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Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Mon Jun 03, 2019 4:50 pm
by fuxxy
Rebuilt CVT myself. New seals. New clutch frictions. Replaced Input Shaft (Planetary). Replaced Drive Pulley. Replaced all gaskets.

Engine starts and idles great, but jerks harshly when placed in gear. Took for a quick test drive, and feels like a clutch is slipping, engine RPMs go up with very slow increase in speed. Never seems to shift out of "first".

I'm getting codes P0701-E0, P0961-60, P0871-60, along with an obvious "hiss" from one of the pulley covers that wasnt there before the rebuild.

Monitored PIDs PCA_MES (Main Pressure Sensor) and PCC_MES (Secondary Pulley Pressure). Both pressures are roughly 170psi with engine running, and climb with engine RPM. They both constantly fluctuate, but stay at roughly the same pressure. The Service Manual suggests that PCA_MES and PCC_MES pressures should have a differential of greater than 44 PSI, which mine never do.

The pinpoint tests from the Service Manual end up telling me to "Replace Transmission". I REALLY don't want to do this, especially since this problem didn't exist prior to the rebuild.

Looking for suggestions what this means, and where to look for problems. I'm sure I overlooked something.

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Tue Jun 04, 2019 5:42 am
by jas88
I see you resolved your earlier issue via the valve body/Mechatronics unit. I am thinking there are still issues there, but this is beyond my experience.

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Tue Jun 04, 2019 7:32 am
by Jim likes catwalks
Hi Jim here in British Columbia. I took mine apart a couple of years ago and replaced small needle bearing but didn’t redo all seals. Mine seemed to be stuck in limp mode(orange wrench light with po942 code) until oil warmed up. Bought a scan tool after much procrastinating and got oil pressure values that were all within specs. So this pointed to TCM/mechatronic. I ordered one from a place in Florida on E-Bay( just a TCM) and they sent me a whole Mechatronic. I was confidant I only needed TCM as I too had pulled mine apart and checked it even got solenoids checked out new assembly in and it worked! All oil pressure were the same. Now however I will get a code saying excessive clutch slippage which had the orange wrench but no limp mode and could be cleared by turning engine off and on. Can’t offhand remember code number will look when I get home or it might be on another one of my posts. Suspecting oil pump issues as now it also ticks whether in gear or not unlike helicopter noise. Thinking your oil pressures sound about right any chance your shifting linkage isn’t quite right I know once I put mine together on top of tranny and thinks weren’t going into gear as they should. Re attached it all then resolved it. Just some thoughts to maybe help?

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Wed Jun 05, 2019 2:34 pm
by fuxxy
Dropped the transmission again. On a whim, I opened the secondary variator cover, as that's where the hissing noise was coming from. Found the O-Ring at the base of the cover split in half. Replaced O-Ring, reassembled transmission, reinstalled.

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Upon first startup, the transmission went into reverse smoothly, into neutral smoothly, into drive smoothly. Pressure differential was around 50 PSI, with PCA_MES on the higher side at 280 PSI. Placed in park, shut off engine, cleared codes. On next startup the transmission was acting as before, Pressures went back to being close to the same, and codes returned.

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Wed Jun 05, 2019 4:14 pm
by fuxxy
suspicions confirmed: Replacement O-Ring blown out as well. I made 100% sure the O-Ring was well-lubricated and seated correctly when installing the cover.

Now for the hard part. Why is this O-Ring blowing out? Incorrect size/material? The rebuild kit I purchased did not have a guide for which O-Rings go where. The replacement O-Ring was new, but found from a bag laying in the shop.

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Wed Jun 05, 2019 5:23 pm
by fuxxy
On a whim, I opened up my disassembly guide - 'CVT Disassemble.pdf' - and on it, it referenced a Secondary Feed Tube Snap Ring.
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I remembered when I reassembled my CFT30, I had a snap ring left over. I scoured over the entire case and shafts, and could not find a location for this snap ring. I dismissed it under the logic that I had 3 CVT's apart at the same time in the shop, when I was scavenging parts for mine. I didnt take much care putting the other two back together, and thought it was left over.

Just to be certain, I looked at my feed tube sticking out of the case under the secondary cover. MINE WAS MISSING A SNAP RING! I still had the "leftover" snap ring sitting on the bench, so I compared the size of the snap ring to the tube, and it looked like a perfect fit.

At the moment, I've installed the missing snap ring, installed another O-Ring (Had to dig through the old O-Rings I removed from the transmission initially), and reinstalled the cover. I replaced the aluminum bolts with Zinc-Coated grade 9 flanged bolts since the aluminum bolts are intended to be used only once - and they're impossible to find a replacement for. For precaution against galvanic corrosion I coated the threads and flange with Ultra-Grey silicone gasket maker, and am currently letting the silicone set before I test.

This missing snap ring could MOST DEFINATELY be the cause for blowing out this O-Ring. We're dealing with pressures up to 500 PSI, more than enough to push things out of place if not properly fastened. Without the snap ring to hold the feed tube in place, the pressure quite possibly pushed the feed tube out of the hole enough to blow the O-Ring out. This just goes to show to take ultimate care when working on a complicated project. Even though I bagged each part individually and kept all my parts on a single workbench to avoid cross-contamination, I still ended up forgetting a piece.

My old Auto Technology teacher put the topic in terms that have stuck with me, 20 years later. Ford sold roughly 235,000 Ford Freestyles and Taurus X's across the US and Canada. If that one snap ring cost 10 cents, if it truly was not needed Ford could have saved 24 thousand dollars! There are really no such thing as "extra parts left over".

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Wed Jun 05, 2019 6:22 pm
by mmsstar
The T-Rex has the 6 speed, no CVT but the 500 had the CVT and the 6 speed

Re: Rebuilt CVT - "CHECK TRANSMISSION" - What did I mess up?

Posted: Wed Jun 05, 2019 8:47 pm
by fuxxy
Just a quick follow-up, after a test drive a couple miles down the road and back, NO TCM codes!

Everything seems to be running fine, aside from a harsh jerk when shifting from Reverse to Drive. I still need to perform the CVT drive cycle re-lean process and doublecheck the fluid level after the test drive.