The Stovebolt Site Forums The Shop Area Engine Shop New Rebuilt Engine Noise

This is gonna sound like my wife describing something to me but anyway here goes. Started the newly rebuilt 261 last weekend, ran it at 1500-2000 rpm for 15 to 20 minutes to break in the cam. Drained the oil and filter. This weekend, I started it back up and let it idle for a while looking for leaks and anything funny. Heard a noise that would come and go lasting only a few seconds each time and seemed to come from under the rocker cover. Was not coming from the carbs, exterior mechanical items, etc. Almost sounded like a pushrod was spinning quickly or like a pulley was loose on a shaft. I know that this sounds non-descript but it's the best I can do. Haven't retorqued the head yet nor readjusted the valves. Any ideas?

49 geezer,

Very interesting. I have no clue if this could be it, but I looked through your engine rebuild pictures just last week and saw something that I questioned.

Again, haven't a clue if this could be your noise, but the rocker arm oil feed line is UNDER the pushrods in the original pix, but in the 'after' pictures you have it outside the pushrods.

I think it belongs inside, snuggled up against the block. Did you actually install it outside the pushrods, and could it be mashed and/or rubbing on a pushrod? Just a thought!

Stuart

I'm not sure how similar your 261 is to my 216 so generically speaking I would first check to make sure the top end is oiling OK, then re set the valves & go from there. Maybe run it a bit with the valve cover off to get a better handle on where the noise is coming from.

Stuart; Interesting indeed. I looked back at the photos and noticed that the line was in place but the pushrods were out, so I'm not sure if it was in back or in front. But, sine I reused the original line, it seems that if it was originally in back, that I would have had to "stretch" it some to put it in front of the pushrods. If it was rubbing, I would think the noise would be constant and not come and go. Will have to go back and see if I did any other pics of the engine at that time. Maybe my manuals will show a pic as well.

Tiny; I pulled the valve cover and looke everything over with the engine not running. Looks okay so far. If I start it up, how much oil will spray/spurt/drip?

49geezer,

You're correct. I "thought" I saw a before picture with the line against the block, but must have been hallucinating because I can't find it now...plus, as you noted, the fitting where it transitions up to the center oiler is pointed outwards in a direction that would make it difficult for the line to zig zag back underneath the pushrods. I'll clean my glasses.

The oil should exit the top of the rocker arms in a gradual manner...no geysers! Ideally there should be enough volume for the rockers to puke oil AND have some coming out of the little overflow tube.

Stuart

You can run it with the cover off. You won,t get any splash unless like Atomarc says you have a geyser, which is not likely or you rev it up real high.

If you have a lifter acting up due to s spec of dirt, it can make a noise and then the noise can disappear. Usually this is a distinctive tick. A small piece of debris could cause an intermittent noise too.

Am going to start it back up without the cover as suggested. However, I was thinking about this:

The head is a 235 head (3835913) and the old rocker arm assembly used the drip tube affair for lubrication. I installed annular solid lifters so the oil could run through the lifter galley and then up to the head. However, the new rocker arm assembly I used was a later version (1959 on I think) where the grooves in the rockers themselves are offset and the shaft was meant to be fed via a center ring with a direct feed from the full flow oil system. Could I be having a problem by using the older drip style oil lubricator with the newer style rocker assembly? Seems like I read something about this once.

49 geezer,

I think there are only two methods for getting oil to the rocker assembly on these engines, and neither one involves the style of lifter.

Your engine receives pressurized oil from a tap on the rear cam bearing, through the little tube, up through the head into the center oiler.

You indicated you were getting oil out of the rocker arms...so it seems to be working properly.

Do you think you have a problems with the rocker arms?

Stuart

Well, started the engine and watched the rocker arm assembly. No noise this time but observed that my oiler overflow tube had lots of flow. Two small holes supposedly dripping on the shaft were actually missing the mark. But what concerned me is that there was little, if any, appreciable oil coming from each rocker arm "weep" hole. Correct me if I'm wrong (because I don't want to take out the shaft assembly if I don't have to), but the center oiler tube ring that holds the overflow tube and fits on the end of each section of the rocker arm shaft, does that ring have a hole inside it that sends oil from the block galley into each end of the hollow shaft? Then through the hollow shaft, oil is forced up through holes in the shaft, lubricates each rocker and oil comes out the rocker arm weep holes? If so, then I think I know what my problem may be. The overflow tube is allowing too much oil to flow out of it and back onto the head and thus diverting necessary oil flow through the hollowshaft and to each rocker arm. If the rockers aren't lubricated enough, then I would get the strange noise that sounded like a dull screeching. If all this is true, I should then crimp down the end of the drip tube and send more oil into the hollow rocker arm shaft. Is this sounding right?

49geezer,

As I remember it, the center oiler is actually through bored the same diameter as the OD of the rocker shafts. It acts as a common distribution point and a shaft support.

The ID of the rocker shafts can plug up something fierce with crud, so this could be a point to check.

I'm pretty sure the proper position of the oil holes in the rocker shafts is 'holes down'. This means the oil exits the shaft in the high wear area on the bottom, and travels to the top and out the hole in the arm.

If it has been assembled with the holes up, you very well could hear a screeching sound, as the highly compressed bottom can't get lubricant.

Restricting the overflow tube is often done, but if all is well and clean with the rocker assemblies, they should get plenty of oil and this 'crimping' won't be necessary.

Stuart

I can only comment on how my 216 works. It may be similar and it may not but your description of the oil line and rocker shafts sounds the same. On my 216 the oil enters the hollow rocker shafts through the fitting you described. The oil then exits the rocker shaft through holes on the bottom of the rocker shaft to lube the rocker arms. The rocker assemblies are easy to pull. It would probably be worth your time to do so & make sure they're up to snuff. If you start pulling them apart make sure you note how they come apart. The rocker arms aren't interchangable between the intake & exhaust valves.

I can not say for with out actually seeing your motor running but 6 cylinder chevys do not require but very little over head oil. With the valve cover off and running, you won't see much oil at idle--- nothing even close to what up would observe looking at a running V8 motor. In fact too much overhead oil on 216-325-261 will cause the rocker cover to over fill and oil will spill into the valve guides.The area that handles the return oil in a chevy 6 head is very shallow in comparison to most motors.I have found when I start a fresh 216-261 motor that it is best to leave the rocker cover off and put all but about a half quart of oil in the motor. Just a few minutes before I start the motor I pour the remaining oil over the rocker shaft, then install the rocker cover and start the motor. I have heard some unusual noises on start up because the rocker shaft is about the last thing to get good oil flow.

This is good. I did an extensive search after my last post on rockers. Apparently Stuart, you are correct as the holes on the shaft should be on the bottom. I'll pull my rockers next weekend to make sure that I installed it that way. Next, the shaft should be the primary source of oil lube to the arms. I believe that I have too much going out the overflow tube and that the arms are starving for oil. So, once I check out the position of the holes in the shaft, I'll crimp up/seal off some of the holes in the overflow tube to provide more lube to the arms themselves. Thanks everyone!

Last weekend, I used JB Weld to close up the old drilled "drip" holes in the tube so all of the oil would then be diverted to either the hollow inside of the rocker arm shaft or out the end of the overflow tube. Then, with the engine running, I watched the weep holes of each rocker arm for oil seepage. I noticed the arms closest to the center connector getting some but the end arms were pretty dry. I started crimping down on the overflow tube end reducing the amount of oil bypassing the rocker shaft and voila! Oil was now seeping out of each arm and a small amount was dripping out the end of the tube. No more noises. Thanks everyone.

Excellent news. Glad you got it figured out. Thanks for the update.