Don't Fear Changing the ST1100 Thermostat!

[JPrieST]

FYI: You can get the o-ring at Napa. Either have them look up the Thermostat o-ring for '80 Civic 1.5 engine, or here is the part number:

ATM TG2903

When I had them look it up under the Civic they first told me it shows a gasket, but after scrolling through they found the o-ring. This has been in my bike for around 4 years now with no problem. You may also be able to find it at other parts stores, but when I tried my local ones other than NAPA, none seemed capable of finding it.

 

[Slasher]

FYI: You can get the o-ring at Napa. Either have them look up the Thermostat o-ring for '80 Civic 1.5 engine, or here is the part number:

ATM TG2903

When I had them look it up under the Civic they first told me it shows a gasket, but after scrolling through they found the o-ring. This has been in my bike for around 4 years now with no problem. You may also be able to find it at other parts stores, but when I tried my local ones other than NAPA, none seemed capable of finding it.

Great info, Thanks for sharing!

 

[acoloreo]

Thanks. Doing the Tstat tomorrow

 

[maximark]

I've changed mine today. Previous owner ( or his mechanic) must have known something about STs because I found stat 180 installed. It look closed but after installing new OEM and O-ring and everything looks back to normal. She's worming up better and she idles better. For some reason that Stat 180 was installed with hole down. Maybe someone knows the reason why would it be like that.
thanks again guys for your help.

 

[sennister]

I've changed mine today. Previous owner ( or his mechanic) must have known something about STs because I found stat 180 installed. It look closed but after installing new OEM and O-ring and everything looks back to normal. She's worming up better and she idles better. For some reason that Stat 180 was installed with hole down. Maybe someone knows the reason why would it be like that.
thanks again guys for your help.

Not sure, mine is hole up.

 

[amad]

I put a new thermostat in mine today, too. The one I got has a little wiggly metal thing in the hole. What is that? I installed it with the hole down. Is that ok?
The first time I installed it with a new o-ring, I filled it with antifreeze and it was leaking like crazy without starting the bike. I took it apart and think I saw that the thermostat had slid out of it's inset which may have caused the housing not to seat properly. Anyway, after putting it back together again (with the original o-ring this time, which didn't look bad), it did not leak. I haven't warmed it up yet because I am waiting until tomorrow to get new spark plugs to put in.

 

[sennister]

I put a new thermostat in mine today, too. The one I got has a little wiggly metal thing in the hole. What is that? I installed it with the hole down. Is that ok?
The first time I installed it with a new o-ring, I filled it with antifreeze and it was leaking like crazy without starting the bike. I took it apart and think I saw that the thermostat had slid out of it's inset which may have caused the housing not to seat properly. Anyway, after putting it back together again (with the original o-ring this time, which didn't look bad), it did not leak. I haven't warmed it up yet because I am waiting until tomorrow to get new spark plugs to put in.

From what I have read they call it a bubble breaker.

I always put them up. I don't know if it is a huge deal if it is down. Maybe someone else will comment on that.

 

[Slasher]

That hole is designed to purge the air out of the system. That is why is should be "up" to purge as much air as possible. I'd say if yours was upside down the PO just didn't know it should ideally be up. Once all the air has worked its way out of the system the hole could be in any position with no difference in function of the thermostat. If your curious, the little brass piece in the hole is called a "jiggle valve".

 

[sennister]

That hole is designed to purge the air out of the system. That is why is should be "up" to purge as much air as possible. I'd say if yours was upside down the PO just didn't know it should ideally be up. Once all the air has worked its way out of the system the hole could be in any position with no difference in function of the thermostat. If your curious, the little brass piece in the hole is called a "jiggle valve".

Yeah, once the air is out I would agree it wouldn't matter. Maybe it will purge the air out faster if it is up. I would imagine once the stat opens up any air in the system should start working its way out.

 

[maximark]

That hole is designed to purge the air out of the system. That is why is should be "up" to purge as much air as possible. I'd say if yours was upside down the PO just didn't know it should ideally be up. Once all the air has worked its way out of the system the hole could be in any position with no difference in function of the thermostat. If your curious, the little brass piece in the hole is called a "jiggle valve".

