1206 mcv valve noise

I recently finished rebuilding a 1206. I overhauled the engine, installed new TA, and completely went through the MCV valve. Everything works as intended but
when the engine is over mid throttle the MCV valve starts making a whining noise like oil is bypassing. If I cycle the clutch to move the dump valve it will
stop. But will start again if the engine is revved up. Any ideas? thanks

Did you put the right thickness gasket between MCV and tractor housing and pump gear is to tight of mesh.

Thanks, no it is not the gear mesh, I checked that before I installed the bottom cover. And it does not sound like a gear noise. It is a hydraulic whine.

Well did you change the springs in the MCV ?? if ya duid did you check the pressure ?? Pressures must be set as you have to TRIM the springs in the pressure reg valve / And did you get ALL the O/Rings installed correctly . Pressure for your MCV should be no more the 265-275 . I have no idea where you screwed up as i was not there . there is a whole lot more to doing a T/A then just twisten nuts and bolts . Shimming the QUIL and lower shaft , checking spring lengths and sping pressures usen the correct gskts making sure the MCV gskt is the same as what came out and when a novices is all done and things did not work out like in the fairy tale book he starts looking for help and we are to come up with a instant magic cure . . One more thing here did you install the correct lower constant mess gear that SHOLD have come with the replacement T/A , and did you shim it the same as the quill , So if you did NOT shim for end play then you get top do this job all over again .

Tractor vet, I really don't appreciate your condescending answer. Did I ask you to wave your magic wand? All I am asking for is some advice from someone a little more familiar with this tractor than I am! As far as being a novice, hardly. I have been wrenching my whole life. 15 years as a John Deere mechanic overhauling more engines and transmissions than I care to remember and the last three years working on 4500 HP locomotive engines. I don't know everything and I don't pretend to so I just would like a little FRIENDLY advice. I will tear the MCV valve back apart if that is what I need to do but before I do more work than I need to maybe there is a simple fix. Like a weak spring or o-ring that someone can point me to. This website is full of knowledgeable people willing to help but it also has its share of grumpy old codgers like yourself that chase off young mechanics like myself just looking for some help. Rant over. And yes I reassembled the TA properly with the new gear that was sent with it. Shimming, torquing, and reassembling with the assistance of my manual. As far as pressures I have not checked yet. I did not change any springs in the MCV valve I just re-sealed it. I have the clutch linkage adjusted so the tractor just starts to move right after the dash light goes out.

Hey get hold of me any time you said you overhauled the mcv that sound like you did right I shim the quill all you do is takeing up in play I have never shim the lower shaft that ta gear that send you has a different pitch of gear teeth 23 degree and there?s 25 degree sounds like it?s that and I have a bad TA sprag gear in the TA when started working on IHs we use to rebuild them hours selfs new ta shaft,houseing ,new TA sprag gear and sprag and clutchs and plates And never had a problem good luck

you don't just have a simple low oil level letting air get in the system. Could try just adding an extra 5 gallon and see if it disappears. Common problem to have a cracked tube so the extra oil covers it and no air .

Hey remember you asked, his reply is based on given info on your post.I would have said the same thing.The day will come one you are and old codger.He is not chasing anybody away.Learn and move on.

Thanks for the ideas, the tractor is 2 hours away from where I live. So I am just trying to get prepared by ordering the parts I might need ahead of time so when I get there I can figure it out and complete it in one trip. I will first re-check the oil level and check the operating pressure. The engine was stuck on this tractor before I started so I do not know if it was doing this before or not. I am thinking a weak spring might be causing a spool to bypass oil. All I have to do is tap the clutch peddle to bump the dump valve a little and the noise stops but starts again about mid throttle. And it is most definitely a hydraulic whine and NOT gear noise.

Well yes i am and OLD fart that knows I H tractor and have a lot more years of working on engines and such from mid to wild . and T/A's son i have worked on more T/A's the just about every one on here except a Couple and they are older then me and i yield to there knowledge . Now as to YOUR ADJUSTMENT of the dump valve ah NO you DO NOT have it set , i hav e covered this somany times as to HOW to set one that ya want to know then look in the archives on the SUBJECT . If this problem did not exists before you got into it then it is SOMETHING you have done and like said i was NOT standing over your shoulder watching ya . So you say resealed it So here that tells me NOTHING what seals did you replace , Gskt. O/rings and where did you change pumps ?? if ya did did you try and use a larger GMP pump . Sorry i got your shorts in a wad but i am NOT P C i tell it like it is and for me to FIX your PROBLEM i would have to back track everything you did . If i am going to a T/A then everything is taken apart every valve , every spring every gskt every O/Ring is gone thru every spring is checked for free length and rated pressure at the given length . one everything is back together pressures are checked all the way around Flow is checked with a Flow rater at Operating temps . Like i said i have no idea what gskt you used or if you forgot one stupid o/ring someplace as i can not tell you how many times i have been out to someoens farm to FIX what they messed up and how manytimes i have been called to go fix a problem with a BOTCHED T/A install even by off brand dealers because there mechanice said they could do it with out farming it out .