Honda Prelude Forum - Prelude Online.com - View Single Post

gills · 08-12-2001, 09:54 PM

I have a spoon thermostat and thermoswitch sitting in my room right now waiting to be installed. If you get a thermostat you should really get a thermoswitch as well for it to beneficial.
Here, read this. It's from a while back before i purchased anything:

The Helm procedure is "correct," but not necessary in my opinion. Here's what I do with good results:

1) slide the a/c temp lever to full hot.
2) run the car until it reaches normal operating temp.
3) shut the car down, wait for at least 20 minutes.
4) drain the radiator from it's drain.
5) pour water into the rad until you get clear water out the drain.
6) plug the rad back up, then fill with water. Be sure to fill it all the way... the level will settle over a minute or so. Be sure it's topped off. Cap the rad.
7) Repeat steps 2-6, with the temp lever on hot. It's faster to drive it, but a PITA since you usually need the car jacked up to get a drain pan under it.

After doing this you should have all the old coolant out. It's not really necessary to do it twice if you flush with OEM coolant regularly. I do it twice or more if the car hasn't been flushed in a while or I'm changing coolant brands.

Change the thermostat every 100k miles. You should do it when you do the water pump and timing belt as PM. It's too cheap a part to have fail and cost you your engine.

Our radiator is fine, it has plenty of capacity. I've never known a non-SS Prelude to overheat. I speculate the SS Prelude has a bunch of coils dedicated to the tranny; I hypothesize that a seperate tranny cooler would solve a lot of SS failure and overheating problems on the track. I think a Fluidyne is a waste of money if you do your cooling system properly (see below).

[DISSERTATION]
Changing the t-stat to a lower temp version is a good idea IF and ONLY IF you change out the fan switch as well. There are a few places where the t-stat only might be good, like for a track-only car. But even then, periods of idling or low-speed driving aren't good. Because...

If you change out the t-stat for a lower temp version it opens up at a lower temp (duh). Cars for the most part used to have low temp thermostats (140 or 160 degrees F) to keep them running cool on inefficient cooling systems. Keep in mind that cars used to all have mechanical fans and thermoclutches which are notorious for going out. They also regulated poorly, so a low temp thermostat was the only way to keep them running. With the advent of the "greenies" and pollution awareness (EPA Nazis) we realize now how evil we were, power is bad, waste is bad, and efficient engines are good. Hot engines complete combustion better. Enter the 180 degree thermostat. A good electric fan with a thermal switch can regulate temperature pretty well, far better than mechanical fans. This was an easy step since most cars were now FWD and couldn't use a mechanical fan anyhow. So now you have a hot t-stat and fan switch at about the same temp.

Now... you want to run your car colder. Some say "power gain" and some say "cooling capacity." The fact is that many ECUs retard timing and add fuel based on intake air temp and engine temp. The S2k is notorious for this, one "feature" the Mugen ECU removes (these safety precautions). Run cooler, get more power.

But cooling is good, too. If you run your car cooler you've got more capacity; as ambient temp rises you should have the same differential (X degrees) between the coolant temp and ambient temp. This should give you more headroom in staying away from the boiling point in hot conditions and hard use.

This brings me back to my point about the fan switch. Let's say you've switched out your t-stat for a colder model. You're running colder, right? Yes, but not near as much as you would be with the fan switch. Your radiator is only effective when there is air moving past it. Since the fan switch is still turning on at the same temp (it's driven off of coolant temp) the fan won't turn on until the coolant gets to the same temp it did before. What does this mean? It means your fan will rarely turn on. But that's good, right? No, not really. You're keeping a lower mean temp (marginally), but at the expense of a wider temp. variation.

So?

So now you're putting your car through more thermal cycles. Not only is this thermal cyclng bad for things like seals and gaskets and such, it's also bad for the radiator.

Get the t-stat and the fan switch and you'll regulate the temp perfectly, just like stock.

Where can you get the switch? So far, nowhere in the states that I've seen. Spoon is the only one I've seen so far that makes it. I haven't comfirmed it, but it should be the same across all models. I know for a fact it's the same between the Civic/Integra and the S2k (all years).

