V8 cooling sequel
Jerry Bright (Citron 1956) provides a sequel to Colin Leisk's comprehensive V8 Workshop Note 15. (Jun 79)

I was interested in Colin Leisk's recent excellent article on the MGBGTV8 cooling system as I have experienced several of the problems he has dealt with. For my "family" transport I have a Rover 3500S and though there were differences between the V8 engine in the MGBGTV8 and the Rover 3500S, the cooling system pressure is the same at 15psi. I had the Rover first and soon after I bought it, found there was a necessity for frequent topping up. As this was expensive I decided I wanted to get a tester to identify all the problems once and for all.

I bought a Sykes-Pichavant Cap and Cooling System Tester (now about £25 plus VAT) and found it comes in a metal box about 6 inches square and 4 inches deep and will test two things:

> The pressure the radiator cap will hold before blowing off.

> That the cooling system can hold the pressure at which it is designed to run.

The device is basically a pump with a built in pressure gauge. Testing the cap is achieved by screwing it to the mouth of the ester and pumping up in this case to 15psi. Any cap which will not reach 15psi before blowing off or will not hold 15psi for about 10 seconds is defective.

In a similar way the cooling system can be tested by attaching the pump to the system with the connecting hose supplies with the kit and pumping up to 15psi. If all is well, the pressure will hold up. If this test is done when the engine is completely cold, the coolant will not evaporate as soon as it escapes and leaks are more easily spotted. The tester can be used to test nearly all British made vehicle radiator caps or cooling systems, and additional connecting hoses are available for those foreign makes!

So what did I find from my tests using the cap and cooling system tester?

Back to Contents listing

Rover 3500S

Radiator cap defective, blowing off at 10psi.

Steam pipe connection to the inlet manifold defective though the clip was apparently tight. The problem was solved by fitting a clip with a smaller width and circumference before tightening up.


> Radiator cap defective, blowing off at 12psi. Solving this was rather more expensive here - two small leaks in the radiator tubes and also a leak where another tube joins the header tank.

> Radiator leaks - I will probably opt for a completely new radiator core before I put the car back on the road in May. Patching up a radiator is at best only a temporary solution.

Although the purchase of a system tester may seem a somewhat drastic step to take, I have convinced myself that it has been well worth the expense. It is always there for use next year and the year after . . . Also the consequences and likely expense of a seriously overheated engine can cost a great deal more than £30!!

Now some notes on heater hoses for the MGBGTV8.

DescriptionPart No
Main hose topGRH512
Main hose bottomGRH511
Bypass hose90611532
Hose heater to valveBHH1083
Hose heater to tubeBHH1082

Peter Beadle suggests a substitute part, AHA9782, for the hose from the heater to tube (BHH1082), which is a Spridget part.

Copyright reserved by the V8 Register