Originally posted by fossil
On a similar subject what are the possible consequences on a turbo diesel of performing a stall recovery on a steep hill i.e.if you can't make the climb, stalling the vehicle, selecting reverse and then starting the vehicle. ... Would this be potentialy damaging to the turbo considering that it is likely that it would have been working hard on the climb and then had the engine shut straight down. I'd be interested in any thoughts.
Iain
Hi Iain,
I wouldn't think it's a problem for two reasons.: 1) The engine would only be stopped for a few seconds - hardly enough time for the 'heat soaking' of the bearing to get going, and 2) even though you may think you engine's working hard in 1st and 2nd low range work, it's really not. The extra low gearing is doing the hard work but the engine's generally not being too heavily loaded. You're very unlikely to be using full throttle at mid to high rpms for minutes at a time in low range - well, not unless you drive a lot different to me.
High load conditions (full throttle, full boost and mid-to-high rpm), which you often get towing caravans or heavy trailers up a incline, or even solo up a steep range, are the ones that send EGT (and hence the turbo housing temps) very high - to 700 C and beyond if you don't back-off or change to a lower gear.
Drivesafe, I take on board your recommendation to talk to people who actually service trubo-diesels and do so at every opportunity. But again I must question your assertions. "modern diesel engines and turbos are dramatically different... but both are now designed to operate at much higher RPMs"
Is the max. rpm of a Td5 that much higher than a 10-year-older-design 200 tdi - not much I think, still about 4500-5000 rpm. AFAIK, typical small high-speed diesel engine turbos still run up around 100,000 rpm but I'll stand corrected if you can quote me some references on this.
"they are also designed to tolerate higher operating temps" Maybe so, but I thought we were talking about the temperatues the bearing oil is subjected to after a 'hot' turbo is shutdown - something not directly related to the 'operating temps', I would have thought. And again, AFAIK, engine oils, even 'u-beaut' synthetics, don't like being subjected to temperatures above about 140-150 C.
I think I'll continue to use my turbo timer, with a setting that allows the EGT to settle to the low 200's before stopping. And I'll try Vlads tactic if I'm ever 'ticked' for it...
Ian &
Leo - SIII 109/GMH3.3
Daphne I - '97 Disco 300Tdi Manual
Daphne II - '03 Disco Td5 Auto
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