Thermostat Housing

Johnny O · Oct 17, 2015

Finally got hit with the dreaded cracked thermostat housing. At least there is a lot of coolant in the engine valley and dripping onto my driveway, so I think that's what it is. Doesn't look to be too hard to change, there is a Member Project on a Gen 1 but it appears the access is actually easier on my Gen 2. Any tips are welcome. The main problem may be finding one tomorrow since it's Sunday.

Igor Smetaniuk · Oct 18, 2015

The housing has 3 little tabs that align it with the hole so you have to watch none break off and go inside the engine. Don't break off the ones on the new Housing when installing.

WARNING: The 3 housing bolts are likely be frozen inside those metal housing sleeves and no way in hell is penetrant going to get down in between both to loosen them. If they don't turn don't force them or you may snap the heads of the bolts off or at the threads (even worse). I took a sharp chisel to the brittle plastic housing and completely chiseled it away from around the bolts/sleeves taking care to shove a rag in the hole below the housing as soon as I got it exposed so as not to get pieces down inside. Then I took a propane torch and carefully heated around the bolt sleeves to expand the threads and the bolts began to turn nice and easy. Don't break a bolt or your job will NOT be so easy!

The metal sleeves are slotted and my bolts were emebeded inside so I toook the chisel and kept hitting it up and down the length of the sleeve until I freed the bolt. You may want to get new bolts see ebay listing (included)

Also make sure you get a new Housing Seal for the base because most Housing kits only give you the thermostat o-ring. It's a special flat sided rubber ring that fits into a narrow slot at the bottom of the housing. your old one is likely to be flattened out and may not seal good after removing the old housing. Make sure to moisten it slightly with coolant before you're ready to mount it.

I decided to get a new OEM sensors and glad I did because the tiny oring was flattened and would have leaked for sure. I did not want to have to change that out later that's for sure.

(Sorry you'll have to cut & paste because I couldn't do multiple links)

HOUSING BOLTS:

http://www.ebay.com/itm/Explorer-Ranger-Mountaineer-B4000-4-0L-Thermostat-Housing-to-Engine-Bolts-/181262706013

HOUSING SEAL:

Motorcraft Part # RG614

http://www.amazon.com/Motorcraft-RG614-Coolant-Thermostat-Housing/product-reviews/B000C5BVYM/ref=dp_top_cm_cr_acr_txt?ie=UTF8&showViewpoints=1

swshawaii · Oct 18, 2015

Johnny, I'm sure you're aware of the aluminum replacement. $180 seems steep but will likely be a lifetime part. IIRC, 2004 and later 4.0L uses the single sensor housing.

Johnny O · Oct 18, 2015

$180 isn't bad when NAPA wants $111 for a plastic one. Todd Z hit me up on the FB page and suggested it might just be the housing-to-manifold O-ring, which upon closer examination seems to be the case. Since $2.50 is a lot less than $111 I will try that first.

EddieS'04 · Oct 18, 2015

I have the metal one ready to go. Bought it in advance for when I service the coolant before winter. Just been waiting for the Texas summer heat to stop.

Johnny O · Oct 19, 2015

Changed the housing O-ring after work today. Only had to disconnect the two bypass hoses and the upper radiator hose and t-stat cover. And the right side spark plug wires from the coil. The new O-ring looked wider than the old, maybe that was the problem, I don't know. Hosed out the coolant from the valley under the intake manifold, drove to the grocery store and back, so far it looks dry. Thanks for the tips. :haveabeer: