C6 vibration and delay in D/R
I been having a vibration issue in P/N between 1500-2000 rpm which seems to be related to my C6, either by flexplate or converter, for I have removed all pulleys from engine and changed harmonic balancer with no change in vibration. I rebuilt the engine and trans back in '91 but the vehicle sat for many years until 2012 when I finished the restoration and put my Ranchero back on the road. The 472/C6 ran and shifted very well with no issues up until about a year ago when the slight vibration started, seemed to be getting worse. This past week took the vehicle out for a drive and noticed a slight surge between 30-45mph in high gear with light pedal, took this as a carb issue since I have been tuning by use of wideband even though the AFR's looked good at 13.7-14.0. I drove to my buddy's place(he owns a 4x4/driveline shop) and spoke to him on what he thought the vibration culprit could be. We discussed balancer/pulleys then engine/trans mounts then on to the converter. I attempted to leave his place and once I started engine and placed trans in R I had to rev the engine a bit to move(it never did this before, once started and placed into D/R the action was instant) it almost feels now like I had to wait for the converter to fill up or it was low on fluid. I checked fluid(type F) and it was clean with no signs of being burnt(looks or smells) and it was to the full mark. I also looked for any signs of leaking or broken line/fitting and found none. My buddy then said it is now more possible for my issues to be converter related(vibration/delayed engagement)I restarted the engine and placed it into reverse and it seemed better but still not an instant positive engagement, but had to get it home. I tested the trans by doing a little hard acceleration and it felt fine no slipping, but on the way home I still felt the surge at 30-45 mph with light pedal. Line pressures have been on the high side since installing valve body mods and it did shift good on my way home. I decided to remove trans, to check flexplate for cracks(vibration) and to have front pump looked at and install a different converter. When I removed converter from trans(on level ground) almost no fluid came out while converter was vertical, like the converter was less than 1/2 full, is this a sign of an internal issue? I vertically hung the trans so I could easily remove the front pump, the front pump gears/housing looked good as did the inside of the trans with very little color in pan(very faint dark color) the fluid was cherry red, there was a slight bit of wear on the converter bushing in the pump. Could this be a drain back valve issue within the stator(delayed action when placed into D/R gear), or could it be something else, I have heard these can give problems but have seen no images of it or exactly where it is located? I wanted a different stall converter anyhow, but now this issue has me concerned of the overall health of this trans. Is there a way to check the drain back valve while removed and on the bench? Please advise if there is and any other things I need to look at while trans is out. Thank you in advance. Todd
Yeah, it's a hybrid...It burns gas and tires.
No matter how good she looks somebody, somewhere is tired of her sh#t.
Last edited by aquartlow; 06-21-2017 at 11:48 AM.