LOUD ''tapping-sound'' from engine
 

Hey guys , took my 1988' 930 coupe out today after about 9 months storage. It is making a God-Awful "tap-tap-tap" ticking sound around 3500rpm and above, eminating from right side of engine? It is loud enough , that I hear it with rolled up windows, and has an almost straight-thru-muffler off the K27 unit. When I had valve-covers off last year to replace gaskets , ALL the rockers seemed normal and tight? No loose set screws or worn lobes? Any and all advice , much appreciated!! Oh ,and it is the engine , cause I can through her in neutral ,and right at 4K rpm , Tick-Tick-Tick!! Man , I hope it's not a ''rod"!! Oh , and about 50K original miles on the car. Thanks;dave

Doesn't sound like a rod, if you're describing it right...thusly called, "The Infamous Rod Knock". If it was truly a rod, you would know it.

Tickticktick describes either a loose valve tappet condition, or some type of exhaust leak. Check for exhaust leaks first, with the motor running of course.

If unable to locate a leak, you will need to locate the tick in your upper or lower valve covers. It would help if you have a listening device, such as a stethescope or hose.

tensioner ?

FWIW, you can almost always hear this stuff better with the windows up, when the noise transmits itself through the body of the car.

Do you know the "I need a valve adjust" sound? Maybe something is sticking in the valve train from 9 months of sitting.

I just fixed an exhaust leak.

It was a tap tap tap.

NOT the tick tick of the valves.
I could hear mine loud and clear at idle though.

Is the sound from the top or the bottom - First.

Valves, time to adjust.

It may also be a loose rocker shaft... I had one (#3 intake) go out on a race car I was helping at the track. Noisy tap tap tap as the rocker position was all out of whack. A wrench helped us out and swapped the shaft out with the engine in the car... Quite amazing really. The car went on to do the Sprint race that afternoon and then the enduro on Sunday... no other mishaps :)

-Michael

ya, sounds like rocker arm moved out, if it was bad enough could disconnect to cam.
Not hat bad of a fix. That would sound like a lot of metal knocking/punching inside as it moves.

Broken head stud? I had a similar sound on my car, like the valves needed adjusting, and it turned out to be a broken head stud.

I just wanted to get to 100!

thanks guys! it is scarry , because it came out of nowhere and so sudden! I'll hopefully be able to look into it next couple of weeks , and let the group here , all know what I find , for their future ''reference", Dave

Tensioner may not have pressurized.

What is the condition and level of the oil?

Broken valve spring? Happened to me 2 weeks ago, came on suddenly, sounds like an extremely sloppy valve.

The oil is Mobil 1 ,2o-50 , Its clean but a couple years old , with maybe 50 miles on it. car never gets driven.

x2... Most likely cause IMO...

Is it still doing it or was it just that one instance during the first drive after storage?

I don't know ,cause the car isn't with me / being driven today , but over weekend I'll drive it again , and update the group. thanks ;dave

A broken or weak valve spring can sound like a "Soft knock"... Not harsh or overly prominent.

If it is a valve spring the knock would only happen every second revolution.

Listen to the engine as it warms up. Take your time and change your position around the car as it idles. See if the noise can be isolated to one area.
If you're not sure ask a mechanic to listen to it... There's nothing like an experienced ear to diagnose such problems.

dave egan

How did this end up? Did you get a resolution?

tap.tap.
 

hi dave is the sound in time with the engine.or half the speed of the engine,if half speed its valve train,if it ran good before you parked it,then one of your valves is slow returning to its seat.its either getting tapped by the piston or the valve cam.anyway i think you will have to take the head off and do the job,while your there do the whole bank,good luck,frank:eek: