Inline 6 - 250 Lifter Question

[pgaffaney]

My inline 250 developed a "ticking" sound during idle and speeds below 45MPH. I isolated the sound to piston 5 or 6 and figured it was a bad lifter. I changed out the lifters and adjusted rockers to spec, but sound still persists. Does anyone have any input or suggestions on next steps?


Thanks in advance.

[Shaky]

More than once on straight sixes, the ticking noise I thought was valve train was actually exhaust manifold leaking. A short length of garden hose against my ear with the other end near the engine helped isolate it.

I don't know if this is your issue, but it's what came to mind...

[pgaffaney]

I put stethoscope on it and the ticking is definitely coming from the back cylinders. I've been focusing on lifters and didn't even think of an exhaust leak. Would an exhaust leak create a ticking sound in an isolated part of the engine?

Thanks.

[geezer#99]

It can.
I hope you didn't change all the lifters.
If so you stand a good chance of wiping a cam lobe or two.

[pgaffaney]

Changed the back 6 lifters, pistons 4, 5, & 6. Recently changed fuel pump. I'm going to check that out.

[Shaky]

Originally Posted by pgaffaney

I put stethoscope on it and the ticking is definitely coming from the back cylinders. I've been focusing on lifters and didn't even think of an exhaust leak. Would an exhaust leak create a ticking sound in an isolated part of the engine?

Thanks.

I've always been amazed at how much an exhaust manifold leak sounds like valve train ticking. I would try the hose trick around the manifolds near the head. At least you could rule that out. Can use an old heater hose. Don't cost much or take much time...