Is this turbo done for? - Page 2 - PeachParts Mercedes-Benz Forum

Graplr · #16 05-27-2014, 04:46 PM

After talking to a guy from the yard at the parts place I am deciding to make the 45 mile drive to check out their turbo from an 84 300TD. He says all the fins are good and their "isn't much play" what ever that means. He told me "all turbos have some play." Ok...mine didn't, even with bad fins. If the fins are good it would be almost worth it price wise just to get the used one and put the two together. I'm hoping it is in good shape. If not I'm out 2 hours and a few gallons of diesel.

mach4 · #17 05-27-2014, 05:19 PM

Quote:

Originally Posted by Graplr

After talking to a guy from the yard at the parts place I am deciding to make the 45 mile drive to check out their turbo from an 84 300TD. He says all the fins are good and their "isn't much play" what ever that means. He told me "all turbos have some play." Ok...mine didn't, even with bad fins. If the fins are good it would be almost worth it price wise just to get the used one and put the two together. I'm hoping it is in good shape. If not I'm out 2 hours and a few gallons of diesel.

It's end play that you don't want. Axial play is normal. The bearings ride on a film of oil that when under pressure takes the axial play out. End play should be zero (OK not technically correct, but you shouldn't be able to detect any) because that's where the seals are.

jay_bob · #18 05-27-2014, 06:29 PM

On the forum a while back was some pictures (whunter?) that showed an OM61x that had a blown head gasket. It also had eaten one of the air cleaner nuts. There was a nut-shaped impression in the top of the cylinder.

The oil film is why the turbo has a massive oil supply and return line. It needs that pressurized oil to build up the film that the spinning shaft rides on.

Remember that the rotational speed of the turbo is north of 100k/min. Yes one hundred thousand. If something fails all that angular momentum has to go somewhere. It is often not pretty. I would be concerned making that drive to get a new turbo, with yours in its current condition.

mach4 · #19 05-27-2014, 06:53 PM

Quote:

Originally Posted by jay_bob

The oil film is why the turbo has a massive oil supply and return line. It needs that pressurized oil to build up the film that the spinning shaft rides on.

Actually the "massive oil supply and return line" is a bit misleading as the turbo oil return line has a .040 orifice that keeps the flow through the turbo relatively low, but keeps the pressure high. It's pressure that's important, not flow. I know I'm picking nits, but if someone is contemplating replacing the lines, it's imperative to have the orifice present.

jay_bob · #20 05-27-2014, 07:01 PM

I figured that had to be the case, I figured the system had to be trading flow for pressure. (Kind of like how we swap volts for amps at work...)

The 45-60 PSI on the oil system isn't going to cut it keeping that shaft floating.

Graplr · #21 05-27-2014, 08:01 PM

Quote:

Originally Posted by jay_bob

On the forum a while back was some pictures (whunter?) that showed an OM61x that had a blown head gasket. It also had eaten one of the air cleaner nuts. There was a nut-shaped impression in the top of the cylinder.

The oil film is why the turbo has a massive oil supply and return line. It needs that pressurized oil to build up the film that the spinning shaft rides on.

Remember that the rotational speed of the turbo is north of 100k/min. Yes one hundred thousand. If something fails all that angular momentum has to go somewhere. It is often not pretty. I would be concerned making that drive to get a new turbo, with yours in its current condition.

Kind of hard to drive it with the engine out, the turbo apart and no transmission!

This thread is about an engine swap from the parts car 82 to my 79. My 79 is parked. I'm driving my suburban.