I've searched through many threads and found nothing relating to this.

I recently replaced the timing chain & guides on my 3.9L as it sounded like a meat grinder when idling. After 230,000 km, I thought it was worth doing at the same time I was putting on better head and cam.

Now, the same chain noise is back, but not a loud. Before I put EL thermo fans on, I never really noticed it as the original clutch fan was noisy most of the time.

Can anyone tell me if this is normal for Ford OHC motors? I checked and double checked the tensioner and chain guides when reassembling everything. No problems there and the motor runs OK otherwise.

What is the condition of the drive gear on the dizzy???
What condition is the oil pump in.....what oil pressure do you have???

I haven't checked the dizzy gear. The oil pump is original and the pressure is steady just above 2KPa (?) on the dash gauge at idle. It increases with the engine revs.

Both the idler pulleys have been replaced recently and the noise is definitely coming from inside the top of the rocker cover. Would a worn camshaft gear cause chain noise? I'm considering replacing it with a vernier gear.

It could, if worn badly.
On vehicles with a lot of K's on them, 250K+ and you change the cam chain, it would be better to replace the whole system, chain, guides & sprockets & tensioner filter & O'rings.

Did you replace the camchain tensioner O'rings/filter.????

Sorry to ask a silly question but did you release the oil pressure tensioner spring and did you release it correctly ?

I replaced the o-rings and cleaned the filter. No filter or sprockets came in the timing kit. In hindsight, I probably should have replaced the lot with a Rollmaster chain & sprocket set.



No question is silly when brainstorming a mechanical problem. Yes, I'm quite sure it's released correctly. I pulled the old tensioner apart and reassembled it twice to make sure I knew how it worked.

Sorry guys, I have to wipe the egg off my face now! I got home from work last night and pulled the rocker cover off to look at the chain & guides again. All still tight. Then I thought what if the noise is outside the engine? I took off the power steering belt and started the engine and ....no noise.

It appears the new idler pulley is resonating, even though the bearing spins freely. If you put your head next to the rocker cover, it sound like noise is coming from inside. (I suppose a mechanic might have worked it out, but I do most of the servicing & repairs myself on our 3 old cars to save money)

At least I can drive my car to work now without worrying something major will fail. Thanks for your input though.