Old wives tale? General turbo question....

[HighSierra86]

We have an older chipper with a cummins 4BT that sat under the overhead irrigation for a week, and when I went to start it, there was water blowing out the stack and the band clamp at the turbo outlet. We got lucky the water never went any further, but im sure it didnt help the life of the bearings. The stack had a curve but no flapper. It does now

This topic was quite interesting....ive heard the warning many times, but never quite knew what to make of it. One of the locals had a John Deere 4455 that was towed backwords for about 250 miles that needed a new turbo. Owner claimed it was from not capping the exhaust, and the dealer ate the cost of a new turbo. Id have to guess it was shot to begin with..but hey, i guess he made out ok.

 

[iamdave0887]

When i had the single stack setup it used to fill with water when it rained. You could tell there was water in the exhaust the second is started up as it was much quieter than usual. That was followed by the stack puking black water out.

The dual 5"s don't seem to collect water, as i've never had them puke water out after starting the motor after a rain storm.

 

[Acesneights1]

I have hauled heavy equipment most of my life from Excavators to 963 cats to payloaders and most of the time they are loaded backwards with curved stack facing directly into the wind. No blown turbos. Just my experience.

 

[midniteplowboyy]

I've seen it happen on some older Deere 404 & 466 engines, but the chances of it happening are slim, engine has to stop right @ valve overlap(which most diesel dont have much of) to have an air flow path through the intake side.

Towing just a few miles at a time, shouldn't never have a problem. Towing 1,000 miles and you'll trash a turbo with no oil if its just barely spinning. A flat cut stack would prolly be ok, but a curved angled cut one facing the airflow=bad.

Most of our equipment we used on wheat harvest had rain caps, we oriented them in the direction that they stayed shut when they were hauled. The ones with no rain cap(curved/slash cut stacks) got taped.

 

[Detroit Dan]

On farm and construction equipment it could, there may be less then 3ft of exhaust pipe there and could come straight down ontop of the engine. No long pipe going down like on a semi truck.

agreed

 

[turbovanman]

I could see it happen, you can spin some turbo's very easily, even blowing on them.

 

[Michaeljp86]

Today I gave it a try and I have to say its a myth. On my truck I put the hose from the shop vac up the exhaust, which is straight piped and flipped it on. The turbo didn't spin so I started the truck to get the engine to stop in a different position. I did this several times and the turbo never moved. This was with 100mph wind blowing up the exhaust and the hose fit in the 3in pipe real tight. This was on my 6.5, maybe it can happen on other engines. I also never felt any air coming out the turbo.


When I went to pull the air filter out it smelled like swampass. A mouse built a big nest in the air cleaner and chewed through the filter. I guess it was a good thing I gave this a try.

 

[Jasonsmack]

It does happen, the airflow ruining the turbocharger due to the rotation with no oil can wreck a turbo.


Facts:

Virtually all four stroke diesel engines have overlap built into the camshafts. If anybody has ever had a camshaft out of an engine this is very obvious if you bother to look.

An engine with as small as a 20 degree overlap (which is a pretty small figure and very unlikely in reality) indicates that both the intake and exhaust valve are open at the same time. Now if that engine is a six cylinder diesel, that adds up to 120 degrees of crankshaft rotation. Run that figure against two complete rotations of the crankshaft (being a four stroke and one rotation of the camshaft) and you have a 120/720 or 16.66 percent chance of adjacent valves being open at any point of the engine stopping. Do you want to take that small chance?

The vacuum created on a stack is quite substantial when you are hauling a vehicle with a large exhaust such as a highway tractor, construction equipment or agricultural implement. Definitely way more than what would be required to turn a turbocharger, has anybody had a turbocharger in their hand and been able to turn the wheels with only their breath? I have never been unable to do this on a turbocharger that was in decent condition.

No the turbo will not get hot, melt down or anything extreme. But it will eventually break the oil film away and there is a pretty substantial possibility that you are creating unnecessary wear, and possibly to the point of cause of failure.

We dont bother to tape small units like bobcats, manlifts, cars and pickups. I t is pretty tough to create enough vacuum or pressure to cause problems on the small pipes and odd locations of the exhaust on these vehicles. We always do tape on the large equipment that has the potential for substantial vaccuum in the exhaust due to large exhaust stacks. The air could move either way, if the exhaust is facing forwards you could easily force air backwards through the engine as well.

We had a tractor burn down in a grass fire when I was a teenager. Unfortunately the fire got to the air cleaner before we could move the tractor. There was several of us there to witness fire making it completely through the engine from the air cleaner to the exhaust stack without the tractor being started. The paint was not even blistered on the tractor yet and one of the old guys actually jumped into the cab and was going to start the tractor after this was going on. There is only one way for the fire to make it from the air cleaner to the exhaust stack, and that would be through one of the cylinders. The fact is that there was no turbocharger or muffler but it is a good example of evidence of the airflow possibility with a stopped engine.

Where the heck is this rain water nonsense coming from? Would the manufacturer not put rain caps on the stack if there was a substantial issue with rain getting in? Most exhaust systems will have a low spot or muffler lower than the exhaust ports and turbocharger if they do not have a rain cap. Most people put an old bucket over the exhaust pipe to simply keep the rain out SO THEIR EXHAUST DOES NOT RUST OUT from the build up of rain water when the unit is not being used.

