'90 190E noisy top-end

[jwilliams]

We've got a 1990 190E. It had some compression issues, so we've removed the head, changed the gaskets and valve stem seals, and put it back together again.

It now has a rattly tapping noise coming from the top end at 3000 rpm upwards. We've double-checked that the rockers are in the right location and torqued correctly, and there's plenty of oil getting getting around.

We suspect the problem to be the hydraulic lifters - does this sound reasonable?

 

[Stevie A]

If it's a tick / tap from the top of the engine it'll be the lifters but it usually manifests itself when the engine is cold and goes away when warmed up.

Only other thing I can think of is rattling timing chain as I've read about that causing a rattle but I think your right about the lifters.

 

[jwilliams]

If it's a tick / tap from the top of the engine it'll be the lifters but it usually manifests itself when the engine is cold and goes away when warmed up.

Only other thing I can think of is rattling timing chain as I've read about that causing a rattle but I think your right about the lifters.

Thanks for the reply.

We've warmed the engine up to operating temperature and the rattle remains. I've heard the rattling lifters on old Mercs before, but only when cold as you say.

We're going to double-check the timing chain tensioner as we've had to remove & refit it serveral times, taking great care to put it back in the right order!

For the £40 it will cost us, I think we'll change the lifters anyway.

 

[Stevie A]

I was thinking about this more as well and thought that it was strange that the tapping is happening over 3000rpm. I get a bit of a tapping sometimes but only when the engine is cold and at low revs too.

Malcolm Television gives a good tip to use a large screwdriver against the engine and one bit at your ear as a stethoscope to listen for engine noise which might be worth trying to identify exactly where the tapping is coming from.

 

[jwilliams]

Good tip.

We've had another look at it today - it actually ran perfectly when we started it, but the noise came back at high revs when the engine had warmed up. The oil pressure was too low when the engine was at operating temp, only reaching 2 rather than jumping to 3 as it should.

We're going to give it a good oil flush and see if that makes a difference.

 

[jwilliams]

Ok - progress.

We discovered that the oil gulley which feeds the pipe on top of the rockers was blocked, causing oil starvation in the top end. We've removed the blockage and flushed the engine.

We've also replaced all the hydraulic lifters.

The engine is now running much smoother

However, there's still some noise from the top end at high revs. We're not sure if we've become so sensitive to it that we're specifically listening for it, or if it actually is a problem.

How much noise is "normal" in these engines?
Is there anything else we could do to reduce it?

 

[Stevie A]

Ok - progress.

We discovered that the oil gulley which feeds the pipe on top of the rockers was blocked, causing oil starvation in the top end. We've removed the blockage and flushed the engine.

We've also replaced all the hydraulic lifters.

The engine is now running much smoother

However, there's still some noise from the top end at high revs. We're not sure if we've become so sensitive to it that we're specifically listening for it, or if it actually is a problem.

How much noise is "normal" in these engines?
Is there anything else we could do to reduce it?

I'm not sure what the noise could be now. Maybe try a forum search and see if there is anything else it could be.

The only other thing I can think of is to find a similar 190E with the same engine and have a listen to the engine.

 

[jwilliams]

The only other thing I can think of is to find a similar 190E with the same engine and have a listen to the engine.

Thinking of doing just that

However, a long drive seems to have settled it down - it's not quite running like new, but it is much sweeter.