towing a turbo diesel backwards - when to cap exhaust?

[lotsofmiles]

I see it on semi trucks being towed backwards, the exhaust capped to stop wind from spinning the turbo.

When should/shouldnt you cap the exhaust when towing a turbo'd vehicle backwards?

 

[jraymer]

I would think only with a stack. When we would haul heavy equipment on long trips we would cap stacks. Bust just running 20 to 40 miles locally I never capped exhaust on anything.

 

[KEVINL]

Never heard of such a thing I don't see any way wind blowing in the exhaust will spin a turbo. It is probably to keep rain out or something

 

[lotsofmiles]

Article I read in the heavy trucking mag said it was to protect the turbo from spinning while no oil is flowing


Hahahaha. Oh well. Wifes jetta tdi just left on the flat bed, backwards with a cap over the tail pipes.

They're gonna think I'm crazy. But I think they'd still rather deal with me vs the wife. They were hiding from her on Sat.

 

[Burn Down]

I don't think you would have a problem with a full exhaust system.

I have had to change turbo's on Caterpillar equipment because the shipper or customer didn't cap the exhaust. Call goes something like this "Ya I just got the machine to the job site and it runs like crap, no power & it smokes like crazy, what do you think?".

So I would rather cap it & have them look at me funny then have to buy a new turbo....

 

[x MadMAX DIESEL]

Never heard of such a thing I don't see any way wind blowing in the exhaust will spin a turbo. It is probably to keep rain out or something

x2 I don't understand how it would spin Either way in that case seems like regular exhaust out the back would "spin the turbo" even more

 

[SmokeShow]

Ever seen a pull truck on the trailer? I'd say 99% are covered when in transport. Those with intakes through the front typically cap those too. It seems minuscule to me too but better safe than sorry IMO.

 

[Chevy1925]

We towed steves truck 1100 miles backwards with no probs but he has a full exhaust

 

[lotsofmiles]

How many miles have been put on the truck since being towed?

 

[SSchmi5519]

1k or so

 

[jraymer]

Either way in that case seems like regular exhaust out the back would "spin the turbo" even more

what do you mean?

 

[x MadMAX DIESEL]

Air would be pushed into a regular exhaust more than like a miter cut stack if it was being towed backward, right? Seems like it would depending on the cab of the tow truck

 

[SSchmi5519]

But it still has to be able to flow freely up the tubing, into the ex. housing, down the uppipes, into the cylinders through open exhaust valves, out of only open intake valves, through the intercooler, and out the filter.

I don't see any wind flowing this path with enough force to spin a charger.

 

[sweetdiesel]

But it still has to be able to flow freely up the tubing, into the ex. housing, down the uppipes, into the cylinders through open exhaust valves, out of only open intake valves, through the intercooler, and out the filter.

I don't see any wind flowing this path with enough force to spin a charger.

Why would it have to do all that?


I think it's not a bad idea at all, each to there own though

 

[SSchmi5519]

Because there has to be flow in and out of the motor for the charger to spin.

If the air is going in the exhaust, it has to come out somewhere.

 

[sweetdiesel]

Take compressed air and point it towards the turbo and tell me if it spins.

If it does and the motor isn't running then it's not getting oil.

Not trying to argue as I've towed my truck a lot with no caps and have not seen any bad come of it. That being said though I've now got some pimp covers from Levi.
What's that saying about a ounce of protection


I know I always put plugs in my muffler on my dirt bike too

 

[SSchmi5519]

I know I always put plugs in my muffler on my dirt bike too

Thats to protect from water when washing.

 

[Chevmeister]

I only towed my truck once (nsbu died). I shoved a convience store soda cup in it and rolled. I have towed turbocharged machines 100s of miles with nothing and they were fine. I've heard it can be a problem, but I never have seen it do any damage.

 

[Burn Down]

Because there has to be flow in and out of the motor for the charger to spin.

If the air is going in the exhaust, it has to come out somewhere.

For no more than piece of mind, or 20 cents worth of tape why would you not?

I have read a ton of threads on guys coming home with problems with there engines, bent or stuck valves, blown out up-pipes, bad exhaust gaskets, etc. etc. Why add the turbo to the list of your problems.

 

[McRat]

Not sure it matters whether it's frontwards or backwards. If it's frontwards, the vacuum at the exh tip with the pressure at the air box should make it spin also.

Can it damage the charger? IMO, no. There is very little air volume at best. Air can't flow through unless there is a cyl at overlap. Overlap has the valves nearly shut, and overlap is < 30 deg x 4 = 120, per 360 deg, or at best a 1/3 chance. Now let's say you are unlucky and the engine stops at overlap. The air must go through the exh valve that are only open <.05" and then the intake, <.05" the through the intercooler, then compressor (which wants to turn the turbine the other direction) then the air filter.

OK, assuming that small amount of air could actually keep the turbo spinning. A turbo is a high powered device. It consumes over 50HP under load. And everytime you shut off your engine, it coasts for upwards of 2 minutes. It's not fragile. But should the oil film somehow go away, the turbo would just stop spinning. The air going through those little valve gaps could not apply enough torque to burn off the bearing material.