Turbo works sporadicaly 85 300SD - Page 2 - PeachParts Mercedes-Benz Forum

rrgrassi · #16 12-12-2008, 04:08 PM

With the engine off, have you removed the U-tube and tried to spin the the turbine by hand? Very little little side to side play is normal, there should be zero end to end play.

stephenc03 · #17 12-12-2008, 05:14 PM

Quote:

Originally Posted by rrgrassi

With the engine off, have you removed the U-tube and tried to spin the the turbine by hand? Very little little side to side play is normal, there should be zero end to end play.

She is a CA car but I know what you mean. I turned the intake side with no binding but my hands are to big to get in there and try to move it side to side and back and forth. I was going to take off the exhuast pipe side and see what the turbine does...should I do that or is the intake side sufficiante?
-Stephen

Diesel911 · #18 12-12-2008, 05:29 PM

Quote:

Originally Posted by Brian Carlton

Vacuum and EGR have absolutely nothing to do with the intermittent behavior of the turbo.

If the EGR is before the Turbo Charger and feeds from the same exhaust gas the powers the Turbo if it is open it can effect the Turbo.

I think if the EGR remains open some exhaust gas is going into the intake manifold decreasing combustion the combustion temp and decreasing the exhaust gas.

Also an open EGR will bleed of part of the exhaust gas pressure that us used to turn the Turbo.

I also figured it was something that was easy to check and eliminate as a problem source; pull the Vac Hose off and Plug Hose. If you drive the car and no longer have a problem you found what is wrong.

Also does his car have the Trap Oxidizer?

rrgrassi · #19 12-12-2008, 05:58 PM

I just use my fingers, but since I have fedemissions, I guess access to the turbo is easier.

stephenc03 · #20 12-12-2008, 05:59 PM

it does not have a trap...in fact Jon at monstercraft fabricated a straight pipe that I installed. when pulling the cat. i broke two of the three bolts where the trap meets the exhuast manifold near the firewall. after installation i took her out for a run with only the one bolt on as the pipe seats very well against the turbo and the exhaust manifold. And the turbo worked fine. after a couple hundred miles is when i started to have intermitant failure of the turbo. I dont have the right tools to ream and re thread the holes so i just left it alone until i can borrow them from a friend. after looking at the straight pipe where the old trap used to be...i see alot of soot seaping out. I did not realize that an exhaust leak could alter the affect of the turbo so much. I am confident that the turbo is failed do to an exhuast leak. does is this assumpsion sound reasonable or is it something else?
-Stephen

Brian Carlton · #21 12-12-2008, 06:13 PM

Quote:

Originally Posted by Diesel911

If the EGR is before the Turbo Charger and feeds from the same exhaust gas the powers the Turbo if it is open it can effect the Turbo.

I think if the EGR remains open some exhaust gas is going into the intake manifold decreasing combustion the combustion temp and decreasing the exhaust gas.

Also an open EGR will bleed of part of the exhaust gas pressure that us used to turn the Turbo.

I also figured it was something that was easy to check and eliminate as a problem source; pull the Vac Hose off and Plug Hose. If you drive the car and no longer have a problem you found what is wrong.

Also does his car have the Trap Oxidizer?

The valve would have to be stuck in the fully open position for any of those scenarios to occur. While it's not impossible, the spring in the valve is extremely stiff and is not easily overcome. It's not a likely scenario.

Brian Carlton · #22 12-12-2008, 06:15 PM

Quote:

Originally Posted by stephenc03

where do you attach the boost guage...

You T the boost gauge into the line from the overboost protection valve to the ALDA.

You can use the wastegate hose if you wish.........but, it's fairly large for the small tubing on the gauge.

stephenc03 · #23 12-12-2008, 06:23 PM

Quote:

Originally Posted by Brian Carlton

You T the boost gauge into the line from the overboost protection valve to the ALDA.

You can use the wastegate hose if you wish.........but, it's fairly large for the small tubing on the gauge.

Well it is Christmas break and I wanted to road trip home (500 miles) with the SD. Without the turbo i know I will have less power and less fuel economy, but running the car without an operable turbo, can I make the trip without damaging anything else or the turbo more? If I get it back home I can drill out the bolts and fix the exhaust leak without having to buy the tools up here.
-Stephen

Brian Carlton · #24 12-12-2008, 06:27 PM

Quote:

Originally Posted by stephenc03

Well it is Christmas break and I wanted to road trip home (500 miles) with the SD. Without the turbo i know I will have less power and less fuel economy, but running the car without an operable turbo, can I make the trip without damaging anything else or the turbo more? If I get it back home I can drill out the bolts and fix the exhaust leak without having to buy the tools up here.
-Stephen

You've drawn the conclusion for the problem prior to any testing. If, by some miracle, you happen to be correct, you can drive the vehicle without a properly functioning turbo.

