95 sl2 engine clicking

at 126k miles my engine has started clicking until rpms hit 3500, mainly idle and 1,2,3 gear. sometimes it doesnt click at all so its an on and off problem.the pulleys and water pump cannot be causing the problem had them replaced winter of 2004. does anyone know what might be wrong and how much it costs to fix? trying to sell the car and dont want to sell it to some only to have it die on them. thank you for your time

might be

More details (year, model, standard or auto trans), please.

You need to try to isolate where the noise is coming from. There are mechanic's stethoscopes available, but I've had good results from a piece of 1"X1" putting the end of the piece of wood where you suspect the noise to be coming from and listening on the other end. Noises easily 'telegraph' through engines.

Does it seem to affect the operation of the engine when the clicking is happening?

Ken

If it's like this, it's likely a spun bearing:

Lane [ lane (at) evilplastic.com ]

the noise isnt that loud and isnt there at cruising speed. about how much do you think that would be to get replaced?

to ken, ill give the 1x1 a try and no it doesnt effect operation, idle rpms are steady.

I have to wonder if it could be an exhaust leak at where the manifold and the head mate.

Ken (MI)

wouldnt that make an air leak noise not knocking?

I thought you had said a "clicking" noise in your OP. An exhaust leak can sometimes sound like a ticking or clicking noise to me. A knocking noise, now that's something different. If not a crank bearing, maybe a broken piston? My (now my son's) '96 SL2 had a knocking noise that turned out to be the #2 piston had pieces broken out of the edge. It was a repo car that I got cheap, but it truned out to not have been too well maintained. A $700 junkyard '97 motor fixed the problem.

Ken