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?
14 steps
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.
Switch on the headlamps. Do they light normally, dimly, or not at all?
Not at all, or barely glowing
Do this
Battery and earth first
Clean and tighten both battery terminals and the earth strap to the chassis, then check the battery on charge. T-Series cars are 12-volt positive earth: the positive terminal goes to the body. A poor earth strap mimics a flat battery exactly.
Ignition and charging →Lights are fine, so the battery is doing its job. Does anything at all happen when you wiggle the ignition key in its barrel and try again?
It springs into life when the key is wiggled
Do this
Worn ignition switch
A tired switch that only works in one position is a known T-Series annoyance, and it will strand you eventually. Deal with it properly rather than learning the magic angle.
Curing an intermittent ignition switch →Still nothing
Next step
Trace the starter circuit
Work from battery to solenoid to starter: battery live at the solenoid, a good earth at the starter body, and a sound cable in between. Pulling the starter switch should give an audible clunk at the solenoid. No clunk means the switch, the cable to it, or the solenoid itself.
Slow, heavy cranking is nearly always current, not the starter. Are the battery terminals, the earth strap and the starter cable all clean and tight?
Green fur on a terminal or a painted-over earth face will drop enough voltage to stop an XPAG spinning.
Some are corroded, loose or painted over
Do this
Clean every connection, then try again
Take the terminals off, clean to bright metal, refit tight and protect with petroleum jelly. Make the chassis earth face bare metal. This alone cures most slow-cranking complaints on T-Types.
Does the engine turn freely by hand on the starting handle or a spanner on the crank nut?
Turns freely
Next step
Suspect the battery or the starter
A battery can hold 12 volts at rest and still collapse under load, so have it load-tested. If the battery is sound and every connection is clean, the starter itself needs attention, brushes, bushes or a dragging armature.
Stiff, or it won't turn at all
Do this
Stop cranking and find out why
A seized or hydraulically locked engine must not be forced on the starter. Remove all four plugs and try again by hand: if it frees up, a cylinder was full of fuel or water and you need to find out how it got there before you run the engine.
Check for spark. Pull a plug lead, hold it about a quarter of an inch from bare metal with insulated pliers, and crank. Is there a fat blue spark?
Insulated pliers, not fingers. Keep clear of the carburettors and any fuel vapour while you do this.
Take the distributor cap off. Is there a bright, dry rotor and cap, or is there damp, tracking, or cracks?
Damp, sooty tracking lines or a cracked cap
Do this
Dry it out and renew the cap and rotor
Damp under the cap is the classic no-start after a wet night. Dry cap, rotor and leads thoroughly. Fine black tracking lines or hairline cracks mean the cap is finished, however good it looks.
Why your distributor matters →Now the points. Turn the engine slowly and watch them. Do they open and close cleanly, with clean grey faces?
The manual gives the gap by distributor type: 0.010–0.012 in for the TD's first type, 0.014–0.016 in for its second type and for the TF. Pitted or oily faces will stop a spark at any gap.
Burnt, pitted, oily, or not opening at all
Do this
Points and condenser
Clean or renew the points, set the gap to the guide figure, and fit a fresh condenser at the same time, a failed condenser gives exactly this symptom and they are cheap. Confirm the setting for your distributor cam afterwards.
The complete tune-up sequence →With the ignition on and the points open, is there battery voltage at the coil's switched terminal?
No voltage there
Do this
The fault is upstream of the coil
You have lost the low-tension supply: ignition switch, the feed from the control box, or a broken or corroded connection in between. Work back from the coil terminal with a test lamp or meter until the voltage reappears.
The Lucas control box →Voltage is present
Result
Coil, or the low-tension wiring in the distributor
Supply is good and the points are working, so suspect the coil itself or the LT lead and insulating washers inside the distributor, a chafed LT wire earthing on the body kills the spark completely. Substitute a known-good coil before buying anything else.
Spark is good, so this is a fuel problem. Switch the ignition on and listen. Is the SU pump ticking?
Silent, no tick at all
Do this
Work the roadside fuel-pump routine
A silent SU pump usually has stuck points, and it is fixable where you stand. Before condemning it, crack the fuel cap open, a blocked tank vent mimics pump failure exactly.
SU fuel pump: the roadside fix →Pull a plug out and look at it. Is it soaking wet with petrol, or bone dry?
Flooded. Was the mixture control (choke) pulled out and the throttle pumped repeatedly before cranking?
Yes, probably my doing
Next step
Clear it and start again
Push the mixture control home, hold the throttle wide open and crank in short bursts to clear the cylinders, then start with a small amount of enrichment only. Dry and refit the plugs if they are badly wetted.
No, it floods on its own
Do this
Float level or a sticking needle valve
Persistent flooding means a float chamber overfilling: a sticking or worn needle valve, a punctured float, or a float level set too high. Check for petrol dripping from the overflow or into the inlet, and set the float level before touching the jets.
SU carburettor tuning →Dry plug with a working pump means fuel is not reaching the cylinders. Is there petrol in the float chambers? Lift the pump lever or press the float-chamber tickler and look.
Float chambers are empty
Do this
Blockage between tank and carburettors
Isolate it with the fuel-line sequence in the pump article: disconnect at the pump and see whether fuel is delivered from the tank side, then whether the pump delivers onward. That tells you in minutes whether you are dealing with a blocked line, a silted tank, or filters.
SU electric fuel pump diagnostics →Fuel is present in the chambers
Result
The jets or the pistons
Fuel at the chamber but nothing at the cylinder points to a blocked jet, a jet dropped out of adjustment, or a piston stuck up in the suction chamber. Lift each piston with the lifting pin and check it falls back with a soft metallic click.
SU carburettor tuning →Hot and won't restart. Does it crank normally but refuse to fire, then start happily once it has cooled for ten or fifteen minutes?
Yes, exactly that
Do this
Vapour lock, not a fault to chase
Petrol is boiling in the float chambers or the line beside the exhaust manifold. A heat shield between the manifold and the SU float chambers is the effective cure, along with routing the fuel line away from heat.
Starting in extreme heat →It cranks slowly when hot
Next step
Heat soak in the starter circuit
Slow hot cranking with brisk cold cranking points at the battery, cables and earths rather than fuel. Check voltage drop across each connection while cranking, and check the starter is not heat-soaking against the exhaust.
Ignition and charging →It stopped suddenly while running, and won't fire at all
Next step
Treat it as a total spark or fuel loss
A clean, sudden stop is usually electrical, a condenser, an LT wire, or the ignition switch. Go back to the start of this flowchart and take the spark test branch.
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.
Frequently asked questions
Why won't my MG T-Type start?
A no-start on a T-Series is nearly always one of three things: the electrical supply that turns the engine over, the spark, or the fuel. How the car refuses tells you which. No lights and no click points at the battery, earth strap or ignition switch; slow heavy cranking points at current; brisk cranking with no fire means spark or fuel.
How do I check for a spark on an XPAG engine?
Pull a plug lead, hold it about a quarter of an inch from bare metal with insulated pliers, and crank the engine. A healthy system gives a fat blue spark. Keep well away from the carburettors and any fuel vapour while you do it.
My SU fuel pump is silent, is it dead?
Not necessarily. Crack the fuel cap open first: the tank vents through the cap, and a blocked vent puts the tank into vacuum so the pump cannot draw. The symptoms are identical to pump failure. If that makes no difference, stuck pump points are the usual cause and can often be freed at the roadside.
Why won't my T-Type restart when hot?
A car that cranks without firing when hot but starts happily after ten or fifteen minutes' cooling has vapour lock, petrol boiling in the float chambers or the fuel line beside the exhaust manifold. A heat shield between the manifold and the SU float chambers, plus routing the fuel line away from heat, is the effective cure.
What plug and points gaps should I use on an XPAG or XPEG?
The factory figure for the plugs is 0.020 to 0.022 in on both the TD and the TF, for the Champion plugs originally fitted; modern practice with a healthy coil is 0.025 in, and both are in common use. The points gap goes by distributor type rather than by model: 0.010 to 0.012 in for the TD's first type, and 0.014 to 0.016 in for its second type and for the TF. Check which distributor is actually on the car before setting anything.