glack

Here's the problem:

This is an 1985 Euro S that is now making a tapping sound (sounds like metal on metal) which increases proportionately with rpms, whether in gear or not. Sounds is not quite local enough to be able to pinpoint to a particular quadrant of the engine space but it just started out of the blue and seems to be increasing in magnitude (maybe I'm just paranoid).

I noticed it after a 250 mile drive wherein the engine stayed cool and the oil pressure stayed nice and high. While I probably shouldn't have, I have put another 150 miles on the car since with no problems at all.

Any helpful ideas would be much appreciated.

I was thinking a loose valve...any other ideas?

Normy

That sounds like a lifter tapping. Is it cold where you are? Has your car sat for a while?

N!
'85 S2 5 Speed

John Speake

Hi Glack,
You might be able to use a long screwdriver or similar, with the handle pressed to your ear, and placing the "sharp" end on various parts of the block, heads etc to localise the source of the noise.

It acts as a kind of stethoscope..............

Is the car a manual, or auto ?

Drewster67

Most likely it is a sticky lifter.

glack

Normy,

Thanks for the reply. The car doesn't sit for more than 4 days at a time and its stays pretty warm here in SoCal.

John Speake,

Thank you for the screwdriver-stethoscope idea. The noise sounds like it is coming from the lower left area of the engine (while looking towards the rear of the car).

Drewster67,

Is this something that needs a wrench or is there some sort of upper cylinder lubricant that might do the trick.
Does this sound consistent with a sticky lifter:
Car sat for the last two days. Upon starting it up this afternoon, I heard no tapping. I drove the car for about 7-8 minutes and parked it, still no tapping. Upon re-starting, the tapping started up.

Lizard928

could be the chain tensioner for the cams

Garth S

Lower left? - Low enough to be the Air pump or the AC compressor: just a thought & easy to comfirm.

jpitman2

See if its a belt or anything driven by belts (apart from the cams). Try spraying a lubricant (wd40, CRC etc) on the belts while running and tapping, see if noise changes. drop the air pump belt, see it it goes away, then the ac belt. See if it taps with ac ON - ie ac pulley bearing not in use...
BTW, the Miata solution for tappet noise is to drain and fill with 3 parts ATF, 1 part 40-50W oil, idle for an hour, drain, new oil and filter. Said that the ATF dissolves oil varnish blocking lifter supply galleries....YMMV
jp 83 Euro S AT 47k

John Speake

Lower left at front, middle, or rear of block ?

concor

Hmm, I just got the same metal sound from my engine. It was hard to pinpoint, but definitely came from the engine and went quicker with higher rpm.

I had it for a 2 minute drive. Then started searching for it and suddenly it started to tap softer but also more frequent, then suddenly it was all gone. Did a 10 minute drive and still gone.

I did notice I have a bit too much oil in the engine, about half a cm over max, checked 30 minutes after turning off the engine. I also did a oil change 2 weeks ago and drove about 20km since.

No idea what it was, hoping it won't come back Is a bit too much oil dangerous?

WallyP

The primary danger with overfilling the oil is foaming, caused by the crank throws hitting the oil. It has be be pretty high for that to happen.

The A/C compressor pulley bearing is ALWAYS in use - if the belt is moving, the bearing is turning.

Lifter tapping is probably the most common noise, but certainly not the only possibility.

A leaking exhaust gasket can sound a lot like metal on metal.

danglerb

If you are in SoCal, why not have somebody that knows the 928 take a look at it?

I took my 83 into Greg at Precision in Anaheim and literally while we looked at the motor trying to locate the sound the tensioner failed. You might be amazed at how much the timing belt moves when that happens.