Jerry Hey wrote:
 >
 > Slightly off topic, but I just bought a l988 normally aspirated

RX-7

 > which has a newly rebuilt engine and a clean radiator. It is
 > exhibiting cooling behavior which I don't understand, in that the
 > water temps are fine at freeway speeds but go up to near the

redline

 > in stop and go traffic.  Fan seems to working properly--no bugs on
 > the rad.      Jerry

 That is strange Jerry. Check the thermostat. Somebody may have put in

the

wrong
 kind. Mazda thermostat are unique. They close off a bypass passage

when

they

 open. If the wrong kind is used they will not close the bypass

passage and

 at low RPM water pump speeds much water will be merely bypassed and

not

 routed through the radiator.

 Paul Lamar

Check for the following condition:

If coolant level in the engine (not the overflow bottle) gets low, there

can

be gas space in the circuit, and the water pump may not have enough
head/suction to get the water moving around the engine-radiator loop at

low

rpm.  When you get to higher rpm, the head is overcome and the coolant
circulates.

This condition I have experienced on two different cars (not rotaries),

one

with a slow head gasket leak, the other with a slow water-pump leak.

With the head gasket leak, the leaking combustion gases would force the
coolant back into the overflow bottle, displacing it from the engine.

Engine

would overheat at traffic lights, but cool okay when RPM went up.

Highway

was fine, slow up in traffic and the temp would start to rise right

away.

Bill Schertz
KIS Cruiser #4045

Barry Gardner wrote:

Bill Schertz' explanation of this problem gets my vote, based on my reading
of a lot of message posts on RX7 car lists. These rotary coolant systems are
notoriously hard to "burp" and I've heard of this problem before. The air
bubble gets broken up when the velocity of the water pump pushes coolant at
high speed but air locks the coolant at idle or low speed. More infuriating,
the symptoms make it appear as if nothing is wrong.

I'd really work on getting all air out of the system and I'll bet the
problem goes away. Good luck.

Barry Gardner
Wheaton, IL

 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org