19 replies to this topic

[happydude2012]

Hi Chaps

 

Ive noticed a tapping sound on cold start of late, not really bad, but its one of those sounds once youre obsessing over it , you hear it all the time.

this might sound mental but if ive parked on a flat surface overnight its not really there, but on a slight forward angle such as down the drive, its quite obvious on ignition, and then seems to reduce considerably once warmed up, maybe 2-3 mins, but its still there in the background very slightly

Also notice it when going down hills, in gear but not accelerating.

 

My valve clearances are 15 thou as per swiftunes spec for the sw5-07 cam, set perfectly and I use 20/50 oil (recently changed from 10/40....I think....) this did make my engine sound and run much smoother when I changed over.

However, I made this change about 3 months ago when I last tweeked the valve clearances and some of them were quite out to be fair, but I think this is when the tapping started as I cant recall it prior to this change.

 

There is no effect on performance and if I put my foot down I cant really hear it (probably because the engine is louder)

I don't think its my rockers hitting the rocker cover.

 

Is this a "thing" or am I just obsessing?

I know im not hearing things, as the sound is 100% there on cold start - it does seem to sound like its tapping with the rockers/valves or somewhere linked to that mechanical process.

 

thanks guys./

 

[Retroman]

Could be a worn cam follower

 

If it has tappet chests on the back, the followers can be inspected and changed without removing the headstuds

[happydude2012]

this can be done with the engine in? ill google that and have alook.

[Cooperman]

Only if it is an 850/997/998/1098 or a genuine Cooper S engine.
All the other 1275 engines have solid blocks with no cam chest covers.
Of course, it may not be a cam follower.

[happydude2012]

its really not that bad - its just on first thing in the morning starts and then very slightly whilst driving. 

but i hear it all the time now and its really doing my head in.

do you think the change of oil viscosity could be to blame?

[Cooperman]

No, it's not the oil as you have changed to the correct viscosity with a 20w50.

 

There are many things it could be, such as a worn rocker bearing, the timing chain tensioner or the timing chain, a worn distributor drive line or even the distributor itself, a worn cam follower or a worn cam lobe. I may have missed out a few other things, but i'm sure my friends on here will list them for you.  It doesn't sound like big end bearings or main bearings. Big-ends knock harshly, if badly worn, at initial start-up and may rattle on normal driving as they get worse. Main bearings 'rumble' when they are going to fail.

 

If the noise gets worse and can't be defined, you might need to take the engine out and strip it to find the problem.

[happydude2012]

so ive re torqued the head which needed doing and checked the valve clearance again and its bang on. Started with no tapping but was still a bit warm from earlier in the afternoon. will see what its like tomorrow.

Im ******* myself, if this thing blows im stuffed. ha ha

[Retroman]

Well hope fully it won't go bang, it doesn't sound terminal.

 

Maybe keep your ear on it...its a reasonably good sign that the tappets were OK,

 

If it was a follower or lobe that would wear pretty quickly and show up every time as a big gap

[russo]

Don't want to alarm you but maybe the top compression ring is either broken or too much clearance in the ring groove. That can cause a rattle/tap like a tappet noise.

[happydude2012]

i should say ive got swiftune sw5-07 duplex cam installed - its only 2 years old so im thinking the probability of wear on the cam and followers is unlikely as the whole engine was rebuilt at this time with new rings, shells , the lot.

Im going to go and double check the valve clearances now the engines cold. and start her up - if the tapping has stopped ill do a hand stand

[happydude2012]

WELL, just triple checked the rockers and everythings fine, oil was a tad low on the bottom of the dip stick so topped it up, so ive got a feckin leak somewhere but  now the tapping on a cold start seems to have stopped.

hand stand on hold while i give it a week.

[Retroman]

We have a local guy with a telescope, let me know if you do a hand stand on the moon, it will be worth watching hahaha

 

Fingers crossed

[merther]

Sorry to go slightly off topic, but with regard to adjusting the tappets. What issues would you have if the tappets were set to tight? Is it likely they would make more noise too?

[Retroman]

With standard retio rockers If they are really tight like 010" or less you may well start burning exhaust valves

 

Power will certainly suffer as compression will be not be ideal

 

Not sure how much they will tap, as I have never been daft enough to do it

 

Its not advisable to set them any less than the recommended gaps

[happydude2012]

well with the swiftune cam, the settings should be 15 thou - i have 1;5;1 roller tip rockers.

you know, maybe thats just the noise they make when they are properly set. maybe im just flapping.

It just seems to be the far right rocker (when facing the engine) thats the problem.

Edited by happydude2012, 24 July 2018 - 05:18 AM.