I just bought a 1987 K5. Today I was driving and the "Service Engine Soon" light came on. Truck seemed to be driving fine, I didnt feel anything troublesome. But when I slowed down I heard a ticking noise. The truck now has an extremely fast tick while its running. Any ideas what that might be?

Thanks

 

bring that to a shop to check that code it sounds like a rod knock witch is really bad if you dont fix it.

 

Could be a lifter, could be an exhaust "tick" at the manifold... gotta do some detective work and figure out where the noise is coming from. Probably has nothing to do with the service engine soon light. How's the oil pressure?

 

the noise isnt very "violent" if you will, its just a really fast paced quiet tick. it cant be felt in while driving.

 

Check under the hood after dark for any arcing from the spark plug wires. Sure sounds like it could be a lifter. Get a long screwdriver and put the handle to your ear... then touch the tip to various parts of the valve covers to maybe isolate the ticking noise.

 

See if its a knock sensor throwing the code