This came up in another thread but it seemed intriguing enough to start a separate thread. Here's what I wrote in the other thread:

Wonder if it's possible to just pressurize the system and seal it up. You'd have to remove the adjustment lever but it seems like it would work without a pump. I know when my main rubber hose broke, everything was copesetic until I stupidly stopped for fuel and the people in the back seat got out, calling for an adjustment which bled off the pressure and then I was sitting at the bottom with no way to get it up.

Has anyone tried this? I know we have threads where people have swapped in standard shocks when they lack a pump due to installation of a non-TD engine. But would it be possible to continue to use the system without a pump as long as it was pressurized?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Do you mean just pressurise the remaining system like a gas filled shock - and not have height adjustment?

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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!

You'd have to plug the return line and the supply line to the valve. If you didn't plug the return line when you loaded the rear I think it would squeeze all the fluid out of the struts and back into the reservoir and you'd loose the pressure. I could also see the extra pressure from loading the rear possibly blowing out any weak spots in the system. Especially if you hit a big bump, the sudden change in struts could blow something out.

I wonder if you could fill the struts and accumulators with fluid with the car unloaded, and then make new hard lines and just loop the passenger side accumulator and strut together and do the same for the driver's side. Then you'd eliminate the valve, res, and pump.

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The problem is that liquid is relatively incompressible with regard to pressure but does expand and contract due to temperature. Using water as an example; if you put liquid water in a sealed container with no gas, a 1F temperature change will change the pressure by about 50 psig.

Tried this? Well my hose broke too. And I stripped it when I tried to replace it. So the old hose stayed, pinhole and all. I disconnected the adjustment lever and ran with it for a whole year. Towards the end it started looking a little saggy. So yeah, it can last several months like that.

A generic 12v "convertible top pump" with the switch located in the glove box worked will. When your rear end sags, hit the switch for a moment. I sold a Euro TD with this system almost up and running but sold the car to a Canadian guy (I found a Dodge PU for a camping rig). He finished it and reported it worked very good. The pump mounted next too the tank and I had a hydraulic shop make up new hoses.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

So the answer to BiodieselTD's comment is that no, that won't happen? A pump is not necessary if no adjustments are called for?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Well it's not like I put 400lbs in it. But it held the weight of the car for quite a while.

But what about the constant recirculation of fluid? On a properly working SLS system, the hyd pump is constantly moving fluid through the valve in the back and up through the filter in the reservoir. Wouldn't you worry about needing to flush the system more often or replace seals in the valve?

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter