Classic Car Fault Finding & Diagnostics
Methodical diagnosis for the faults that have everyone else stumped.
Classic car problems are rarely straightforward. An intermittent misfire that only shows up on a warm day. An electrical gremlin that comes and goes with no obvious pattern. A handling quirk that's been "just how the car is" for years because nobody's taken the time to actually work out why. These are the jobs we're asked to look at most, usually after other garages have already had a go.
Our approach is methodical rather than experimental. That means understanding how the system is supposed to work before we touch anything, gathering evidence about how and when the fault actually presents, and testing our theory before reaching for a spanner — not swapping parts one at a time and hoping something sticks. It's slower up front, and it's why the fault actually gets fixed instead of masked.
What We Diagnose
- Engine running and performance faults — misfires, poor starting, rough idle, loss of power
- Electrical and wiring faults, including old cloth looms, deteriorated earths, and non-standard rewiring from past repairs
- Brake, clutch, and gearbox issues — judder, slip, poor selection, unexpected noise
- Fuel system diagnosis, from carburettors to early fuel injection
- Cooling system problems and overheating, including intermittent overheating that only shows in traffic or on long runs
- Suspension, steering, and handling complaints — vibration, pulling, wander, unexpected noise over bumps
- Intermittent and hard-to-replicate faults generally
How a Diagnosis Actually Works
We start by talking through exactly what the car is doing — when it happens, under what conditions, whether anything's been touched recently. From there we work through the system methodically: checking the straightforward possibilities first, ruling things in or out with evidence rather than assumption, and only moving to more invasive checks once the simpler explanations are exhausted. If a fault needs to be replicated to catch it in the act — a long run, a fully warmed engine, a specific load — we'll do that rather than guess from a five-minute look on the ramp.
What You Get
A written diagnosis report explaining what we found, what's causing it, and what the fix involves — before any repair work is authorised. If the cause turns out to be something that needs further investigation once we're into the job, we'll tell you that too, rather than quietly padding the bill with parts that were never the problem.
What's Excluded
The diagnosis fee covers identifying the fault, not the repair itself — rectification is quoted separately once we know exactly what's needed. On faults that are genuinely intermittent, we'll be upfront if more time or a specific set of conditions is needed to catch it reliably, rather than promising a same-day answer we can't stand behind.
Frequently Asked Questions
My fault is intermittent — can you still diagnose it?
Intermittent faults are exactly where methodical diagnosis matters most. We build a picture from when and how the fault occurs, check the likely causes systematically, and where needed replicate the conditions that trigger it rather than guessing at a fix.
Do you diagnose electrical faults on old wiring looms?
Yes — old cloth looms, deteriorated earths, and non-standard wiring from decades of previous repairs are common on classics, and it's one of our most requested diagnostic jobs.
What if the previous garage already tried replacing parts?
That's a very common starting point for us. We start again from the symptoms rather than assuming the earlier parts-swapping ruled things out correctly, since it often hasn't.