Engine 89 GT Thermostat replacement woes

gearhead77 · Mar 30, 2019

So, first off, someone did not think of thermostat replacement when they decided how the thermostat housing should bolt to the engine. That lower t-stat bolt is the most effin stupid thing I've seen thus far on this car. I'm not a tech and this is my first big project car but wow, WTF? A slight change to the casting for the water pump would have made this a simple task.

Obviously there's a trick to this thermostat replacement. I notice there aren't any videos for this and it seems LMR (and others) have videos for everything. If you've got a method, I'd love to hear it.

Because while while I was trying to screw the t-stat housing back on, I mangled the threads in the lower bolt hole. They aren't totally gone, but might as well be. No bolt will go in without binding and that's without trying to put the housing on at the same time. Tips, suggestions, etc. are appreciated on how to fix this bolt hole problem. Re-tap the threads?

Thanks in advance.

Blown88GT · Mar 30, 2019

It's just one of many stupid things Ford did. No different from Toyota or any of the others.
Engineering vs. Bean Counters.
Score: Engineering = 5; Bean Counters = 95

gearhead77 · Mar 30, 2019

Blown88GT said:
It's just one of many stupid things Ford did. No different from Toyota or any of the others.
Engineering vs. Bean Counters.
Score: Engineering = 5; Bean Counters = 95

Nah, I get it, cars are meant to be screwed together cheaply and effectively, not taken apart. No manufacturer of any nationality is immune.

Rt jam · Mar 30, 2019

Silicone the thermostat and gasket to the housing. Insert the bolts to ensure the holes are lined up. When it is dry enough to be held sideways and not fall down. Silicone the other side of the gasket and place onto the manifold.
The best tool is a swivel socket. Not a socket on a swivel. As for retapping the bolt holes. Technically this will not restore threads that have been crossthreaded. Retapping is only good for cleaning threads.

gearhead77 · Mar 30, 2019

Rt jam said:
Silicone the thermostat and gasket to the housing. Insert the bolts to ensure the holes are lined up. When it is dry enough to be held sideways and not fall down. Silicone the other side of the gasket and place onto the manifold.
The best tool is a swivel socket. Not a socket on a swivel. As for retapping the bolt holes. Technically this will not restore threads that have been crossthreaded. Retapping is only good for cleaning threads.

I’m a noob to this, but the Fel-Pro site (which I have) and a few other old threads I found on here say you shouldn’t use anything on the gasket. It seems to be quite the argument on whether to use a sealant or not.

The swivel socket looks like it will work. The main problem is trying to clear the water pump housing to get a socket on the bolt.

I might be able to salvage the threads. They aren’t entirely ruined that I can tell. Maybe a chaser will work.

Rdub6 · Mar 30, 2019

Rt jam said:
Silicone the thermostat and gasket to the housing. Insert the bolts to ensure the holes are lined up. When it is dry enough to be held sideways and not fall down. Silicone the other side of the gasket and place onto the manifold.
The best tool is a swivel socket. Not a socket on a swivel. As for retapping the bolt holes. Technically this will not restore threads that have been crossthreaded. Retapping is only good for cleaning threads.

I inherited a few of those “socket swivels” from my dad, and sometimes that’s exactly what you need! A swivel plus the socket is just sometimes too long!

jrichker · Mar 30, 2019

A 1/4" drive swivel socket is what you need. Make friends with the Snap-On or MAC tool sales guy...

gearhead77 · Mar 31, 2019

jrichker said:
A 1/4" drive swivel socket is what you need. Make friends with the Snap-On or MAC tool sales guy...

Ok, so I bought a 1/4 drive flex socket set ( thanks Amazon). Do I need to put sealant on the gasket? The gasket maker (Fel-pro) seems to say no, but I’ve searched various old threads here and it seems like everyone has a different opinion.

General karthief · Mar 31, 2019

A skim coat will hold the gasket and stat in place while you manipulate the housing into place and start the bolts. If I remember correctly the difficult bolt is shorter than the other, I would use a small amount of anti seize on the threads and I stick the bolts into the housing then install the housing.

