All,

I am thinking of putting in a boost gauge on the 1983 300D. I don't want to tee into the ALDA line (even though that might be easier). Instead I would like to remove the plug from the test port on the manifold (not the banjo bolt fitting on the rear, but the test port on the right rear by the overboost switch and the transmission dipstick).

First off, is there any reason why this would not work, and second, does anyone know the size and thread pitch of the plug so I could get an adapter of the same size and thread pitch?

Thanks,

Glenn

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Here is a picture of what I am talking about.

Glenn

Attached Thumbnails

 

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

When I first put in my boost gauge I used that port. A 1/8 NPT bung fit in pretty well. Once I removed the alda, I put the plug back in and just went for the Alda banjo.

Edit. Oh your picture shows that you already did it.

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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.

No, actually I have not already done the job yet. The picture is of a car that has done what I would like to do....i.e. hook up the boost gauge to the manifold test port. I'll try a 1/8 NPT bolt as a test, but I ha the impression the bolt would be some metric size and thread pitch.

Anyone?

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

the port is 10x1 threaded. My local hardware store had the 1/8x27 NPT fitting and they work for this.

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

In 2007 I didn't own a diesel.

Here is another pic of my original adaptor.

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

In 2007 I didn't own a diesel.

Using the plumbing adapter works because it is the same basic diameter (although it is tapered slightly) and the threading is very close. The plumbing adaptor has 27 threads per inch and the metric fitting has 25.4 threads per inch. You can hold them next to each other and check it out. The threads start binding after a couple of turns which is ok You only need to tighten this fitting enough to keep it from leaking at 20 psi. Wrap a bit of plumbers teflon tape on the threads and screw it in until snug with a short wrench.

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

In 2007 I didn't own a diesel.

Gee, just put some Loctite or Pipe Tape in the threads ought to seal the threads.

__________________
84 300D, 82 Volvo 244Gl Diesel

Thanks guys.....That was just what I was looking for. I appreciate it.

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)