Engine "Booming" Noise

[Anonymous]

I am fine tuning at present so tell me if I am going too far…..

I cannot remember this before I took the engine out but when I am hitting speeds of 100kph the engine seems to boom with noise, like it hurts your ears a little. It does settle down after 120kph and below 95kph it is fine. But this booming noise is a little too much.

Could it be the height of the engine, meaning the rear rubber block (brand new, changed when I put the engine back in…) could be touching the bulked to tight and transmitting the vibration into the car ❓

I have adjusted the side engine mounts to raise it slightly, is this the way to give it more “Float”

What else could it be ❓ Engine seems to run very smoothly now (after setting the valves for the umpteenth time) And the new clutch is a dream.

Just need to sort this excessive noise out (could also be that I have no sound proofing on the bulkhead, but as I mentioned I can remember this noise before, but it has been a while)

[Anonymous]

You drove through the Traction’s “sonic boom”.

[Anonymous]

@Den Hewitt wrote:

You drove through the Traction’s “sonic boom”.

I wish… it is the same under acceleration so when the engine is working it booms….

[Anonymous]

Have you replaced the volute springs with the non-standard rubber bushes? I have no experience of these but I would expect to get more noise with those. Also I would try lowering the side mounts not raising them. If you think about it the rear engine mount needs to be set so that there is no up, down or side pressure on its mounting bolts,neither should it be forced against the any of the four sides of its carrier in the bulkhead.

[Anonymous]

OK – I have taken the bulkhead panel off to reveal the rear engine mount. I have recently changed this for a new one when I had the engine out.

It appears that the engine mount in sitting heavily on the edge of the bulkhead, i.e. it was job to get the panel off as it was resting on the bottom of the inside of the panel.

So it looks to me as if the engine is tilted down toward the rear. Which way do I need to move the side engine mount adjusters to level off the engine. I have them set at present to their highest point, i.e. no bolt thread shows at the top beyond the locking nut.

[attachment=1:2brlr3g1]P1070733.jpeg[/attachment:2brlr3g1]

[attachment=0:2brlr3g1]P1070734.jpeg[/attachment:2brlr3g1]

I have a sneaky feeling this is the cause of my “booming” noise 🙁

[Anonymous]

I will answer my own question – I had the engine adjusted all the way down it seems, there is me thinking the other way round. So I wound down the bottom nut onto the spring which of course lifts the engine mount.

About 2cm on each side and the miraculously the rear mount is raised off the bulkhead. A bit of fine adjustment and it is centred in the hole. Tomorrow I am putting in some FatMat sound insulation on the bulkhead and I will go and try him out again. 😀

[Anonymous]

I read in a back issue of someone else having a boom noise around 100KPH they found it was the rear mount so it looks like you may have found the problem Ian. I was thinking the non standard rubber engine mounts would have resulted in less noise. I hope so because I am going to try them.

[Anonymous]

So all tightened up. Panel back on and I also put a layer of Fat Mat sound insulation on the bulkhead (wish I had done this job when the car was just a shell, bloody tough trying to do it with everything in it).

So did my test run (as per water pump thread) and booming noise has near enough gone. Seems a lot more muted than before. Not quiet but bearable now.

I think I may go for the rubber engine mounts just to make it a little better….. but so far so good. 😀 😀

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