2003 Volvo V40 1.9T with 130,000 miles makes this tapping sound when started after the engine has cooled down. The sound goes away after the first minute or so, so I presume it is piston slap.

http://www.supload.com/listen?s=Gx2A38

You can hear me revv the engine a couple hundred RPMs, which during the revv the tapping goes away. When I return to idle, the tapping reappears. I do this a couple of times. By the end of the 1.5 minute recording, the tapping has almost completely disappeared, presumably since the engine has heated up, the oil pressure has increased, yada, yada, yada. I don't hear any tapping while I'm driving around, the engine performs really well. And if I restart the engine while it is warm I hear no tapping.

 

That's an exhaust leak. Piston slap has a metallic ring/light knocking sound.

Regards, Andrew.

 

Is that something I could pinpoint and repair without major disassembly? What part would I be looking into replacing, or is something far worse like the block, cracked?

 

No. It'll be an exhaust gasket or a cracked exhaust manifold. Get a piece of hose, place one end to your ear and move the other end of teh hose around the gasket surfaces and manifold with engine running. Use caution due to very hot manifold.
The fact the sound is worse when cold makes me suspect a crack.

Regards, Andrew.

 

Or you can suck a little bit of seafoam or something like that through a hose into the intake and when it burns it the car will smoke. Also you will see the smoke coming from the area it is leaking. If you go that route then make sure you only suck a little in at a time and rev it when you suck it in.

 

Thanks. If it is a cracked manifold, what sort of damage might have been done to the engine as a result, or and I don't get to soon, will the engine incur any damage?

 

I would try to get it fixed soon it will not really cause that much damage just cause a leak.

 

Any reason not to suspect the oil pan o-rings?

https://volvoforums.com/forum/volvo-s80-18/oil-pan-o-ring-replacement-instructions-1451/

 

I would suspect them.

 

OK, I took the heat shield off and felt each of the nuts/studs of the exhaust manifold. There was one missing and another one back off half way. I'm having Volvo parts order just the 2 nuts to replace the one that was missing and the one that was backed off.

When I get them I'm going to put those two on, tighten them, and see if that takes care of the noise. If not, I'm going to see if the rest could use any tightening. Question: If the noise is still there after replacing the two and tightening the remaining, is the next step to replace the gasket? If so, do I need to replace the remaining nuts/studs to ensure they go on there tight?

 

It worked! I replaced the one that was missing and the one that was backed off, tightened those and the rest, and the sound is now gone. Freaking awesome! Thanks a million everyone for your help.