02 4.0L coolant leak under intake manifold

[thoorn]

I have an 02 4.0L that is leaking coolant underneath the intake manifold. I look just behind the thermostat housing, up underneath the manifold, and there is large puddles of coolant. I have found many posts about intake manifold coolant leaks, but it appears that in 01-03, they have a new design for the intake manifold. It no longer has coolant running through it from what I can tell. What else could be leaking coolant under there? There is some sort of electrical connector under there that looks like a sensor of some sort (possible knock sensor) and a plug similar to a freeze plug. I am really hoping it isn't head gasket. The engine runs fine, no codes, good idle, good power, and no smoke that I can see from the tail pipe. Anyone have a similar leak or an idea of what could be happening?

 

[Tee Rev]

The thermostat housing can split, or the o-ring seals on the temp sensors can rot & leak.
I had the housing split on my 06 last year.

 

[thoorn]

Yes, it turns out to be leaking from the housing. So far, I have gotten 2 of the three bolts out. There is always one that likes to be stubborn.

I have another question. There are two sensors in the housing. I imagine one is a temp sensor, but what is the other one? I want to replace, but I am not sure what each one actually is.

 

[Tee Rev]

They are both temp sensors, one is for the gauge the other is for the ECU.
If you loosen the intake bolts, it'll give you some much needed room to remove & reinstall everything.

 

[thoorn]

Are they both the same part number?

Also, if I loosen the manifold bolts, will I risk having intake leak afterwards?

 

[Tee Rev]

You'll know after you remove them. My 06 had two different part #'s, so I ordered one of each. Turned out that both were the same?! so I had to make an exchange.

If you don't remove the intake bolts completely & you're somewhat careful, you won't have a problem.

*****When you get the new housing & sensors, test fit the sensor. I had to get a different housing because the new sensors & o-ring seals were loose in the housing.*****

 

[adsm08]

You 100% do not need to remove or even loosen the intake to get the thermostat housing out. You just need a long wrench.

 

[Tee Rev]

You 100% do not need to remove or even loosen the intake to get the thermostat housing out. You just need a long wrench.

You are 100% correct!!
But if you want to make it an easier job, loosen the intake!

 

[black_demon69]

You are 100% correct!!
But if you want to make it an easier job, loosen the intake!

Imo you only loosen intake bolts when you intend to replace gaskets. Just to much risk of intake leaking afteryou tighten them back up.

 

[Tee Rev]

Imo you only loosen intake bolts when you intend to replace gaskets. Just to much risk of intake leaking afteryou tighten them back up.

You are certainly entitled to your opinion, but the chance of that happening with the captured rubber gasket on the SOHC's intake is pretty slim.

I'm not the first to do it this way without issue & I definitely won't be the last.

I'm just trying to help the OP with my personal experience with this issue.

 

[black_demon69]

You are certainly entitled to your opinion, but the chance of that happening with the captured rubber gasket on the SOHC's intake is pretty slim.

I'm not the first to do it this way without issue & I definitely won't be the last.

I'm just trying to help the OP with my personal experience with this issue.

yes but for the sake of argument and assuming that someone less mechanically inclined and happens to have the older 4.0l ohv this method could get them into trouble. and i have seen "captured rubber gasket" s fail once removed. also it seems like alot more work again imo..

ps this is a good discussion and no offense is taken or meant by this post. also OP should read and make a decision based on tools available, level of experience, and what they feel comfortable with....

 

[XLTsplash]

The leaking plastic thermostat housing is so common you can buy a new one at Napa Auto parts. Ford sell everything in pieces. Napa sells the complete thermostat housing assembly upper and lower with seals and thermostat for a lot less money. The aftermarket part seems to work as well as the Ford part in this case.

 

[Chris_1]

I don't think you should touch the intake bolts either, for what that's worth. Especially if you have to ask the difference between a temp sensor and a temp sender. Nothing wrong with asking that - but don't make the job bigger for someone who's learning is all.