An MG T-Type that won't start is almost always failing in one of three places: the electrical supply that turns it over, the spark, or the fuel. Establish which before you touch a spanner — the way the car refuses tells you where to look, and the flowchart below walks the sequence in the order a workshop would.
The car was fine yesterday. This morning you turn the key, pull the starter, and it does something other than fire up. Resist the urge to start adjusting things. A no-start is one of the easiest faults on a T-Series to diagnose logically, because the engine is simple and the failure patterns are well worn.
Every figure quoted here is a guide. Heads have been skimmed, distributors swapped and camshafts changed over seventy years, so confirm the specification for the engine in front of you against the workshop manual for your car.
Listen to how it refuses
Before anything else, note precisely what happens when you pull the starter. This single observation removes two thirds of the possibilities:
| What it does | Where the fault lives |
|---|---|
| Nothing at all — no click, no lights | Battery, earth strap, ignition switch or starter circuit |
| A click, or slow heavy cranking | Current: battery, cables, earths — or a tight engine |
| Cranks briskly but never fires | Spark or fuel |
| Ran, stopped hot, won't restart | Vapour lock, or a sudden electrical failure |
Interactive flowchart
It won't start — where is the fault?
Step 1
Turn the key and pull the starter. What actually happens?
The way the car refuses tells you which third of the system to look at: electrical supply, spark, or fuel.
Cranks briskly but won't fire: split spark from fuel
This is the most common case and the one where most time gets wasted. Settle the question in two minutes with a spark test.
Pull a plug lead, hold it about a quarter of an inch from bare metal with insulated pliers, and have someone crank the engine. A healthy system gives a fat blue spark that will jump the gap willingly.
- Good spark → the ignition side is doing its job. Go to the fuel section.
- No spark, or a thin yellow one → the fault is in the ignition. Work through the ignition section.
The ignition side, in order
Work from the outside in. The order matters, because each step is cheaper and more likely than the one after it.
- Damp. Take the cap off. Damp under the cap after a wet night is the classic no-start. Dry the cap, rotor and leads thoroughly and try again.
- Cap and rotor. Look for fine black tracking lines, hairline cracks, and burning at the rotor tip. Any of these condemns the part however new it looks.
- Points. Turn the engine slowly and watch them open and close. Clean grey faces, opening freely, gap to the guide figure of around 0.010–0.012 in. Pitted, oily or seized points give no spark at all.
- Condenser. A failed condenser produces precisely this symptom, and it is a cheap part. Renew it with the points as a matter of course.
- Low-tension supply. With the ignition on and the points open, check for battery voltage at the coil's switched terminal. No voltage means the fault is upstream — ignition switch, the feed from the control box, or a corroded connection.
- Coil, and the LT wire inside the distributor. A chafed low-tension wire earthing against the distributor body kills the spark stone dead, and it is easy to miss. Substitute a known-good coil before buying parts.
Points, gap and dwell figures for each distributor cam are set out in the complete tune-up guide, and the reasons cheap reproduction ignition parts cause repeat no-starts are covered in why your distributor matters.
The fuel side, in order
Spark good, still no fire. Switch the ignition on and listen for the SU pump.
The pump is silent
A silent SU pump is the most famous failure in British classic motoring, and it is usually fixable at the roadside. Before you condemn it, crack the fuel cap open: the tank vents through the cap, and a blocked vent puts the tank into vacuum so the pump cannot draw against it. The symptoms are identical to pump failure.
The full sequence — freeing stuck points, isolating a blocked line, and the mistake that turns a blocked pipe into a dead pump — is in the roadside fuel-pump article.
The pump ticks
Then look at what is arriving at the cylinder. Pull a plug:
- Soaking wet with petrol — flooded. Push the mixture control home, hold the throttle wide open, and crank in short bursts to clear it. If it floods on its own, suspect a sticking needle valve, a punctured float, or a float level set too high.
- Bone dry — nothing is getting through. Check whether the float chambers hold fuel. Empty chambers mean a blockage between tank and carburettor; full chambers with a dry plug mean a blocked jet or a piston stuck up in its suction chamber.
Lift each carburettor piston with the lifting pin: it should drop back with a soft metallic click. A piston that sticks up will not meter fuel at cranking airflow.
Nothing at all, or slow cranking
If the engine barely turns, or does not turn:
- Switch the headlamps on. Dim or dead lamps point straight at the battery or its connections.
- Clean both battery terminals and the chassis earth strap to bright metal. T-Series cars are 12-volt positive earth, so the positive terminal goes to the body; a painted or corroded earth face drops enough voltage to stop the engine turning.
- Have the battery load-tested. A battery can show 12 volts at rest and collapse the moment the starter is engaged.
- Try the engine by hand on the starting handle or a spanner on the crank nut. If it is stiff or immovable, stop: remove all four plugs before trying again, and find out why before running it.
- If the key only works when wiggled, the ignition switch is worn out. See curing an intermittent ignition switch.
Hot, and it won't restart
A car that ran perfectly, stopped hot, and then cranks without firing — but starts happily after fifteen minutes' cooling — has vapour lock, not a fault to chase. Petrol is boiling in the float chambers or in the line running past the exhaust manifold. A heat shield between the manifold and the SU float chambers, plus fuel-line routing away from heat, is the cure. See starting in extreme heat.
After it starts: don't just drive away
A no-start is nearly always a symptom of something drifting out of adjustment or wearing out. Once you have found the cause, fix it properly rather than settling for the field expedient:
- Renewed points at the roadside? Set the gap or dwell properly at home.
- Freed a stuck pump by tapping it? The points inside need cleaning or renewing.
- Cleared a flood? Find out why it flooded.
The complete tune-up guide is the right follow-up: compression, valve clearances, ignition, then carburettors, in that order.