Ticking/tapping noise, 305 Chevy, Can't Figure it Out!

[Rust-O-Matic]

Ok engine guys, I need your help. My '66 has a late 70's model 305 small block Chevy in it that is making a ticking or tapping noise from the top end, only when it's warmed up. It runs good, and sounds fine when it's first started up cold, but starts tapping as it gets up to operating temp.

I put a stethoscope to the valve covers while it was idling and the noise appears to be coming from under the front of the passenger side cover. So I pulled both covers and adjusted the rocker arms the old school way, by backing them off till they click, tightening slowly til the noise stops, then going 1/2 turn past that point. I did the passenger side 2 or 3 times, just to be sure. Noise still persists.

Then I pushed all of the rocker arms/tops of pushrods in that area around with the wooden handle from a hammer (while it was idling) to check for slop. None was noted.

Then I changed the oil from 10w30 to 10w40 to see if that helped, then added a quart of Lucas to it as well. Still exactly the same.

So now I'm not sure what else to do. My thought was maybe it's a collapsed or stuck lifter, but it seems to me that it would make noise all the time, not just when hot. I'm reluctant to tear the top end apart to replace the lifters, since I'm not sure if that's the problem, and the fact I can probably find a used 350 for not a whole lot more money or effort. Any input you guys could give would be much appreciated. I've spent hours reading different forums and links online, but haven't got it figured out yet.

[B. W.]

I would have gone through the same checks / steps you did. Two questions:

When you pushed with the hammer handle did you push on the lifter side of the rocker & how hard did you push? It could be a bad lifter, I sometimes need to put a lot of force on it to make it show.

What is your oil pressure? With low oil pressure the top end starves first.

[Dead Parrot]

Double check for exhaust leak. They can sound real close to an engine tick.

Do the plugs for that cylinder and the adjacent one look normal?

Warm the motor and pull the belts. See if the noise goes away. Had a PS pump that started making a knocking noise right after I had installed a new crate motor. Was really happy when the knocking noise stopped with no belts installed.

[geezer#99]

Fuel pump pushrod could be it.
Do you have any bolts in the two bolt holes on the block front edge near the pump?

[Rust-O-Matic]

When you pushed with the hammer handle did you push on the lifter side of the rocker & how hard did you push? It could be a bad lifter, I sometimes need to put a lot of force on it to make it show.

What is your oil pressure? With low oil pressure the top end starves first.

I mainly pushed around on the valve end of the rockers with the hammer handle, because I had read a bunch of stuff about 305 valve guides/seals wearing and making noise due to the slop it causes. Would a bad lifter cause the noise only when warm, or would it do it all the time? I could pull that cover back off and push on the other end of the rocker if I knew what exactly I'm looking for. Oil pressure is up between 40-60 psi when driving lately, but was a little lower than that before the 10w40 and Lucas. At idle the (when pressure is least) the tick is almost inaudible. It's worst when maintaining speed going down the road, or decelerating.

Double check for exhaust leak. They can sound real close to an engine tick.

Do the plugs for that cylinder and the adjacent one look normal?

Warm the motor and pull the belts. See if the noise goes away. Had a PS pump that started making a knocking noise right after I had installed a new crate motor. Was really happy when the knocking noise stopped with no belts installed.

Exhaust is all brand new from headers to tail pipes, but I'll double check the header and flange bolts anyway. I didn't think to check the plugs in that area; that's a good idea. The only accessories I have are alternator, water pump, and power steering pump, all three of which are brand new (though, these days that doesn't mean much). I checked them with the stethoscope while I was at it and did not hear the noise. The noise is most prominent when I touch the stethoscope to the front 1/4 of the passenger side valve cover.

[Rust-O-Matic]

Geezer-
I actually just read another forum where someone mentioned the fuel pump push rod. Are we talking about the actual steel bar that falls out of the engine when the pump is removed, or the lever doo-dad that is attached to the back of the pump itself? And I'm not sure I follow your question about the bolts. The only bolts I remember in that area are the 2 that hold the plate to the block, and the 2 more that hold the pump to the plate. Are you asking about something else?

Regardless, this makes me think I need to check around the pump with with my stethoscope now as well.

[geezer#99]

Yup!!
The actual steel bar.
THe bolts or bolt holes are the two by the pump that point straight ahead. THey're usually open but sometimes there could be bolts in them. Some motors had an airpump bracket there. The bolt holes go all the way in to the rod. People sometimes use one hole with a longer bolt to hold the rod up when they change the fuel pump.
If there are bolts there, one could be a little long and hanging up or ticking the pushrod.
THere's some pics here.
http://garage.grumpysperformance.com...sh-rods.11093/

[Rust-O-Matic]

Ah-ha! Thanks for the info, I see exactly what you mean now. I will take a closer look at that this weekend. Wish I didn't have to work for a living and could go check it out right now haha.

