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tolsen

450 Cdi turbo oil drain

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Contrary to popular belief our KKK KP31 turbo does not have oil seals. The turbo has piston seals and their purpose is to seal against gas pressure, i.e. prevent turbo boost and exhaust pressurizing bearing housing. Oil level inside bearing housing must be below level of the piston seals or some oil may leak out into air inlet duct and into exhaust. This is only possible if oil drain is unobstructed and oil is not too thick.

I currently have my engine on a stand so took the opportunity to check out turbo oil drain passage from outlet of bearing housing to sump.

DSC04141.jpg

A freshly painted turbo oil drain pipe connected without hose clips to oil drain connection at aft facing side of engine. Engine is sitting on a £18 engine stand that came all the way from China. Allows engine to be swiveled around so easy to work on.

DSC04142.jpg

There is a sudden change in flow diameter where rubber elbow connects to the special alloy flange connector. I have tapered out the bore as shown using a tungsten rotary cutter. Tip of barb did originally have casting flash that reduced the bore. Also casting flash at other end.

DSC04144.jpg

Here we see the internals of oil drain connection at side of engine. Turbo drain connects to the left rectangular passage where I have rounded off the sharp edges to improve flow. Done with various shapes of rotary tungsten cutters.

The two drain passages seen above do also drain oil from cylinder head.

I recommend against using pencil grinders for any of these improvements. Their grinding dust is bad for bearing surfaces.

Of course you get tiny bits of metal flying every where so have to complete a very thorough clean before recommissioning engine.

I intend to refit engine with an old turbo that is known to leak a wee bit of oil into inlet duct so will soon learn whether this exercise was worth while.

Another issue - dip stick tube.

I had trouble pulling out my oil drain tube out of dip stick when changing oil. I found the lower end of the tube had not been deburred. The burr was rather sharp so no wonder my oil drain tube tended to get stuck. Easily sorted by removing dip stick tube and deburring with a large diameter drill or a suitable round file.

Edited by tolsen

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Peiceing all these photos together over the past months your car has to be down to the frame? Are you doing a full rebuild of the girl?

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Peiceing all these photos together over the past months your car has to be down to the frame? Are you doing a full rebuild of the girl?

My Cabrio was getting in such a bad state due to rust that I only had two options. Either scrap the car or do a complete rebuild. I used up both ends of a 200 litre oil drum when weld repairing a total of 42 rust holes.

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Did you have a problem with turbo leaks?

I have a leaking turbo that wont stop, fitted a new core and its still leaking badly out the compressor.

Excessive pressure or a bad drain is the usual culprits but its clear.

Would you recommend this fix? 

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This is a 8 year old thread if you didn't notice and many members move on.....lol

 

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