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Thermostat housing leaking

gnx547

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I replaced the thermostat on a 99 Explorer 4.0 SOHC and now it is leaking from the housing. It does have a new o-ring gasket Duralast/Flel-pro #35617 and the 3 bolts are tight. I don't understand why it is leaking? Any ideas or suggestions? Maybe use some RTV?

2u5eyyb.jpg
 


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swshawaii

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gnx547

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Will it work for a 99? Its says 2001 but pretty sure they are all same for the 4.0.
 




swshawaii

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Both use the RH144 two sensor lower housing. DO NOT over tighten or they will warp and will leak. 89 INCH pound
(7-8 ft/lb) torque spec for lower and upper housings. Follow the linked "how to" to the letter and you will be set. GL

BTW, Dorman has the sensor clips if the dealer doesn't have them in stock.
http://www.rockauto.com/catalog/moreinfo.php?pk=5677395&cc=1304413


gnx547- You are correct, mistake in the bengrosser "how to" introduction. Otherwise, one of the best repair tutorials ever.
The Ford 4.0L V6 SOHC engine is found in a number of models, including the Ford Ranger, Ford Sport Trac, Ford Mustang, and the Ford Explorer. It was manufactured starting in 2001<--- WRONG Started in 1997 for the Explorer
The SOHC version was introduced in 1997 in the Ford Explorer, alongside the original pushrod version
http://en.wikipedia.org/wiki/Ford_Cologne_V6_engine#4.0
 




locknload1

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I picked up a replacement here.
http://www.am-autoparts.com/1999/Ford/Explorer/ThermostatHousingRel.html
I have to admit that at first I was hesitant to buy parts from this company a few years ago because the prices are so low but after buying everything from o2 sensors to complete brake and rotor combos. They haven't disappointed me yet.

I replaced the thermostat on a 99 Explorer 4.0 SOHC and now it is leaking from the housing. It does have a new o-ring gasket Duralast/Flel-pro #35617 and the 3 bolts are tight. I don't understand why it is leaking? Any ideas or suggestions? Maybe use some RTV?

2u5eyyb.jpg
 




gnx547

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Before I replaced the thermostat, the housing was not leaking. Can I just use RTV to seal the housing?
 




swshawaii

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Before I replaced the thermostat, the housing was not leaking. Can I just use RTV to seal the housing?
The lower housing splits apart from it's sonically welded seams. Never heard of a long term repair using RTV or two part epoxy.
You can try sealing with RTV sealant, but I'll bet odds it will leak in a very short time. Don't cut corners, this isn't a difficult job,
just confined and time consuming. Search "lower thermostat housing", it's one of the most common failures with the 4.0L SOHC.
 




gnx547

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I removed the housing and I notice in the valley there is a lot of coolant, I'm pretty sure it is from the factory housing. But how would I know if it was the intake manifold gaskets that are bad?

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swshawaii

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That's all coolant residue in the valley. There's no coolant running through the intake manifold.
Gasket leaks will usually throw a CEL, lean trouble codes, and cause your engine to run poorly.
 




gnx547

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Before I removed the housing I was having a hard time with this wire loom, getting it over the sensor because there is no slack at all. How do I go about getting this wire loom out of the way? I removed one tab holding the loom but still there is not enough slack to get it out of the way. I know I will have a hard time installing the new housing with this wire loom in the way.


vyqjph.jpg

2vuk8c0.jpg
 




swshawaii

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See step 4 in the linked "how to" above. Looks like you broke the nipple for the bypass hose. Make sure the broken piece doesn't get into the cooling system. Be especially careful with the three lower housing alignment tabs, and o-ring seals when reinstalling.
 




drdoom

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I believe you are referring to the CKP harness, it attaches to the front of the engine, with a few of those dreadful white barbed wire guides. Definitely worth moving out of the way.
 




gnx547

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See step 4 in the linked "how to" above. Looks like you broke the nipple for the bypass hose. Make sure the broken piece doesn't get into the cooling system. Be especially careful with the three lower housing alignment tabs, and o-ring seals when reinstalling.

When I removed the bottom hose, it broke and I think a few pieces fell down in the water pump. Will this be a big problem? Maybe when I remove the hose I might be able to see some pieces that fell down. Or pour water down and flush it out? I read step 4 and it does not talk about removing the crankshaft wire harness.

http://bengrosser.com/howto/fordthermostat/remove-thermostat-disconnect-sensors.php

I believe you are referring to the CKP harness, it attaches to the front of the engine, with a few of those dreadful white barbed wire guides. Definitely worth moving out of the way.

What is the best way to get it out? I was prying a little bit but nothing.
 




PAExplorerXLT

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What was wrong with the thermostat?
 








gnx547

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I bought the new housing and installed the new coolant sensors. The one with the black connecter sits higher than the other one. Is this normal? The sensor is tight and underneath I can see some extra threads. Does it need to be turned some more? I'm thinking it is to high and I might not be able to get the connector on. I'm afraid if I turn it some more it might break. Does it look right?

2nhnx4z.jpg
 




PAExplorerXLT

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Is that plastic? Be careful. Did they make a metallic one?
 




gnx547

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Yes it is plastic, I believe they are all plastic. Even the OEM is plastic
 




swshawaii

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gnx547

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I could not compare the threads to the old one because, when I removed the sensor it broke off the plastic and the threads are stuck on there. I did not use teflon tape but I use thread sealant.
 




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