Tech Tips

TECH TORQUE TECH TIPS

Tech Tip from: Safety Fast! Archive Carburettor Petrol Leak on my Midget

I have tried various ways to stop my front carb leaking, with no luck; therefore could you give some pointers to rectify this. Several things to check here. Examine the float to see if it is punctured and contains fuel. Also check there is no wear where the float pushes against the valve. Check the end of the valve for wear on the end normally a ridge around its lower circumference. If OK it could be the valve has been changed without changing the valve seat. They should of course both be changed at the same time, but is very often overlooked as owners don’t have the right spanner to remove this or they don’t realise the importance of it. You can check if it’s OK by connecting a rubber hose and submerging the float chamber in a pint of water. Blow as hard as you can down the tube with the valve in its home position and see if there are any bubbles.

We are frequently asked technical questions covering all varieties of MG. With the help of our Registers, members, and past Safety Fast! magazines, here is a selection of the more commonly asked questions and solutions.

Tech Tip from: Safety Fast! Archive Do I need an oil cooler?

I have done some mild tuning on my MGB. Do you think it would be wise to fit an oil cooler and oil temp gauge? An oil cooler is not normally necessary for mild tuning, but it’s a good idea to fit an oil temp gauge. A tuned engine, which would generate more heat, would benefit from an oil cooler because excessively hot oil becomes too thin and can cause accelerated wear to bearing surfaces. But one fitted to a mild tune engine generating less heat would keep the oil too cool and the oil would be thicker and wouldn’t flow as quickly through the bearings and cause overheating. Fitting a temp gauge in both instances is a good idea and the engine should run around 70-80°C. An engine running at over 90°C would require an oil cooler. A final point is that a thermostat can be fitted with the oil cooler which will stop over cooling.

Tech Tip from: Safety Fast! Archive Poor starting on my MGB

I have a 1971 MGB GT and have difficulty starting the car from cold, even though the car is garaged overnight. Once warm, it starts fine. I have done many things to overcome this, such as checking the distributor, replacing points and plugs, and even fitted a new fuel pump, but with no improvement. It sounds like this is the result of an air leak. Your car is fitted with a form of basic emission control that prevents crankcase gases escaping to the atmosphere. The piping system draws, via suction from the inlet manifold, fumes from the crankcase into the carburettor throats. The fumes then mix with the fuel/air mix to be burnt in the cylinder. Clean air is drawn into the crankcase via a filtered oil filler cap. After a period of time the tubes perish, harden and crack and allow air leaks, so it’s important to check these pipes at the service intervals and replace as necessary.

Tech Tip from: Safety Fast! Archive My mid-seventies MGB has electrical problems. Firstly the ignition light will not go out and with the engine running the headlamps are dim?

The ignition light should go out when the engine is started and it exceeds 800rpm. The fact your ignition light won’t go out and the lights are dim, sounds like it could be down to a faulty alternator. A simple check is to put your test meter on 20V scale then check the voltage of the battery which should be in excess of 12V, if not charge it up. Start the engine and put your test meter on to the battery terminals making sure you place them correctly. You should get a reading of around 13.5 to 14.5v. If so the alternator is good and you may have wiring issues. But if the voltage stays around 12v then the alternator is more than likely faulty.

Note: The above solutions should only be carried out by a home mechanic who has the necessary tools and experience to be able to do the work safely. If you are unsure of your ability then you should entrust the work to an MG specialist