Crankshaft Repair
Also called crank grinding
The crankshaft runs in soft bearing shells fed by pressurised oil. When oil supply drops or the engine is run past its service intervals, those shells wear and the journals score, producing a deep knock and falling oil pressure. Repair means removing the crankshaft, measuring it, grinding the journals undersize where possible and fitting matching bearings. If the crankshaft is cracked or ground beyond its limit it must be replaced, and continuing to drive with a knock makes that outcome likely.
Signs you need this
- A deep rhythmic knock from low in the engine that worsens under load
- Oil pressure warning light at idle or at low engine speed
- Metal flakes in the oil or on the sump magnet
- The engine has run low on oil or lost oil pressure previously
- Knocking that follows engine speed rather than road speed
Not all of these have to be present, and one of them on its own can mean something else entirely. That is what the diagnosis is for.
What the job includes
- Oil pressure measured with a mechanical gauge before strip down
- Bearing shells removed and read for wear pattern and contamination
- Journals measured for wear, taper and ovality
- Grinding to the next undersize where the crankshaft is within limits
- New matched bearing shells fitted with clearances checked
- Oil pump, pickup strainer and oil galleries cleaned or replaced
How we do it
Measure oil pressure
A mechanical gauge gives a real figure, because the dashboard light only warns at a dangerously low pressure.
Inspect the bearings
Shells are removed and read, since their wear pattern shows whether the cause was oil starvation, dirt or simple mileage.
Measure the crankshaft
Journals are measured for wear and ovality to decide whether grinding will recover it or it must be replaced.
Grind and fit bearings
The crankshaft is ground undersize, matched shells are fitted, and running clearance is checked on assembly.
Restore oil supply
The pump, strainer and galleries are cleaned or replaced so the new bearings are not destroyed by the original cause.
How we work
The same on every job, which is why we can write it down.
Diagnosis before quote
We find the fault first. A price given over the phone for a noise nobody has heard is a guess.
The price is agreed first
You approve the work and the cost before a spanner is picked up. Extra work means another call.
Parts you can check
We tell you whether a part is genuine, OEM, aftermarket or used, and what each one costs.
Old parts returned
Ask and we will hand back whatever we replaced. It is the simplest proof that the job was done.
Book crankshaft repair
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We call you
To confirm the car, the time and the location.
Tell us the car and the symptom
We will arrange a mechanic at your location, or a slot at the nearest workshop. No payment until the price is agreed.