Boost Question - PeachParts Mercedes-Benz Forum

Quinn8it · #1 03-27-2007, 12:06 AM

I'm pretty new at working on these diesels, and I searched and couldn't find an exact answer to my question.
First it appears that a P.O. had bypassed the over boost solenoid. I currently only have the clear boost line running from the Alda to the Banjo bolt.
Two weeks ago I tapped into this line (probably at the bypass point) with a boost gauge. It seems to be working fine and is showing 9.5 psi as a max boost.
My question is, 1) do I need to work the over boost solenoid back into the system?(since I have a gauge) and 2) where would I tie in a boost adjuster in the current system?
I put the boost adjuster in the line after the "t" for the gauge (between "t" and Banjo) and my gauge would rise and then drop as boost kicked in. when I switched them (between "t" and alda) I couldn't register a boost higher than 4psi. I removed the boost adjuster, but I would like to correctly install it...
Thanks for your help

angst · #2 03-27-2007, 12:28 AM

your Q 1: if the overboost valve that resides near the brake master cylinder is still there why not go ahead and plumb through it. No real money spent and not a hard fix. 1/4 poly line has worked fine for me. $2 for 25ft at Home depot.
Your Q 2:
Here are some boost controller links
http://www.geocities.com/chmwatson/FAQs/mbc.html
Questions on a boost controller.....
boost controller install...

But the easiest way to control boost is just adjusting the wastegate that is already installed at the factory. I hope to add a boost controller someday, but until I can get around to it I did this.
http://www.serenitysys.com/MB/Service_Info/Turbo_Tweak/tweaking_the_mercedes_617_turbo_.htm

l3ushwig · #3 03-27-2007, 01:21 AM

Quote:

Originally Posted by angst

But the easiest way to control boost is just adjusting the wastegate that is already installed at the factory. I hope to add a boost controller someday, but until I can get around to it I did this.
http://www.serenitysys.com/MB/Service_Info/Turbo_Tweak/tweaking_the_mercedes_617_turbo_.htm

Wouldn't something like this be easier to control it?

http://cgi.ebay.com/ebaymotors/High-Quality-Manual-Boost-Controller-Ecliplse-Talon-NR_W0QQitemZ190094703610QQcategoryZ33742QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

2.5Turbo · #4 03-27-2007, 12:29 AM

The overboost solenoid is probably bypassed because it is plugged with EGR gunk. It'll save your engine in case your wastegate takes a dump for some reason. It's simply a safety device.

The boost controller doesn't go between the manifold and the ALDA. All that line does is send pressure to the ALDA which allows the rack to open fully on full boost. If I remember correctly, it goes on the wastegate pressure hose on the turbo. I don't have a pressure activated wastegate on my car, so I haven't been able to tinker with boost controllers.

Just as a note, you aren't going to get any more performance out of turning up the turbo boost alone. All you'll do is increase the intake air temp. To make use of the extra air, more fuel must be added. To do that safely, an EGT gauge must be installed. To go any farther than a little power increase, an intercooler must be installed to avoid melting the engine.

#5 03-27-2007, 01:03 AM

Quote:

Originally Posted by 2.5Turbo

Just as a note, you aren't going to get any more performance out of turning up the turbo boost alone. All you'll do is increase the intake air temp. To make use of the extra air, more fuel must be added. To do that safely, an EGT gauge must be installed. To go any farther than a little power increase, an intercooler must be installed to avoid melting the engine.

That's if he wants more than 13psi. Since he is only getting 9.5psi right now, going to 13psi will come with a bit more power.

Quinn8it · #6 03-27-2007, 01:15 AM

Quote:

Originally Posted by ForcedInduction

That's if he wants more than 13psi. Since he is only getting 9.5psi right now, going to 13psi will come with a bit more power.

Thats what I was thinking. I just wanted to get it back to where it is supposed to be. Before I install the EGT gauge.
As far as where I stuck the boost adjuster... Im retarded

! I think I have a better Idea where it should be now...Thanks
Assuming that the PO bypassed the over boost solenoid because its bad/dirty, is it worth the time to clean or replace it or is it unnecessary?

#7 03-27-2007, 01:23 AM

It's a 1:100,000 chance that you will ever need/use the overboost valve because of a wastegate failure.

If you have a boost gauge, you keep your engine in decent mechanical condition, and you know what sounds are normal/not normal for your car, IMHO, it's not needed.

Quinn8it · #8 03-27-2007, 01:26 AM

Quote:

Originally Posted by ForcedInduction

IMHO, it's not needed.

Thanks... That was what I was assuming, just wanted to hear it from someone with more experience...