When I put the fuel pump on this particular engine I dabbed a little grease on the cam end of that shaft to hold it in place. I had no idea I could put a bolt through those holes to hold it there. Learn something new every day. I love this site.

I'll keep you guys posted.

[Rust-O-Matic]

I had just enough daylight left after work to warm the truck up and take another quick look.

Of the 2 holes in front of the fuel pump Geezer asked about; the upper one has a bolt in it (but I don't know how long yet), and the bottom hole is empty. I put the stethoscope all over and around the pump, and there is definitely a ticking sound when touching the body of the pump, but I'm not sure if it's abnormal or not. When touching the engine block adjacent to the pump, I don't hear anything. I might just go ahead and replace the pump to be sure. It's old, and they're cheap.

While I was in there, I touched the 'scope to the alternator, PS pump, and water pump as well, and none of them made any sort of ticking noise.

Then I decided to take a closer listen to the valve covers again. When touching the stethoscope to the top of the valve covers in several different spots I hear nothing out of the ordinary. Just the rockers working underneath. When I touched the SIDE of the passenger valve cover though, it about popped my ear drums. The only spot I could hear this loud ticking was about 3" back from the front end of the valve cover, on the side that meets the intake manifold. I don't hear it anywhere else on that cover, or on the driver side cover at all. Now, when I say loud ticking I only mean loud through the stethoscope, it's so faint standing under the hood at idle I can't always hear it over the engine and exhaust hum. It's much more noticable in the cab when driving down the road.

So I guess my next question is, does anybody know what would cause a valvetrain noise I can only hear when listening to the side of the valve cover? I'm not even sure what to search the forums or Google for at this point. It seems really strange I can't hear it from the top as well. Is it possible the valve (or something related) has too much play laterally and is clacking side to side?

[geezer#99]

Is there an intake bolt right where you can hear it?
I had a motor once that one intake bolt was a touch long and was touching the pushrod.

[Dead Parrot]

Does the motor have a PVC valve there? Normally on the driver's side but seems worth asking since it is a mix of years.

[Rust-O-Matic]

Yeah, there is an intake bolt pretty close to there. Seems unlikely it would be touching a pushrod though, because this is the valve side of the head rather than the pushrod side. Unless I'm overlooking something.

My PCV goes into the driver side valve cover. There is a breather pretty close to the area of the noise on the pass. cover, but there's nothing there to make any noise. The cheapo valve covers don't have baffles in them either, so I know the rocker isn't hitting that.

I'm pointing to the noise in the attached pic. For some reason, this forum rotates all the pics I upload from my phone, this one included, but I think you guys get the idea.

[geezer#99]

THe pushrods are on the intake side.
THe pushrod for #2 exhaust is situated right by that bolt.
It's just a long shot guess.

Might even be a rocker touching the valve cover.

[nonstop]

Is it still making the noise with the valve cover off and running?

Is it the same ticking at the fuel pump? The fuel pump will make a certain amount of noise with a stethoscope held to it. BUT I spent a fair amount of time chasing a mystery tick on my 241 hemi. I finally pulled the fuel pump off and found the arm was broken in a spot and it turned out to be my ticking noise. I Replaced it and the noise is gone.

Could be one more spot to investigate!

[homemade87]

With all you have done its possible a wrist pin on the piston .They can tick just like a lifter . Pull a couple spark plugs where you hear the noise and the noise should change . Might be something to consider and rule out since no definite answer yet .

Also this test does not affect the valve train so it will be a separate test .

[Rust-O-Matic]

Thanks for all the input, guys!

Geezer,
You are right as usual about the pushrods being on the intake side lol. I looked at another cylinder head, and it's totally opposite of what I had in my mind. I think I'll take that cover off this weekend and look for visible issues again.

Nonstop,
The problem is, it's hard to hear the ticking at idle, and if I remove the valve cover and rev it up so I can hear it I'll end up shooting oil all over the neighborhood and the nicely painted surrounding engine parts. I didn't notice any damage to the fuel pump when I had it off a few months ago while I was cleaning and painting everything, but I'm kinda wondering if the pivot is worn where the arm comes out of the back of it, allowing a little noise. This still doesn't explain the noise I'm hearing from the side of the valve cover though.

Homemade87-
You better knock on wood, because I don't wanna hear that! Ha! I want to see what the ends of those plugs look like anyway though, so I will probably give that a whirl. Although, I definitely wouldn't expect to hear a wrist pin when putting my 'scope to the side of the valve cover. Seems like I would be able to hear it when touching the side of the block and/or the entire surrounding area. This noise appears to be directly behind the valve cover wall. I swear I can even feel the tapping against the stethoscope probe in my fingers.

