seveninphilly

iTrader: (7)

here's the lowdown. it's an 89 N/A. the car runs fine, no smoke at start up or at full throttle. all of this leads me to believe it's not a problem within the engine. (ie seals) can anyone think of a reason that the car would overheat or show signs of overheating besides thermostat, or water pump?

thanks,
josh

1987RX7guy

iTrader: (3)

Well it could be a bad heater core. Or you should tr flushing your system and putting new Cooliant in. Also your oil cooler cools the engine aswell so check that out.

seveninphilly

iTrader: (7)

Hummm never thought about the heater core. I will do a flush This is a car I'm about to buy for a great price Will take a long trip with no prob but sitting stop go raises the temp. Possible fan clutch?

duffles

almost definetly fan clutch that was my problem, new one from mazdatrix (actually a subaru part ) and about 20 minutes and it was running cool, and LOUD sounds like a prop plane taking off when it kicks on! nuts right? my old one did not really have any play, but just wasn't working right, great on highway, ran at 2/3rds of gauge in town one blown engine and i found my problem hope you get a GREAT DEAL and i hope your engine is not too far gone.

saltlakebay

I agree. Double check the clutch fan.

Also, do the following. Check your A/C condensor and Radiator for crap. Make sure the fins are clean.

Oh, and if you dont have a "Mazda" thermostat, get one! It took me 3 Stant brand thermostats to realize that the Mazda one was the only one that kept my car cool. Dont ask me why, but many others say the same thing.

Amur_

saltlakebay is right - the aftermarket thermostats are crap.

Consider putting an electric fan in instead of the clutch...

https://www.rx7club.com/forum/showth...ight=fiero+fan

seveninphilly

iTrader: (7)

Well after some more work on the car, a good radiator flush, removed thermostat, the car almost instantly builds too much pressure in the system. So I flushed it some more and it was doing ok but still building pressure here is the kicker as it gets warm (normal operating temp) I get no heat from the heater.

So I'm going to try to bypass the heater to see if that helps.

Any other Ideas suggestions.

Oh from cold start to warm there is no smoke at all from the exhaust.

1987RX7guy

iTrader: (3)

When you did the flush did you have the heater on full blast? IF you did not then that part did not get flushed.

seveninphilly

iTrader: (7)

I tried but I get no heat period. I really think its blocked
would this cause the whole system to pressurize.

Amur_

You might have 2 separate things happening.

No heat is probably your Logicon (computer for your heat/ducting.) That or the motor(s) that controls the doors in the ducting is pooched.


Building pressure? Like how much pressure? Grab a new rad cap from Mazda (not aftermarket.)

NZConvertible

First of all you need to tell us when it's over heating. If it's overheating when you're driving at constant medium-high speeds or after accelerating it's not the fan! If the temp starts to climb when idling or when you stop at lights , then it's the fan. The fan is only required when airflow through the radiator is too low to cool the engine.

Put the thermostat back in! Preferably get a new one (Mazda only) and put that in. Don't run without a thermostat, you'll cause all sorts of problems including both overcooling or undercooling depending on the situation.

If the fan's OK, the system is flushed and the thermostat is new and it still overheats, the pump is the next suspect. Consider pulling it off for inspection. If it's been run without enough corrosion-inhibiting coolant in the past it may have rotted the impeller.

Give us a better description of when and how much it's overheating. It'll help diagnosis.

Amur_

****! I can't believe I didn't catch that bit!

Scott 89t2

ummm no...

Aaron Cake

iTrader: (1)

Do yourself a favour, check out http://www.aaroncake.net/rx-7/cooling.htm

1987RX7guy

iTrader: (3)

You all told me that when my car was overheating. I just passed on the info that you all gave me. Sorry

seveninphilly

iTrader: (7)

Now the car is up and running !

I decided to give this a shot

Hear is a bandaid fix that has been known to work when performed properly. It usually last about a year. Just follow the instructions exactly. It will give you more time to save up for that rebuild.

Origanally posted on the FB mailing list by Dale Thomas:

My 'spare' Turbo II was leaking large amounts of
water into the
engine
as well (front and rear). It got so bad that it
wouldn't start
without
removing the plugs and turning over the motor to
blast out the 1/2
cup
or so of water that was inside!