[/DISSERTATION]

Marcucci explained why you should get a thermoswitch as well, so i did

As far as the mugen temp rating, i have no idea. Sorry...

gills

08-12-2001, 09:54 PM	#3 (permalink)
gills dumb ginny Join Date: Jun 2000 Location: Stony Brook, NY Posts: 1,622 iTrader: (0)	I have a spoon thermostat and thermoswitch sitting in my room right now waiting to be installed. If you get a thermostat you should really get a thermoswitch as well for it to beneficial. Here, read this. It's from a while back before i purchased anything: The Helm procedure is "correct," but not necessary in my opinion. Here's what I do with good results: 1) slide the a/c temp lever to full hot. 2) run the car until it reaches normal operating temp. 3) shut the car down, wait for at least 20 minutes. 4) drain the radiator from it's drain. 5) pour water into the rad until you get clear water out the drain. 6) plug the rad back up, then fill with water. Be sure to fill it all the way... the level will settle over a minute or so. Be sure it's topped off. Cap the rad. 7) Repeat steps 2-6, with the temp lever on hot. It's faster to drive it, but a PITA since you usually need the car jacked up to get a drain pan under it. After doing this you should have all the old coolant out. It's not really necessary to do it twice if you flush with OEM coolant regularly. I do it twice or more if the car hasn't been flushed in a while or I'm changing coolant brands. Change the thermostat every 100k miles. You should do it when you do the water pump and timing belt as PM. It's too cheap a part to have fail and cost you your engine. Our radiator is fine, it has plenty of capacity. I've never known a non-SS Prelude to overheat. I speculate the SS Prelude has a bunch of coils dedicated to the tranny; I hypothesize that a seperate tranny cooler would solve a lot of SS failure and overheating problems on the track. I think a Fluidyne is a waste of money if you do your cooling system properly (see below). [DISSERTATION] Changing the t-stat to a lower temp version is a good idea IF and ONLY IF you change out the fan switch as well. There are a few places where the t-stat only might be good, like for a track-only car. But even then, periods of idling or low-speed driving aren't good. Because... If you change out the t-stat for a lower temp version it opens up at a lower temp (duh). Cars for the most part used to have low temp thermostats (140 or 160 degrees F) to keep them running cool on inefficient cooling systems. Keep in mind that cars used to all have mechanical fans and thermoclutches which are notorious for going out. They also regulated poorly, so a low temp thermostat was the only way to keep them running. With the advent of the "greenies" and pollution awareness (EPA Nazis) we realize now how evil we were, power is bad, waste is bad, and efficient engines are good. Hot engines complete combustion better. Enter the 180 degree thermostat. A good electric fan with a thermal switch can regulate temperature pretty well, far better than mechanical fans. This was an easy step since most cars were now FWD and couldn't use a mechanical fan anyhow. So now you have a hot t-stat and fan switch at about the same temp. Now... you want to run your car colder. Some say "power gain" and some say "cooling capacity." The fact is that many ECUs retard timing and add fuel based on intake air temp and engine temp. The S2k is notorious for this, one "feature" the Mugen ECU removes (these safety precautions). Run cooler, get more power. But cooling is good, too. If you run your car cooler you've got more capacity; as ambient temp rises you should have the same differential (X degrees) between the coolant temp and ambient temp. This should give you more headroom in staying away from the boiling point in hot conditions and hard use. This brings me back to my point about the fan switch. Let's say you've switched out your t-stat for a colder model. You're running colder, right? Yes, but not near as much as you would be with the fan switch. Your radiator is only effective when there is air moving past it. Since the fan switch is still turning on at the same temp (it's driven off of coolant temp) the fan won't turn on until the coolant gets to the same temp it did before. What does this mean? It means your fan will rarely turn on. But that's good, right? No, not really. You're keeping a lower mean temp (marginally), but at the expense of a wider temp. variation. So? So now you're putting your car through more thermal cycles. Not only is this thermal cyclng bad for things like seals and gaskets and such, it's also bad for the radiator. Get the t-stat and the fan switch and you'll regulate the temp perfectly, just like stock. Where can you get the switch? So far, nowhere in the states that I've seen. Spoon is the only one I've seen so far that makes it. I haven't comfirmed it, but it should be the same across all models. I know for a fact it's the same between the Civic/Integra and the S2k (all years). [/DISSERTATION] Marcucci explained why you should get a thermoswitch as well, so i did As far as the mugen temp rating, i have no idea. Sorry... gills Last edited by gills : 08-12-2001 at 09:58 PM.