before. I just looked at mine (97 Bird 4.6) and the bolts look easy enough to get at. My question is this: If the metal inserts should spin in the plastic, can you remove them and put new or larger inserts in? How are they anchored? Epoxy? Pressed?
Frank
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I suppose you could. Being that I work on other peoples vehicles I would never take the chance.

They appear to be pressed in.

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Does anyone make a metal replacement?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Professional Shop Rat: 14,267 days in a GM plant. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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plastic intake into the block.
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They have changed many times through the years. They do not go into the block, but the drivers side head. My bad, I forgot about that.

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have to pull the bolts out.......
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This problem is not isolated to Ford, GM and "exotic luxury models" also have this problem with the plastic intakes. Consider cutting up and replacing the thermostat housing (removing the "ears" from under bolts) and using a good penetrating oil and CRC battery terminal cleaner to remove any corrosion Regards, Jay
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