 

[Turbine Doc]

Where the heck is this rain water nonsense coming from? Would the manufacturer not put rain caps on the stack if there was a substantial issue with rain getting in? Most exhaust systems will have a low spot or muffler lower than the exhaust ports and turbocharger if they do not have a rain cap. Most people put an old bucket over the exhaust pipe to simply keep the rain out SO THEIR EXHAUST DOES NOT RUST OUT from the build up of rain water when the unit is not being used.

No not nonsense fact, we just changed 3 PA's last month on one that hydrolocked, & bent rods from water looked like a gyser with all water up the stacks, std procedure is to open compression reliefs on each cyl and bar engine over slowly with air turning motor, guys forget potential of water on top of a piston & fast turn with batteries/alternator and bend the rods.

On Diesel locomotives it is a very stupid design, no drain incorporated in bottom of the turbo case, some have a drain plug others don't we have canvas stack covers that go on them for long term storage when folks remember to put them on. But shut down even a steady rain can collect enough water in the collector to be an issue.

My 535 Ford nor my 2020 Deere had them until I installed/reinstalled them, possibly lost/removed by PO.

My Ford did hydro-lock once wind blew off the small can over the pipe before I had replaced the rain cap fortunately batts were weak and would not turn over the engine, I pulled the injectors, and shot out water on 2 of 3 cyls about 5 ft in air with jumper cables on the batt.

 

[JiFaire]

So what the two of you are saying is, Duct tape is Cheap and it only takes a few seconds to tape the stack shut?

 

[DieselCash]

I do not think I would want duck tape on my stack, it is sometimes hard to get off!):h

 

[Jasonsmack]

So what the two of you are saying is, Duct tape is Cheap and it only takes a few seconds to tape the stack shut?

No, I guess what TD is saying is that when you are hauling something with a PA (I have no idea what a PA is) there is a greater chance of water getting into the engine because somebody stole the rain caps? I can only assume that he is talking about something that is being hauled, seeing that is what the thread is about?

Nah, he is probably just starting an argument with me again.

By the way my 6.5 project is coming along good but I could not bother to post here because it is a known fact that you do not put cans over your exhaust stacks to prevent corrosion in the exhaust system.

 

[DEERE3594]

That is something I would never ever worry about, I also dont cover my stacks on my truck or any equipment even when it rains. It always blows out the black water when you start it ):h

 

[Turbine Doc]

No, I guess what TD is saying is that when you are hauling something with a PA (I have no idea what a PA is) there is a greater chance of water getting into the engine because somebody stole the rain caps? I can only assume that he is talking about something that is being hauled, seeing that is what the thread is about?

Nah, he is probably just starting an argument with me again.

By the way my 6.5 project is coming along good but I could not bother to post here because it is a known fact that you do not put cans over your exhaust stacks to prevent corrosion in the exhaust system.

:thumbsup: on the 6.5 project progress looking forward to seeing the big numbers you hope to lay down. Bill Heath can't be the only one capable of it. As far as cans & corrosion I don't do it for that; I do it to keep rain water out period, no drains in the bottoms exhaust manifolds or turbo collectors that point up to the sky on any of the equipment I've been around lately.

Jason so many "negative waves and your name isn't even Moriarity" I wasn't picking a fight with you, but was sharing that rain can get into an engine via the exhaust side, GMCTD & I posted that reverse turbo rotation was as low on probability scale of occurances as you seem to think rainwater damage has potential of occurring to an engine.

Opinions vary but also some basis of fact, I figured you would pick up at some point a locomotive isn't same as equipment, so I then posted 2 examples of equipement (tractors) that did get water in the engines from an open exhaust stack/pipe/muffler pointed straight up, those should have had rain caps but didn't; but also weren't turboed engines so are we back to begining that for whatever the reason including wives tales; probably not a bad idea for long term storage or transportation to just go ahead and cover it. And while not a 6.5 discussion that was already a given since Chris started the discussion with :

Hey Guys,

This is not really 6.5 related at all (unless your ride has stacks and you need to tow it), but it is about a diesel turbo and I know there are a few guys on here that might be able to answer it.

Then Chris digressed into combine movement & such things which is okay, maybe my error was to not have moved it to the off topic forum since it wasn't a specific 6.5 technical discussion, the week has been a little slow so I figured what the heck a little theoretical discussion diversion every now & again won't hurt much. Win-win here, as in overall discusiion we are all correct I think :cheers2:



As to your other question, what the heck is a PA; "silly goose" :biggrinjester: every tech that works on a Diesel locomotive in the GE locomotives, knows that the PA is the power assembly {Head-rod-valves-piston-liner-fuel/air/oil guides/lines-injector-strongback(housing)} that gets bolted to one of the 12 or 16 cylinder mounting bosses above the crankshaft on a locomotive Diesel engines block/frame, if need be so long as crank & cam below the PA are still serviceable just the PA for each throw position on the crank shaft can be replaced.

I'll be up at the training school learning the new EFI control system replacing the MFI system next week maybe they'll have a training mock up cut-away I can post pics of, I have one at our shop, but I won't be back there for a month.