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Cooling System
From: F8LDZZ <f8ldzz@lava.net>
Date: Tue, 28 Jan 1997 04:26:50 -1000 (HST)
Subject: Re: (rx7) rx7 [2] Resoldered CPU, now what?
On Sat, 25 Jan 1997, Jerome Wieber wrote:
> Anyway, now my horn works again. Unfortunately, my car is still running
> erratically at high RPMs, and the "add coolant" light (and annoying
> buzzer) are still coming on periodically. I'm at a loss. Any ideas
> before I consign my 2nd gen (and my dollars) to the shop?
There's a plethora of problems that could be causing this...
Make sure that the coolant is topped off. This mean having both the
engine side and radiator side full with coolant. You might have to
remove/unscrew the coolant sensor that sits on top of the radiator and
fill it carefully and slowly with coolant.
1) Check all hoses and clamps. Make sure none of these are leaking. A
small leak would not leave any obvious signs except for some white,
powdery crud. Make sure all hoses and clamps are clean.
2) Check both coolant hoses for the interior heater that go in and out of the
firewall. Both of these hose are know to leak. Because of the close
proximity of the hoses to the firewall, the leak does not go down the
firewall but enters the interior. A sure sign of this is frequent
clouding/hazing of your interior glass surfaces with a greasy film.
Even with constant cleaning, the haze usually returns every few days;
this is coolant evaporating and redepositing on the glass.
3) Check the heater hose on the driver's side of the engine. This hose
runs under the oil filter mount. Sloppy oil filter removal and
consequent drips of oil on the rubber hose makes the hose very soft;
the oil coated hose will eventually burst on you.
4) Lower intake manifold o-rings. This is almost impossible to inspect
without removing almost everything on top of the engine. The coolant
will usually drip down onto the hot exhaust manifold and evaporate,
leaving no trace. Some possible signs are lots of white smoke upon
normal start-up and/or driving; this is a sign that the engine is
ingesting significant amounts of coolant.
5) This is a doozy, but the most major coolant leak you can get is
failure of the engine internal water o-rings. This will necessitate
a total engine rebuild or swap with a replacement engine.
- -Ted
Ted Koseki 1987 Mazda RX-7 Turbo II | Team.FC3S
f8ldzz@lava.net Interact! SUCKS! | Founded 1995!
F8LSpeed Development Honolulu, Hawaii | list@teamfc3s.org
---
From: Mark Schroeder <mazrx7@Onramp.NET>
Date: Thu, 22 Aug 1996 12:33:29 -0500
Subject: Re: overheating
Terry Loveless wrote:
>
> Overheating the _result_ of another problem. Narrow it down for
> us. MOST of the time overheating is the result of coolant loss.
> Park the car on a known clean surface start it up and look for
> leaks. If none found, look again. Look for stains around the
> watter pump. Drive the car, let it cool, check the level in the
> radiator (not the overflow bottle). Check the level in the
> radiator every day. Don't count boil-over as coolant loss.
>
> If you are _fully_ and _completly_ satisfied that _no_ coolant
> is being lost due to leaks, then you have a capacity problem.
> i.e. the radiator may be partialy plugged or too small for your
> climate.
>
> I often have to increase the radiator capacity on vehicles I buy
> because I hate driving a car that gets warm. This Texas heat and
> the Dallas traffic realy tests a cars cooling system.
Also, small leaks such as rad. caps, upper radi hoses, radiator cores,
and water pumps sometimes to not leak to the ground. The hot metal,
such as rad. or water pump housings often causes the leaked water to
evaporate before runs to ground.
Also be advised, the T-stat is the most common overheating disorder on
these cars. Always use factory t-stat. replace as needed or every 2
years. Cheap insurance. Flush cooling system anually.
Mazda radiators are in general kinda cheesy & expensive. Replacement
multi-core rads provide much better heat dissipation, as well as being
constructed of slightly heavier gauge metals, and do not combine alum. &
plastic. BTW, all aftermarket rads are not created equal.
The main cause of engine failure due to overheating is the long heater
hose rupturing below the oil filter on drivers side of engine. Oil
soaked rubber, under 10 psi of hot water pressure, does not last very
long. Common oil leak due to bad o-rings under the oil filter pedestal.
Simple fix. If this happens while driving, the water is pumped out at
10 psi in a matter of seconds. Engine will overheat and cook in less
than 5 minutes of driving.
Hope helps, sorry for the speech. This will be in chapter 12 of my book.
- -Mark Schroeder
mazrx7@onramp.net
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Date: Tue, 18 Nov 1997 12:38:54 -0800
From: rx7guy <rx7guy@mailhost.ocii.com>
Subject: (rx7){2}radiator fix..(long)
HI All,.. Just E-mailing on a radiator fix that may be inculded in the
FAQ.
My radiator produced a leak beside my tire this morning, the car had
been needing several top-ups for some months before, but I could ever
seem to find a leak.I never noticed any leaks or anything unusual during
this time. After the puddle appeared ,I looked further and after
removing the bottom plastic skid plate, I found the source of the leak
to be: top of pass. side, front of rad,(what looked like 1 small
leak), So I took it to a local rad shop and asked if it could be fixed,
they tested it at 15 lbs. And she leaked in all four corners!! ( I saw
only 1 leak, but all four corner "rods" were broken loose). No wonder I
was losing fluid all the time!!! , but I couldn't account for the loss
,as it was very slow. The cause was perhaps due to vibration or design.
GOOD NEWS !! They may be able to fix!! By using an epoxy, that welds to
aluminum, called "Accutech" ,they can fix these broken tubes. The tube
of epoxy costs about 40$, BUT,that don't include the gun or mixing
tips, which are about $2.00 a pop. One tube could do two rads They
charge $60.00 for a repair. This beats the cost of replacment (some
$800 at the dealer or $350 from the aftermarket). Unless your rad is
really shot(ie. corroded).You should try to have your old rad fixed
first. It may even last longer than you new rad (ie. aftermarket)!!!.
For any details that I may have missed, or if anyonelse has noticed
coolant loss but no leak , please feel free to contact me via the list
or in pirvate.
Chris Flett
red 87 base.
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---
From: tegarcia@nettally.com (Thomas Garcia)
Date: Tue, 8 Apr 1997 07:49:58 -0400
Subject: Fw: (rx7) [2] Help, Coolant problem
Repost per xap@mindspring.com
- ----------
> From: Thomas Garcia <tegarcia@nettally.com>
> To: ThermalRX7@aol.com; rx7@world.std.com
> Subject: Re: (rx7) [2] Help, Coolant problem
> Date: Friday, April 04, 1997 8:19 AM
>
> Thermal,
>
> All RXs require an enhanced 'top-off' procedure, especially 86-92s.
Loosen
> the bleeder on the top radiator inlet to the point it drips, rev the
motor
> to 2-3000 rpm, heat on, and top off at the engine (full warm!), close the
> bleed, replace the cap, reduce rpm. That should do it.
>
> Thomas Garcia