Diesel bottom engine mount & knocking sound
 

Background:

I have had a knocking sound for a little while, happens generally when I go over speed bumps & if/when I lift off the gas in low gears.

The mechanic I use was unable to trace it when the car was in for service/mot (March). His suggestion was to leave it until it gets more noticeable and then have another look.

It did get worse so, Me being me, I decided to replace the bottom engine mount. Not a difficult task and would rule out that item. Note mileage is 145K. I fitted the mount for the 2.5V6 as recommended.

The noise/knock is far less noticeable since fitting the new mount. The old one had cracks in 2 places.

So to my question.
Where could the knock be coming from?

When driving the noise does sound like it's coming from near/under the drivers feet.

If replacing the lower mount has reduced the noise, could it be that the engine is still moving on the mounts (as it should, hence why they are rubber) and the exhaust is the item that is actually knocking?

Weather permitting I hope to get under the car at the weekend to check the exhaust mounts.


SteveN

HI Steve.
Most likely the lower wishbone bushes, they more or less go after the lower engine mount as failed because of strain on them and vice versa, you will need to get the car jacked up or on ramps to check them.

Not an easy job to do, some members have taken 3 hours or more on one side, so a garage maybe better, but purchase good replacements only with the right amount of substantial rubber in them.

https://i.imgur.com/O6uTnsil.jpg1

https://i.imgur.com/bvRo6J5l.jpg2


You will need to look at these below.
https://i.imgur.com/cUDtujAl.jpg3

https://i.imgur.com/Gj6N57Jl.jpg4

As stated purchase only good ones with enough rubber in them.
https://i.imgur.com/sXcfxsDl.jpg5

https://i.imgur.com/uqPSIiwl.jpg6

Keep away from these types, Chinese rubbish, be careful also of ebay as they portray photo's of the good mount with enough rubber but you get the NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- sent to you.
https://i.imgur.com/HMUObjrl.jpg7

https://i.imgur.com/alTA4Sbl.jpg8

The Unipart ones I have in my first photo are really hard to come by now.

DMGRS did used to sell these below if they do now or not I don't know maybe check them out.
https://i.imgur.com/OuEooO9l.jpg9

https://i.imgur.com/qqAfL6Al.jpg10

HI Steve, nice pics.

I have the same problem as the OP. I bought a new bottom mount before looking at the existing one. When I got around to taking the existing one off the car it was in perfect condition.

Next try will be an inspection of those rubber bushes you mentioned.

Thanks Steve, again :D
I looked at those when I was under changing the bottom mount. They looked fine, but so did the bottom mount until I put a large lever in, then the split was easy to see.


I've just read the 'how to' for the wish bone bushes. Seems a lot of faffing about to remove the 2 bolts, but I remember when I looked at them that there's not much room:shrug: there's also a vid on youtube.


DMGRS does have them, come with a 5 year warranty only £50 the pair.

Go see Trikey.

I've got those " Chinesey" ones on my ZT as supplied by a well known trader..


And also some new ones fitted to some lower arms just purchased from the same source :duh:.



Any actual proof they are no good other than the lesser amount of rubber.;)

Take a look at pictures 3 -6 above and you can see what happens to the ones with lesser rubber, personally I would not take the chance on fitting them, we all know how hard these can be to fit :eek:

A knocking exhaust is very common . When you are under the car , grab the pipe under the front seat area and see if you can easily move it to hit any of the cross-brace bars .If you can , it's usually a misalignment problem and solvable by slackening the rear box joint and twisting the box to raise the pipe. You'll see what I mean when you are under there . :}

Yes indeed . . . took me a week . . . then I threw in the sponge . . . or spanner . . . but if you're near a certain gentleman on Tyneside, then he can whip them off and back . . . in twenty minutes . . . or less.

okey dokey, will be putting the new arms on sometime, even tho' the last MOT in Sept passed ok , despite the awfull knocking over pot holes.
I even pointed it out pre MOT ..


So will have a looksee at the Rear Bushsd then ;)