You guys may have a hard time believing this, but
the motor is fixed
(for now) and running better than it did before.
Total cost: $25

Paul Yaw at YawPower performed this emergency
surgery to my vehicle
to
keep me rolling while we finish the Vortech blown
Turbo II that'll be
ready soon. He had done this to another motor
before and the repair
has
lasted for two years on that motor (in his ported
rotary shop truck).

If you're interested in what is to be considered
a temporary fix,
read
on.

The recipe: two cans of Block Weld and some
Purple Power degreaser
from
Pep Boys. The Block Weld is a clear liquid with
copper granules
blended
in.

The process takes *hours* but can be very
worthwhile! Step 1: Clean
the
heck out of the cooling system - drain the
radiator, fill with water
and degreaser, run the motor until warm. Step 2:
Repeat 5 or 6 more
times. Step 3: Drain the radiator, fill with
water only and run the
motor until warm. Step 4: Repeat 2 or 3 times.
You must rinse the
system with water until no degreaser is left
inside, this is *very*
important. Step 5: When you are sure that the
cooling system is very
clean inside, refill with water plus two cans of
Block Weld (no
anti-freeze). Run the motor until warm (about 30
minutes). This
hardens
the Block Weld where the water is leaking into
the motor. Do not rev
the motor into high RPM during this process! Step
6: Leave the motor
off for a minimum of three hours. Step 7: Drive
for 20-30 minutes in
the local area to make sure that the repair has
worked. Keep the RPM
down! If successful, drain a small amount of
water from the radiator
and add some anti-freeze. If it's still leaking
water into the
engine,
add another bottle of Block Weld and run the
engine for 20-30
minutes.
Let stand for three hours again. Test drive
again. Step 8: Drive the
car around like you used to... assuming that the
process worked!

This process can be a real pain to perform
because you have to start
the motor to accomplish the warm ups during the
steps. Don't forget
to
pull the fuse when you turn the motor over to
push out the water
prior
to each start up. Cups and cups of water came out
of my motor
throughout the process! I have been driving the
car pretty hard since
the temporary fix and it has held up well. It now
starts easily, has
plenty of power, and hasn't needed any water to
be added to the
system
since I added the Block Weld (about two months
ago). It was a lot
easier to do this temporary fix than to go out
and buy another
motor/car, especially since my other one is
almost done.

If your motor is shot (like mine was) you've got
nothing to lose. If
it
works for you thank Paul Yaw at YawPower. His
crappy little shop
truck
has been driven pretty hard for two years after
this same kind of
temporary fix. He claims that his truck's motor
was blowing even more
water out of it than mine was.

If you follow the directions on the can of Block
Weld, it will not
work
for this type of repair! Follow the steps listed
above. Be very
aggressive in your efforts to clean the inside of
the cooling system.

I still need to replace all the hoses and get a new thermostat and radiator cap (Mazda). But under all conditions Idle, full throttle the temp stays cool. Hope it lasts till Ican get a new engine.

powermalex

Hey I have a similar problem but not over heating.
Replaced: Upper and Lower hoses including heater hoses. new cap new thrermostate.

Its a 86 N/a with 136XXX mile runs and pulls very strong.
No water in oil pan no white smoke at exhaust.

Problem is coolant overflows to reserve tank after shut down. When motor cools down it does not draw it back in. Seems like pressure build to fast. During driving it does not over flow only at shut down.

Now this mourning when I check to see if the latest fix did the job. I looked at overflow reserve and oit was full.

Motor is now cool after over night cool down. I opened cap and it released coolant and pressure. The radiator held pressure. Which explains why coolant never drew back.

I think its the inner water seal failed????
I can't explain any other reason for the pressure building up.

Like I said engine runs like new no water in oil and coolant does not look contaminated from blow in gased from water seal.

Could pressure be building from intake compression stroke? If so should my coolant smell like gas also.

Also did a infrared scan of the radiator. Lower hose is 35 degreeds lower than upper so I know radiator is cooling.

I'm stumped!!!!!!!!!!!!!

Alex

powermalex

Could inner water seal have failed and acting as a check valve to allow gases to enter and not exit to combustion area?

Is it time for a rebuild because of seal failure?

