Thermostat removal

[Dadsworkshop]

Hi guys,

I am new to the forum and wanted to introduce myself. I have been driving grand marquis' since 1996 and currently have three in the fold (1998, 1999, and 2001) plus 2007 F1510 Supercrew. Yes we are an all Ford family. I need to flush the coolant systems of these cars are they were all purchased used and maintenance was not performed regularly. I am concerned about cracking plastic intake manifold when removing the thermostat. It happen to one earlier marquis' and I had to have the manifold replaced. All I did was remove the bolts to the thermostat housing and snap, the manifold cracked . Can anyone share a way that will allow me to remove the thermostat and not crack the manifold. Thanks in advance for your help.

[VicCrownVic]

Welcome!

I'm not too familiar with the 4.6, but I believe 98-01 that you have would fall into the range where that plastic intake breaks on it's own. Your best bet would be to get the new updated intake before you touch anything. Someone else more knowledgeable will be along soon enough to fill in the details that I am unaware of.

[pantera77]

Do you have the intake with the plastic crossover tube? If so you may as well replace it anyways, because it will crack and leak in the future regardless.

[VicCrownVic]

Do you have the intake with the plastic crossover tube? If so you may as well replace it anyways, because it will crack and leak in the future regardless.

^The details that I was missing.

[IPreferDIY]

Welcome!

+1 for replacing the intake manifold if you still have the all-plastic one. If you want to buy some time, you might consider draining two gallons of coolant from the rad drain (easy enough with the car parked on a down slope, or with the rear on ramps) and adding two gallons of fresh stuff. That should improve things enough until you get around to doing the intake manifold.

When replacing the intake manifold, you have a choice between NPI (non-performance improved) and PI (performance improved). The NPI is the same as you have now, except with an aluminum crossover. The PI is the one they used in later years, but there are a few things you need to do to make it work properly. You're supposed to get a bit of performance improvement with the PI one. (A simple thing you can do along this line is take out the restrictive trumpet on the air filter box. Ideally, you should replace it with something bigger.)

[Dadsworkshop]

I going to try the approach IPreferDIY suggested.

Draining two gallons of coolant from the rad drain (easy enough with the car parked on a down slope, or with the rear on ramps).

Thanks

[IPreferDIY]

I might as well add that it takes some time since the spout is so small, and mine starts to dribble from the stopcock if I open it too much, but it's convenient if you're not in a rush. Sticking a piece of hose on the spout is useful for directing the coolant where you want it to go.