Removing Cams - Question

[Larrym]

It went Erk-Erk-Erk-Errrrrrrrrrrrrrrrrrrrr. It is loud and sounds like something is terribly wrong.

Been following this fOaR a while cuz I also will have to deal with my very own valve seal(s). ʕʘ̅͟͜͡ʘ̲̅ʔ

Might I suggest pulling the plugs and taking a peep inside with a borescope/snake camera? ( •_•)

One I gots looks like THIS-



I got it from Harbor Freight... HERE-

https://www.harborfreight.com/digita...RoCYpQQAvD_BwE

I suggest NOT doing any mOaR start/run tests until you can actually SEE something what explains them scarey noises... ƪ( ` ▿▿▿▿ ´ ƪ)

Based on your excellent audio descriptions? (O_o)

Imma expecting for the camera to see crescent shaped dent(s) in the tops of the piston(s) from the valve edges. (╯•﹏•╰)

[Radioguylogs]

Everything looks hunky dory under the valve cover.

Valve clearances haven't changed much since I shimmed them. Three are a hair more loose, but less than 0.0005 from where I left them.

Timing dots line up correctly.

Cam chain tension look good.

Everything has lots of clean oil on it.

Based on the compression on all cylinders, I am wondering if the head gasket is leaking exhaust fumes into the oil gally(s). If so, I pray I didn't starve the crank or rod bearings to the point of failure. I haven't studied the oil distribution system to know anything about it.

Any ideas before I pull the head again?

PS: Checked exhaust nuts. Most were still fully tight. There were a few that could use a little snugging, but not to the point they would make leaky noise.

[Radioguylogs]

Looks like there is no chance a leaking head gasket could directly have exhaust gases starve any bearings of oil:




That's comforting.

[DEEBS11]

I believe that oil looked like it just had some condensation moisture in it. Normal for short start ups. Screeching can only be moving parts that have been worked on last (most likely). The crank & pistons (should) be ok. Maybe cam chain or cam bearings. Maybe an oil galley got plugged. I would take it down again and check everything. It's a pain but you need to find the issue (obviously).

[DEEBS11]

Some of the sounds you describe could also be a simple failed head gasket. Check to see if pressure is escaping from the head gasket area with soapy water. Sometimes these aftermarket parts are junk. Also did you oil the threads on the head bolts before torqueing? A dry bolt with some corrosion debris can give a false torque value because of galling. A cheap torque wrench can also give you headaches.

[Radioguylogs]

Some of the sounds you describe could also be a simple failed head gasket. Check to see if pressure is escaping from the head gasket area with soapy water. Sometimes these aftermarket parts are junk. Also did you oil the threads on the head bolts before torqueing? A dry bolt with some corrosion debris can give a false torque value because of galling. A cheap torque wrench can also give you headaches.

Deebs:

Thanks for your help.

I apprreciate your thoughts about the foamy oil.

I am also beginning to conclude it is a failed head gasket. The soapy water is a good idea. I may try that with a cold engine, but the problem happens as the engine heats up. I guess I could put the valve cover back on and hook everything back up, but it seems there is no other explananation except the head gasket.

I have a Harbor Fright torque wrench. It's cheap, but they actually get good ratings. Could be the problem.

I believe I put oil on the stud threads, but not on the head surface that the nut flange sits on. Do you think the flange should have oil under it?

More to follow...

[jetmechmarty]

It has been my understanding that the torque values in any factory service manual are referenced to clean, dry threads. Of course, this is born of my training and experience as an Airframe & Powerplant technician. Case in point, my Moto Guzzi Service manual states right up front that all listed torques are "lube torque" unless otherwise stated. If the Yamaha specs are lube torque, I can't find it. Therefore, torque values are clean, dry threads. This post is just FYI.


Lubricated Bolts and Reduced Torque

[jetmechmarty]

I have a Harbor Fright torque wrench. It's cheap, but they actually get good ratings. Could be the problem.

Those tools are generally good in the middle of the scale. So, a 0-150 ft lb torque wrench is most accurate at 75 ft lbs. Several years ago, I tested my cheap wrenches in a calibration lab that I had easy access to. My cheap wrenches were all dead on in the middle of the scale. If the manufacturer stated that their tool was within 6% accuracy, my results were 6% over torque at the bottom of the scale and 6% under torque at the top of the scale. It's a much smaller discrepancy than adding lube where it isn't called for.