Engine noise

[RangerXLTMan]

Maybe some of you guys can help me identify a noise coming from my 5.0 roller engine. It's difficult I know to explain to anyone what the noise sounds like without them being able to hear it, but I will try to describe the noise for you. At first I thought I had a lifter that was not working right because of the rapping noise I was hearing, I'm still not convinced it wasn't but I did go through all 16 of the rockers and checked for correct movement and they all seemed okay. The rapping noise goes up and down with engine speed and doesn't go away. I have considered that one of the rods was knocking but it doesn't sound like a knocking sound to me, more like a tapping sound. Still it could be a rod but and I could be wrong about the symptoms. I would hate to have to pull the engine and tear it down if it turned out to be something else other than a rod. If anyone has had a similar problem and can shed any light on this for me I would greatly appreciate the information, otherwise I will have to assume it's something faulty with the crankshaft rotating assembly. If that's what you guys also think then I will have to get a crankshaft kit and install that and hope that cures the noise. Thanks in advance....

[colnago]

Take a video of the noise and post it on YouTube. Then post a link to it here.

Joseph

[MadMike]

Check the harmonic damper/balancer. Seems pretty common for the 50oz balancer ring to slip or loosen. It can sound like rod knock or a timing chain smacking the cover.

If the engine has some miles, place it on TDC, then rotate it backwards while watching the distributor rotor, stop when you see the rotor turn, look down at the balancer, if there is 8° or more slop then the timing chain set needs to be replaced, it can cause a knocking sound as well. Same for a mechanical fuel pump.

Also when installing the roller engine, did you use the correct balancer and fly/flexplate?
The incorrect imbalance can cause excess wear and noise on the rotating assembly.

[RangerXLTMan]

Thanks MadMike for your suggestions, they all sound feasible. This not a high mileage engine and it was rebuilt before I bought and installed it a few years ago. I did make sure that the flex plate was the correct one for the roller motor (50 oz). The harmonic balancer came with the engine and may be old and needing to be replaced because I know that the timing marks are off register. Maybe the rubber separator has gone bad and is making a noise like you suggested. I think I'll replace it with a new one regardless as it needs replacing anyway. It's the type that has 3 holes to mount the C/S pulley instead of the usual 4 holes. I will try this first and see if that cures the rapping sound, thanks again for your help, I really appreciate it.

[RangerXLTMan]

After much concern and frustration in chasing the tapping noise in my engine I decided to pull the engine and tear it apart to have a look at everything. The cylinder bores showed no wear at all as the engine had previously been bored 0.020. The crank main and rod bearings were in excellent shape as well. The cylinder heads looked really good too but I took them and the crankshaft to the machine to be examined by the experts. The crankshaft measured out perfect and was standard on the rods and mains. I just told the shop to polish the journals for me. I decided to leave my heads and have a fresh valve job done just to be sure that all the valves were sealing good. When I returned to the machine shop the shop owner showed me one of the exhaust valves that came out of one of the heads.....the stem was broken in half! That had to be the cause of the rapping and tapping noise that I was hearing. In all the years of working on engines I had never seen that happen. The shop owner has been in business since 1945 and has seen just about everything that one can imagine, but he told me that this was a new one on him as well. I just thought I would share this information in hopes that it might help someone else.

[idaho_cowboy]

Thanks for posting the update! Interesting find. Now you'll have confidence when you get it back in, that it's not about to grenade!

- Joseph