Was driving from Boston to Conneticut and all of a sudden started to hear a tappity sound from front right. Pulled into lay by and sound was coming from right side of engine but not consistently. Increased in intensity but not sound when engine was revved. Continued drive and there were times when sound was not there at all and then it would come back with no set speed or acceleration determining when the tapping sound came. Definitely coming from the rocker area of engine.
She has 115,000 miles on it and is due exhaust manifold gaskets and a complete exhaust…..
Comments suggestions or otherwise so as to help identify the culprit….
She’s a 2000 P38 4.6 …….

Was it worse when pulling and virtually disappeared when on the over run? That's usually a leaking head to manifold gasket and it will also change with temperature (might only be there when cold or might only be there when hot). Sounds just like a tappet though.

Gilbertd, it was difficult to replicate the sound on demand. Was never constant and sometimes when accelerating it would not be there and other times it would come back. Never really lasted longer than 5 minutes then would be gone as quickly as it came. Had her in cruise control at 70MPH, opened pax side window as I passed a truck and you could hear the tappity sound reverberate then about 10 mins later passing another truck did the same and nothing. Ambient temperature was about 50F.

Investigated tappity sound and I have cracked exhaust manifold on right side…. Further along I have both rear exhausts rusted and the center box pipes are no better. So bad are leaks that very little exhaust is emitting from either rear exhaust.
Question, whilst this has been answered in previous posts, as I’d like to get an updated reply, can anyone recommend a good brand and source for the mid and rear exhaust system for a 2000 P38 as well as a manifold for right side?
While I’m at it, should I just replace the entire exhaust system and one side of manifold while I’m at it?

Either this https://www.ebay.co.uk/itm/272214722398 or this https://www.ebay.co.uk/itm/262391772282 depending on whether GEMS or Thor. Not sure about shipping though so it might be worth contacting them directly, https://www.maltingsoffroad.co.uk/

The system they supply is Allmakes and seems to be pretty good although the cats are smaller than original if that is of any relevance where you are.

Mild steel exhausts for P38's have been the one job I've hated on them the most as they never seem to fit properly. Once this one we have now needs one it's going to get a Double S stainless one. They're not cheap but I've read that they fit first time without needing modifying and should last a long time.

You're lucky as when ours sounded tappety and it was coming and going it was the liner hitting the head! Glad yours isn't such an extreme problem.

David.

As David says, Double S stuff is good. I managed to find (don't aske me how) an OEM centre and back box when I first got the car, but front pipes were to elude me a couple of years later when the cats had obviously collapsed.

Rimmers had a sale so I bit the bullet and shipped their Double S front pipes over. Lovely quality and bolted up first time. In two pieces as well, so if they ever have to come off again, gearbox X-member can stay where it is.

They also come ready for two lambda sensors (pre and post-cat) on each pipe for the US. I had to blank one set, as mine's European spec, but no problem.

And yes, like above, my last '38 in the UK had a little tappity sound, just before it shoved No.7 piston out! :-)