Tick noise at idle

My 78 sc 3.0 with 109k miles has developed a tick noise at idle .It does not sound like multiple ticks such as valves but a steady tick about 2x a second and it seems to get louder as the car heats up when the motor is reved past about 1300rpm it goes away.Could this be a valve or ?Any ideas would be appreciated.

[This message has been edited by jryerson (edited 08-22-1999).]

Hard to guess at stuff like this, but maybe you have a broken valve spring? Broken valves springs seem kinda common, esp. on the '78 SC. Just a guess.

Maybe take the valve covers off, adjust the valves and take a careful look at the springs, head studs, etc.

Brian

A very good way to figure out the cause of a noise is to take a very very large screwdriver (or similar solid device) and place one end against your ear, and one end touching different parts of the engine as you search for the noise. Surprisingly, you will be able to hear very well what's going on inside, and you will be able to localize the noise. You may even be able to tell what is causing the noise by doing this.
I would be sure your valves are adjusted properly, as this is an easy thing to do, and an easy way to start ruling certain things out. Plus, you get some maintenance stuff done! Good luck!

Thanks for the input .It is time to adjust my valves.

just a thought.... sounds like it might be an exhaust leak....

could be. do you know what the signs are(discoloration on manifold or gaskets)?

An exhaust leak is generally not a mechanical type of sound, more like pufft-pufft-pufft. A valve that is out of adjustment or that has a worn guide will be a sharper tic-tic-tic sound and can go away when rev go up. The screw driver idea works, but I finally bought a mechanic's stethscope and it works much better. Unfortunatly, most 911 engines make it really hard to listen to the top with all the intake stuff up there. I would jack up the rear of the car, put on stands, remove both wheels and listen on the valve covers and exhaust headers where they exit the heads.

Thanks for the reply John, it is a shsrp sound so probably a valve, also it is true as your valves get out of adjustment they get tighter?

easiest way I know of to find out if it is an exhast leak ( I have heard some "tick" if it is close enough to the manifold/head area) is to have the car COLD.. then spray soapy water liberally over the manifolds.. have someone start the car and keep spraying .. then just look for bubbles.. you dont have long to do this before it vaporizes the soap/water though.. good luck, I hope it's not a valve cause my 87 is doing the same thing...

I agree that your sound is probably a valve, not an exhaust leak, but I would like to relay an interesting type of exhaust leak I recently came across. 911sc's built before 1980 came with an air injection pump, which injects air into the exhaust stream as it exits each cylinder. A lot of these pumps have been removed, leaving holes in the exhaust manifold that would have had to be plugged. If one of these plugs works it's way loose, you get a major exhaust leak. This just happened to my friends '79. If your car has an oxygen sensor, it never had the air pump.

I had a similar type of noise from my 79 SC. Investigation of the problem found it to be a faulty spark plug resistor/connector. As the revs increased, the noise disappeared. This is an easy check by removing and replacing the leads one at a time.

Thanks for all the replies.I guess I know what i'll be doing this labor day(valve adjustment time)
Does anyone know if you need to drain the engine oil before removing the valve covers or will you end up with a mess akin to a mini Valdez in your driveway?

If you don't want to change your oil, you can be creative to save causing a mess. Jack up your car with the original jack in the jack receiver so your car tilts to one side. This will let the oil drain through the lower oil return tubes into the opposite side, out of the lower valve cover area. Now, when you remove the lower valve cover on the raised side, you don't make a mess. This has worked well for me. I have also done it the hard way - pulling off the valve cover and trying to plug the oil return tubes with a rag to prevent draining, but a mess still results. I hope this helps.

Great idea, thanks Garrett I am already on double probation from that last escapade when I put on a Carrera front cooler and started my car after it had been sitting for a few hours ,I thought the thermostat would be closed by then musta spilled 10qts in about 20 seconds in the driveway.