Im interested in cranking up my turbo boost (ie adjusting the wastegate).
After not finding a boost gauge in my budget I decided to just temporarily plumb in a 0-30 pressure gauge that I had in my garage.
I brought my gauge and the bolt for my intake gauge port into the Ace hardware. Fitting my gauge to ¼ in poly line was no prob. A $2 adapter and that half is done. I could find no brass fittings that would match the threads of my port bolt though. Most of the fittings were NPT. The closest match seemed to be stuff in the 1/8th compression genre but this did not seem right and I did not want to risk cross threading the hole.
What size fitting do I need to connect ¼ poly tube to the intake port?
After pawing through at the selection for 30 minutes I ended up getting a plastic T so I could do some testing. I T’ed into the pressure line near the switch that is near the brake booster using the flimsy plastic T that fit inside the poly tubing.
Im not confident in the readings that I am getting of a max of about 8lbs when winding out over 4Krpm. Is it ok to take a reading from this far away tapped in near the switch? Pressure is pressure right and in theory should not matter how far away from the intake the measurement is taken?

Also once my gauge readings are solid how high should the pressure be turned up?
Ive been using this guide
and this guide and this mercedesshop thread
I get the impression that 12 is about the target to go for at 4000 rpms and to be sure not to exceed 15. Sound right?

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84 300SD 274K
38K miles on flatplate heat exchanger and various diesel/veg blends. prior to that 4K miles on unheated veggie blends with kero and DinoD.

Stock boost is 11 psi..IIRC..

Anything more than 12-13 psi won't do anything unless you turn up the full load fuel on the IP. Extra air, without any fuel has very little benefit.

The port takes a 1/8 inch NPT (tapered) fitting. I read somewhere that when the ISO ("metric") standard for threads was being developed, they decided to copy what the English were using for pipe thread.

Also note that there are two kinds of pipe thread: Threads that are parallel (example: drain plugs; they seal using a crush washer or an o-ring) and threads that are tapered (example: household plumbing or the thread for a boost gauge in your Mercedes' intake manifold; they seal using a sealing compound such as Teflon tape or pipe dope).

See this thread:

http://www.peachparts.com/shopforum/showthread.php?t=170191&highlight=boost+gauge+hardware

and look at the picture in post #7 in that thread. I got the fittings at an ordinary hardware store.

Jeremy

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"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

Sweet. Thanks for that.
My port bolt that I brought into the store to match seemed to be a tighter thread pitch than the pipe thread stuff on the shelf.
My bolt looked to be NON tapered and more of a thread like all metric threads Ive seen. Ill go back and check the NPT fittings at the store again.
I thought NPT is always tapered. Can NPT be both tapered and non tapered?


Regarding fuel adjustments, I not sure I will mess with the ALDA after turning up the boost. The protective cap is off of it and there is no telling what the prior owner has done. I read in a search that they can break with little provication. If it is possible then it would likley happen to me.

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84 300SD 274K
38K miles on flatplate heat exchanger and various diesel/veg blends. prior to that 4K miles on unheated veggie blends with kero and DinoD.

If you want to mess with the ALDA without the risk of breaking it by over tightening the screw, just add a shim under the unit. It has the same effect. I believe somebody on here figured that a certain thickness washer equated to a certain number of turns of the screw...but I don't remember what the numbers were.

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Dale

http://i52.photobucket.com/albums/g1...MG_2277sig.jpg

1990 300D 2.5 Turbo -155k
2000 E430 - 103k
2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k
2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz

Pre-glow - A moment of silence in honor of Rudolph Diesel

Close, but no. It's a M10x1.0 fitting.

It was a pain in the ass for me to find the right fittings. I had to use a coupla adapters and such but I got it done. Took about half an hour at Ace Hardware and all the employees' help

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1985 CA 300D Turbo , 213K mi

That's why I go out of my way to shop at an ACE that does not have all the fittings behind the counter.

I don't remember the thread pitch offhand, but those European straight pipe threads use an "R" tap & die.......

those sizes are very close to out NPT system.......

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

In my amateur opinion it visually appears to look exactly like that. I can get a M10 bolt at Ace but I do I parlay that into an attachment for my line?
Hey, Why don't I just bust out the tap and die kit I got for christmas and make it fit?! Take the conventional NPT water fitting and just run the die over the threads.
To get a regular M10 bolt adapted to fit a line is going to take some fabrication anyway. Ive gone through Ace and Lowes looking for hollow bolts before with no luck.

What kind of Ace has all the fittings behind the counter? I can see a shopkeeper getting tired of people chucking stuff in the wrong bin and probably half the stuff goes straight in peoples pockets but the concept is hard to grasp. Ace is expensive because its convienent and they know it. Take away the convience and Im heading to the big warehouse hardware store.

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84 300SD 274K
38K miles on flatplate heat exchanger and various diesel/veg blends. prior to that 4K miles on unheated veggie blends with kero and DinoD.

Duh......why didn't I think to mention this earlier.....try your local auto parts stores.....most have some metric fittings, and have the tubing connections and ferrules for oil pressure gages and such.....

I have found a NAPA store that has a great stash of metric stuff.....because they have a Volvo Dealership and a Import Indy Shop that frequent their store.....

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2009622/p-2009622/N-111+10201+600010337/c-10101

Most Pep Boys, et al. have something like this.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Not sure what car you have, but on my 1984 300SD a 10x1.0 mm brake bleeder threaded into the intake manifold (remove the plug already there). You can slip a section of tubing over the end of the bleeder nipple. Works perfectly.

My guage from JC Whitney works perfectly, came with a variety of fittings to choose from, came with the hose, mounting plate and compression fittings, and it all works fine. Cost I believe was $27. If it were me, I'd get everything you need in one box.