Need help - rebuilt turbo whines like a siren - PeachParts Mercedes-Benz Forum

mcneil · #1 01-10-2011, 12:19 AM

I had turbo city in Orange, CA, rebuild the T3 on my '82 300SD (not a california model). This was part of a head R&R, so I had new gaskets all around, EGR delete, new oil feed line.

The turbo sounds like a siren. I can hear the turbo's RPM very clearly from the high pitched whine.

I did everything per the instructions that accompanied the turbo. Couldn't find a turbo feed line, so I had to make one myself. I used new 10mm steel hydraulic line and brazed on the original fittings. I verified that the line is unobstructed.

I cranked the motor for a couple minutes (intermittently.. 30-45 sec at a time) before firing it up, then let it warm up at idle.

Here's what it looked like right after I put the oil line on:

Here's the gallery of all the pictures of the head replacement, if you want more info:
http://picasaweb.google.com/mechromancer/BenzHead#

ForcedInduction · #2 01-10-2011, 02:29 AM

Quote:

Originally Posted by mcneil

Couldn't find a turbo feed line, so I had to make one myself. I used new 10mm steel hydraulic line and brazed on the original fittings.

Did you put a restriction orifice in place?

Diesel911 · #3 01-10-2011, 02:30 AM

It could be a manifold leak.
But, it also could be the Turbo itself.
Take the Car back to where you had the Turbo Rebuilt and see if you can get them to take a test drive with you.

Engine not running grab the Turbo Compressor wheel and push it back towards the Bearing Housing and rotate it to see if it is dragging on anything.
Do the best you can to pull it back towards the Air Inlet and rotate it again to see if it is dragging on the Housing.
If there is any dragging there is too much play in the rotating assembly or there was not enough clearance between the wheels and the Housings.

leathermang · #4 01-10-2011, 02:30 AM

Check for leaks in low pressure areas.

Diesel911 · #5 01-10-2011, 02:39 AM

If it whines when you rev the Engine standing still you should be able to locate where the sound is from with a Mechanics Stethoscope.

Is it possible there is something else rotating that is making the noise?

leathermang · #6 01-10-2011, 02:45 AM

Also, if you can shoot some oil at suspected leaks... it will temporarily stop it and let you know where to do the repair. This only works on leaks drawing IN air. but does work well...

Diesel911 · #7 01-10-2011, 02:56 AM

Dish Soap and water sprayed on a Cold Intake Manifold bubbling might tell you where an Intake Manifold leak is when you rev the Engine.

Codifex Maximus · #8 01-10-2011, 07:23 AM

Did you put the air cleaner back on with all the air cleaner tubing in place? Even a simple loss of tubing integrity can allow the noise of the turbo to be heard - not to mention dirty air getting in the turbo itself.

mcneil · #9 01-10-2011, 12:12 PM

Why can't I ever get a nice easy answer, like "sure, don't worry about it, the whine will go away the first time it gets up to temp"?

Turbo's coming off, going back to the rebuilder.

And Diesel911 is right - engine stethescopes are awesome, even if people make engine-doctor jokes when you're using it.

300sdToronto · #10 01-10-2011, 01:51 PM

I had the "siren problem" on my 617 turbo and the issue turned out to be a poorly seated gasket where the turbo air intake tube mates with the air cleaner housing. A simple pull it off, reseat the gasket and reinstall cured my suspected "failed turbo" problem. One of the gaskets is hard to align properly (see the Dieselgiant write up) and using some kind of jelly lube to help it seat is a good idea.

Indie was all over me to buy a new turbo.......

Diesel911 · #11 01-10-2011, 09:35 PM

Quote:

Originally Posted by 300sdToronto

I had the "siren problem" on my 617 turbo and the issue turned out to be a poorly seated gasket where the turbo air intake tube mates with the air cleaner housing. A simple pull it off, reseat the gasket and reinstall cured my suspected "failed turbo" problem. One of the gaskets is hard to align properly (see the Dieselgiant write up) and using some kind of jelly lube to help it seat is a good idea.

Indie was all over me to buy a new turbo.......

This sort of goes along with the above.
When the Turbo was rebuilt It may be they did not index the Aluminum Compressor Housing exactly. Meaning that the part the hooks up to the Intake manifold may be a degree or two off. That might keep the Tube between the Turbo and the Intake Manifold from sealing well.
If that is what the problem is not a big deal to line it back up; just loosen the Compressor Housing Bolts enough to rotate it a little to line it up.
A leak there should show up if you use the Soapy Water on the area.

mcneil · #12 01-10-2011, 10:49 PM

Right, I re-indexed it on assembly.. any tricks for the tube from the compressor outlet to the intake manifold? I just put fresh o-rings on it and lined it up so the gap looked even all around.

ForcedInduction · #13 01-11-2011, 02:53 AM

T series turbos are not match balanced. A turbo that is match balanced will be obvious as material will be removed from the compressor's nut.

mcneil · #14 01-11-2011, 05:18 PM

There's a cut taken off the compressor wheel that could be for balance. It's visible in the picture slightly hidden behind the nut.

leathermang · #15 01-11-2011, 07:51 PM

Quote:

Originally Posted by Diesel911

Dish Soap and water sprayed on a Cold Intake Manifold bubbling might tell you where an Intake Manifold leak is when you rev the Engine.

I have never seen a loud noise from a pressurized leak.. soap and water would be good for air coming out..
but not for air going in... it might not be thick enough to stop the leak momentarily for diagnostic purposes...

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