17 replies to this topic

[mini mayhem]

998cc 1985 94K

after adjusting my valve clearances the engine ran very smoothly for the first 30 secs and then the ticking, tapping, knocking noise from the tappets returned. so i left the engine cool down and did it all again ( didnt really do much) . same thing happened quite for 30 seconds and then the noise came back. left it idling for a while the noise persisted. turned it off and started it again noise is there from start up.

could it be wear after 94k miles??

bent rods???
im sure im setting them right.
any ideas??


EDIT:

The noise is just the top of the valve stem and the rocker arm hitting each other.

What you can do is when the engine is running, get a hammer with a wooden handle and just touch it agaist each valve in turn, you should find out which valves are noisey this way



^^^ could this really solve my problem??

Edited by mini mayhem, 16 September 2009 - 01:55 PM.

[Cater_Racer]

998cc 1985 94K

after adjusting my valve clearances the engine ran very smoothly for the first 30 secs and then the ticking, tapping, knocking noise from the tappets returned. so i left the engine cool down and did it all again ( didnt really do much) . same thing happened quite for 30 seconds and then the noise came back. left it idling for a while the noise persisted. turned it off and started it again noise is there from start up.

could it be wear after 94k miles??

bent rods???
im sure im setting them right.
any ideas??


EDIT:

The noise is just the top of the valve stem and the rocker arm hitting each other.

What you can do is when the engine is running, get a hammer with a wooden handle and just touch it agaist each valve in turn, you should find out which valves are noisey this way



^^^ could this really solve my problem??

If you run the engine with rocker cover removed, is it throwing oil all over the place? It should.... If not it could be poor oil feed to the rockershaft.

[Sherlock]

If your engine has been well maintained for 94k miles, I wouldn't expect such a dramatic effect from just wear. My 998 has done over 100k with original rocker gear, makes no real noise. Is there a good amount of oil flow to the rockers, you can check by running the engine & looking in the oil filler with a torch. There should be noticeable oil running from the rocker shaft on to the head, even at idle speed. If not you could have a blocked rocker shaft, without the cushioning effect of the oil, your tappets will sound noisy & if not corrected, considerable wear will result.

[mini mayhem]

ive just adjusted them again and went for a spin noise came back. seems to only be the tappets for valves 3 and 6 that are giving noise.

there is warm oil on the rocker gear. i'll try looking for the oil moving.

EDIT:tappets for 3 and 6 also have a noticable amount of wear compared to the others

Edited by mini mayhem, 16 September 2009 - 03:49 PM.

[mini mayhem]

would double nutting on the loose tappets be a suitable solution

[Figs122uk]

Just a quick question. Should you be able to hear the tappets at all ?

Because i can hear mine. Very Quietly mind after about a min or so, with my radio of, and when im at a steady speed... There set at 0.31mm.

PS: is it completely compressed simpley when it is fully down, and about to return upwards?

Edited by Figs122uk, 17 September 2009 - 07:17 PM.

[Sherlock]

Figs:It's not unusual to hear tappets mildly ticking in the background, but they shouldn't really be obtrusive. The valve is open when the spring is fully compressed, the noise happens when the valve has closed & is about to open again.
Mini Mayhem: In the case of these tappets in question, ever heard of an SPQR tappet adjuster? it was a popular tool with which you could adjust your tappets & compensate for worn rocker arms. I never used one, I prefer to see exactly what's happening with a feeler gauge, but there must be hundreds of these tools around somewhere, if you could borrow one it would prove a point as to whether worn rockers are the problem. I'm sure you've been doing the job right, but can I just ascertain that you are setting no1 tappet when no8 valve is fully open, no2 with no7 open etc, whichever valve is fully open, you adjust the opposite & the numbers always add up to 9. Please understand, I'm not suggesting you do it wrong, just have to check.

[Figs122uk]

Thank you Sherlock..... My mind is getting at ease. Although it seams ive lost a little power till it warms up now. |

Edited by Figs122uk, 17 September 2009 - 09:08 PM.

[JD8891]

Dont forget by the valve been open it means the rocker is pushing on the rod.......not that i made that mistake

JD

[Figs122uk]

Dont forget by the valve been open it means the rocker is pushing on the rod.......not that i made that mistake

JD

[JD8891]

Dont forget by the valve been open it means the rocker is pushing on the rod.......not that i made that mistake

JD

I figured it out once i started the engine, i was actually impressed that it did start, but boy were they some noisey tappets.
JD

[Jimmy Morris]

Someone may have mentioned but I will say it anyway if the rocker arm where it runs on the valve stem tip has a groove worn in it from years of wear you will never get a proper clearance using feeler gauges. If you have roller rockers they maybe fouling the cover???

[mini mayhem]

Figs:It's not unusual to hear tappets mildly ticking in the background, but they shouldn't really be obtrusive. The valve is open when the spring is fully compressed, the noise happens when the valve has closed & is about to open again.
Mini Mayhem: In the case of these tappets in question, ever heard of an SPQR tappet adjuster? it was a popular tool with which you could adjust your tappets & compensate for worn rocker arms. I never used one, I prefer to see exactly what's happening with a feeler gauge, but there must be hundreds of these tools around somewhere, if you could borrow one it would prove a point as to whether worn rockers are the problem. I'm sure you've been doing the job right, but can I just ascertain that you are setting no1 tappet when no8 valve is fully open, no2 with no7 open etc, whichever valve is fully open, you adjust the opposite & the numbers always add up to 9. Please understand, I'm not suggesting you do it wrong, just have to check.

ahuh thats the way i have done them.

after double nutting the noise was still really bad and i think i may have over tightened a wee bit. i took off the double nut and completly re did every tappet and valve. now it is backfireing between 1500 rpm and 3000 rpm and then it goes fine (quick acceleratin) when i accelerate slowly its fine.

have i bent the rods by having them slightly too close???

still have noiser than should be tappets

[bmcecosse]

You certainly don't need 'double nuts' !! Set exhausts to 15 thou and inlts to 12 thou - and as long as there is oil coming up and over the rockers (runit at idle with cover off) it will be fine !

[Sherlock]

You won't bend the pushrods by having tappets slightly tight, that only happens if the valves hit the pistons.