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  #1  
Old 10-27-2008, 04:03 PM
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Transmission 2 to 3 shifting and turbo causing temp to go up

Hi all,

Over the past two weeks, I've had sometime to work on some nagging issues. I completely drained my transmission (including torque converter), changed the filter and installed a K1 kit. I also refreshed all the major vac tubes on the driver's side of the engine, disabled the EGR, EGT and ARV (no blocking plates yet). And over this weekend, I changed out all the IP seals. Of note, the 2 that were leaking had the wrong size/shaped o-rings. They were flat sided!

Transmission shifts from 1 to 2 is superb in most cases. However, shifts from 2 to 3 is a big problem: the transmission won't let go until around 4,000 rpm and as a result, the turbo is turning at the same time. This is especially bad on long hill climbs. I'm often foot/pedal modulating the shift point

I am going to start trouble shooting the transmission first by following that loooong thread on transmission vacuum and cable adjustments for shifting. I plan to soften the shift firmness a tad, but move up (shorter transitions between gears) the shift points too.

However what concerns me is how fast the turbo is causing the temps to go up. On a particularly long hill climb (3 actually), my temp gauge got above 100C. About 105 if i were to guess. I read that this is normal, but you other OM603 engine'd owners put the fear of God in me about high temps and cracked heads! So is this a sign that something is wrong w/ the turbo? Or will the solution be to fix the transmission shifting points? Or does this also relate to the radiator and clutch/fan? A few times on these hill climbs i turned on and turned off the A/C. As you can imagine, the temps were higher w/ the A/C on and somewhat sluggish.

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Old 10-27-2008, 04:04 PM
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Why do you think the turbo is the cause?
Stuck kickdown switch can also lengthen shifts.
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Old 10-27-2008, 04:08 PM
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kerry,

so a stuck kickdown switch = higher rpms would cause the engine temps to go up quickly? sorry, i'm new to diesels and the concept of a kickdown switch is totally new to me.

why turbo? because i believe i hear and feel it. perhaps my ears and butt deceive me
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Old 10-27-2008, 04:12 PM
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Kickdown switch is the switch that controls downshifting underneath the accelerator pedal.
I think it is the extra work the engine is doing on a hill climb that is causing the temperature to rise, not the turbo per se.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #5  
Old 10-27-2008, 04:18 PM
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The turbo doesn't significantly affect the engine (water) temperature. It spins whenever the engine is running. The more fuel burned, the more heat to the turbo, and it can affect Exhaust Gas Temperature (EGT), a gauge for which your car doesn't have.

If it is shifting late, unplug the downshift switch under the loud pedal and see if that helps. Also check the "bowden cable" or downshift cable, sticks forward beneath the firewall next to the windshield-washer reservoir, make sure it is sliding in/out freely and not stuck out.

- Jeff
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  #6  
Old 10-27-2008, 06:15 PM
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I'm thinking maybe you've got a cooling system issue to go along with your trans issue.
Doesn't vacuum have some effect on shift points or is that just on shift modulation?

Anyway I don't think your running at high rpm like that should cause the temp to rise. Do you have the correct yellow coolant? Has it been change recently? Have you cleaned between the condensor and radiator?
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Old 10-28-2008, 12:24 AM
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Have you pulled the radiator to give the fins a good cleaning?

Sixto
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  #8  
Old 10-28-2008, 11:46 AM
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guys,

kerry and jeff: turbo and diesel vehicle, so i appreciate the good info, thanks. i'm going to unplug the KD switch and report back results.

kurt: i changed out the nasty green stuff for the mbz formula coolant the week after i bought this car. however, i am going to change out the gasket and the thermostat within the coming weeks. i actually purchased one about 6 months ago, but can't find the damn thing now :bang: last night i was doing some "spirited" driving, doing some 0-60 runs and some long uphills while flooring it, most of the time with the AC on as well as manipulating the kickdown switch w/ some pedal modulating to allow it to downshift. I was purposely trying to see how fast the engine temps rise and fall. since it was night time, it didnt rise as quickly as the other day, but i still got it above 100C. however, it did fall pretty quickly, so i think i'm ok here. i will change the coolant out when i replace the thermostat though. do you run zerex by chance? and if so, do you find zerex 05 better than the mbz coolant? i suppose there's probably a long thread about this somewhere

sixto: ok, i'll add that to the list of things to do when i recondition the cooling system. at one point, w/ my harbor freight dental pic in hand, i contemplated cleaning the fins out w/ it!

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