Hydraulic Hard Line Replacement with Flexible Hose
 

The steel lines running to the rear of my wagon are shot so I'm faced with replacing them. Gut check: it seems easier to replace them with flexible hoses than deal with trying to ben steel lines under the car (and having them rust out again some day). I'm thinking something like these thermoplastic lines: http://www.swseal.com/pdf/Polyflex.pdf

Things to consider are:

(1) Pressure. Most of these hoses are designed for heavy industrial applications. I can't imagine the SLS system puts out near that much pressure. Does anyone know what the actual pressure is?

(2) Temperature. If anything I would be worried about low temps making the hose less flexible. High temp shouldn't be an issue except for under the hood, but I'll leave that section of hose alone for now.

(3) Chemical capatibility with the fluid. The fluid is mineral oil based, so according to the list on pg AB-16 here it should be fine with all their hoses. I can't find the specific fluid on their list.

(4) Fittings. I haven't pulled the lines yet so I'm not sure what they look like but I don't expect any issues here. Could be wrong...

I haven't done a cost analysis of the two options but would be happy to do so and share. If I go ahead with this I'll be sure to post plenty of photos and do a DIY walkthru. I've gotten lots of help on here reading through old threads so happy to contribute anything I can.

I'd go with either steel line, or cunifer lines. the plastic, as you state, will be difficult in cold, fittings are likely to be an issue, and I DOUBT the price is comparable.

IIRC the pressure on those lines is pretty high. You should be able to make do with metal brake lines custom bent (yourself) and the appropriate fittings on the end. