Drivetrain Temp Questions

[rustyk]

I posted this in another thread, but I really transitioned to a different topic:

Brief: Engine and tranny temps in the past few thousand miles have gone up as listed below. Neither is even approaching overtemp, but it's been an "item of interest". The engine used to run around 160° and the tranny 150°. Now it's 190°/180°.
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"Quasi-Epilogue: Because the transmission is operating normally, I replaced the thermostats (5-hour job because obstructions necessitated the removal of the entire housing to get at the 'stats).

New 'stats were installed, and after 370 miles, the temps are still "what I'm not used to". But testing the old (OEM) 'stats revealed one was sticky, and in testing neither 180° stat cracked until over 195°.

Coolant temp on straight-and-level runs around 190° with the new 'stats. Tranny temp is nailed around 180°. This is what I would expect in theory.

I suspect that one of the OEM 'stats was stuck open, and only recently closed normally; prior "normal" temps were coolant <160°, tranny ~150°. These are cooler than I would have expected. Apparently, the stuck-open 'stat corrected itself, and in operating normally, increased the temps.

Anyway, The tranny is due for change of fluid, which I'll do when I get home. I expect no difference in operating temps after. But at least I'll be able to collect any TC lockup residue for the Missy Good Wench Museum and Leftover Parts Emporium.

Bottom line: I think the system is now working normally after not for a long period."

Any comments would be appreciated, especially about causes for the change in operation that I've overlooked.

[rustyk]

I should have added that temps for the first 5-7 miles of a cold start are in the 160°/150° range (I can see the twtch as the 'stats open), but then creep up to 190°/180°.

So my guesses are:

1. The old 'stats had one stuck open so temps didn't go to 190°/180° until it "unstuck".

2. The torque converter clutches are shot, and the TC never locks up (It's always been hard to tell), increasing the heat (would an unlocked converter produce enough heat to cause this result?).

Comments, or any other possibilities (a water pump impeller slipping on the shaft has been suggested, but after 2K miles, it should have failed by now)?

[DmaxMaverick]

It's difficult to say absolutely, but I suspect your torque converter never locking is at least the largest contributor. If there are other contributors, you can't diagnose properly until the TC issue is resolved. Unless something is blatantly obvious, your first course of action must be the TC. Your TC is not only open, but the friction from the TC attempting to lock up will, in fact, be capable of developing a lot of heat (not just from fluid friction) your system is not designed to manage. Heat is used energy, so your driving and trying to maintain a similar power level is using more energy (fuel), which in turn, produces more heat throughout the system, including the engine cooling system. All the while, the TC is adding wear materials to your transmission, which in turn, causes more wear. You have several cause-effect circles in progress, and none of them will lead to a positive result. Your TC is not "open", but is slipping while attempting to lock. This is a worst case scenario for all components involved.

[rustyk]

Thanks for the reply, and your advice makes perfect sense; I wasn't sure how much the dying TC could contribute to heat.

While the local rebuilder I use is excellent, he did use HD parts for the tranny, but the TC was from another supplier.

I kind of suspected the advice would single out the TC; fortunately, after 5 road trips and 6K miles this year, I'll be able to park the coach for 6 weeks and get a Real HD TC installed.

If the tranny is again ill, this round I'll have time to get a robust one from a specialty shop.

Any suggestions on suppliers of HD trannies? And installers in the North Florida area?

I'd prefer a package with an HD tranny with the Transgo kit installed, and a good TC (stall characteristics suitable for the 6.5L) to be done by someone experienced in these speciality products.

[ronniejoe]

Sun Coast Converters

[Robyn]

From what I have seen over the years, a converter that has lost the clutch will generally chew itelf up in fairly short order and things will start failing to work right real quick.

Checking the pan for debris will tell the story.

I think the coolant temp anomaly is just about what you are thinking, unless there is a gauge issue creeping into the picture.

Swapping out the sending unit would possibly give a clue along these lines.

Missy

[rustyk]

Sun Coast Converters

So far, Sun Coast has been a disappointment - the Guru who was supposed to call, didn't. More later if they show they want business.

"90% of success is just showing up!" - Woody Allen