Not Another Oil Thread
Fleet Mechanic
Joined: Apr 2019
Posts: 1,736
Likes: 659
From: South AR
It’s an auto. But I was told by a friend who has been a Toyota mechanic for 30 years and a good mechanic on side.. not just dealership ... that that particular transmission locks TC only in OD and when shift to 4 manually it can help diagnose a very common issue with that model being the TC. It immediately did as he suggested and you can’t get it to slip or stutter unless back to OD. Flush and modifier fixed it or at least put a decent bandaid.
read on Toyota forum a description by someone akin to a Mark here that said the TC will start to get glazing and if you catch it soon enough a change and specific additive can potentially rehab it if caught in time. So far so good. Apparently they replace tons of just TC in these transmissions to fix this common issue and don’t do rebuilds and they are good to go. Not sure of root cause but really seems like a flaw in design somewhere.
btw. Sorry for the hijack
read on Toyota forum a description by someone akin to a Mark here that said the TC will start to get glazing and if you catch it soon enough a change and specific additive can potentially rehab it if caught in time. So far so good. Apparently they replace tons of just TC in these transmissions to fix this common issue and don’t do rebuilds and they are good to go. Not sure of root cause but really seems like a flaw in design somewhere.
btw. Sorry for the hijack
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FTE Chapter Leader
Joined: May 2020
Posts: 2,930
Likes: 2,188
From: Langley B.C. Canada
No problem on the hijack. After all we’re still talking about oil changes, and intervals. Maybe not the motor, nor a 7.3, but one day this will be useful to somebody considering the stuff I’ve found from a simple google search. Sometimes in the least expected- oddest places we find a nugget of knowledge.
Lead Driver
Joined: Jul 2017
Posts: 6,853
Likes: 2,330
From: WV
Brian it now sounds like you are describing TC shudder. Yes absolutely makes sense now. This isn’t ‘slip’ but more of a clutch chatter (picture a manual with chatter). TC LU designs have moved to include partial Lock Up conditions which are basically controlled slip to allow better fuel economy.
And sorry, I got that it was an Auto. Not sure what I said wrong that made it sound otherwise.
Probably my poor quick description of the TC LU function. I’ll try to explain it better (if anyone cares lol). Normally the TC slips as the 2 fans are making a fluid coupling. This fluid coupling is required to allow stopping while in gear (engine at idle speed, Input Shaft at zero). Otherwise it would stall like a manual. Once up to speed this equates to loss of efficiency (1 revolution from engine = less than 1 going into the trans). The TC LU clutch will engage to make it become a 1:1 condition and get rid of the slip of the fluid coupling.
And yes, sorry for the off topic discussion.
And sorry, I got that it was an Auto. Not sure what I said wrong that made it sound otherwise.
Probably my poor quick description of the TC LU function. I’ll try to explain it better (if anyone cares lol). Normally the TC slips as the 2 fans are making a fluid coupling. This fluid coupling is required to allow stopping while in gear (engine at idle speed, Input Shaft at zero). Otherwise it would stall like a manual. Once up to speed this equates to loss of efficiency (1 revolution from engine = less than 1 going into the trans). The TC LU clutch will engage to make it become a 1:1 condition and get rid of the slip of the fluid coupling.And yes, sorry for the off topic discussion.
Fleet Mechanic
Joined: Nov 2008
Posts: 1,573
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From: Seattle
https://www.blackstone-labs.net/BSto...spx?cid=G02286
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