Thermostat and Thermostat housing and coupling

[Corvette95]

I removed my thermostat housing since I had the room, I went through the solutions, seems to be a lot of issues about which thermostat will work and which won't. I ordered a 180 degree "fail safe" thermostat from RockAuto and gasket/seal (pic below minus seal) . It looks correct as to what was posted online, but the thread was from 2013. I don't have the new thermostat in my hands yet, it is due to arrive Monday. What is so different about the LT5 thermostat? I also want to get a new plastic retainer for the housing (see pics below), and maybe a new coupler if available. There is only one bolt holding the thermostat housing on, what precautions should I take in removing the old thermostat and installing a new one? It looks pretty simple with the housing off, but have read many threads saying how difficult it is to get the housing back on with the seal in place. I know to when it comes to it, I need to get the air out, there are several different methods, I was going to try to reverse bleed it with air blowing in from the driver side and using vacuum at the tank....suggestions? See pics below...I am planning on soda blasting the housing before I put it back on. (1990)

[owwdee]

For the nipple (coupler), Jerry has you covered. https://www.jerrysgaskets.com/nipple-heater-coolant-return-90-95-7c4/

Use care when removing this nipple. I have read about them breaking off in the housing.

Dorman 800-407 for the retainer clip. The large is 3/4”, the nipple side is 5/8”, but it is included with the new nipple from Jerry.

Putting the thermostat in is a piece of cake when the whole housing is out of the car.

Jerry used to sell the correct thermostat. Doesn’t look like he has them in stock now. I believe Stant is the correct brand, but can be a crapshoot on whether what is in the box is the right one.

Marc Haibeck has good articles on refilling the coolant.

[Corvette95]

Thanks! I have had pretty good luck with bolts not breaking so far, only victim was the small single butterfly plate brass screws in the throttle body. Let the cam covers bolts sit with WD40 for 4 days. Letting the nipple on this sit with WD40 now.

For the nipple (coupler), Jerry has you covered. https://www.jerrysgaskets.com/nipple-heater-coolant-return-90-95-7c4/

Use care when removing this nipple. I have read about them breaking off in the housing.

Dorman 800-407 for the retainer clip. The large is 3/4”, the nipple side is 5/8”, but it is included with the new nipple from Jerry.

Putting the thermostat in is a piece of cake when the whole housing is out of the car.

Jerry used to sell the correct thermostat. Doesn’t look like he has them in stock now. I believe Stant is the correct brand, but can be a crapshoot on whether what is in the box is the right one.

Marc Haibeck has good articles on refilling the coolant.

[Dynomite]

https://cimg4.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x500-1/80-img_2936_9a468a0b8b16da085f782f9e81be5105bdafb1cc. jpghttps://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x500-1/80-23d8abf6_05e1_436c_8049_d58b3ad16c03_1__8b27a2c053 6d0e4ab4735290f0c0b6ead9daffa4.png

Post 7 - Thermostats, Fans, Water Pump, and Radiators (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp.html#post1580070558)

[Corvette95]

Thanks, I read that posts, but can't I use the thermostat I ordered?

[A26B]

Thanks! I have had pretty good luck with bolts not breaking so far, only victim was the small single butterfly plate brass screws in the throttle body. Let the cam covers bolts sit with WD40 for 4 days. Letting the nipple on this sit with WD40 now.

owwdee is right about being careful removing the heater hose connector on the T-stat housing. It's not made from steel. It's a fragile, pot metal and breaks easily after all these years of corrosion. Soaking in a good penetrant for a day or so and heating the housing before trying to break it loose could help. Once it is removed, you should chase the threads in the housing to clean them up. The thread is a NPT, which is a tapered thread, so run the tap deep enough to clean up the threads, but no deeper than what is necessary.

[Corvette95]

I don't think I have a chaser that big at home and we are under quarantine. I have been paying for UPS pick up service to send out the parts for porting to Pete, FPR for rebuild to Jagdpanzer and tensioner to Marc H
Do you know the thread size off hand, I might can get one from Amazon. (this is why I have time to work on the car right now, my business is closed)

owwdee is right about being careful removing the heater hose connector on the T-stat housing. It's not made from steel. It's a fragile, pot metal and breaks easily after all these years of corrosion. Soaking in a good penetrant for a day or so and heating the housing before trying to break it loose could help. Once it is removed, you should chase the threads in the housing to clean them up. The thread is a NPT, which is a tapered thread, so run the tap deep enough to clean up the threads, but no deeper than what is necessary.

[Corvette95]

I got the coupling off... used heat, it was very tight, but came off, threads look ok, would certainly run a chaser through them if I can, the 13 mm bolt that is still on the thermostat cover is being difficult. It is soaking in WD40 right now. I ad sprayed both of them yesterday afternoon and let them sit over night.

