Jeep: loud clicking noise, vacuum leak, manifold problems


Question
I have an 87 Wrangler 258 cu.in automatic transmission. When I start the vehicle, there is a slight clicking noise...almost sounds like a valve tap.  After 2-3 minutes when it warms up, the noise becomes more pronounced.  I had the engine checked for oil pressure and a valve noise.  The engine is fine.  The noise sounds like it is coming from the bell housing area.  I suspect an exhaust leak, but it really sounds like a valve noise though.

Answer
Hi Ed,

Well, the 258's were known for exhaust manifold problems, particularly where the tubes join (cracks, etc). They also are known for the retaining bolts being loose, resulting in either an exhaust leak (normally the front bolt or the rear one), or a vacuum leak and high RPM (any of the inner bolts). Still, they've always had issues with lifters, and other than rear main leaks, lifter jobs were the norm for these engines. Other than that, a cracked flywheel can cause a tick that sounds very similar to this, and is obviously heard loudest in the bellhousing.

The best way to attack this is with a stethoscope, and try to narrow down the origin point by point. If you can't get one, a very long, thin screwdriver (even a long prybar works well) works extremely well in its place. Just position the handle to your ear and proceed the same way. Good luck!