Hi, I have a rebuilt 390 in my 66 f100. It has almost 4000 moles on it since the rebuild and it has been making a ticking noise ever since. It seems to be from the drivers side head. At first you would only hear it at certain throttle positions (mainly at high rpms while light on the throttle, or deceleration) I know that probably sounds like a lifter but the thing has plenty of oil pressure all the time. It has about 40 pounds at idle and up to tempurature. But it seems to be getting a little more consistent. Last night I really noticed it just at cruising speed so I tried different throttle positions to see if it changed and it didnt. The engine starts on the first or second rotation, still makes plenty of power and fires on all 8. Do you think it could be a bent pushrod or what? If it is what do you have to replace besides pushrods (lifters? Rocker arms?) Any help would be appreciated.

 

I would clean up the area around the valve cover (to avoid contamination) and remove the valve cover. See if anything looks visibly worn or broken.

If you have to take any component out of the valve train, make sure you keep it in order and put it back where it came from on the engine. This will help aide in organization and eliminate possible further issues down the road.

you might have a lifter that has come apart/collapsed causing excessive pushrod clearance. You could have a worn valve guide and the valve is rattling. Broken valve spring causing erratic valve control. Loose or broken rocker. Bent pushrod.

Only a thorough inspection will really tell. Can you duplicate the noise consistently each time? Have you tried to use the screwdriver to the ear trick and listen to the valve cover? Place the flat-tip blade on the valve cover and the handle gently on your ear, move the screwdriver tip around (similar to how a doctor checks your breathing with a stethoscope) and see where the noise is most prominent.

Please note, you might feel more play in the components with closed valves due to the spring pressure being substantially less while the spring is "at rest"

 

We did take the valve cover off a couple thousand miles ago and nothing appeared to be broken or loose. One thing I noticed was that one if the rocker arms moved back and fourth on the shafts slightly. I figured that was what the noise was but now that it's a little more prominent I don't know. Also no, I can't duplicate it exactly every time. There are some times where it is almost completely gone, then the next time I drive it, it's very noticeable. I appreciate the help though, so i should just pull the push rods out and check them and the lifters. At least then it will be narrowed down a little.

 

FD66, Have you looked for an exhaust leak??

 

Yes, it's not exhaust. I drive around for 2 years in a fairlane with a broken manifold and it's a completely different sound from that

 

Somehow, a small exhaust leak at the flange can sound exactly like a lifter. Don't ask me how I know.

After visual inspection of valvatrain, may be worth re-sealing the manifold before pulling lifters. If needed, most machine shops can skim cut the mount face for a few bucks to get it smooth and straight. A little high temp RTV helps seal also.

 

I have found bad ,worn or out of adjustment , rocker arms by having a shop rag in my hand and push on each arm with it running. The sound will go away or change, this will work if they do it at idle. Higher RPM i have no suggestion other than what some others have brought up .

 

If I were in your shoes I would get an automotive stethoscope and pinpoint the noise to a relative or exact location. It might take some time and it might take 2 people but it will help you not chase your tail. Mainly it will help rule out certain parts that are in question and give you a more specific area to examine.

If you are around a HF or tool store you are looking at spending 10-20 bucks on a stethoscope. It will have a long metal rod and the rest will look like what a doc wears. You can gently run the tip across the valve cover pausing every inch or so... listen for the noise to get louder then louder then quieter, then you know where its the loudest. then go top to bottom and ensure its not something in the block or another part resonating to the head.

I have heard pistons with some skirt slop sound like its a top end or warped valve stems or springs all cause a similar noise. Some noises on a car are very distinctive and some all mish-mash and sound the same.

Like I said, locating the noise is the hard part. Once you find EXACTLY where its at then you know what few parts to thoroughly examine.

 

The reason I know it's not an exhaust leak is because when I drove around for two years with one, it never once went away. As I said this sound is only present at higher rpms with little to no throttle. I may try to make a video if I can get the sound to come through. I have a few things I would like to try though before I pull the top end apart.

 

Are you sure it has adequate lifter pre-load? Many things contribute to the modification of your factory valve-train geometry. May need longer pushrods...