by Engine mounts are cheap, easy to check and frequently overlooked. Their failure produces symptoms that mimic much more expensive faults, so a van gets quoted for a dual mass flywheel or a driveshaft when the actual problem is a collapsed mount costing a fraction as much.
What they do
Mounts hold the engine and gearbox in the vehicle while isolating their vibration from the body. They also resist the torque reaction of the engine, which tries to twist in its bay every time you accelerate or lift off.
Most are rubber bonded to metal. Some are hydraulic, containing fluid for better damping, and these can leak. Vans typically use several mounts including a torque restraint mount, often a dog-bone shape, which takes most of the fore and aft load. That one is usually the first to wear and the easiest to check.
Safety notes
Allow the engine to cool before working near the exhaust, turbo or manifold, as these retain heat long after the engine is switched off. Never work under a van supported only by a jack; use rated axle stands on firm level ground with the wheels chocked.
Keep hands, tools and loose clothing clear of belts, pulleys and cooling fans whenever the engine may run. A cooling fan can start without warning.
Symptoms
- A clunk when taking up drive, pulling away or shifting between forward and reverse. The classic symptom, and the one most often misattributed.
- Vibration through the floor, seat or steering wheel at idle, often worse in gear with the clutch up at a standstill.
- A thud over bumps as the engine moves more than it should.
- Excessive engine movement visible when the throttle is blipped.
- Vibration that changes markedly with engine load rather than road speed.
- Exhaust or pipework knocking against the body, because the engine is moving beyond its designed range. For placing engine noises generally, see diesel knock and rattle.
- Gear selection feeling notchy on some vans, where engine movement affects the linkage.
What else causes the same symptoms
This is the important part, since it is the reason mounts get missed.
- Dual mass flywheel wear produces idle rattle and pull-away judder. See dual mass flywheel symptoms.
- Worn CV joints or driveshafts produce clunks on drive take-up. See CV joint and driveshaft faults.
- Gearbox mount or linkage wear produces similar clunks.
- A misfire or injector fault produces vibration at idle that feels mechanical. See diesel injector problems.
- Exhaust mountings that have perished, letting the system knock against the underside.
Because mounts are cheap and quick to inspect, checking them first is simply good sequencing.
Diagnostic sequence
1. Visual inspection
Check: Look at each mount for cracked, split or perished rubber, for rubber that has separated from its metal, and for the engine sitting visibly off-centre or low. On hydraulic mounts look for fluid leakage.
Result and next action: Visible separation or collapse is conclusive. A wet hydraulic mount has failed.
2. The load test
Check: With the parking brake firmly applied and wheels chocked, and nobody standing in front of or behind the van, watch the engine while an assistant selects drive or first gear and applies gentle throttle against the brakes, then reverse.
Result and next action: Some movement is normal. Excessive movement, or a distinct clunk as the load reverses, indicates a worn mount. Compare fore and aft movement, since the torque restraint mount usually shows it first.
Safety: Keep hands clear of belts and fans, apply the brake firmly, and do this briefly. Do not have anyone standing in the path of the vehicle.
3. Lever test
Check: With the engine off, use a pry bar carefully against a solid part of the engine or subframe and look for movement at each mount.
Next action: You are looking for movement within the mount itself rather than flex elsewhere. Be careful what you lever against.
4. Support and unload test
Check: With the engine safely supported from below by a jack with a block of wood, take the weight off the mounts and inspect each in an unloaded state.
Next action: Deterioration is far more obvious when the mount is not compressed by engine weight.
5. Rule out the alternatives
Check: Exhaust mountings, gearbox mounts, driveshafts and engine running quality.
Next action: If the mounts check out, work through the list above rather than replacing them speculatively.
Replacement notes
- Support the engine properly before removing any mount. The engine must be held securely, and the support must not damage the sump.
- Replace one at a time where possible, so the engine stays located.
- Check alignment before final tightening. An engine bolted up out of position puts continuous load on the new mounts and on driveshafts.
- Torque to specification. Overtightening damages the rubber bonding.
- Consider replacing as a set on a high-mileage van, since one failed mount usually means the others have had the same life. Once one has collapsed, the others have been carrying extra load.
Indicative UK costs
Broad context only. Mounts commonly run from around twenty pounds into the low hundreds each depending on the van and whether they are hydraulic. Labour varies considerably with access: a torque restraint mount may be quick, while a mount buried behind other components takes longer. Get quotes.
Common mistakes
- Diagnosing a flywheel or driveshaft without checking mounts first. Mounts are the cheapest suspect and should be eliminated early.
- Inspecting only while loaded. Take the weight off to see the real condition.
- Replacing one and leaving the others. On a high-mileage engine the rest are usually close behind.
- Not checking alignment before final torque. Leaves the engine loaded off-centre.
- Ignoring engine running quality. A misfire produces vibration no mount can isolate.
- Levering against something fragile. Damage the sump or a plastic housing and the cheap job stops being cheap.
When to stop and get help
Get help if a mount has failed completely and the engine is visibly sitting low or contacting anything, since that can damage pipework, wiring and driveshafts. Also get help if you are not equipped to support the engine safely, which is the part of the job with real risk. Do not run with a fully collapsed mount, as the resulting movement stresses driveshafts, exhaust and gear linkage.
Prevention
Avoid harsh clutch take-up and sudden shifts between forward and reverse, which shock-load the mounts. Address engine misfires promptly, since sustained vibration accelerates mount wear. Have them inspected at each service, as it is a quick visual check. Avoid overloading, which increases the loads everything sees.
Frequently asked questions
How do I tell a mount from a flywheel problem?
A mount usually produces a clunk on drive take-up and vibration that changes with engine load. A flywheel typically produces rattle at idle that changes when the clutch pedal is pressed. Check the mounts first because they are cheaper.
Can I drive with a worn engine mount?
In the short term usually yes, but a fully collapsed mount lets the engine move enough to damage other components, so it is worth doing promptly.
Should I replace all of them?
On a high-mileage van it is often sensible, since they have all done the same work and a failed one loads the others.
Why does my van vibrate at idle only in gear?
Holding the van against the clutch loads the mounts in one direction, which reveals wear that is not apparent in neutral.
This guide is general information for UK van owners, not vehicle-specific repair instructions. Procedures, tolerances and component layouts vary by engine code and model year. Confirm any figures against your VIN and manufacturer workshop information, and see our Disclaimer before carrying out any work.