Thanks for explanation Don.

 

[hotrod1]

Doing a t-stat change on two ST 1100's.

1. Is the Stant just as good as the Fail Safe and/or OEM?
2. I have the "new" Prestone, it states it's good for all makes and models. Good choice?
3. Has anyone flushed the coolant system with Prestone flush or CLR?

Thanks for your help here, trying to get both bikes ready for a ride in three weeks...Rod

 

[Brant]

Yeah, once the air is out I would agree it wouldn't matter. Maybe it will purge the air out faster if it is up. I would imagine once the stat opens up any air in the system should start working its way out.

Actual reality is that is a weep hole so a small amount of coolant passes through from water pump induced pressure until motor warms up coolant to thermostat STARTING to open up partially temp. wise of coolant. As yes, that being there DOES matter!. Majority of thermostats has stamped into metal FACES TO RADIATOR. Spring/pellet assembly ALWAYS faces toward water pump side of flow.

 

[Slasher]

Doing a t-stat change on two ST 1100's.

1. Is the Stant just as good as the Fail Safe and/or OEM?
2. I have the "new" Prestone, it states it's good for all makes and models. Good choice?
3. Has anyone flushed the coolant system with Prestone flush or CLR?

Thanks for your help here, trying to get both bikes ready for a ride in three weeks...Rod

Ive been running the same stant thermostat since I started this thread with no issues. It's not only the cost that makes them appealing but, you can also walk into any auto parts store and buy one.

I cant comment on Prestone coolant but, I'm pretty sure others on here have used it, as long as it is silicate free. I personally use after market honda car anti freeze made by Beck Arnly since that's what the auto parts place had.

There are some pretty impressive videos on you tube of the Prestone flush, but I honestly wouldn't bother unless your cooling system is really dirty. I filled up mine with water, ran it, blew it out, repeat x 3 then filled up with coolant. Also, don't forget to clean the expansion tank in the rear of the bike, they get really nasty. You can take it off the bike, put some cleaner in it along with some loose change or nuts and bolts and shake it up, cleans it up pretty well.

 

[Joseph/TX]

Tuning in late here, but thought I'd throw in my experience as well: My '94 had the exact same symptoms when I got it in February and my first thought also was that the thermostat was bad.
Wish I had discovered this forum then; I ordered one from the dealer, for a whole lot more than $5.99 (Seems like it was something ridiculous, like $40) with the idea that I would install it myself at the first opportunity. As it happened, I ended up putting the bike in the shop to get the valves adjusted/carbs synched and told them to go ahead and install it if it was easily accessible after removing the plastic for the other stuff, otherwise I would put it in myself later. Not wanting to miss a chance to run up my bill, they went ahead and did it without telling me and kept the bike an extra week because they had to order the O ring, which did not come with my $40 thermostat! Anyhow, they did save the original thermostat, and, as I had suspected, it was stuck in the open position. After reading the above posts, it would seem that this is a more common problem than many of us realized..

 

[hotrod1]

Just changed the 94', Stuck open. $6 stat and FIPG over old o-ring and now its fixed.

 

[Joseph/TX]

I suppose we should be happy that they stick open instead of closed..

 

[hotrod1]

Agreed

 

[Brant]

I suppose we should be happy that they stick open instead of closed..

Yeppers.......thermo. manufacturers fortunatley have changed the open/close design function several yrs. back so not blowing caps off anymore.......just makes for a cool heater in winter with cages.

 

[Gymbo]

I used the "SuperStat" version of the Stant with similarly good results.

NAPA had both versions and the SuperStat version seemed to be built much beefier and was only a dollar or so more.

1973-80 Honda Civic 1.5L 180?

Stant SuperStat 45868

Stant: OE 13868

 

[hotrod1]

Question: My new Stant t-stat is working, but it seems too hot. It stays on the first part of the M in TEMP. Fluids are good with no leaks. Fan is not always on, but starts as I come to a stop. It was 110 today in Vegas, but my other ST 1100 runs cooler in the same temperature. Any input, Thanks Ladies and Gents.......Rod