300 SDL Chargin airline and EGR bolts torque? - PeachParts Mercedes-Benz Forum

julio.garcia.fc · #1 10-04-2014, 02:11 PM

I have an annoying leak from the seal between the manifold charging air line and air line (TURBO-ENGINE INTAKE MANIFOLD. Fits: Mercedes | Mercedes-Benz of South Atlanta). Gunk seems to find its way all the way to the floor. I do not know if I should tighten it or replace the gasket. Either way, what is the correct torque for those bolts? Any thoughts on that?

Also, for testing purposes, I want to follow Sixto's instructions to block the EGR (86' 300SDL EGR questions). What is the correct torque for those bolts? They also leak gunk:

Lastly, should I even care about the leaks other than the stains on the driveway? Is this a losing battle?

Thanks for any wisdom.

Mxfrank · #2 10-04-2014, 05:45 PM

There's a lot of bad advice on this board with regard to EGR valves, leave it be.

Your leak is oily...which suggests that you have a leaky turbo seal or excessive blowby. Either way, your problem isn't EGR related. First thing is to remove the intake hose from the front of the turbo, and see whether the oil is entering from crankcase vent.

I'm not sure you could get a torque wrench in there, even if you knew the spec. My recent experience with a bad turbo seal is that oil will blow through this joint even if the gaskets are new and the bolts are snug.

julio.garcia.fc · #3 10-04-2014, 06:29 PM

MxFrank,

If I sound ignorant is because I am

. I am learning a whole lot from working on my car and reading his forum. In this diagram, which seal are you referring to?
TURBOCHARGER. Fits: 1987 Mercedes 300 SDL Sedan | Mercedes-Benz of South Atlanta

411, 405 or both?

Also, what causes excessive blowby? I need to read through this discussion: Should I rebuild my turbo or replace?

Mxfrank · #4 10-04-2014, 10:11 PM

In your first photo, you are pointing to the junction of the intake manifold and crossover pipe. There is a gasket in there. This is a weak point, and is probably where most of the oil is escaping. You may have additional leakage around the intake manifold gasket.

There are also several seals, piston rings, and oil deflectors internal to your turbo cartridge, and it's likely that one of these is the actual source. The internal seals aren't shown in your diagram.. I'm not sure if you have a Garrett or a KKK, but here's a diagram of a Garrett T25 that should make things clearer:

http://gpopshop.com/t2-t25-and-t28-rebild-kits/

Before you decide what to do, take off the big hose at the front of the turbo and look inside, you will be able to see the compressor wheel. Also look into the hose to see if there is a puddle around the breather passage. If the oil is coming from the crankcase breather, that's one thing. If it's leaking through the compressor side of the turbo, that's another. If the front of the turbo is dry, look for oily ooze coming in through the EGR. This wouldn't mean you have a problem with the EGR: the most likely cause would be a bad turbine seal, and the turbo would have to be rebuilt.

In answer to the question posed in that thread, don't rebuild the turbo unless you have to. And if you must, have it professionally done. The reason is that the compressor spins at 150,000 RPM. If you assemble out of balance, it will break apart. It's also possible that the shaft or the case may need machining to bring up to spec. Personally, I'm not equipped for high speed balancing, and I don't trust ad-hoc balancing methods. You would also find that disassembling the turbo is far harder than it looks. There is a huge snap ring that requires the biggest snap ring pliers you can find. The bolts on the turbine case tend to rust solidly in place, and may have to be drilled out.

I used a local rebuilder, Cheetah Turbos (http://www.cheetahturbo.com/). They took a long time, but their work was excellent. Gpopshop.com is another popular rebuilder. Ordering from Mercedes will get you a rebuilt turbo for three or four times the price. The only advantage is that they will be able to offer an exchange against your used core. Otherwise, your car will be off the road until the turbo comes back.

julio.garcia.fc · #5 10-05-2014, 09:47 AM

Fantastic information MxFrank. Thank you! No, I would not dream of rebuilding my turbo. I was just reading that thread to get information. I will remove the intake hose and have a look next weekend.

Thanks!

P.S.

Would you mind pointing out the bits of bad EGR advice that you have seen? I would imagine that your statement is controversial, so if you can do it in a private message, it would be appreciated too. Again, I am just learning and forming opinions.

Thanks for the pointers.

dieselbenz1 · #6 10-05-2014, 11:37 AM

Please share the information regarding the EGR I am quite interested in learning more also!

Mxfrank · #7 10-05-2014, 02:22 PM

The EGR is a polution control device. It's illegal to remove it in the US. A lot of wind is wasted on these boards describing how to disable it, plug the control line, or blank it off. If you do so, nothing visible will happen. You won't get any measurable improvement in fuel economy or performance. You will, however, produce increased volumes of NOx gasses as you drive. Nitrogen oxides are the major precursor of photochemical smog, which is the grey mist you used to see around big cities. There aren't too many things you can do that would produce more pollution than removing your EGR, except maybe venting your crankcase breather to the air.

Many, perhaps most, states don't measure Diesel emissions on these old cars. So you may not be hit with the $3500 civil penalty. But that's no excuse for being a bad citizen and disabling your controls. Here are a few examples of what happens when the EGR vacuum line is plugged with a BB (stupid dog trick), from a state of Maryland publication. These are gas cars, the increase in NOx is greater with Diesel:

julio.garcia.fc · #8 10-06-2014, 12:05 PM

Thank you MxFrank. I will leave well enough alone and pursue the annoying oil gunk leak. I will post findings and results on another thread.

Again, thanks for the education ...