I hope its somthing I over looked causeing the pressure.

Digi7ech

iTrader: (1)

Don't think of that just yet. Check your Radiator cap again.

I had/have the same exact problem. Ever since it started getting hot here my car would purge the coolant out after I park.

At first I checked the threads for info and they said coolant seal.

A way to check this would be take the filler cap off and run the car(start when cold,not as messy).
Check to see Coolant bubble or even gush out. If it slowly just rises then it shouldn't be the seals.
If you get white smoke or if it smells sweet from the exhaust then it's seals.

So far I have gone a half week with out mine purging with a new checker rad cap(13Lbs).

powermalex

Ok Started engine cold no cap. With in less than a min. bubbles came out and the coolant level rised and started to flow over. I put the rad cap on the pressure continued to rise. But not enough to purge the 13psi cap. Pressure built up before the coolant became even warm. So now its the seal I suppose. This sucks because the engine pulls hard and strong. It doesn't smoke at all through the exhaust.

Also as a note I think I smell coolant burning coming from the exhaust manifold. I see a hint of smoke in the area from the heat shield from the exhaust outlet. Could this be where the pressure is comming from. Any way looks like rebuild time.

That is of course if some one comes up with another fix with out a rebuild. Like I said I hate to pull engine when it runs strong.

Amur_

Then you're FINE. If it had started geysering out when the engine caught, THEN you'd know a seal was out. Time to start looking elsewhere for your temp problem.

Gotta head out - I'll respond more when I get back...

Amur_

No (white) smoke from the exhaust says to me that your seals are fine. You'd only get a cloud of white smoke for the first few seconds at start-up, btw.

Quote:

Also as a note I think I smell coolant burning coming from the exhaust manifold. I see a hint of smoke in the area from the heat shield from the exhaust outlet. Could this be where the pressure is comming from. Any way looks like rebuild time.

Exhaust manifold? Did you smell it after you did your start with the rad cap off? If so, I'd suggest that some of what spilled from the filler neck made it's way to or near the manifold and was evaporated/boiled away as the manifold warmed up. Could you give more details about this "hint of smoke?"
I always rinse away any spilled coolant from the motor cuz I hate that ******** smell* of burning coolant - makes me paranoid.

No, it doesn't look like it's time for a rebuild. Let's keep working on this.

Byw, was that new rad cap Mazda or aftermarket?

AE_Racer

iTrader: (1)

isnt there a coolant line that runs to a nipple on the intake mani?

SureShot

If the coolant is not drawing back on cool down -
1) the radiator cap
2) the filler neck
3) a small leak somewhere in the system

Here are some possibilities:
1) On the stat, about 1" under the valve is a spring loaded disc. It's function is to close a bypass port down in the pump housing. If the disc or it's seat don't block that coolant path, you get enough bypassing to act like a partially blocked radiator.
2) Further down inside the pump housing is an air bleed hole. It can erode to a larger opening and cause symptoms like the above.

powermalex

OK First that for all the reply's
The engine never over heats. I checked the upper and lower hoses and it shows about a 35 to 45 degree difference. So radiator is fine.
No spilled coolant on exhaust cause I rinsed it out before I started it. Also when the engine is cool there is still pressure in system so no vacuum to draw coolant back.
Here's a more detailed sequence of events.
1. Started cold engine with no cap.
2. Engine starts normal as usual
3. Bobbles form at cap location.
4. Coolant starts to flow over.
(All this happens with less than a min.)
5. I put cap back on pressure still builds.
6. Shut down motor
7. Graps upper hose and felt pressure like it was ran and driven for several miles.
8. Release pressure and check temp of coolant and it was less than 100 degrees.

All this and no smoke from exhaust.
I smell coolant burning and a very slight hint of smoke vapor. ( You would have to look carefully to notice it.)

My conclusion is I have a bad water seal in the exhaust area. The exhaust must be pressurizing the coolant jacket very slightly and leaking at exterior of manifold under heat sheild.

Do you guy's agree.
Like I said no over heating problem temp is below185~170 degrees. I checked temp with a IR scanner at the hoses and at black iron plates on plug side.

Cap is OK pressure tested at 180 and the vacuum valve is free.

I think I have a water seal acting like a check valve???