Car vibrating at speeds of 70mph

[redman]

Hi guys. I have resently noticed that when I reach speeds of 70mph and or slightly above my car starts to vibrate . This stops when I reduce the speed to about 68mph. I think it all started when I had my first rear off side slow puncture. I have had the front tyres rebalanced at local kwik fit but the problem still persits. The car has also started to loose the 'umph' at low speed where before you could feel the car ready to go... Wonder what is wrong..... the car is a 99 1.8 20v passat APT engine at 72000miles. oil change service and brake fluid change done about 2 months ago.

Thanks.

[creedxup]

If a car vibrates at 70 mph, it is almost always a wheel balance problem, it may have been incorrectly balanced or the weight may have fallen off, regardless, I would take it back and they should/will re-balance both wheels free of charge.

Chris

[redman]

thought so too. I will have the rear wheels balanced and swapped around.

many thanks,
redman

[KeithS]

Checking all wheels are balanced is the obvious thing. I also get this problem when the rear tyres are worn (still within the legal limit though). Manifests itself as a vibration which starts above 65mph and seems worse when braking.

You could also try swapping the front and rear wheels.

[Crasher]

A loss of low end torque is common on these engines. First of all you should have a fault code read done. The most common reason we find for power low end torque loss is the end of the actuator rod for the variable inlet manifold change over barrel snapping off. On the front of the inlet manifold you will see a capsule point up at an angle and a plastic cover over the front of the unit. Prise this cover off and you will see the actuator rod for the change over capsule. Look at the end of the rod and you can see if the end has split open.

[redman]

many thanks guys, I have just had the four wheels rebalanced and two of them were completly way off balance. The HiQ fellows also swapped the wheels around and the vibration seems to have stopped at a small stretch of 70mph. I will go on the motoway and test it at a longer stretch.

I am now going to fiqure out what crasher is 'telling' me. Will report back as soon as i find my way round.

[Crasher]

I wish I had a picture that made this clearer. The inlet manifold is plastic and is on the left of the engine (by left, I mean as looking from the drivers seat). Looking into the engine bay, look down at the engine and the inlet manifold is to YOUR right and at the front of the manifold there is a unit sticking up at about 45 degrees to your right with a vacuum pipe going to it and the top is round. Below the vacuum unit there is a cover that is sort of triangular shaped and it can be gently prised off.

[redman]

Thanks Crasher. I will look at it in the morning with enough day light. I will then inform you whether its broken or not.

redman.

[redman]

Hello guys,

Thanks again Crasher. I have found the inlet thing and prised open it and you were 100% right. The end of the rod(the small round part) has split in two. What do I do now? . how easy is it to repair or fit in a new one.

Many thanks.

Redman.

[Crasher]

This is where it gets a bit annoying. The operating rod and its diaphragm can be removed and replaced quite quickly BUT you can’t buy it! The only solution is to buy the whole assembly which goes right down the full length of the inlet manifold and this means removing the inlet manifold or dropping down the front panel, which is the way I prefer to do it. This is because the unit is so long it will not come out. You have to be extremely careful when withdrawing the old unit as bits can snap off and fall inside the manifold and the new unit has to be inserted extremely carefully for the same reason. The part is VW number 06B 133 619 A and costs £134.22. PM me your email address and vehicle chassis or reg number and I will send you some info on the parts.