2004 4.0 overheated yesterday

[KyleTay]

The coolant thermostat housing cracked yesterday on my way to work. Seems like the thermostat stuck closed and caused the housing to fail.

What a stupid design tho! You have to remove the throttle body to replace the thermostat and the entire intake to get to the housing!

I think I rode for about 3 minutes with the engine overheating... I did not notice the gauge being pegged out until I started hearing detonation. Then I got off the highway and luckily was very close to a QuickTrip.

So, I remove the intake, and thermostat housing... waiting on a new one, then will put it all back together and hope the engine is ok. No coolant in oil or visa versa so keep your fingers crossed for me!

Anything else I should replace while I have the intake off?

 

[KyleTay]

With the overwhelming amount of input and help from the site I was able to repair my trucko.

The thermostat housing exploded. I replaced it and the thermostat, runs 95% as well as before. Gonna leave the battery disconnected tonight and see if that fixes the SLIGHT hesitation.

BTW, the intake does have to come off, or at least loose, to access the thermostat housing.

I noticed a large amount of sludgy film on the intake runners and the runners on the head. Any ideas what would cause that?

 

[Earl43P]

Excess oil blow-by (bad rings) or bad pcv valve.
Some crud is to be expected.

I found a piece of an old thermostat in my 99 Ex's housing, randomly blocking the port making it get hot (heater would tame it).

You're right, that design sux. Might as well have done the intake gaskets for all the work involved.

 

[KyleTay]

well the pcv will be replace soon