Bad turbo equals blow-by

A few weeks ago I posted about needing to locate a rebuild kit for a 3406E because of excessive blowby, the other day we went to order a kit for it and it crossed my mind...... Why all of the sudden did this thing have crazy amount of blowby, truck runs and starts great no smoke no problems other than developed a lot of blowby within a couple of weeks.

I thought about it and after I realized that if I took off the air tube and placed my hand over it the blowby tube would almost whip around......

After calling a few turbo shops to find one I asked them if they pressure checked them and the response was always NO and one of them called me crazy for believing that a turbo could cause blowby.....

Long of the short, turbo on the ground with the exhaust down intake up, dump water in the intake and watch it run through the cartridge faster than your pouring it in..... Flip it over pour in exhaust and does the same thing.

Anyone else ever ran across a turbo bad enough to do this but does not smoke the stacks ?

Oh btw the shaft only wiggles a little not enough to trash the compressor wheel or housing etc.

Pj

Yes, I have seen turbos cause blow-by. Measure your blow-by then remove the oil drain hose from the turbo and run it into a pail and measure your blow-by again. That will answer your question.

I have only seen it once and that was on a Cummins QSC8.3. When I talked to a couple of other mechanics they all said the same thing, that they had seen it or heard of it at least once. I think its one of things that can happen but isnt the first thing that you think of when you have excessive blow-by. Good idea about testing blow by after removing the turbo drain tube that would have been interesting to see what the results are.

Does this unit have a waste gate? I've seen the gates get frozen closed or partially open and they start getting too much boost. That creates some extra blowby and I've been told it can get head gaskets.

PJ let me know how this works out. I have a c15 in our lowboy tractor that looks like it is on fire after a heavy pull. Be nice if I had to just change two turbos instead of a complete inframe overhaul.

Yes it is a waste gated turbo but the previous owner had plugged the WG line..... An ole bull hauler trick

I have no way to measure blowby, I guess I could put a ballon on the tube and use a stopwatch to see when it pops lol

Pj

I saw it too in an ISC 8.3. It would blow smoke and oil out the breather something fierce when loaded down, but not much was happening when idling or putzing around. Replaced the turbo under warranty (again) and all was well....for a while anyway

If you have a water tube manometer or a gauge that measures in inches of water you can hook it into the dipstick tube. Run the engine and try get a load put on it and see what it reads. Usually the Cats don't show a lot of pressure but I've seen some up around 5 inches that were pretty hard to start. I've seen some Cummins engines run 16 inches. Anyway that might give you an indication.

I doubt I have one I'm gonna have to google it to even know what it is lol

Pj

powerjoke said:

I doubt I have one I'm gonna have to google it to even know what it is lol

Pj

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Look in Mc Master Car or Grainger catalogs

Had a Hino motor in an EX300 Hitachi that developed sudden blow by and it was the turbo seals. A while back I stopped at a customers shop and the mechanic was pressure washing a KW with a 3406E in it. The entire under side was covered in oil and he said it had been using excessive oil and blowing it out the breather tube. If I remember right he said the original tube was located on the side of the motor and they replaced one valve cover and moved it up there and that ended the problem.

powerjoke said:

I doubt I have one I'm gonna have to google it to even know what it is lol

Pj

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A yard stick and a few feet of clear tubing and you have one! A few drops of food coloring is an added bonus.

That will tell you pressure but not volume right ?

I'm worried about the volume of air out the blowby tube more than anything, even with a small amount of combustion in the oilpan sooner or later it will equalize with pressures on top of the piston

Pj

I have a c15 in my lowboy tractor and after a hard pull it blows out the blow by especially when it got close to 10000 miles when I normally changed the oil and then I put a aftermarket extra oil filter on and had 16000 miles and did a sample and they said the oil was still fine but when I pulled hard it blew out blow by! you all pry heard this before but cat makes a little device that helps with the excessive blow by on sum of the cats and it goes in the blow by hose and puts the excessive oil back in the motor sum how but that wudnt solve the problem if sumthing else was wrong! So could my turbo be loose or bad or is it getting by the rings? It starts and runs fine! Thanks Jerry

Saw that happen on my dads truck. C15 with the breather tube right across from where the turbo drain line comes into the block. It was blowing out as much oil as air. Turbo seals fixed it.

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powerjoke said:

That will tell you pressure but not volume right ?

I'm worried about the volume of air out the blowby tube more than anything, even with a small amount of combustion in the oilpan sooner or later it will equalize with pressures on top of the piston

Pj

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Yes, a manometer is just a low pressure gauge. The way JohnC described sounded like he left the crankcase vent unplugged so he was indirectly measuring volume (that would create a certain pressure blowing out). I don't know of any simple volume measurement for a flow like this.

here is a article in a truck mag I was looking at and thot was kinda interest http://www.tenfourmagazine.com/2014/01/performance-zone/its-turbo-time/

well we LUCKED OUT!! swapping turbo's cured it I would have never thought it would have made that much difference but we have basically NO blow-by now. what a relief! with all the other crap that went bad on me last week i wouldnt have been suprised if it would have locked up not even running lol.

the truck always had a tinge of blue-ish smoke out the chimney but that too is gone, in the past when a turbo went bad it was very clear what the problem was but after inspecting this one i realized the oil supply line was restricted down to about a 1/8" inch (factory drilled hole in supply port on the top of turbo) and now i realize why i wasnt dumping more oil out of the stack..... she wasnt getting fed with enough oil to make a lot of smoke even if it consumed all it had.

I bought a E model turbo on ebay for $300 new in box, and it came in but was for a B model but who needs a wastegate anyway lol

Pj