I think that I may be having trouble with my turbo. This turbo is a replacement for one that was leaking oil. I have installed a boost gauge that is tapped off of the intake manifold, I'm not sure if this is the right place to do it and would welcome input on that. (pix below) The boost right now is at about 5-6 psi when @ 3000 rpm at 70 mph. I've read that others are getting about 10+ psi, but I wasn't sure if that had been
modified some how. Can the turbo be checked to make sure that enough pressure is being applied to the waste gate? Is the waste gate normally open or closed?

Thanks Dan

1986 300SDL

Attached Thumbnails

 

That is normal boost for cruising speed and a perfect measurement location. Maximum boost has to be measured at 4000rpm and full throttle.

Dan,

Here are some notes from my early tests on my 617.950 engine:

"We used a Snap-On Vacuum/Pressure Gauge for this test. We attached a fitting into the plug at the front of the intake manifold. This allowed us to retain the Overboost Protection Circuit. The air filter was left in place.

At an idle speed of 875 rpm, the needle fluctuates slightly, which gives you an idea of how sensitive this instrument is.

Snapping the throttle wide open (and quickly releasing it) indicated 7-8 psi on the gauge. Rpm peaked at about 3200 during this portion of the test.

As we took the car out for a drive, we noticed the boost gauge imitated the movement of the tachometer. We were registering about 3-4 psi by 1200 rpm and it continued to climb in relation to engine rpm very rapidly.

At a 65 mph cruise, we were developing 6.5 psi at an indicated engine rpm of 3000. Opening the throttle fully, instantly swings the needle past 10 psi of boost.

We then conducted the WOT test, holding the engine against the brakes at 4000 rpm in the second speed range. We recorded 14.5 psi of boost pressure...."

Hope this helps....Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Which means there is a problem. Stock boost from the factory is 9psi and the most the engine can use without internal injection pump adjustments is 12psi.

I thought 13 psi was the normal maximum? 9 psi sounds low. In any case, 5-6 psi is what I get with the '87 300D at 65 MPH on a flat road, with the boost gauge (0-15 psi VDO) connected in exactly the same place as the OP. It is also what I got with the '85 300D when the boost gauge (same one) was on that car.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

0.7-0.8bar (10.1-11.6psi).

Its what every one of them came set at from the factory.

Attached Thumbnails

 

I adjusted my wastegate to yield the 14.5 psi measurement and I would have to take issue with your statement of the stock IP settings not yielding any benefit over 12.0 psi.

I have tested this system to see if the overboost circuit was working and IIRC, it activated at about 15.5 to 16.0 psi. The performance from the car at 15.0 psi, before the overboost protection activated, was phenomenal.

I have the ALDA backed out CCW all the way and have changed the shim thicknesses under it slightly, although I cannot recal exactly which way I went without my notes.

Either way, I drive this car over 100+ miles day (round trip) to work with 14.5 psi of boost recorded at WOT. I have very little smoke, even at WOT (certainly normal opacity for a 617.950) and the car has V8 performance.

My last two tanks of fuel, keeping engine rpm at or below 3000 rpm, have netted 28.6 mpg...I am still shooting for the elusive 30 mpg figure on a consistent basis. I am hoping a future change to a 2.47:1 will get me in the ballpark.

Forced Induction:

I am not trying to be argumentative or discredit you. Here is how I approach things: If theory agrees with results, accept theory. If results disprove theory, adopt results. In the case of my 617.950, the IP has never been touched and the fact is, regardless of theory, the car wil absolutely fly when you increase the boost, even above the 12.0 psi figure you quoted.

I may not be able to explain to you why, all I do know is the results are outstanding...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

my 602 gets 11PSI - 5-6 is waay too low for peak pressure on a 6-pot

in your picture one of the nipples on the manifold looks open -- is that plugged or connected now? if not - is it possible you are just losing a ton of pressure though that?

__________________
1992 850i 6 speed
1991 M3 S54B32 swap
2007 328iT/6 RWD sport wagon
1987 325E 330iZHP engine swap
2004 Vespa 200GT
1976 W115 240D getting a much bigger engine. 5.5L
1997 R129 SL600 5AT

Thats because you aren't disclosing the truth, you've turned up your injection pump.

Thats because you aren't disclosing the truth, you've turned up your pump.

Nothing hidden here, Forcey,

I have never adjusted anything but the ALDA because the performance was acceptable. The only modification done to that pump was when I installed the new rear cover with the rack damper.

Every car reacts differently...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

..

But....Not in my daily driver...

You must accept that due to variables in all things mechanical that nothing, not even your theories are absolute...neither are mine...Results trump theory everytime...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Except for known facts. I'll take Mercedes' multimillion dollar R&D department's specs before anyone else's unscientific observations any day.

Again, you insist on living in a world of absolutes when no such place exists. For someone who seems to enjoy going outside of what MBZ dictates on your own cars, that is a pretty bold statement. Again, you create a specific standard for yourself and decry everyone esle who does not subscribe as an idiot.

You remind me of a fellow I once knew. He repeatedly lost the lower end (rod bearings) in a race car he was campaigning against us and one day I told him he was running too lean. He asked me, "How do you know? Just by looking at a piston or listening to the engine? Do you have an engineering degree? If not, then keep your opinions and theories to yourself."

Night after night, lap after lap, we turned 8500+ rpm on the straights, running 4 full seasons on one engine, tearing it down before the 5th season only for a mandatory technical inspection.

He could not accept the fact that his lean fuel curves were causing high combustion chamber temperatures and detonation. He had good oil and plenty of pressure for his journal diameters. He just couldn't get past the fact that somebody knew something that he didn't and he could never seem to understand the correlation between his jetting and rod bearing failures.

You are very much like this man. You elevate yourself to a position of MBZ Godhood and rain down your divine urine on anyone who doesn't agree with you. Even when faced with facts that a 617 could possibly react differently than yours, you disagree.

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership