gills

First, i would like to say that i've never changed/flushed coolant from any car. It will be the first time that i do in the upcoming week so any advice on what to do would be great. I would say that i'm pretty mechanically inclined. I've installed my exhaust/headers/intake/UO pullies(yes that damn crank pulley too)/Cam gears/springs and shocks...etc so i think i will be ready for the coolant flush.
Here's a question though, is there some kind of tool that lets you flush the system instead of draining it? Because in the helms manual it tells you to drain from the drain plug that's slightly above the oil filter and one on the bottom of the radiator. But i've seen posts in here saying that people flush it instead of draining it. So if anyone would like to explain that situation to me that would be just dandy.
Now for running a colder thermostat. I figured since i'm going to change my coolant and add water wetter i might as well look into running a cooler thermostat. I would just like to know if there's any down side on running a colder one and things i should look for and if my engine will actually benefit from this mod. Also, are there any other companies besides Spoon that makes one for the H22A? I think that will be all. Yes i tried doing a search on this and nothing beneficial came up.

gracie,
gills

 

iranman

First, all a colder thermostat does (from what I know) is open a lot sooner (read: lower temperature) than the stock thermostat (now somebody tells me what this does--allow coolant to flow? allow MORE coolant to flow?). Either way, there is more coolant flowing into the engine. However, if the stock radiator cannot cool the water efficiently at this higher rate, it's not going to make any difference (at least, not much). A better combination would be a colder thermostat + a more efficient radiator (fluidyne, C&R).

I believe Mugen makes one as well, and JR rebadges one (but I don't know who's thermostat they rebadge).

Any reason why the coolant change?

__________________

Sina
My JRSC Site

NSLRACER

I know...I'm also interested in learning how to flush or drain the coolant. I just bought some Redline water wetter and have been waiting for the right moment to put it in.

__________________
92 Prelude Si w/ JDM H22A(Significantly modded)
14.6@95 without Crower setup
Low 14's with setup.

marcucci

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]

BLUDE

marcucci, that brought a tear to my eye. Makes sense.

gills

Does this go for OBD1 and OBD2 ECUs or just OBD2? Also, how exactly does this fan switch work? Is it just a sensor set to turn on at lower temp compared to the stock one? Or does it work like a thermostat but for the fan instead of coolant flow. Fill me in...
Other than that, that was an excellent response marcucci, thank you very much. I found a site that sells the spoon one. They call it a thermoswitch though. It's probably the same thing..90 bucks... http://www.godspeed-motorsports.com

Iranman, i'm closing in on 60k miles so i'm going to give my car the scheduled goods it needs and i figured i might as well throw a little extra something in there and make it run cooler. But i would like to do it the right way, that's why i've posted...

If anyone else has anything to add throw it at us...

gills

BoYgUaN

i did my coolent flush. i could not find the engine drain bolt. the one above the oil filter on the base model did something funny for me so i got scared. i loosed it and when i took the bolt out some oil came out. i quickly tightened it back up. i have been looking through the helms and cant find what i loosened. this is what i did. i would flush the radiator by taking the plastic bolt out from the bottom by using a hose and a towel to clean it out. then i would open the bleeder valve near the cam intake and let it blead out. i would then leave the valve open and flush it again making fluid come out of the valve. i then filled it back up and closed the valve and started the car. i let it run and repeated the steps till the water coming from the bleader valve was clear. then i added coolent, water wetter and water.

__________________

CATZ BULBS H3's FOR SALE !!!!!!!!

johnsoncranium

hey fellas, here's a question for the enviromentally conscious.

Where do you guys dump all the used coolant?

I've taken mine to a dealer and a tech took it. But there's gotta be a better/closer way if you don't live near any car dealerships/repair shops.

Oh..i've called nearby Autozones and Kragens and they only take oil.

I need to get rid of my used brake and clutch fluid too. I ain't just gona dump it somewhere.