[Ccmano]

Be careful with the thermostats you receive from suppliers. More often that not their wrong. Only the Stant long thermostat with the cut outs in the bottom piece is correct. I actually got a wrong thermostat in a correct Stant box! Read what happened to me...
H
:cheers:

http://www.zr1.net/forum/showthread.php?p=280824#post280824

[Corvette95]

I read the thread, what is special about the stant other than the two cut outs, I saw the Delco one you bought, why was that not usable? I haven't located a Stant. Here is my OE one...

[Corvette95]

I found this one on ebay, says it is new, box looks rough....

[A26B]

I read the thread, what is special about the stant other than the two cut outs, I saw the Delco one you bought, why was that not usable? I haven't located a Stant. Here is my OE one...

If you don't find a correct one, you could just check the original one. Put it in a small saucepan of water, using a meat thermometer, turn the heat on medium & see if yours opens fully at 180~185f.

[A26B]

I found this one on ebay, says it is new, box looks rough....

I wouldn't be concerned with the box. Stat looks right.

[Ccmano]

I read the thread, what is special about the stant other than the two cut outs, I saw the Delco one you bought, why was that not usable? I haven't located a Stant. Here is my OE one...

I had the same question you did. I was cautioned by people who know more than I including Jerry and Marc Haibeck. As I understand it the lower plate is the bypass valve. The cuts allow hot coolant to the sensor on the thermostat allowing it to open at the proper time. The attached article by Marc explains how it works.
H
:cheers:

http://www.zr1specialist.com/HAT%20Web/facts%20and%20failures/thermostat.htm

[Corvette95]

There is another thermostat on Ebay that looks to be a defective unit per Marc's write up.... look at the spring...
https://www.ebay.com/itm/Engine-Coolant-Thermostat-OE-Type-Thermostat-Stant-fits-90-95-Corvette-5-7L-V8/293503629128?epid=74950985&hash=item44562df748:g:mOwAAOSwGIZeZASk

[Jitse]

Another way to fix the "weak" heat hose connectors problem can be done by welding AN fittings to the thermostat housing and using Jiffi-tite quick connectors.
I changed out the hoses too, 30 year old rubber.... reliability
Modified to 10 AN and 12 AN hose size.

used 2x heater core to radiator surge tank hoses, one hose modified to connect with a 10 AN hose to barb adapter ( 5/8").

1x weld fittings 10AN and 1x 12AN aluminium for on the housing.

1x Jiffi-tite 10 AN quick connector 1 x Jiffi-tite 12 AN quick connector, do not forget to order the female part which screws on the weld AN fittings.

And when finished you can have a brand new heater hose/ to thermostat housing assembly, but if you like te keep everything Vin correct, this is not the way to go.

Regards, Jitse

[Jitse]

Some more pictures:

[Corvette95]

Thanks, I have seen your write up on that before. If the stock line doesn't hold ( I am working on it as we speak - with an other Registry member that is sourcing some donor parts) that will be my go to. I may reach out if that is the case. I am trying something new I haven't done before, I am completing a 12 hour anti-freeze low temp soak of the thermostat housing on the stove in a super large pot for cleaning. Have no idea if is a hoax or not, if it doesn't clean up, going to have it powder coated too.

[A26B]

Very nice job Jitse!!

[secondchance]

I am completing a 12 hour anti-freeze low temp soak of the thermostat housing on the stove in a super large pot for cleaning. Have no idea if is a hoax or not, if it doesn't clean up, going to have it powder coated too.

If you are trying to make thermostat housing look clean, you might try aluminum wheel cleaner spray and sunlight followed by a water rinse.

[Ccmano]

Thanks, I have seen your write up on that before. If the stock line doesn't hold ( I am working on it as we speak - with an other Registry member that is sourcing some donor parts) that will be my go to. I may reach out if that is the case. I am trying something new I haven't done before, I am completing a 12 hour anti-freeze low temp soak of the thermostat housing on the stove in a super large pot for cleaning. Have no idea if is a hoax or not, if it doesn't clean up, going to have it powder coated too.

I use this.... comes out fantastic!
H
:cheers:

https://farm66.staticflickr.com/65535/49770352163_1ddaed3e41_c.jpg (https://flic.kr/p/2iQ34J4)

[Corvette95]

Is that acidic?

[Ccmano]

Is that acidic?

Not sure if it’s acidic or basic, it’s one of those because it interacts with the metal. Here’s how my suspension arms came out.
H
:cheers:

https://farm66.staticflickr.com/65535/49770660478_50a0ed5085_c.jpg (https://flic.kr/p/2iQ4DnQ)

[Jagdpanzer]

Ingredients listed here

http://s7d9.scene7.com/is/content/GenuinePartsCompany/156818746pdf


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[Corvette95]

I asked about the acid because I wondered if it could be used for parts ON the car, of course, most anything will ruin the leaf springs, I will get some and use if for the parts OFF THE CAR while I can. Thanks for the suggestion, and thanks Phil for the ingredients! BTW those suspension arms looks great!