Engine rock

[RichyB]

Hi there,

When I let off the throttle there is an annoying clunk as the engine seems to rock forward. It can be felt in the steering wheel and pedals too, and the gear stick noticeably moves forward. It's done this ever since I've owned it. The front lower engine steady was broken when I got the car and quite hard to reach so I left it off. In place of this, I've tried all sorts of things to solve the problem but nothing has worked.

So far I've:

-Replaced head steady rubber bushes with polybushes
-Fitted a lower gearbox to subframe steady (also polybushed)
-Replaced all engine mounts
-Replaced all subframe to body mounts
-Fitted a Minisport extra engine steady (thermostat to bulkhead)

And it still moves around.. Is the lower front mount so important that it could cause this? I would have thought that the head steady would stop the most engine movement. Could the fact that I can feel it in the pedals and steering wheel mean that it could be a suspension issue? Or maybe the rear subframe?

I'm out of ideas on this one, anyone else have a similar problem?

Help greatly appreciated!

Rich

[Kenneth Murphy]

Has the top mount pulled away from the body? My old one did and wrecked my head banging,

[woody]

The extra lower and lefthand steady should make up for the missing lower steady. Where the righthand steady meets the bulkhead make sure the bottom part of the bracket hasn't broken off the bulkhead.

If the engine is sitting solid in the subframe maybe its the subframe that's moving.

[RichyB]

Thanks for the replies!
Head steady is solid, and the engine doesn't seem to move at all when I rock it by hand. So now I'm thinking it could be the subframe. But I replaced the front subframe rear mounts a few weeks ago, and the tower bolts are polybushed. The front teardrop mounts were replaced last year. Do these need replacing often? I have new polybush ones to replace them with.

Rich

[mgb1978]

Front teardrops shouldn't really cause this much noise and clunking.
Pull back the carpets and check that the floor is sound where the lower subframe mounts bolt through.
They often crack around this area.....not the hardest thing to fix.
Also try rocking the car backwards and forwards by hand (in 2nd gear) and see if you can locate any noise or movement.

ps. had one once where the box section for one of the top mounts was squashed slighly, even though it seemed the Tower bolt was tight there was still room for movement.

[RichyB]

So, the lads out in Minifix have informed me that my steering rack is bunched. Could a crap steering rack be a source of movement when I let off the throttle? I can feel the rock through the steering wheel..

The engine seems solid when I rock it by hand so it's probably not that. When I'm replacing the rack I'll have a good proper look at the whole suspension and subframe and see if I can find the source of the rock.

[woody]

Have somebody drive your car over a rough surface and with your feet pressed to the lower bulkhead over the rack you should feel a knocking if the rack is gone. This knock would be constant and not just when accelerating or decellerating. The rack gone wouldn't cause the gearstick to move.

[vincieshile]

I had a similar (the same) problem. Everything seemed tight and solid. Finally Mervyn Johnson discovered that the tower bolts, even though they seemed full tight, needed more tightening. The right socket and ratchet along with 4 feet of steel pipe tightened them that little bit extra and put an end to my problem.

[The Marcos Graveyard]

This is easily detected, have someone turn the steering wheel left and right as you observe the movement between the tower bolts and the body. The tower bolts, if over tightened can distort the bulkhead cross beam only over emphasizing the problem.

[RichyB]

I think I can feel that just driving around Woody, noticed it recently that I could feel a knocking coming through the floor behind the pedals. Better get this rack sorted ASAP!

I have the tower bolts torqued to 67nm, should I try tighter?

Thanks for all the replies!

[Dylan8660]

If you replaced the front subframe rear mounts with polybush ones then I would look closely at them, those things are badly engineered. If you put the steering on full right lock, let the steering lock engage, jack up the lhs and try to turn the wheel back to centre, you might observe the rear of the subframe moving. If there is movement it has a greater effect on steering rack arm movement which will be very evident. Go back to standard or solid.

[Scoobasteve7]

Another thing you could check would be the shocks.

My dad has an old corolla and the rubber in the middle of the shock wore away over time with the end result being the whole bottom half of the shock and the hub swayed. Didn't realise it until it was put up on a car lift and the whole lot fell downwards.

It affected the steering with a bad knock. It was more noticeable at lower speed going through bumps too. Might not be the same but worth a quick look anyways.

[vincieshile]

Did you ever get the problem sorted and how?

[RichyB]

Yes! Meant to update this thread much sooner..

I replaced my steering rack and that sorted out my engine rock. The rack I put in wasn't new, but I couldn't feel anything wrong with it. The rack I took out had noticeable play in it. There's still a little engine rock, but its about the same as my dad's 2000 MPi now.

Car is much nicer to drive now, feels more solid and responsive. Thanks to everyone for their help and suggestions! Much appreciated.

Rich