9 replies to this topic

[Curare]

Hey all, just after some advice on a new noise my 998 A+ rover has developed.

It's a flutter ticking noise thats only there under load. the more I put my foot down the louder it gets, it's rev dependant (not gearbox related, unless it's the input shaft) and doesn't sound like pining.

I've tried pulling the choke out under load to see if it went away with a rich mixture, but no it doesn't , and it's not that "marbles" sound it's rythmical fluttery click.

I did the tappets not long ago, and i'll check them again, but it does hot and cold, and performance doesn't seem to be down. It has a stage one kit on it, but this noise has only developed (as far as I could hear) in the last day or two.

Any ideas?

[Minimininut's Dad]

Hi,

I doubt it would be tappets as load is not likely to affect any noise from them. If you are sure it's not pinking, then it's difficult without actually hearing the sound to say what it could be.

I just wonder if it could be the exhaust blowing, perhaps at the manifold gasket? Often when this starts it can sound quite like a mechanical ticking sound, and then over a few miles/days it gets louder as the gasket material burns away.

It can be difficult to find where it's blowing from, but you can sometimes feel the puffs with your hand but BEWARE it's VERY HOT so don't touch the manifold/pipe. If it makes the noise when the engine is cold it's easier to check quickly before it get too hot but the noise is often less when the engine is cold!

Anyway this is my guess - hope it helps - only if it's something to eliminate?

Take care,

[minimender]

I'm with Minimininutsdad on this. Exhaust blowing.

[Nobbie]

Exhaust blowing at the manifold, or the 2-1 joint, that's where mine was last week.

[Curare]

Right, after much phaffing; I have done the following:

1. checked the tappets. No joy, they're all sweet as a nut.

2. run it on premium fuel, no joy.

3. waited for it to cool down, then ran my hand around the manifold, feeling for a puff.

BINGO.

So for those who said manifold leak, kudos to you.

Now, what do I have to do to fix it? Is it another gasket? Please dont' tell me it's another gasket, I can't bear to fit another gasket.

PLEASE DOC NO! I ONLY HAVE TWO MONTHS TO LIVE!?!?!

Ok mildy overdramatic, but I really don't want to have to do all that crap again!..

[bmcecosse]

Obviously it needs a new gasket -where's the drama in that ? You can try tightening the nuts on the old gasket and see if that helps - but it's likely it was not properly tightened before - and now a section will have been erroded away.

[Minimininut's Dad]

Hi again Curare,

Minimininnut's Dad here! Glad you've tracked the cause down. You say you've had to replace the manifold gasket before, and that you have a Stage One kit fitted. Please click on my photo/profile and you'll see my statement referring to problems with flanges on the manifolds. I have more info on what we did to stop gaskets blowing so often but I have not had time to write it up yet. Please let me know if you would like me to let you know about what I did.

[Curare]

Hi again Curare,

Minimininnut's Dad here! Glad you've tracked the cause down. You say you've had to replace the manifold gasket before, and that you have a Stage One kit fitted. Please click on my photo/profile and you'll see my statement referring to problems with flanges on the manifolds. I have more info on what we did to stop gaskets blowing so often but I have not had time to write it up yet. Please let me know if you would like me to let you know about what I did.

I take it you're referring to the difference in flange thickness? I was worried about that, so I put a vernier across the flanges, and they were all within 0.1mm of each other, surely this isn't enough to cause my annoying little leak?


bmcecosse: sorry, I should have pointed out earlier that I'm lazier than a council road worker on a sunday. Having to move my digits to type hurts.

[Minimininut's Dad]

Our inlet manifold flanges were 1 mm thicker and this was too much so I made the thick washers 1mm thicker on one half, then positioned them carefully before very fully tightening up the nuts.

Your mere 0.1mm variation should be an acceptable tolerance. If the gasket tends to blow in the same place(s) each time this may show what the problem is? You could make sure that the faces are square/flat to the head face; the pipe fixing/clamp at the back of the transmission casing could be holding the pipe to far out or too close in meaning that the top and bottom of the flanges are not meeting the head evenly. Should this be the case then it's best to loosen or remove the clamp and better still to disconnect the exhaust pipe from the manifold before tightening the manifold to head nuts. I use a little Firegum on just the exhaust flange faces and a new gasket of course. Then refit the pipe clamp to the transmission casing bracket without straining the pipe in any direction, check the engine steadies are in place and then reconnect the exhaust pipe. Also see my post in the topic Exhaust Problem (18th Sept).

Attached Files

•  Pad_on_washer.jpg   54.19K   7 downloads

Edited by Minimininut's Dad, 23 September 2009 - 12:31 PM.

[Dan6061]

Had this problem with mine. Just put a new manifold gasket on this evening, but it's still doing it?
Thanks to some cowboy mechanic, I have one stud on the end with a stripped thread, and another one with the wrong type of nut on! So as I tightened it, it's stripped the thread on the nut. So it's still blowing.

Just ordered some new studs and nuts, so hopefully when they're on it'll sort it out!