__________________
I'M ON MY THIRD PRELUDE!!!
1.93' Prelude Si w/ sh*t load of mods - Got Stolen in 96', found in East Los Angeles with nothing
2.97' Prelude Typesh w/ a few mods - Got Hit in 99', severe front end damage
3.93' Prelude VTEC w/ a few mods - What I Got Now and I am keeping this one! (knock on wood)

marcucci

I'm not sure. I would guess it's worse on OBD2 units. You should still see some power gain from the reduced chance of detonation and knock retard, but I certainly couldn't quantify it. Running cooler is generally running safer.

Quote:

Also, how exactly does this fan switch work? Is it just a sensor set to turn on at lower temp compared to the stock one? Or does it work like a thermostat but for the fan instead of coolant flow. Fill me in...

It's a thermoelectric switch. It screws into the head and has a probe that is in the coolant flow. When the probe temp reaches a certain setpoing, the two terminals on the switch become shorted. This generally is used inline with the fan relay or as an input to the ECU or a fan controller. The lower temp units are just that- they turn on at a lower temp.

Quote:

Other than that, that was an excellent response marcucci, thank you very much. I found a site that sells the spoon one. They call it a thermoswitch though. It's probably the same thing..90 bucks... http://www.godspeed-motorsports.com

A little pricey, but yes, they have it. Keep in mind the stock unit sells for about $29 from hparts.com or manhonda.com.

BoYgUaN:
The bleeder is used to bleed air out of the radiator. What I should have added to my list above:

8) After running the engine the last cycle, let it cool down. Top off the overflow reserviour to MAX. Remove the rad cap and make sure it is topped off. Restart the engine (cold) and open the bleed bolt. Close the bleed bolt once you get a steady stream of coolant flow (no air).

There's no need to use the bleed bolt while just draining the coolant. Once you've drained the rad, there shouldn't be anything left in the head to come out the bleed bolt.

johnsoncranium:
I used to dump mine at Pep Boys, they were the only place I knew of that took it. Lately I've been dumping it in the toilet (no one nearby takes it). I don't doubt that this is bad, most waste treatment centers can't handle coolant properly, but I don't have anywhere else to take it. Try flushing 3 cars on a regular basis and you'll know what I mean. I'm sure local shops have to pay to have it disposed of, and many won't just "take it." My personal feel is that waste treatment centers *should* have to deal with it, and need to.

Brake, tranny, p/s, and other "oil-ish" fluids get mixed in with my motor oil : )

I also wanted to add that I usually use a 20-80 mix of coolant-water. If you live where it's hot all the time, this is good. If you live where it freezes, NEVER go below a 50-50 mix, and if you're in subzero temps a lot, you should be running a higher concentration of antifreeze. I also found out that in '01 Honda switched to a pre-mixed coolant. Keep than in mind if you're buying the factory stuff. Both should work fine in any Honda, I believe the only difference is that the "new" stuff now comes pre-mixed.

gills

Well, i would assume the spoon thermoswitch would work well with in conjunction with the spoon thermostat, correct? Also, is there a way to get a stock thermoswitch to turn on at a lower temp(i'm asking because why did you refer a stock unit?)

thanks a lot again,
gills

71dsp

Because the Spoon part is 3 times as expensive as stock!

__________________
Billy - 98 Prelude
#27 H2 NASA TX HondaChallenge
#27 PTB NASA TX Performance Touring
Racing makes heroin addiction seem like a vague wish for something salty. -- Peter Egan

marcucci

I mentioned if for the reason Billy mentioned. It's expensive compared to stock.

The brands of thermostat/switch shouldn't matter as long as the switch activates a few degrees higher than the rad. The reason for that is so that you get some flow before the fan turns on, there's no reason to have the fan going before coolant is there. It would happen that the temps for the Mugen and Spoon t-stat are the same, I wouldn't be surprised if they were the identical part.

There's no way to get the stock switch to turn on before the rated temp.

gills

well, spoon is the only company that i've found that makes a thermoswitch. If i could find one that activates at a lower temp for a better price, I would be all over it, trust me....

so i've ordered the the spoon T-stat and thermoswitch and i hope they work properly together. I don't need my fans turning on before my coolant starts to flow so i hope spoon made them to work in harmony


thanks again,
gills