4.0 SOHC Thermostat housing | Ford Explorer Forums - Serious Explorations

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4.0 SOHC Thermostat housing

rmelo99

Member
Joined
July 27, 2004
Messages
23
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City, State
Bridgeport, CT
Year, Model & Trim Level
1998 Explorer Sport
I've developed another leak at the thermostat housing on my 1998 4.0 SOHC.

I've found the post to upgrade to a better assembly, and I would be inclined to do so however the posts says to reuse the old upper half of the housing and that's where my problem is.

I found a "non-oem" upper half at autozone to replace my cracked factory one. That worked for a couple months and another leak. I'm on my second one and same problem. I think the aftermarket one warps or something.

I either need to located a "good" oem upper half to put on my existing lower, or do the uprgraded swap and still need an upper?

Please help. The explorer has been out of commission since end of winter!! Need to get this bad boy fixed!!
 



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two days ago i noticed this exact same leak on my 99 eddie. im hoping my thermo housing isnt craked and its just the gasket. my local advance auto parts has the felpro replacelment and a stant thermostat for about $16

ill be following this thread for any advice/info
 






Not sure who made the replacement I purchased but it looks like the stock on...but is not the same.

When I put the first one in I had to cut about 1/4"or so of the hose bc of the outlet angle being off by just a bit.

The 2 I've had seem to warp and leak on the backside where there is no screw. The 3 screws are all along the front.
 






ok, so I bought aftermarket thermostat housing cover number 3.

It was reinstalled yesterday, this time with some (cough) gasket sealer in a tube around the rim.

I'm letting it setup overnight(full cure time) and will fill up with antifreeze today.

I'm all for doing the upgrade to the sport-trac thermostat housing, but I need some help on the original post!
 






Ok, so I filled up the car with water to do a leak test. I ran it for a while and all was good.

Then water started leaking from below. I can't tell where the water is coming from but it doesn't appear to be coming from the thermostat housing. It was more than a drip, more like slow leak.

The lower radiator hose looks ok. Not new but ok.
Does that hose go to the engine or up to the lower part of the thermostat housing?

Help me find this leak where else could it be? The engine oil is ok, I think that means I'm ok with gasket right?
 






Check the bypass hose.
 






Ok...back to square one. Good news is I found the leak, bad news is it's the upper housing cap.

These aftermarket ones from AutoZone are not 100% like the stock one. The water outlet/house connection angle is off by just a few degrees.

If I put the housing in place w/o the hose connected it sits flat all around.
Because of the angle difference there is not enough clearance for the hose. The outlet touches a "vaccum" or some other line that sits behind the thermostat housing. When the hose is connected it pushes up against that line and lifts the housing in the rear, therby causing a leak.

So I need to get another stock housing cover or a better aftermarket one.
No more autozone. I checked RockAuto and they carry 2 different ones. One by ACDelco and another by FourSeasons.

I fear this will happen again with another aftermarket one. You can't buy the stock one from Ford as many others have found.

HEEELLLLPPP!!
 






Anyone use the ACDelco part? It's $38 and the local parts place can get it for me....but I need to be sure I won't have the same problem.
 






What was your final solution? I have a 2002 with the 4.0 and have a leak at the mating line.
 






My 2000 with 188k miles is now showing signs of this exact same thermostat housing issue. I had it pressure checked this morning and was told the leak was coming from "around the temperature sensors". I then Googled and found this site. Looks like I may be in for a housing replacement. I will investigate further in the next few days.
 






Ok, I looked closed this evening when I got home and there is a bit of antifreeze buildup on and around the thermostat housing. I was unable to get a real close look at it as the intake manifold was in the way, but from researching this and other message boards, it's a pretty safe guess the housing could be cracked and leaking. O'Reilly Auto can get me a Dorman replacement for $149. My question is, can this be replaced without removing the intake manifold?
http://www.oreillyauto.com/site/c/d...keyword=thermostat+housing&pt=C0420&ppt=C0331
 






Let me ask another question. My brother-in-law works for CarMax and he can get me a replacement housing at a great price. My question is, my current housing has 2 sensors attached to it, and they appear to be the "o ring" type. My new housing has threaded connections. Does anyone know (1) what the part numbers for the sensors are, and (2) what are the sensors? I know one is the temp sending unit but what is the other one?
 












Ah, I see. Thank you very much.
 






Just replaced mine last week. Crack on underside. Had to pull the intake to swap. Now the horrible news. Used the Ford redesined one (made in Mexico, not Germany). Had to use new sensors, Thermostat and bypass hose. $350 in parts alone.
 






I just got my parts in from midtennfordparts.com and the DY1004 sensor came without an o-ring. Is that right?

Can I get one at the parts store?

Not to hi-jack this thread...sorry.
 






Just replaced mine last week. Crack on underside. Had to pull the intake to swap. Now the horrible news. Used the Ford redesined one (made in Mexico, not Germany). Had to use new sensors, Thermostat and bypass hose. $350 in parts alone.

Thanks joecrna. That's typical for the way my luck runs. I'm hoping you only had to remove the upper intake and not the whole thing. I'll probably be able to get the parts through my bro-in-law for about $200. Now I just have to find the time to get it done.
 












I've developed another leak at the thermostat housing on my 1998 4.0 SOHC.

I've found the post to upgrade to a better assembly, and I would be inclined to do so however the posts says to reuse the old upper half of the housing and that's where my problem is.

I found a "non-oem" upper half at autozone to replace my cracked factory one. That worked for a couple months and another leak. I'm on my second one and same problem. I think the aftermarket one warps or something.

I either need to located a "good" oem upper half to put on my existing lower, or do the uprgraded swap and still need an upper?

Please help. The explorer has been out of commission since end of winter!! Need to get this bad boy fixed!!
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





I've developed another leak at the thermostat housing on my 1998 4.0 SOHC.

I've found the post to upgrade to a better assembly, and I would be inclined to do so however the posts says to reuse the old upper half of the housing and that's where my problem is.

I found a "non-oem" upper half at autozone to replace my cracked factory one. That worked for a couple months and another leak. I'm on my second one and same problem. I think the aftermarket one warps or something.

I either need to located a "good" oem upper half to put on my existing lower, or do the uprgraded swap and still need an upper?

Please help. The explorer has been out of commission since end of winter!! Need to get this bad boy fixed!!
 






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