Gr33nh07n

Hi, Max here, since I've owned my 8 I've been an avid reader of your forum but never contributed. The faults a long story and hopefully I can do it justice with my description, my car knowledge has exploded since owning my 8. My knowledge of engineering as a whole is good but limited with cars.

Originally I bought my 8 with a fault present (no heating), this didn't worry me as I quite like the cold . I followed various threads on this forum and tried testing the potentiometer, although this failed as my UK model has a different version. Instead I removed it and checked all soldered joints (all good). I then proceded to take my car to Mazda (usless), £60 later and I knew absoloutley nothing about what could be the cause.

A bit of googling and reading this site I found out that I did indeed have slight heat (on slow blow) from my passenger side, which from reading is only through transfer across and not from the matrix. Again from reading and trying to flush my heater core that it was indeed blocked, I tried various chemicals, water and air pressure but it would not budge. Ultimitely attempted to remove the heater matrix and quickly realised the difficulty level was above me, I couldn't get the damn steering wheel off . I've taken it to various garages and they are not keen to do it either!.

This fault evolved and grew new, more worrying problems when I noticed my coolant level was lowering (orginally it had lowered but very slowly), upon investigating I found my radiator was leaking and that it was leaking quite a volume (pouring from the bottom). I had the radiator replaced and all was sealed .

Or so I thought, I now have an issue with my coolant resivour cap is discharing volumes of coolant, but only when the engine is up to temperature for a short while (mid way for 5 mins), the engine then overheats, or would do if I hadn't of pulled over. I have replaced the cap and resivour (with my fingers crossed but doubting myself), it had absoloutley no effect. The fans are coming on and will raise to full rate and the level of coolant is correct.

I have read various things it could be and understand it could be as bad as the exhaust gasses passing into the coolant. I have read there are tests to confirm this and can find various vague descritions of "the champagne test" or "remove fuse and rev".

My various questions are,

Could you describe the above tests in more detail (which fuse / how many revs / how many bubbles is too many).

Also what other basic checks can I do?

Can you recommend a rotary specialist near Hemel Hempstead, Herts, England? (bespoke performance in Ware? anyone used them?)

Would it be worth removing every coolant hose and checking them? replace?

What is the coolant thermostats job?



Many thanks and appologies for either giving too much or not enough detail. I am willing to get stuck in but need guidance from people who know more.


Max

Carbon8

iTrader: (4)

Coolant system pressure tester, you can rent them at auto stores in the states not sure about the UK.

Essentially this is what you need.
ATD Tools 3300 Cooling System Pressure Test Kit | StockWiseAuto

Gr33nh07n

Thanks, I've looked at the cost of buying one............ I'll see if I can rent or borrow one.

I take it that would just tell me the pressure is too high? Or a drop in pressure and no visible leak indicate an internal one?

Would the fact I've changed both the reservoir and the cap rule out premature ejaculation ;-) of the coolant at low pressures?

Gr33nh07n

Hi again,

I have bought a pressure tester, is the rx8 relief pressure 1.2 bar?
If so should I just pump the pressure up and check for leaks?
If there are none do I assume the seal between the coolant and combustion has gone?



Thank you

9krpmrx8

iTrader: (46)

http://foxed.ca/rx7manual/2003mazdarx8/


1. Inspect the engine coolant level.

2. Remove the cooling system cap.

3. Clean the installation parts of the cooling system cap and the upper radiator hose.

4. Install the SST and a radiator cap tester to the coolant reserve tank filler port.

5. Apply pressure using the radiator cap tester.

Caution

• Applying more than 127 kPa {1.3 kgf/cm2, 18 psi} can damage the hoses, fittings, and other components, and cause leaks.

Pressure
127 kPa {1.3 kgf/cm2, 18 psi} [1 min]

6. When pressurizing the radiator, verify that the pressure is maintained.

• If the gauge needle drops, it may indicate water leakage, therefore perform leakage inspection.

– If engine coolant leaks from the upper hose installation part, replace the upper hose and the clamp.
– If the engine coolant leaks from the main body of the radiator (caulked part), replace the radiator.

Gr33nh07n

Thank you, I did a little test last night but it was too wet (rain) to reliably see what or where was the leak. Although it dropped 15 psi in less then 5 minutes, I'll retest at 18 psi.

I'll report back once we get a dry spell in England, thank you again.