I've always just filled up the rad until it is all the way the top, squeeze the upper rad hose to get any air out of it, and top the rad back off as necessary... Then start the car with the cap off, make sure it didn't drop down significantly, then top back up as necessary. I generally fill the overflow reservoir to the 'max' line and then start the car up, drive it around the block, and with the car facing *up-hill*, I pop the purge valve for a couple seconds until the coolant comes out, then shut it right back off. I've never had a problem with temperatures fluctuating (except when the engine was really running hot, due to my turbo and a crappy 170k mile stock worn-out radiator).
If you have a ZC engine, you will want to be on a level surface, or maybe facing slightly DOWNHILL, due to the location of the bleeder valve. Ricky On Fri, 16 Aug 2002, Robert K. Kuhn wrote: > As mentioned yesterday, I swapped out the thermostat and temperature gauge > sending unit. > > Got both parts from a local Honda dealership (Cush Honda in Escondido; > http://www.cushauto.com): > Thermostat (# 19301-P08-316) $17.54 (USD) > Thermo Unit (# 37750-PH2-014) $ 33.06 (USD) > > I probably could have gotten both for less. > > Thermostat came with gasket where as the one I had used before, a Stant, > did not come with one and I had to purchase it separately (not that it as > all that expensive...). I have used Stant in the past (thermostat's, > radiator caps, gas gaps and gaskets...) and I own a Stant pressure tester > (does both cap and radiator... Had to get an adapter to fit the smaller > Honda radiator filler neck...) so this is not a knock on their product (and > I'm not even 100% sure that the problem was the thermostat...). > > Drained the coolant, swapped out the thermostat and the temp-gauge sending > unit. I was hoping to find it either completely shut or not within spec > when *cold*. But it wasn't. > > The sending unit was a bugger to get out not because of location (which was > very accessible...) but because of the grip it had. I doubt that it had > ever been loosened since the day it came from the factory... After about > 10 minutes of grunting and some PG-13 potty mouth language, it gave in and > I was able to get it out without any damage to the threads in the block. > > Though the manual did call for the use of any sort of sealant, I did coat > the threads with a very light coat of Permagasket goo (the brown stuff used > for waterpumps, thermostat and other water fittings...) and torqued it down > as per the Helm and made sure to re-attach the wire. > > I decided to swap the sending unit because it was felt that I could be > getting false readings. > > Filled the system back up with coolant, checked for any leaks and then > started it up and let it come up to temp before taking it out. > > Drove into work this morning. The conditions were not as cool as it was > earlier this week and the humidity was a bit higher. The temp gauge needle > stayed put at it's normal resting position. But I'll keep my eye on it > these next few days. I am also going to see about transplanting my stock > hood-insulation to my Carbon Fiber one. I talked with a Honda Tech > yesterday who said recommends that I do so to maintain proper operating > temps under the hood. > > Here's my question about filling the system back up because it's been > described to me in different ways: > > (1) The Helm states to fill the overflow bottle with water half way between > the MIN and MAX lines and then fill it with straight coolant to the MAX > line. Next it says to open the bleed valve and fill the system with > coolant to where it's under the filler neck and when there's a steady > stream of coolant coming from the bleed valve before closing said valve > off. Then start the engine with the radiator cap off and let the engine > come up to temp (fan kicks on at least once...) and fill the radiator if > needed. Then close up the radiator and re-check the coolant level after > it's cooled down. > > The first time I did this (back in 1999 when I did the timing belt and > waterpump...), I think I overfilled the system because the overflow bottle > could not handle the overflow. Then about 10 months later, I had to R&R > the waterpump again because it started to make an awful squealing > sound. Filled the system as per the Helm with the same result as the last > time. > > When I did the thermostat earlier this year, I just filled the system back > up but bypassing the filling of the overflow bottle. Actually, I just > filled the overflow bottle with coolant (50/50 mix...) to the MIN mark and > that seemed to work. I did that again when I recently did the radiator and > then again yesterday. > > (2) Other people have told me to NOT open the bleeder valve during filling > but to do it after the system has been filled and the engine has been > brought up to operating temp (fan kicks on at least once...) and then left > to cool for a couple of hours. Then I crack the valve to release any > trapped air. The reasoning here is since the manuals state to start the > engine with the cap off until the engine comes up to temp, there's no need > to crack the bleed valve -- suggesting that the cap off the neck is acting > as the bleed valve. As for the overflow bottle, they said to check (and > fill if needed...) it after the engine has cooled and after the valve has > been opened to release any trapped air. > > (3) And the other way that was told to me was to pull the top radiator hose > and fill it with coolant first. Fill it until it begins to start spilling > out and then re-attach it to the radiator. Then fill the system as > normal. I've had to do it this way on a past car of mine where it didn't > have an overflow bottle and it was a complete *closed* system. By > backfilling it via the top radiator hose, you're purging air out as you > fill it with coolant.. > > I did, BTW, take pics of the thermostat and temp-gauge sending unit > R&R. But I don't know when I will have it up on the site to view. Getting > ready to leave town next week Wednesday so I probably won't get a chance to > work on it until mid-September at the earliest (after the Labor Day Mount > Laguna Drive we're doing down here in San Diego...). > > Anyway, any comments on the filling of the coolant system would be > appreciated and welcomed. I will also keep you guys up to date to see if I > fixed the problem I was having. > > > Robert K. Kuhn > CRX Owners Group President (http://www.crx.org/southcal) > > 1990 Honda CRXsi (http://drive.to/jiggy) > ICQ # 3714283 (nickname: godzilla) > > Mount Laguna Cruise (San Diego County) - September 2, 2002 > http://www.crx.org/southcal/events.html > > To see who all is coming: > <http://www.crx.org/southcal/rsvp.htm>http://www.crx.org/southcal/rsvp.html > > >
