Poll: Pre or Post Turbo Gauge

[RobbyRam]

OK! Lets have a poll. Turbo Failures experienced by:

Those who have pre-turbo gauges; those who have post; those who have both; but finally, and most importantly, who, with or without gauges, pre or post, who have frozen a turbo soley because of regularly not letting the turbo reach 325 to 300 degrees before shutdown. No metal shavings from drilling manifold failures allowed

 

[illflem]

good poll idea

My understanding is hot turbo shutdowns don't usually damage the turbo but rather damage the oil. The high temps cook the oil into extremely hard particles that get washed into the sump on the next startup. They spend very little time in the turbo bushings and only when the turbo is at low rpms. These particles are then very abrasive to the oil pump and can plug the oil filter. Particles small enough to make it past the filter can then go on to cause more damage.

This is a cumulative thing, an occasional hot shut down is of little concern.

 

[dpuckett]

I was led to believe (and I could be wrong) that the extra heat caused the turbo to spin faster, and shutting it down at 400 or 500 deg let the shaft spin fast enough to keep spinning long after sufficient oil supply had long since ceased. No lubrication on bearings= roasted turbo bearings after time. I agree an occasional hot shut down (within reason) shouldnt affect anything.

 

[dresslered]

During a tour that I took at Cummins San Leandro, one of the chief mechanics claimed the most common failures that he has seen on these engines was turbo failures due to not cooling them down properly. I was under the belief that the "cooked" oil gummed up the bearings which finally results in premature failure.



I didn't vote on the pole because I don't quite see grounds for any kind of correlation. Both post- and pre- pyros can be installed properly and offer two different kinds of measurements, but only the post can actually read for proper cool down temperatures.

 

[OTRPU]

Well, the results are in. . . and only one failure of any kind reported. Out of about 200 haulers I run with and talk to, nobody has lost a turbo due to not cooling to 300 degrees before shutting down. Can't even imagine waiting that long, would have to take nothing but hour long breaks. After a long haul with a load my turbo gets cooled as much as I'm going to while driving in the city to dealers lot. Then maybe a 5 minute cool off and that's it. This goes for either my Ram 3500 or my F350. But then I only drive 10 hours a day 6 days a week, maybe I'm missing something. If turning it off hot was causing failures it would show up in my crowd real fast. As far as I'm concerned it's another myth. Watched a growed man take his 650+ HP Dmax out and stand on it affore it was up to temp, poured the propane & NOX to it, and proceeded to blow the head gasket. In fact my head gasket is seeping alittle coolant. I think overloading before up to temp is greater problem than shutting down too hot.



Cheers,

Steve J.

 

[illflem]

From the Cummins Turbo Diesel News

Question: I tow a trailer during the summer. Is there any special cooldown needed?



Cummins : If you are towing heavy loads in the summer, you should let the engine idle for a three- to five-minute cooldown after extended full-throttle or high-power operation. However, under normal driving conditions a cooldown isn’t needed.

Unless you have a custom built turbo there are no bearings just bushings.

 

[ndurbin]

mine went out before I got my gauge in. And I was told to let it cool for acouple min before I shut down.

 

[Turbo Horseman]

Turbo failures look like more of an urban myth than reality from the poll numbers.

 

[dresslered]

Unless you have a custom built turbo there are no bearings just bushings.

I use the term loosely, Illflem. I also often refer to engines as motors and windshields as windscreens. Must be some of my Eurpean car interests surfacing.



Also, I would consider a premature turbo failure occuring at 200,000-miles which many of us might never see on our trucks.

 

[illflem]

I know what you mean. I usually call bearings the ones with balls or rollers and the solid or split type bushings, but the terms are used interchangeably by a lot of folks.



I have no proof of it but it just seems that a bearing with overheated coked oil would be more susceptible to damage than a bushing.

 

[C. Harlan]

I blew my turbo by way of 49 psi... . not by shutting it off hot... so I just checked the majority answer on the poll. . there was not an option for me. . Oh well,



-Chris-

 

[CFAR]

It would also depend on what type of oil used, dino or synth.



Heat dino oil up to 600f and see what happens?



I think a bushing would be much more susceptible to failure from coke particles than a bearing. Aren't bearing are "usually" make of harder material?

 

[illflem]

You're correct bearings are harder. My thought was the coked oil would remain in the bearings longer to do damage but would flush out of a bushing faster. Clearances on a bearing are also tighter.



The way most turbos with bushings work is that there is quite a bit of clearance between the shaft and bushing so that it spins on a rather thick layer of oil. That's why a little bit of side to side play on your compressor wheel is normal.