The IP side of the actuator has something attached to it reducing the effective area of the piston. The pressure would have to be higher on the IP side than the equivalent vacuum (negative pressure) on the other side to produce the same force.

5 inch Hg comes in at about 2.5 PSI - interesting

Current score 2:1!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I am still puzzled as to what the info is needed for????

__________________
84 300D, 82 Volvo 244Gl Diesel

I'm just bored - this time of the year working outside on an old car isn't much fun. I spend most of my time shouting at the bad weather so I amuse myself by thinking about certain things that have happened here on the forum...

...let me be specific - things that happen or get reported on the technical forums!

I'm interested in your report that the engine shut down when the crank case pressure reached 3.1 PSI. Most people say that that's because the shut off valve operated. I'm just thinking that perhaps something else happened instead.

An increase in pumping losses could explain what you observed.



In the big scheme of things it doesn't really matter why - unless you have a pedantic inquiring mind and you've turned yourself into some kind of forum myth buster!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

If the Shutoff is being pushed by the Crankcase Pressure that will cerate a pumping loss.

If you remove the Brown hose and plug off the Shutoff Valve when you block the Crancase Vent on the Valve Cover it should at the very least delay the Shutoff. It might even keep it from shutting off.

But, I think doing that is going to allow the Crankcase Pressure to go higher increasing the risk of the Seal Being popped out.

If you really want a project remove the Shutoff Valve from the IP and make a Plate to cover the Hole and do the test. If the pressure reaches the Point that would have activeted the shutoff and nothing happens the point has been proved.

When I went to look at My Steering Colum Lock there was some Oil leaking from the little Shutoff Vavle on that; indicating that Oil is getting Pulled through the Shutoff Diaphragm on the Fuel Injection Pump.
If a Shutoff Diaphragm has holes in it I would expect that the Crankcase Pressure would need to be higher to shut the Engine Down.

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84 300D, 82 Volvo 244Gl Diesel

What is a "pumping loss?"

This is the "loss" associated with the pumping of air in and out of the engine.

Engine efficiency - Wikipedia, the free encyclopedia

Damn you friction and pumping losses!!!!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I reckon a safer test is to gradually apply a vacuum to the proper side of the shut off valve and see if that reproduces what you observed.

=> a gradual slowing of the engine until it finally stops <=

I reckon with one lucky person and one unlucky person - with seals popping out or not - pretty poor odds of something going wrong have been demonstrated so far.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Just to be clear - when I've been talking about pumping loss in this thread - I'm not talking about a loss associated with the injector pump. The pumping loss I'm talking about is a little bit like an increase in "evil" forces such as friction that are working against combustion.

Most road going engines are set to idle so that they are operating just above the point of stall. Adding a force that works against the engine can upset the point at which the engine will idle. In other words it just isn't strong enough to keep on running if you increase friction (e.g. push a clutch up against a flywheel) or increase pumping losses (vacuum on the air intake / excessive crank case pressure).

At higher than idle engine speeds the effects of friction and pumping losses are not great enough to influence the engine in a severely negative way - so if you were mad enough to block your crank case vent at say 2000 RPM + I think it would be unlikely that you'd be able to replicate the observations that have been made when the engine is idling.

PLEASE NOTE - blocking your crank case vent is not something I am saying anyone should do - READ WARNING in post #1

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!