12 replies to this topic

[JetBLICK]

Ok... so, i got a noise, kinda like an excessively loud tapety noise. Thanks to the benefit of cooper s tappet chest covers i've narrowed the noise down to the inlet valve on no 1 piston.

What i basically did was slacken all the rockers off, and take the split pins out the shaft.
Then i pushed the rockers on springs to one side and removed the push rods, and slid the two end rockers off and removed those pushrods too.
With all the pushrods removed i took out the followers.
Then turned the engine over and the noise was gone.
So in opposite pairs i replaced the pushrods and followers then adjusted them and turned the engine over inbetween. 1&8 went in with no noise... 2&7 made the noise come back, so i removed them again... 3&6 where fine, as where 4&5 (you have to put them in in pairs to adjust them properly)
I put 2&7 back in and adjusted them and the noise returned, then i just took out #2 (inlet valve on #1 cylinder) and the noise went away.
I put #2 back in and the noise came back. So i took the spark plug out and turned it over and it went quiet again.

From looking at the rocker going up and down whilst turning it over it seems to be happening when the valve it coming up... possibly when its seating.


So, in summary for people who dont care how i found out... the tappety noise occurs when the inlet valve on #1 cylinder comes back up and seats, but it goes away again when i take the sparkplug out.

Any theorys/ideas welcome.

Thanks, Dan

[ginigwunkle]

is the head std?

have you made any changes or has this just started on its own??

[JetBLICK]

yea, started doing it all on its own... and the head is far from standard.

[Dog]

cracked seat?

[ginigwunkle]

is the spark plug ok?

the plug couldnt be hitting the valve could it?

checked the spring for cracks?

id take the head off at least, remove the valves and like dog says check the condition....

[JetBLICK]

Wouldnt have thought the valve could hit the plug... and both springs are still in one piece.

Did have a fear that it could be a cracked seat, just thought i'd put it out their to see what others think. I dont really want to take the head off at the moment tho, because the cars with me at uni and i ent got all my tools

Thing is its not down on power at all... still runs fine? ... not that i ran it far after i started hearing the noise

Guess i'll ave to get the head off... or call the RAC

[*DJH*]

Don't take this the wrong way, but are you sure it's the head where the noise is coming from? i had a really nasty rattling noise an i feared the worst, but it turned out to be the big nut on the clutch plunger.

Edited by DJH MINI MOTORSPORT, 16 March 2008 - 10:05 PM.

[HARBER07]

I have a very annoying tapping noise which i believe to be the mechanical fuel pump.

[JetBLICK]

Don't take this the wrong way, but are you sure it's the head where the noise is coming from? i had a really nasty rattling noise an i feared the worst, but it turned out to be the big nut on the clutch plunger.

/\ re-read first post... i'm certain its on that inlet, i'd put copious amounts of money on it, anyways its to regular to just be a rattle. I've checked the engine over and its fairly obvious it was coming from that side of the motor, even before i took bits off.

I have a very annoying tapping noise which i believe to be the mechanical fuel pump.

Mines electric .... it's already got its own noise, it goes 'wuuuuuuuuuuuuuuuuuuuuuuuuuuur', then wen its sucked the 'tank dry it gets angry and goes 'guuuuuuuuuuuuuuuuuuuuuuuuur' instead

[*DJH*]

Don't take this the wrong way, but are you sure it's the head where the noise is coming from? i had a really nasty rattling noise an i feared the worst, but it turned out to be the big nut on the clutch plunger.

/\ re-read first post... i'm certain its on that inlet, i'd put copious amounts of money on it, anyways its to regular to just be a rattle. I've checked the engine over and its fairly obvious it was coming from that side of the motor, even before i took bits off.

ah right, that'll teach me to not to speed read

Edited by DJH MINI MOTORSPORT, 16 March 2008 - 10:29 PM.

[T.Harper]

what condition was the follower in on this valve?

[JetBLICK]

Looks mint... at first i thought it might be that.. or something knocking the cam.. but they both look fine, i'd kinda expect so too considering the cam is a billet from swiftune and the followers are from iskey.

[Sterling M]

Wondered how you got on with this noise?

I have just recently rebuilt my 998 with new followers, new lead free seats in the exhaust valves, and new rocker shaft. It has developed a tapping noise like you reported and for the life of me I just can't find the cause.

It is present when at idle and goes away when the rev's pickup from idle.

I've removed the rocker gear and disassembled, checked and everything looks good. Because it's a new shaft, it has a second feed hole at post number two, so I drilled and tapped this out to insert a blanking bung same as post one to ensure it was not loosing oil pressure through the hole. No change to the noise.

Did a compression test (cold) and with the same amount of cranking, they were 180, 170, 170, 180 PSI.

The motor runs exceptionally well with great power and no missing what so ever.

I've checked with a stethoscope and still can't locate the source. Checked all auxiliaries, (generator, front pulley, fuel pump, water pump, distributor, carburettor, clutch/throw out bearing) and all ok. Front/back, each side with no louder at any point than the other. Clutch depressed makes no difference so not the primary gear.

I've reset the rocker clearances multiple times with no change.

I've ran the motor with the rocker cover off and ran a 2 thou feeler gauge under each rocker in turn with no change with the noise.

It has been doing it for about 2600km with no other changes in performance or noises.

Can anyone suggest anything else before I pull the head and check the valve seats as that's the only thing I can think of for the next step?

TIA.

Edited by Sterling M, 27 April 2024 - 08:59 AM.