Steel1 · Mar 31, 2019

Last time I did that I used this gasket, it's self adhesive. Oh, and a lot of cussing.
https://www.rockauto.com/en/moreinfo.php?pk=48929&jsn=3

Blown88GT · Mar 31, 2019

gearhead77 said:
Ok, so I bought a 1/4 drive flex socket set ( thanks Amazon). Do I need to put sealant on the gasket? The gasket maker (Fel-pro) seems to say no, but I’ve searched various old threads here and it seems like everyone has a different opinion.

I did both. They not precision machined surfaces, i.e. not a head gasket. Sealants & adhesives today are better than 30 years ago.

Wayne Waldrep · Mar 31, 2019

Another tip that I do is get a piece of sand paper. I use one of the full sheets that's about a foot square. If you want, you can tape two opposing sides to a flat table. Place the housing surface that the thermostat goes in on the paper. Sand back and forth. Use this to clean up the surface of pitting or whatever. Don't take too much off. You are just looking for a clean flat surface. This helps with sealing.

gearhead77 · Mar 31, 2019

Blown88GT said:
I did both. They not precision machined surfaces, i.e. not a head gasket. Sealants & adhesives today are better than 30 years ago.

As are gaskets, but I understand your point completely.

gearhead77 · Mar 31, 2019

Two questions:

The sealer: Would the little package of it that's sold at the checkout of nearly every autoparts store be what I'm looking for or should I get a tube of stuff? This car will need other gaskets done, but I know this stuff doesn't last forever once opened.

The sequence for putting it back on:

(The threads aren't as bad as I thought. I chased them a bit with just the bolt today and it worked.)

As far as the sequence for putting it all back together:

-Apply sealer to gasket, place gasket on inlet at the block. Let sit for silicone to set-up.
- Thermostat with spring-end toward front of car and "burp" hole at the top into gasket OR
-Thermostat into housing (with a bit of sealer to hold) let it set, then place whole neck and tstat into the inlet and start bolts.

- Seems like its best to snug the little (top) bolt first to hold it all, then deal with the $%#@ bottom one.

Thanks all.

General karthief · Mar 31, 2019

I put a skim coat of rtv on the housing, stick the thermostat in, hole at the top then the gasket, let it sit a few minutes, stick the difficult bolt into the housing and start that one first. You can cut the head off a bolt and thread it into the top hole first as a guide too if it makes it easier

Wayne Waldrep · Mar 31, 2019

I'd suggest Permatex Ultra Black. I won't use anything else.
Also, two things that are important in my opinion when using sealant. Let it tack before install. Second, after install, snug the bolts and leave for a day before any use at all. No coolant etc touching. Then finish tightening. Keep in mind there are tons of ways to do things. These are just what I do.

General karthief · Mar 31, 2019

I use blue, just enough to hold everything together.
black works good too. All your doing is holding the gasket and stat in place

Wayne Waldrep · Mar 31, 2019

General karthief said:
I put a skim coat of rtv on the housing, stick the thermostat in, hole at the top then the gasket, let it sit a few minutes, stick the difficult bolt into the housing and start that one first. You can cut the head off a bolt and thread it into the top hole first as a guide too if it makes it easier

Same order I like to do. I also put a skim coat on the intake side of the gasket.

gearhead77 · Mar 31, 2019

General karthief said:
I put a skim coat of rtv on the housing, stick the thermostat in, hole at the top then the gasket, let it sit a few minutes, stick the difficult bolt into the housing and start that one first. You can cut the head off a bolt and thread it into the top hole first as a guide too if it makes it easier

Using a guide for the top bolt while working the bottom one. I like it.

gearhead77 · Apr 11, 2019

Anyone have a preference on water outlet gasket? I ordered a bunch from RockAuto. 2 Mahle ( 14 cents per gasket!) a Motorcraft and Fel-Pro. I've screwed up twice now, butchering two Fel-Pro and still getting a good leak from the bottom of the housing. I think I've figured out where I've been going wrong I was wondering what preference everyone has for gaskets, if any. I'm inclined to go with the Motorcraft for my third and hopefully final attempt at this, since it's OEM.

Engine 89 GT Thermostat replacement woes

gearhead77

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Rdub6

So while I wait to figure out my rear end issues

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wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

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Engine 89 GT Thermostat replacement woes

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wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

Before I post a pic, do you have one of yours?

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