Tappety Tap Tap

[paulW]

Hmmm...

All of a sudden in the middle of driving, get a god awful tapping noise from the top of the engine, kind of like noisy tappets but very, VERY loud.

Engine speed related, well seemed to increase exponentially with revs, but that might have been my imagination.

Drove 5 miles, pulled over and did the usual checks, water, oil, all ok, nothing lose, noise coming from high up in the engine.
Stopped engine, restarted, several times, and noise was persistant.

Figured, any damage done was already done, and limped it home, no loss in power and engine ran pretty smooth.

15 miles later, and it just as suddenly disappears and goes quiet again???


Any way a tappet could seize or not get enough oil or something and then un-sieze itself again?

Any other ideas? precautions? maybe do an oil change and go panning for metal?

Driven another 40 miles and the noise hasn't returned...

Thanks, Paul.

[mac]

exhaust gasket?


Mac

[paulW]

exhaust gasket?


Mac

certainly possible. I'll check my nuts.
kind of hard to try and find the fault when its not there anymore.

[robin]

Certainly possible. Was there any loss in performance at the same time?

Cheers,
Robin

[paulW]

Certainly possible. Was there any loss in performance at the same time?

Cheers,
Robin

No loss in power, obviously i backed off significantly and let the revs drop, but it still pulled well.

[robin]

Well, it's either a bearing due to mysterious drop in oil pressure or it's a hydraulic tappet that's stuck. The other things that go tap-tap-tap very loudly usually make some permanent damage to valve and/or piston and you would be running on three cylinders at best. The engine won't last long with no oil pressure, so if it was a bearing and you ran it for 5 minutes with it hammering away, I think it would still be knocking away now. Of course you cannot be sure, but given that the engine sat around a fair while before you installed it, I think you are probably looking at a sticky hydraulic tappet. It's easy enough to strip down and remove them; they're not serviceable as such, but you could certainly clean/drain them and check the oil ways to the tappets weren't blocked - the oil ways are formed by the cam ladder clamped onto head - so when you split the ladder off you can see whether the oil ways look clear?

Cheers,
Robin

[Rich H]

Check the oil level....

[paulW]

Thanks Robin.

The engine has done 900 miles since its been installed, so would have hoped it will be free'd up by now.

Hopefully a one off, but a bit of a mystery as to why it happened.

Tried to think about events leading up to it, but nothing really, filled up fuel and immediately prior to it happening did a shady overtake, which was momentarily aborted in the middle. ie Full throttle, lift off completely and then immedaitely back on the throttle. Was a twisty windy road, but wasn't really throwing it round the corners. (sticking to 60) and no hard braking either.

Got another trip back up to Scotland this weekend, so will see if the problem reoccurs and get an oil change done at the start of the week.


Rich H, that was my immediate though too, and first thing I checked by the side of the road. oil level was good.

[fd]

Sounds like a tappet to me, a bearing noise will come, then get worse, then go bang, not disappear . . . question is, did it stick or did it fall out of tolerance because either it had low oil pressure or it's internal valve stuck . . . only other thing I can think of is the oil pump pressure release valve sticking and reducing oil pressure, and one of the tappets going flat because of it . . . but that would probably cause other more major issues . . .

Fd

[Kayfur]

Paul,

I had this happen with my Elise about a year ago. Fairly loud tapping sound for a couple of miles which had me a little concerned - I was pretty sure it was a dodgy tappet however it disappeared after I switched the engine off and re-started. Still not 100% sure of the cause It's been ok ever since.

Kevin

[BiggestNizzy]

I had a tappety noise a wee while back, when I put some more oil in ot however it wen't a way :$

[Shug]

Mine used to do it with the old hairy high lift cams (BP285H) when I used 0W40 oil and ragged it for some time. Never happened after I moved to 15W50. Shat a brick the first time as it sounded as if the top end was coming off...

[paulW]

Well drove up to Stirling and back this weekend.

Kicked in at about Dumfries and disappeared at Bellshill, so 50 miles, then was gone for the rest of the trip, besides on the way back down last night it happened for 5 seconds and went away immediately.

I am suspicious about the oil, previous owner said he had switched to fully synthetic, and the oil looks very thin on the dipstick and still golden even after I've put another 1,000 miles on it. I tried switching to fully synthetic on my old VVC engine and it went tappety, switch back to 10W40 semi, and it went away again. Got a can of fully synth 5W40 to go in, once I've picked up an oil filter.

(Although trying to describe noises on the internet is difficult, noisy tappets sounded more "rattlely tappety", whereas the noise I am getting now is more "lollipop stick stuck in the spokes of your push bike and then spun at 10,000 rpm.)


I did almost convince myself it sounded more like the exhaust gasket, but it was a little bit too warm to go routing about trying to see if the nuts were tight.

It doesn't gradually come in, it just starts and then goes...very weird.


PS. such an amazing run home last night in the early hours, roads were damp, but not wet, completely empty and almost a full moon...was superb.
(I should of had the roof off. )

[steve_weegie]

Frayed belt?

[robin]

Eek. I wonder if it might be something closer to what you actually describe - might be worth whipping off the top timing belt cover and checking that all is well in there - especially the wee bolts that live behind the pulleys (visions of lollipop in spokes ...)).

Cheers,
Robin