Turbo malfunctioning in the cold

[calsbeek]

Today was the first day cold enough that I had to glow on start up. Just like last winter, in the cold air my turbo seems to come on late and stay on long after I take my foot off the accelerator. There is also a whining sound from under the hood that sounds like the turbo revving. Last winter this happened every day, until the air warmed up again and everything went back to normal on its own. Is this typical? Is there something I should or can do to ameliorate the situation?

 

[coldtaco]

probably helps if you mentioned engine/turbo? don't know why cold would make your turbo come on late and stay on late unless something screwy with the oil or water to/from the turbo? I've had a 13B-T in -40's F without any problems

 

[calsbeek]

right sorry. Its the 13-BT running in my 1986 BJ74

 

[coldtaco]

Are you sure it’s the turbo? I only hear the turbo under boost and then only with some modefications like bigger exhaust, muffler removed, and/or snorkel installed. You sure you are not hearing the radiator fan?

 

[calsbeek]

I'm not sure but here is why I think it is the turbo.

Cold start goes off without a hitch (single cycle on the glow screen and it always starts immediately), the green turbo light comes on pretty much anytime I touch the accelerator during the summer, but this morning (and all of last winter) the green light doesn't come on until up to 20 seconds after I depress the accelerator. The green light normally shuts off the moment I take my foot OFF of the accelerator in summer, but in winter the light remains on for 10-15 seconds after I let of the accelerator. The sound only arises on these cold days and happens with or without the fan on. When the engine finally gets really warm (say 20 minutes not the highway), then sound goes away....

I should add that the sound I'm hearing is not the high pitched whistle of the turbo spooling, which as cold taco noted is something that I only hear from time to time in summer...its more like just a reving sound coming from under the hood that is not the engine.

 

[Nas90tdi]

That was my thought as well. I don't think you are hearing the turbo. The outside temp should have no effect on when your turbo spools up.
I can hear my turbo as Coldtaco says, but I am also running a snorkel and lots of added boost ect. Normally the turbos are really not that noticeable in an unmodified truck. You really have to listen for them.
It could very well be the fan clutch behaving differently at colder temps.

Now you turbo light behaving oddly could be the boost sensor being touchy in the cold weather.

 

[coldtaco]

Ok, now I would say look into the boost light system.

 

[Reinhardtius]

At least your rig starts, @calsbeek. No whining. Just let me know if you need a ride to work

 

[AirheadNut]

It would be easy to check whether it is the turbo or the boost lights with an aftermarket boost gauge. I can imagine why a turbo wouldn’t spool right away in the cold, perhaps due to cold oil providing extra friction on the bearings, but I don’t see how a turbo would stay spooled up when the throttle is released (once there isn’t high exhaust flow there is nothing to exert force on the turbine blades)