However, understand that a turbo is a very basic device. It takes in exhaust gas and rotates. If the rotation is not compromised, the device functions properly in just about every case.

stephenc03 · #25 12-12-2008, 06:34 PM

Quote:

Originally Posted by Brian Carlton

You've drawn the conclusion for the problem prior to any testing. If, by some miracle, you happen to be correct, you can drive the vehicle without a properly functioning turbo.

However, understand that a turbo is a very basic device. It takes in exhaust gas and rotates. If the rotation is not compromised, the device functions properly in just about every case.

So I am off to go get a boost guage and instalation sounds like it will take all of about 15 minutes so.....what numbers am I looking for? How do I performe a boost test. I have seen on the forum that some people test the engine cold and test seperatly when the engine is hot. Under normal operation conditions what boost should the turbo be putting out and I assume if it is an exhuast leak the boost will be minimal?
-Stephen

Brian Carlton · #26 12-12-2008, 06:37 PM

Quote:

Originally Posted by stephenc03

So I am off to go get a boost guage and instalation sounds like it will take all of about 15 minutes so.....what numbers am I looking for? How do I performe a boost test. I have seen on the forum that some people test the engine cold and test seperatly when the engine is hot. Under normal operation conditions what boost should the turbo be putting out and I assume if it is an exhuast leak the boost will be minimal?
-Stephen

You route the gauge into the cabin so you can read it while you drive.

With the engine fully warm, you put it in third gear and mash the pedal until the revs climb above 3000 rpm............then you read the gauge.

Proper boost is about 12 psi, but the typical boost for a vehicle that has never been adjusted will be down around 8 psi or so.

Unless you cut a hole in the exhaust manifold that's at least 1" in diameter, no exhaust leak will have any meaningful effect on the boost. It might delay the onset slightly, but, above 3000 rpm..........you should be well into the wastegate range and the turbo is dumping excess exhaust.

71inka02 · #27 12-12-2008, 11:05 PM

Quote:

Originally Posted by Brian Carlton

Problem number one is the banjo bolt.

Problem number two is the overboost solenoid. You can clean it with brake cleaner.........but, don't go crazy..........it's plastic.

As a test, you can also bypass it. Run the line from the manifold directly to the ALDA............if the vehicle is transformed...........the problem is the solenoid.

I suspect I may some turbo issues with my 85 SD, a very unusual sound thing goin on ---- and being that I'm technically challenged

above a certain point --- Could someone please attach a pic of the Banjo bolt, overboost solenoid and ALDA. I've heard of these items, but telling me where it's at, doesn't process for me. I need pics to fully understand. thanks....

stephenc03 · #28 12-13-2008, 03:48 PM

Quote:

Originally Posted by Brian Carlton

You route the gauge into the cabin so you can read it while you drive.

With the engine fully warm, you put it in third gear and mash the pedal until the revs climb above 3000 rpm............then you read the gauge.

Proper boost is about 12 psi, but the typical boost for a vehicle that has never been adjusted will be down around 8 psi or so.

Unless you cut a hole in the exhaust manifold that's at least 1" in diameter, no exhaust leak will have any meaningful effect on the boost. It might delay the onset slightly, but, above 3000 rpm..........you should be well into the wastegate range and the turbo is dumping excess exhaust.

Brian, I hooked up the gauge this morning. just to check to see if the gauge worked I reved the engine when parked over 3000 RPM and the gauge had about 4Hg of vacumme. after that i took her around the block and in third gear at 3000RPM there was no reading...i pushed her above 3500 and instead of reading boost i had a reading of 1 psi....the gauge reads 1-20 going down of Hg vacumme and 1-30 going up of psi if that makes any sence. here is to the picture of my gauge: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98478

What does this mean and is there further testing that should be done thanks, stephen

stephenc03 · #29 12-13-2008, 03:49 PM

I tee'd into the vacumme line right before it goes into the ALDA....stephen

Jeremy5848 · #30 12-13-2008, 03:57 PM

Quote:

Originally Posted by stephenc03

I tee'd into the vacumme line right before it goes into the ALDA....stephen

Assuming you teed into the boost line just before ALDA, that should be correct. You should also try teeing into the line before the overboost solenoid; it's possible that the solenoid is broken or clogged, hence not allowing boost from the intake manifold to get to ALDA.

Jeremy