35 replies to this topic

[spiguy]

Spoke to soon... It was back this morning. Aarrgghh! That's the car done 6 cold starts now without a whisper, and then bam it's back, exactly as before. Can't figure it out. I'm thinking it must be a worn cam follower, as someone suggested before, and that the noise happens as the push rod and follower rotate (noisy when on the worn side) however all the push rods were spinning when I started it up the first time, so why should it take several starts for the noise to return?

[spiguy]

Spent a bit more time looking at the rocker assembly when the engine is running (strangely hypnotic actually..) and I noticed that whilst pushrods 1-5 spin away quite quickly, 6-8 turn much slower, sometimes a couple of them don't appear to be turning at all.

 

I can spin them all very freely with my fingers (engine off of course). Does this matter? I thought the followers spin by design - could the follower be spinning and the push rod not?  Just wondering if I have a follower that doesn't spin and has ended up with an uneven wear, causing the noise until either oil / expansion / rotating to the 'quiet bit' shuts it up.

[jaydee]

The pushrod must spin round in circle, no back-forth.

No movement at all is an indication of followers are not in a good shape thus not turning round in their seat as they should and this would cause camshaft lobes pitting and wear (its the reason why some camshaft wear badly then people blame the manifacturer although its actually a follower problem, and not a camshaft problem).

I doubt it causes your noise but may well be.

Mark the pushrods with a lick of paint and watch them spinning, maybe some just move slowly when engine cold.

[spiguy]

Thanks jaydee (Sorry, forgot to check back on this thread).

 

From investigation, there is no doubt that as soon as oil starts to flow down the pushrod holes, the noise stops. From reading online, I see that the drain back oil from the rocker area is by design, intended to lubricate the cam lobes and so obviously also then the contact area between lobe and follower.

 

Is this the only oil supply for the followers? Is the follower supposed to hold some oil or something (like a little bucket), so that there is some oil available for cold starts?

[gazza82]

The design of the followers means that they should hold oil once it has flowed .. some have a small hole which allows some to drain out but it should leave some ..

[spiguy]

I'm convinced it is follower related. I wonder if maybe one of the holes the followers run in is worn, allow sideways slap and once the oil is flowing down the pushrod holes, it is damping this behaviour?   Either way, I don't intend on pulling the engine apart unless it gets worse or starts to affect the running of the car. I have no misfire and it goes away after a few minutes,  less if I just drive off as soon as I start it. I  just hate rattly noises!