944 S2 engine problem

[z3944]

The engine vibrates quite badly between 3000 and 3400 rpm. It doesn't affect performance or ride or make the car shake, but I can feel it through, and see it on the gear stick. Up to 3000 it's very smooth, above 3400 it's very smooth - but then I'm also speeding so I only did it once to test the engine! The vibration occurs whether moving or stationary, and with the clutch in or out. Any ideas please? Thank you.

[z3944]

Everything has been changed and done when it's supposed to be. The car is well looked after. One owner before me, I've had it twelve months and done 16000 miles in it (because it was off the road for three months). It has FSH, and at 155000 miles has original everything except brakes and tyres. You might be right with mountings.

[z3944]

It's only started a week or so ago. I only really noticed it as I could feel it while accelerating (if I can call it that) through the gears - I usually change between 2000 - 2500rpm, but if I'm feeling daring I will occaisionally go above 3000 rpm.

[z3944]

Thank you all for your advice. I will investigate and update with findings later.

Thanks again.

John.

[z3944]

Thanks for all the advice. Checked everything out. All the timing was spot-on, but the balance shaft belt was loose. Adjusting the belt has reduced the vibrations, or rather narrowed the range to between 3200 and 3400. Doesn't happen before or after those revs. Any ideas as to what else is a common problem that may be contributing to this (now improved) problem?

Thank you

John.

[z3944]

Nick is right. When they are set up right the engines are amazingly smooth. The belts were fitted by JZ Machtec. They were checked / tensioned at the necessary mileage post-fitting. I said the belt was 'loose', but it wasn't flapping around or jumping - it just needed a slight tensioning. The vibration is now only at 3200 - 3400 (it was 3000 - 3400). Unlike other threads I have read it does not occur before or after this rev band. The problem has only recently started. If the cam had been incorrectly lined up when the belt was fitted then I assume I would have had the vibration from the beginning. The engine itself does not move anywhere when you rev it, i.e. solid as a rock - so I assume the mountings are fine.

[z3944]

stevep2000 said:

I may be wrong (again!), but I thought I'd read somewhere that no movement is a problem, i.e. the mount has collapsed & is not insulating the engine movement / vibration from the body?

At the risk of starting to bore people.

My fault this, poor description. When I said 'solid as a rock' I meant that it wasn't moving around when you rev it, like some engines do when the mounts are gone.

John, did the vibration occur all the time, or just during a narrow rev band like mine does?

[john ward]

It's only 32 miles - I might just drop in at Hartech. It's clearly the easiest way. It takes all the guessing out of it. Thanks for all your help anyway.

[john ward]

On Friday 5th January I decided to bob up to Hartech. After spending 30 minutes in traffic from the A666 towards Crompton Way (ambulances and police cars suggested something was wrong ahead), I had to (unfortunately) turn back and go into Manchester for a business appointment that I couldn't miss. So close yet so far - sorry Baz (I didn't have an appointment by the way).

Today I went to see Stewart, my regular mechanic (top bloke), who was adamant it was nothing to do with the balance shafts. He took the belt cover off, took the flange washers off the gear wheels and determined that the shafts and gear wheels were all set up as they should be.

He then telephoned JZ Mactech, the guys who did the belt and cam chain replacement in September 2004 (20000 miles ago), and Steve was good enough to call back. Without being given a registration number or any info other than 944S2 he remembered the car and guaranteed that everything in the engine was fine. Steve advised Stewart to check the engine mounts. He did and found that the off-side one is worn out. Had I got to Hartech they would have told me the same last Friday and I could have had it fixed by now.

So we're ordering the parts now, and I will post an update once the job is done.

Thanks to all of you for your input so far.