Turbo coking... when?

[wemay]

Not a tracked car but a daily driver that is occassionally opened up.

When is the primary time a turbo cokes?

When shuting down too soon after a spirited drive. (my belief for years)
or
During the spirited drive itself.

Aside: Is this still a major problem in todays water/oil cooled turbos?

 

[Eddie]

I have read that coking occures after shut-down but, is not the issue it was after water cooling. However; My Mazda CX7 turbo was idled for 1 to 3 minutes after a highway run as recommended by the manufacture. Ed

 

[Swift101]

I hear this isn't a major problem any more. As you mentioned modern turbos are water/oil cooled. Only time I idle before turning my car off after some spirited driving, although I'm not sure it's completely necessary.

One of the techs at the dealer told me to let it idle a bit before turning it off as well.

 

[wemay]

My neighborhood kind of takes care of it on its own with the various speed bumps you need to traverse before reaching the house.

 

[Merkava_4]

You have speed bumps in your neighborhood ?

 

[wemay]

Its a gated community, lots of kids skateboarding, people biking, walking, running, etc., Im glad it is to be honest. Keeps the speeds down and boy racers out.

 

[TiredTrucker]

I have not had any issues with turbo coking for well over 2 decades. I had one engine that went to 1.4 million and never anything major done, and had the original turbo. It was an oil only Holset turbo. Modern oils make the difference as much as anything else. Next up would be having an operable pyrometer.

 

[Swift101]

Originally Posted By: wemay
Its a gated community, lots of kids skateboarding, people biking, walking, running, etc., Im glad it is to be honest. Keeps the speeds down and boy racers out.


Just get your Santa Fe lifted and put on some monster truck tires, you won't feel those speed bumps at all.

 

[wemay]

Originally Posted By: Swift101
Originally Posted By: wemay
Its a gated community, lots of kids skateboarding, people biking, walking, running, etc., Im glad it is to be honest. Keeps the speeds down and boy racers out.


Just get your Santa Fe lifted and put on some monster truck tires, you won't feel those speed bumps at all.

Swamp buggy down here in the glades, right? Lol

 

[wemay]

Originally Posted By: TiredTrucker
I have not had any issues with turbo coking for well over 2 decades. I had one engine that went to 1.4 million and never anything major done, and had the original turbo. It was an oil only Holset turbo. Modern oils make the difference as much as anything else. Next up would be having an operable pyrometer.


Syn or conventional?

 

[artificialist]

Originally Posted By: TiredTrucker
I have not had any issues with turbo coking for well over 2 decades. I had one engine that went to 1.4 million and never anything major done, and had the original turbo. It was an oil only Holset turbo. Modern oils make the difference as much as anything else. Next up would be having an operable pyrometer.

Is this a diesel engine or a gasoline engine?
The lower EGT of a diesel may prevent this problem, although I have read that some DPF equipped engines are having some problems.

 

[FetchFar]

Honda Acura worried about coking on turbos about 8 years ago, and created the HTO-06 spec to pass. If u have a turbo, that would give you added peace of mind.

 

[wemay]

Originally Posted By: FetchFar
Honda Acura worried about coking on turbos about 8 years ago, and created the HTO-06 spec to pass. If u have a turbo, that would give you added peace of mind.


Isnt this spec outdated if 8 years old?

 

[FetchFar]

Originally Posted By: wemay
Originally Posted By: FetchFar
Honda Acura worried about coking on turbos about 8 years ago, and created the HTO-06 spec to pass. If u have a turbo, that would give you added peace of mind.


Isnt this spec outdated if 8 years old?


I think Honda Acura still requires it for their turbo engines. Its a neat test, I saw an explanation a while back of what it is. Lots of full synthetics list it as current.

 

[jrustles]

coking would happen after hot shutdown. the oil stops moving and simmers in the heatsoaked bearing section, unable to get away. this is where the teost test is most relevant in the automotive realm.

water cooled turbos have also been around for a very long time, so they're not the reason why turbos fare better today, it's the oil imo. i remember in my old 88 mx6 turbo, the coolant would boil in the turbo after a hot shutdown, which you could hear as little small popping noises

some engines have after-run coolant circulators that operate after a hot shutdown, like the vw awp engine but only certain models i believe like those mated to an auto. heck, i think even the old audi 5000CD turbo 5cylinder had one.

 

[jrustles]

also, it doesnt take much to get a turbo glowing hot. i'd see the housing glow in the evening/night at a service stop after steady highway cruising

 

[TiredTrucker]

And I have a blanket on my current turbo on my Series 60 Detroit engine. I also have a ported/polished/ceramic coated exhaust manifold and high flow mufflers. EGT's, even under a hard load and a hot day never get above 900F. Well, they would, but I do know how to keep the engine inside the right RPM range and monitor boost. Get a turbo glowing hot and someone isn't operating the engine properly, or has a very restrictive exhaust system.

 

[Revving2Redline]

Maybe time for a apexi turbo timer. We had one on a MA70 Toyota Supra and it ran about 2-4 minutes then shutoff. But I was lighty paranoid so I increased the weight to 10/40 Valvoline Synpower in summer to help.

 

[Shannow]

Originally Posted By: TiredTrucker
And I have a blanket on my current turbo on my Series 60 Detroit engine. I also have a ported/polished/ceramic coated exhaust manifold and high flow mufflers. EGT's, even under a hard load and a hot day never get above 900F. Well, they would, but I do know how to keep the engine inside the right RPM range and monitor boost. Get a turbo glowing hot and someone isn't operating the engine properly, or has a very restrictive exhaust system.


diesels and gasoline engines operate very differently, having different crank angle pressure curves, and most importantly for EGTs, different stoichiometric ratios during operation.

Can't correlate your superior piloting skills on a diesel truck to petrol engine operation

 

[SteveSRT8]

Thermo syphon designs are now the favorite, where temp differences in the cooling system move water even with the engine shut off.

Judging from the failure rates modern turbo cars are quite reliable these days until modified. Mfgrs torture test them pretty roughly, too.

Ans sorry there TT, the diesel experience you quote is not relevant to a gasoline engine.