Can a turbo bearing seize up? - PeachParts Mercedes-Benz Forum

rickjordan · #1 03-11-2009, 05:57 PM

First of all it has been quite a while since I have been on this board. Used to be on it religously, but got a bit distracted when I bought my 911.

Anyways, I am having an acceleration issue with my '87 300TD Turbo. It is almost like the turbo isn't there. It used to have a surge of power/acceleration around 2K RPMs. Now though the RPMs go up, but no surge. I have used the search function and did get some idea on where to look. In a lot of those posts, it was mentioned to check the play/lack thereof, of the turbine itself. My car does not have smoke blowing out the back, and there are no unusaul puddles of oil under the car. I know that the typical sign of a bearing failure is oil burning (smoke). My question is, can a bearing seize up? Hence the turbo is not working.

BTW, yes I have replaced the fuel filters.

The car has 221,000 on her.

Thanks in advance for any further tips.

babymog · #2 03-11-2009, 06:05 PM

In theory, yes.

First thing to check however, is the most common (and cheapest). Pull the vacuum/pressure line that runs from the intake to the switchover valve (which is mounted to the left strut tower/inner fender) and run a wire into the intake to ensure that it is not clogged. Next, bypass the switchover valve on the fender (run that hose directly to the ALDA on the Injection Pump) and see if it restores your power. If it does, typical clogged switchover valve, spray WD-40 or equivalent through it if it is clogged and it should solve the problem.

Other issues are possible, but this is a good start IMO.

oldsinner111 · #3 03-11-2009, 06:25 PM

My buddy bought a CD with a bad turbo.He cleaned out oil supply tube,and put MMO in the turbo,spun it with his fingers,and freeded it.
I guess someone ran her hard and did not cool down before shut down.Also nasty oil changing habits.

rickjordan · #4 03-11-2009, 06:58 PM

Jeff,

Thanks a million. I was just out there looking the system over and did see that cloth covered line going from the intake over to the fender. I haven't done anything with it yet, but you mentioning that possibly being clogged reminded me of something. A long time ago I replaced the valve cover gasket and naturally you had to pull the crossover pipe off. Well when I did, there was some serious soot/carbon build up. So, looking at where that line connects to the intake manifold, it certainly would surprise me if that was clogged. It's getting dark here, so I will look into this again tomorrow.

Exactly what does the switch over valve do?

Oldsinner, While I was out there I was going to try and spin the turbo vanes, but I can't get to them. I used to own a 1983 300TD with the 617 engine. All you had to do was pull the air cleaner assy. and "U" tube off, to expose the turbo. It's not that easy on the 603s.

babymog · #5 03-11-2009, 08:41 PM

The switchover valve is a normally-open valve.

With it open, boost pressure passes through to the ALDA, enabling it to add fuel as boost pressure goes up thus creating more power.

If the boost pressure gets above the limit, the sensor on the intake will trigger and close and vent the pressure on the ALDA side, dropping the fuel to non-boost levels, thus limiting the heat and pressure and resultant power.

It is very common for the fitting on the intake plenum to become clogged with soot, and for the switchover valve to become clogged with soot, I've had it on two 603s and one 602. If you can blow through the switchover valve in both directions, it is not (completely) clogged. The intake plenum line should hook to the bottom of the switchover valve, the ALDA line to the top.

rickjordan · #6 03-14-2009, 07:59 PM

Jeff,

I owe you a milion dollars. I can't thank you enough for pointing me towards that switchover valve. It was clogged. I first removed the line from the intake and ran a piece of wire into the intake. There was some oily soot all over the wire. I by-passed the valve as you suggested and wholly cow, the old girl was back. I actually had forgotten how much boost that turbo provides. The line running from the intake to the s/o valve didn't seem to be plugged, but I clean it out anyways. I shot some brake cleaner throught the switchover valve until it came out clear. Put everything back to together and she runs as she once did.

Thank you again!!!

babymog · #7 03-14-2009, 11:41 PM

You're very welcome. It is however, one of the first things I learned on this forum years ago, so another success goes to the forum.

vwnate1 · #8 03-15-2009, 01:57 AM

I'm the guy with the 1984 300CD , the turbo barely turned when I bought it , the MMO and twirling it helped a LOT but the power still doesn't come on until 2,700 ROM's and I can _feel_ the impeller isn't as free as it is on other CM617 engines so I'm hoping the short oil changes will help loosen it up . no blue/white smoke though so the seals are O.K. and no play in the bearings atall .

I LOVE this car ! . it's everthing bot my NA Diesel Coupes never were .

compress ignite · #9 03-15-2009, 03:12 AM

Try using Synthetic Oil to clean out the "Goo" in the turbo cartridge.
Mobil1 5W40 Truck+SUV
(Mobil) Delvac1 [Same oil as above,different packaging]
Red Line 15W40 Diesel
Royal Purple 15W40 Diesel
Rotella T Synthetic 5W40 (Yes,I Know it's not Primo Base Stock,But it'll clean)
Whatever Amsoil buys from Mobil in a Diesel formulation.

Only one problem...If the oil residue is really "Coked" in there it may take a while.

These Turbochargers do not have free rotating bearings,but Bushings AND the
tolerances are so fine that the Turbo's shaft "Floats" on a film of Oil between
the shaft and the bushing (That's the reason why I started using Synthetic
as soon as it was on the market...Better heat tolerance...Better cleaning...
AND less likelihood of a "Coked" Turbocharger Cartridge.)

Ian White · #10 03-15-2009, 02:50 PM

I've used Delvac 1 and had excellent luck. I recently lost the bearnings in my garrett and a located a KKK and am going to use. But to answer your question yes it happens, it just did to me and I am anal about all my vehicles, not one iota of abuse.

my .02 worth,

vwnate1 · #11 03-15-2009, 09:39 PM

The folks who do our oil analysys tell us that Mobil 1 synthetic has more detergents than any other oil available so that's what I used .

So far so good , it's running better & better all the time .

Still has off idle power lag though .