5.8 blew thermostat gasket - Ford Bronco Forum
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post #1 of 16 (permalink) Old 03-16-2017, 12:40 AM Thread Starter
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5.8 blew thermostat gasket

So this happened a few hours ago, it's cold and dark so I haven't had a chance to dig deeper.

Cranked the bronco it was about 32 degrees out. It warmed up for maybe 5 minutes before I hit the road. I may have gotten on the throttle a bit about 2 minutes into the drive, so 7 minutes after startup.

I didn't notice anything at the time. But about 4 miles later I smelled coolant and pulled over to check and some some drips underneath the motor. Popped the hood and found a good sized leaks coming from the thermostat housing.

Is it possible that the sudden acceleration and force with the thermostat closed could have blown the gasket?

I'll dig into it in more depth when it's warmer and the sun is up tomorrow.

Thanks




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post #2 of 16 (permalink) Old 03-16-2017, 01:19 AM Thread Starter
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I should qualify my statement about the throttle. I got on it. Broke traction from a stop. I don't do not often. But it was in the moment and had a great song playing.


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post #3 of 16 (permalink) Old 03-16-2017, 05:08 AM
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More likely that you had a differential heating issue that broke the seal. Possibly the thermal shock may have broken something.
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post #4 of 16 (permalink) Old 03-17-2017, 01:23 AM Thread Starter
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So it's definitely leaking from the thermostat housing. Not sure if it's the hose or the gasket yet. Didn't have much time to mess around with it today. I've got a pressure tester on loan to dig deeper this weekend.


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post #5 of 16 (permalink) Old 03-17-2017, 01:51 AM
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Check the hose for pin hole leaks by putting a "pressure guage" on the radiator neck (12lbs max) and see where the leak is actually coming from, though it's not uncommon for T-stat gaskets to leak from the bottom so I'd replace that as a matter of routine maintenance and see how it turns out with the hose....

Good Luck ~
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post #6 of 16 (permalink) Old 03-17-2017, 02:14 AM Thread Starter
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Originally Posted by JKossarides View Post
Check the hose for pin hole leaks by putting a "pressure guage" on the radiator neck (12lbs max) and see where the leak is actually coming from, though it's not uncommon for T-stat gaskets to leak from the bottom so I'd replace that as a matter of routine maintenance and see how it turns out with the hose....

Good Luck ~
Thanks for the tip, buddy dropped off the pressure gauge earlier so I'll play with that tomorrow. It's very strange since I replaced the thermostat and gasket at the same time I did the water pump and timing chain. It has been bone dry up there ever since. All of the sudden, it sprang a leak after some hard acceleration while cold.

I'll be able to better pinpoint it with the pressure guage and without the fan spinning.

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post #7 of 16 (permalink) Old 03-17-2017, 02:19 AM Thread Starter
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I picked this thermostat housing up from VatoZone yesterday just in case: More Information for DORMAN 9021001

I'm having a real hard time finding any reviews, I guess this must be a fairly new part.

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post #8 of 16 (permalink) Old 03-17-2017, 02:31 AM Thread Starter
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Can someone shed some light on this for me?? What in the world could possibly be different between a 1994 5.8 and a 1995 5.8 that it has a different thermostat housing?

This thread (thermostat housing is leaking) suggests that he solved his problem once realizing he was given the wrong part, he has a 94 and was given the housing for a 95 and had leaks, once getting the right part for the 94, his problem was resolved.

I checked autozone and they do list two different part numbers, for the 94 it's 902-1001 and for the 95 it's 902-1019.

What is different on the intake manifold between the years?

Thanks

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post #9 of 16 (permalink) Old 03-17-2017, 11:30 AM
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Quote:
Originally Posted by jtetterton View Post
Can someone shed some light on this for me?? What in the world could possibly be different between a 1994 5.8 and a 1995 5.8 that it has a different thermostat housing?

This thread (thermostat housing is leaking) suggests that he solved his problem once realizing he was given the wrong part, he has a 94 and was given the housing for a 95 and had leaks, once getting the right part for the 94, his problem was resolved.

I checked autozone and they do list two different part numbers, for the 94 it's 902-1001 and for the 95 it's 902-1019.

What is different on the intake manifold between the years?

Thanks
902-1001 has the threaded port on top, 902-1019 does not. Either will work. Ford has used the same mounting pattern on the housing since the 60's.
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post #10 of 16 (permalink) Old 03-17-2017, 01:54 PM Thread Starter
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That's what I thought, what's the point of the threaded port? It's not needed on my 5.8. I also thought it was odd that the problem solved that OP's problem, perhaps the first one was just warped.

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post #11 of 16 (permalink) Old 03-17-2017, 02:18 PM
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Quote:
Originally Posted by jtetterton View Post
That's what I thought, what's the point of the threaded port? It's not needed on my 5.8. I also thought it was odd that the problem solved that OP's problem, perhaps the first one was just warped.
Temp sender for aftermarket gauge
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post #12 of 16 (permalink) Old 03-17-2017, 04:01 PM
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If you have the type with the threaded port and it remains unused, you MUST remove the port, seal the threads and reinstall tight or you WILL have leaks.

As for the fitment, in my experience, if you don't have the thermostat seated exactly right in the proper indentations, the whole seal/housing won't sit flush and you will end up with leaking. It sounds really simple, but can actually be a decent PITA to get all put together properly.

Double check the port/threads as well as the installation. You shouldn't need anything more than a standard Fel-Pro gasket to seal properly.




Quote:
Originally Posted by jtetterton View Post
That's what I thought, what's the point of the threaded port? It's not needed on my 5.8. I also thought it was odd that the problem solved that OP's problem, perhaps the first one was just warped.
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post #13 of 16 (permalink) Old 03-17-2017, 04:06 PM Thread Starter
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Quote:
Originally Posted by csilvestri View Post
If you have the type with the threaded port and it remains unused, you MUST remove the port, seal the threads and reinstall tight or you WILL have leaks.



As for the fitment, in my experience, if you don't have the thermostat seated exactly right in the proper indentations, the whole seal/housing won't sit flush and you will end up with leaking. It sounds really simple, but can actually be a decent PITA to get all put together properly.



Double check the port/threads as well as the installation. You shouldn't need anything more than a standard Fel-Pro gasket to seal properly.


My original housing, which is leaking, does not have a threaded port. I suspect the thermostat may not be swayed properly as everyone has mentioned. Since I already have the dorman replacement should I use it or keep the oem one of its not damaged?

The dorman has the threaded port so I would need to seal it.


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post #14 of 16 (permalink) Old 03-17-2017, 04:10 PM
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I tried to reuse my original housing and even though it was super clean and appeared to be in good shape, it still leaked once installed. I then got a new one (threaded type) and installed. The leak was gone EXCEPT for dripping from the threads. I had assumed that port was sealed out of the box... not so. Anyway, a little mess and cussing later, I sealed up the threads and have been good to go since.
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post #15 of 16 (permalink) Old 03-17-2017, 05:47 PM Thread Starter
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Dodged a bullet. With the pressure tester on I was able to determine, without loosing a finger, that the leak was coming from the hose where it meets the housing. I thought the clamp was pretty tight but I ran it down some more and the leak appeared to stop.

Thanks for all the help guys, love coming here to get solid feedback and advice.


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post #16 of 16 (permalink) Old 03-19-2017, 06:54 PM
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Glad it was a simple fix for you and it's sorted out! ~
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