Hydraulic mount symptoms

[hst125]

Ever since I bought it my CDTi has had a habit of vibrating the roof lining hoop. It’s gradually got worse and the exhaust joined in a while back. Now it’s unbearable and the exhaust bangs when I switch off, no rocking from the engine, I’m assuming this is hydraulic mount failure? Ordered a three piece set from DMG so will do it next week and I’ve laid the car up for now!


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[clf]

Originally Posted by hst125

Ever since I bought it my CDTi has had a habit of vibrating the roof lining hoop. It’s gradually got worse and the exhaust joined in a while back. Now it’s unbearable and the exhaust bangs when I switch off, no rocking from the engine, I’m assuming this is hydraulic mount failure? Ordered a three piece set from DMG so will do it next week and I’ve laid the car up for now!


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Since there is no movement on the engine, have you checked the heat shields? These commonly tear at the screw mounts and rattle, especially when switching off. If it is, add some penny washers, and reattached. I would also advise adding a rubber washer between the washer and the heat shield too, as this will absorb vibration and reduce the chances of it tearing again.

Also check the exhaust mountings, if it is not the heat shield, but these failing, is less common than the heat shields.

[hst125]

It’s definitely at least the exhaust, it really bangs under the floor when the engine switches off. The vibration/resonance has got significantly worse in the 1500 miles I’ve had the car. I’d think it was the mount collapsing into itself as it seems it’s moved the exhaust system.

[clf]

Originally Posted by hst125

It’s definitely at least the exhaust, it really bangs under the floor when the engine switches off. The vibration/resonance has got significantly worse in the 1500 miles I’ve had the car. I’d think it was the mount collapsing into itself as it seems it’s moved the exhaust system.

I would check this visually at least. It could be more than one issue (eg rear hanger with something else). The engine mount, if shaking the exhaust, would allow the engine to be seen to move at the same time.

[hst125]

I’ll check it somehow, I’ll be working solo! I meant there’s no knocking under power/lift off.


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[clf]

Originally Posted by hst125

I’ll check it somehow, I’ll be working solo! I meant there’s no knocking under power/lift off.


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My heat shields did not knock on lift off, and I would not expect them to. I would expect an engine mount to cause an exhaust rattle though on acceleration and a sudden lift off or braking.

With the displaced exhaust, I would look to the bracket, or a badly fitted replacement.

The knock at switch off, I would look at the heat shields first.

A failed engine mount that has failed enough to cause the engine to move enough to move the exhaust that much would be visibly obvious, at start up and switch off, possibly even running.

But the only way to be sure is a visual and physical check.

Drive up on a kerb if it is too low, but it could be checked by lying beside the car. You can reach the heat shield from the drivers door. Crawl below the silencer at the rear to check the bracket also give the tail pipe a shake.

[Mike Noc]

Replacement exhausts can swivel at the join if not clamped tight enough and drop down and rattle against one of the cross braces.

[hst125]

I’ve found excellent threads on here to assist with this job, and a Haynes manual, and I’m happy to give it a go on Monday. I think the deal maker was realising only the teardrop mount has to be done from underneath, the rest is from above albeit involving a jack and block of wood. I’m going to combine it with bumper removal, horn upgrade and possibly headlight bulb upgrade to HID.
Simple question therefore:
If I’m doing all three, what order is best to do it in????


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[COLVERT]

Start first with the two top mounts then try the car. If the problem has gone then there's no need to crawl about underneath the car.---