Does anyone know if the fuel system is pressurized in a 300TD? I'm installing a fuel swith to add a WVO tank. The 6 port solinoid I bought claims it can only have 8 psi of pressure in it.

JamesStein,

Don't know about later models but the W123 300DT models are at atmospheric pressure until they get into the pumps. The line from the tank to the connection at the injection pump is basically gravity fed. There is a venting system to prevent pressure or vacuum, which can get plugged and cause problems of its own. Hope this helps, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

James,
Where are you installing the solenoid?
If before the lift pump, pressures are at or below atmospheric.
If between the lift pump and IP, the pressures are above atmodpheric, but until I have the time for investigation, I cannot tell the pressures at that point, so play it safe and use a fuel pressure regulator to ensure that damage does not occur.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

James,
Where are you installing the solenoid?
If before the lift pump, pressures are at or below atmospheric.
If between the lift pump and IP, the pressures are above atmodpheric, but until I have the time for investigation, I cannot tell the pressures at that point, so play it safe and use a fuel pressure regulator to ensure that damage does not occur.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

I was planning on installing it into the engine compartment. Where is the lift pump?

BTW its an '84 300TD

I think that was OzzySpeak for injection pump....

On a '84 300D (non-turbo), the lift pump is mounted on the side of the injector pump.
The fuel comes from the tank, flows thru a pre-filter and then into the lift pump. From the lift pump, the fuel goes thru the main fuel filter and then to the injector pump.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

I've installed the valve.. So far it appears to be working without any trouble.

It's installed before the lift pump. Fuel comes in from the fuel lines through the valve into the lift pump.

I've bled and bled and bled and I can't seem to evacuate all of the air from the small filter in line right before the lift pump. Other than installing bleeder valves all over the place is there an easy way to get the last bit of air out? It doesn't seem to be effecting the performance of the engine (at least not in a way noticable to the eye/ear).

__________________
'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.

That bubble in the prefilter is always there. Don't worry about it.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
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