pretty nice 94 rmw cheap but a solid knock in engine when idling?

http://treasure.craigslist.org/cto/4274193382.html

Went to look at this RMW this evening. Looks like a pretty good deal. 148K miles and been in one family since new. Currently being sold by the brother of original owner (70 yr woman). She bought a new car a few weeks ago and left him to sell it.

The only thing that concerned me was a solid knock in the engine - but only when idling. As soon as she got gas it would smooth right out and knock would totally dissappear. When it was there, it sounded like it was up high in the engine and almost sounded like it was under one of the valve covers. However, it was impossible to determine where it was coming from.

I drove it around the park since it had no tag and it felt solid - no rattles. Everytime I stopped and let it idle the knock returned. I checked out all the usual stuff - AC/heat, all power windows, seats, antenna, radio, cruise control etc. and everything worked. The interior is in excellent shape except for the headliner which is just starting to let go on one side in the rear.I let it run over one spot for about ten minutes and there was no sign of any oil or transmission leaks. Overall, it looks like a good deal to me except for that I just don't know what to make of that knock.

I'd like to have it for a second wagon just to have for when I get visitors from up north to drive around in while I'm at work.

Any LT1 experts that can help me understand what that knock might be? It almost sounds like a vibration - possibly in the exhaust?

I forgot that I could have used the climate control center to check for codes. Maybe tomorrow, I'll go back and see if she's throwing any codes.

Any ideas on the knock?

 

Is there an oil pressure gauge? Only thing I can think of might be a spun cam bearing, judging from the description. Another possibility, with those miles, might be a timing chain with enough slack to where it's slapping the timing cover. The latter is what is wrong with my '68 Dodge 318.

 

No pressure guage - oil looks good and clean. has service sticker on the window for 2 months ago.

 

I had a 95 RMW just like that one. I noticed the same thing on mine. I thought it was a rod knock cause I only noticed it on idle. I read somewhere (might have been on this site) that these cars were noted for the flywheel to crack around were it bolts up and it sounded like a knock. Had mine checked and that was the problem. Had it replaced and it took care of the knock.

 

Might be an exhaust manifold thing.
My '96 L99 has a cold knock on start-up., bu think it's a rocker arm.
It's been that way for over 30,000 miles and I haven't addressed the issue.
These are tough motors.