The rubber anti-vibration mountings of an engine may crack or come away from the metal plates to which they are bonded.
Engine mountings on a longitudinal engine
A typical rubber front mounting on a longitudinally mounted engine; one of a pair, clearly visible from above.
Check with the engine running. Pull the throttle linkage of the carburettor so that the engine speeds up for a moment.
As it does so, watch the mountings; as the engine suddenly rocks on the mountings, any cracks or unbonded areas should open up.
This video course is the best way to learn everything about cars.
Three hours of instruction available right now, and many more hours in production.
- 4K HD with full subtitles
- Complete disassembly of a sports car
Repeat with the engine switched off by rocking the engine by hand on its mountings.
An engine that is mounted longitudinally usually has two front mountings, which are easy to see. It also has rear mountings at the gearbox.
A transverse engine may have three or four mountings, some of which have to be checked (and if necessary replaced) from under the car.
Raise the front wheels on ramps with the handbrake applied and the rear wheels chocked. Ask a helper to actuate the throttle.
If any mounting is faulty, replace both front ones for a longitudinally mounted engine, or all the mountings of a transverse one.
Replacing the mountings
Spread the load on the sump with a broad piece of wood.
If the engine has a steady bar or damper (See Checking engine dampers) holding it to the body, unbolt one end of the bar or damper and swing it clear.
Support the engine with an adequate jack under the sump, as nearly as possible exactly between the mountings.
Protect the sump with a wood block at least 6 in. (150 mm) square and 1 in. (25 mm) thick.
Unscrew the nuts and bolts.
Screw up the jack until the engine just rises. Look at the radiator hoses, exhaust, cables, pipes and linkages to make sure further movement will not strain them. Disconnect anything that seems at risk.
Raise the engine until the mountings are not bearing any load. The car body rises some distance too.
You may need to stand on a stool or wooden box to reach the mountings.
If you need to get under the car, make sure both engine and wheels are safely supported. On any car, disconnect only one mounting at a time so that the engine is never supported by the jack alone.
Undo the nuts and bolts holding the mounting to the engine and body, noting exactly how they and any washers are fitted.
Remove the mounting bracket to free the rubber part of the mounting.
Also note which way round the rubber part is fitted, then remove it and put in the new one.
Refit the nuts and bolts, but do not tighten them fully.
Replace other mountings as necessary in the same way.
Take out the rubber mounting and renew.
Slowly lower the jack and remove it. Reconnect the steady bar and any disconnected engine fittings.
Start the engine and let it idle for a few minutes so that it can settle down into its normal place on the mountings. Tighten the nuts and bolts.
Finally, check the tightness of all the clips holding pipes and hoses to the engine, in case any have pulled loose.
Transverse-engine mountings
One type of mounting used on a transverse engine has a single central bolt, which is removed. The engine is raised sufficiently to prise away the rubber mounting.
