Interesting your tang is at 6 o'clock, which gives better access..

Both turbos that I have has the tang at 12 o'clock, which means working blind and the inlet housing is in the way of prying.
.
The engine is running well. I'll have to do some 0-60 runs to see if it runs any faster with the 2.5 psi higher boost.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I took the easy way and made a manual boost controller. Never needed to dig into the waste gate controller.

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85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

Hi guys! I read with interest your comments on boost pressure. I drive a 84 300SD though it stays in the garage mostly. Recently I converted a 1960 studebaker 3/4 ton pickup by installing an engine from an 85 300 SD. It performs quite well but would like to find a speedo drive gear that would slow the speedometer down about 5MPH. The trans is from a 300D with a standard cable.
The interest in boost pressure comes from the new turbo recently installed in the pickup. 1.1 bar translates to 15.95 PSI boost. I have connected the ALDA direct to the manifold and eliminated the overide circut. That means I am depending on the waste gate to control the boost. How much greater than 16 is safe. My waste gate is adjustable and I have a 3" straight exhaust. Connecting a boost gage is easy but where would one best connect the EGT gage for the correct reading while doing trial and error with the waste gate. I have alwo removed the EGR.

16psi is already WAY too much. 12psi is all your engine can use, anything more is just heating the intake air.

unless an intercooler is added.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I run or try to shift at 16,but I have been as high as 26 psi with no lack of fuel.only mods were ALDA delete, and strait exhaust

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

/

just curious....what was the temp while 26psi?


.

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

I like it!

16psi is too much. If you haven't been in the pump to mess with anything, 12psi is all you need. For the EGT gauge you want to tap into the manifold, pre turbo, directly in front of the turbo inlet. You will have to pull the turbo to do this-the up side is that with the turbo off it will be very easy to adjust the wastegate.

5mph isn't terribly far off, but I'm sure some other people can chime in with the correct year speedo to grab for a conversion

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Does anyone know how stiff the spring is on a Garrett T3 turbo waste gate actuator? Most says that the boost to open the waste gate should be around 10 psi, but if I stick a compressed air into the actuator port, the waste gate does not pop open till about 60 psi on the compressor gauge. Please advise if I'm doing it wrong. The engine is a OM617 on a 84 300sd. Thanks. ( If there is a thread for this can someone redirect me to it)

You are right the waste gate should start opening at 9-11 psi.

Do you have a boost gauge on your car to verify what you are getting over the road?

Do you have an air leak in your test setup. Perhaps the diaphragm is leaking.

__________________
85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

temp is 80,I have a 170f thermstat in my diesel also.I know it should be not possible,but maybe someone messed with the car before I got it.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

.

thanks mate,... but not the coolant temp....exhaust temp...

I think you are close to total meltdown just joking but I suppose that
you are way over regular temps....


.

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

don't know,I don't stay there long,and beside now 16 is all I go and for a short time.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

9.9.2018 I just discovered this great thread, THANK YOU ALL for the detailed inputs and ideas .

I discovered a you tube video from that place in Bellingham, Washington (Kent) that shows him removing the wastgate cover spring with a crappo Harbor Freight pick tool .

My wastegate diaphragm is toast, it leaks pressure/vacuum so it was disconnected and plugged when I bought the car, now I know I need to find another diaphragm before I open it up, hopefully on the car .

I see Funola is still driving and enjoying his car, that's good to know ,I've only had this car 6 ~ 9 years and am still discovering bugs and DPO / DPM bodges here and there .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

This is the style of turbo I have, what's the thing with triangular cover and vacuum nipple ? .




TIA,

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better