Engine Coolant Temp / Pressure Test.

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Hi all, having recently bought a 96' UK TT auto (1 month ago) and having just replaced the Radiator and Thermostat, I thought I would carry out a Temp / pressure test on the system just to make sure everything was ok and working as it should. In a previous thread I had some concerns about my temprature gauge working properly, so this test was intended to put my mind at ease.

The equipment used was a Taskmaster Cooling System Tester , a Fluke 62 Infra red Digital Thermometer and a Head Gasket Sniffer Kit. The temprature readings were taken at the same point each time, the alloy pipe that connects to the top hose.

From cold I started the engine and recorded the build up in Temprature and Pressure over time. Here are the results :

Test started at 19c 0psi

2 mins. 33c 2psi

3 mins 42c 3psi

4 mins 52c 4psi

5 mins 58c 5psi

6 mins 66c 6.5psi

7 mins 69c 7psi

8 mins 74c 8psi

9 mins 77c 9psi

10 mins 81c 10psi

11 mins 85c 11.5psi

12 mins 86c 12psi

13 mins 87c 13psi

14 mins 87c 13.5psi

15 mins 89c 14psi

16 mins 90c 14.75psi

17 mins 92c 15.5psi

18 mins " "

19 mins " "

20 mins " "

This test was done with the engine idling on my drive way.

I then waited 15 minutes (had to watch the start of the Turkish F1 race) then removed the pressure tester and carried out a CO2 Test using a Head gasket Sniffer kit, the results were negative

Personally I think the results are ok and indicate no problems.

Interesting is how much pressure the system builds while just idling, around 15.5psi / 1.1bar / 108kpa.

1.1bar is the maximum working pressure for the radiator cap which means when I am sat in a traffic jam the system is just about working at its maximum pressure. Obviously when driving the pressure would be less due to the cooling effect of the extra air passing through the radiator. After a run I have checked the expansion tank and it is higher than when cold but after several hours it returns to it's original level as it should in a system operating correctly.

The electric fan at the bottom right of the radiator never came on at all (in fact I have never known it to come on on this or my previous Supra). If the switch that operates this fan is the one in the bottom right of the rad (near the fan) it doesn't surprise me as the bottom of the rad never seems to get above 45c. The switch is new by the way, and very expensive too £50!!!

So there you go, the results of a cooling system test on my car. Just thought I would share them with you, might help some one out one day.

Cheers mate will come in handy very soon!

Actually could have been doing with that a week or 2 ago, my supe is in for a head gasket change at the mo!!

Hi, I hope it does prove useful, it took me a half hour to type it up.

Hope whoever is doing your Head Gasket does a good job for you.

Might be a good idea to replace all those hard to get to vacuum hoses while they have got good access, most of my hoses are rock hard and badly need changing, if it's a high miler then replacing the valve seals would be wise too, in fact I would replace them anyway.

All the best, Fred.