Green_Hornet

As you can tell from the post count, I'm new to this forum & car. Have a 1983 12A engine and want to change the coolant - how do I make sure I've fully drained the engine, and how do I burp the system to get all the air out? From doing searches, I didn't find a thread 'dedicated' to this topic, although it appears the engine doesn't 'burp' itself through the overflow tank very well. I did see the point about the coolant drain plug below the oil filler tube - this appears to be just above the crankcase. btw, there's no heater hoses...that's been removed. TIA ~

bliffle

Since I take special care of the cooling systems on ALL my rotary engines, I first install a plastic tee (available in a $6 Prestone kit at any autostore) in a heater hose. For the 12A that hose is on the passenger side, down low, just before it enters that fixture near the bottom of the radiator. When not being used to drain or refill the system , i.e., normal service, there is a plastic cap that screws onto the tee.

To drain the system I unscrew the plastic cap to let coolant drain out, and unscrew the rad cap to allow air into the system.

To flush the system I attach the anti-siphon fixture (from the Prestone kit) to the tee (so as not to accidentally draw coolant into the house water system!) and then attach the garden hose to the anti-syphon. Then I turn on the street bib just enough to let house water go thru the system and bubble up gently (not fiercely) thru the radiator neck and over the side. You can let that run a few minutes to flush the system, you can turn the heater valve on to flush the heater. You can even start the engine to make sure water is forced through the system just like coolant is normally. This charges the system pretty good with solid clean water, almost totally bubble free. But not quite, of course, in this imperfect world.

When I'm satisfied with the quality of the water exiting thru the radiator neck I turn off the bib. Then, if I'm adding coolant, I remove the anti-siphon gadget and allow a couple quarts (by eyeball) to drian out on the ground and replace the plastic cap on the tee. then add the coolant into the radiator, water wetter, if desired, etc., Around here 2-3 quarts is all you need, but if you're concerned about low temps use your coolant hydrometer to test the ad adjust the coolant mix.

I sorta do the adjustment by feel, having done it many times before, even in cold northern states. You can find charts and calculators to figure out how much to drain and how much to add to make proper adjustment, but as long as you are close with the hydrometer you'll be OK even to 30 below.

The key thing is that the lower portion of the engine, underneath the keg, stays filled with fluid and doesn't allow air to hide in there.

Wheen it all looks good I start the engine (the rad cap is still off) and let it idle a few minutes until the temp guage moves up and the engine gets warm. then I observe to make sure there's a little crosscurrent of coolant visible looking down thru the rad neck. I rock the car getly to dislodge air bubbles hidden in nooks and crannies.

Then I put a quart or two of water/coolant in the back of the car and start driving the car. But every morning for the first week I check the radiator and top up as necessary, because as the car is used the micro-bubbles dissolved in the water (all tap water is aerated, it tastes better that way) collect together into larger bubbles, and bubbles still hidden in nooks and crannies are driven out into the mainstream.

7aull

iTrader: (2)

Biffle has some great points - esp prestone drain/flush kit idea. Some other thoughts:

1)yes the 12a block, and presumably the 13b, has an ENGINE BLOCK DRAIN on the bottom, spark plug side of the center housing (14mm bolt) - this should also be removed for draining and flushing
2) Always use DISTILLED water, not tap water for the rad mix. Tap water can be very mineralized, leaving calcium-type build-ups inside whole system
3) whatever coolant you do use DON'T MIX the RED STUFF and the GREEN STUFF! Different and non-compatible types!!!!!!!
4) unless your intended flushing is part of an on-going, periodic flush CHANGE COOLING HOSES including the HEATER HOSES, unless you know this has been done in the recent past. (like last 3-5 yrs) They do not last forever, and this is obviously the time to swap them out. Just because they look OK on the OUTside does NOT guarantee they are OK INSIDE.
5) Likewise, if it has never been done to your knowledge, REMOVE the rad and have it professionally chem-flushed at a rad shop! Years of accumulated hardened grunge will not necessarily float free on a home-style flush. About $65 last time I did it - money in the bank for a rotary.
Stu Aull
80GS
Alaska

Green_Hornet

Got it, and thanks for the tips. Next weekend, this is my project for Saturday!

pinoyremix

i have reinstalled a radiator..and car swap..and what i basically did..was to pull the engine coolant drain plug right in the center housing..below the oil fill tube..and then once that is drained..then also pull the bottom radiator hose..that will make sure that both the engine and radiator are drained..

bliffle

If the car is around 100k or over I'll replace the radiator upon the least provocation because it is so cheap ($139) and easy. Good time to replace hoses, too, especially the 5/8" heater hose that goes under the beehive because dripping oil rots it out until it bursts and drains all the coolant on the pavement. It's easiest to install the warped OEM hose from mazdatrix, but I've done it in an emergency with off-the-shelf tubing.

bliffle

If the car is around 100k or over I'll replace the radiator upon the least provocation because it is so cheap ($139) and easy. Good time to replace hoses, too, especially the 5/8" heater hose that goes under the beehive because dripping oil rots it out until it bursts and drains all the coolant on the pavement. It's easiest to install the warped OEM hose from mazdatrix, but I've done it in an emergency with off-the-shelf tubing.