So, if I take the valve cover back off this weekend to look at that particular cylinder's valves/rockers/pushrods, can you guys tell me exactly what to inspect? I mean, I'm pretty familiar with all this stuff but I don't wanna overlook anything.

I'm thinking I'll pull the pushrods out and make sure one isn't bent or something obvious, and check the inside of the valve cover for rubbed spots, shavings, etc. I'll probably check the valve spring and keeper for slop again, as well. Is there any particular way to test the lifters for that cylinder? Like pushing on it or something to see if it moves? That may seem like a dumb question, but these damn things are so reliable, in 20 years of driving old Chevys I've never had an issue with one that needed to be checked.

[geezer#99]

Run a straight edge over all the rocker studs to see if you have one pulling out.
One sitting higher could change the rocker contact on the valve tip.

And check the valve tips for strange wear patterns.
When you check the pushrods check for any rubbing marks.

[Boog]

If you do replace the fuel pump spend the money on an AC Delco one. The springs on the cheaper ones tend to give out and start pecking. Sounds just like a lifter peck.

[Rust-O-Matic]

I pulled the valve cover this weekend, and you can clearly see the two rubbed spots inside of it from the tips of the (stock) rockers. I pulled the first two rockers and inspected the parts. Pushrods are filthy but straight and oil runs clear thru. Nothing appears to be bent or loose.

So I decided to turn the valve cover around 180 degrees and see if there was more clearance. Nope. I could actually see the sheet metal move every time the rockers moved as it idled. So I took it back off and dented that area out just slightly with a ball peen hammer. That actually stopped the contact between the valve cover and rocker arm tip, and I could no longer hear it with the stethoscope.

So then I started it back up and listened to the fuel pump again with the 'scope. No noise, but the engine was still cold.

Then I took about a 10 mile ride to get some gas, and as soon as it was up to temp it started ticking again. When I got back home I left it idling and put the 'scope against the side of the valve cover I "massaged" with the hammer and it sounded just fine. No more loud clicking.

Next I listened to the fuel pump and it was clicking like pretty loud through the stethoscope now that all was warmed up.

So I still don't know exactly what the problem is, but I've got a new Delco pump coming my way, and I'm probably gonna find some different valve covers. I don't know if there's a reason the rockers were rubbing, or if it's just because of the poor fit and quality of that particular cheap aftermarket valve cover. I think I found this pair of covers in some boxes of old parts and junk. I don't even know where I got em, but I'm sure they're second hand.

[Rust-O-Matic]

Update:
The ticking is gone! It was the fuel pump itself. I replaced it with a new ACDelco unit (which happens to come in a plain white box and has the same part number as a cheaper Airtex pump) and the noise vanished. I could feel the slop on the old one where the arm pivots once it was removed.

Apparently the noise and rubbing of my rocker arms against the valve cover was a separate issue altogether. Now to find some better fitting covers...

Thanks for all the input and suggestions, I'm super glad to get this resolved.

[Boog]

I have had two pumps do this over the years. Thanks for posting your result.
Strange about those rockers rubbing the valve cover though.

[clockdoc]

I am experiencing the same rocker interference with a recently built and installed 327 in my 1978 truck. I've tried both tall and stock height cast aluminum with 5/16 cork gaskets with the same result. Witness spots show up on the intake side of the cover and the noise gets worse as the engine heats up. I am planning to try fabricated covers as they appear to provide significantly more clearance. If you would like, I'll let you know what happens.

[Port&PolishMan]

Originally Posted by Boog

I have had two pumps do this over the years. Thanks for posting your result.
Strange about those rockers rubbing the valve cover though.

I have seen Certain Valve Covers - Hit up against the After Market Intake
Stops - which seem to Protrude to Far , If you ask Me ..

This will Push the Valve Cover - in the Downward or toward Exhuast Side.

Which the Picture - Shows

I have had to do Slight Notches - in - Valve Covers where the Edges
Slam up against the Intake Stops . ( In one Case - Double Gaskets )

[clockdoc]

I put on fabricated valve covers and eliminated the rocker interference but still have too much noise when hot. Several have suggested improper pushrod length. Since I didn't check this when assembling I guess I'll check that out. I also have A tapping coming the fuel pump, so plan to replace that

[Port&PolishMan]

What did the Fabricated Covers Due _ that _ Originals with Wide Flange or
Alu. didn't ?

Intake Pushed the Valve Cover - in the Downward or toward Exhuast Side.

Which the Picture - Shows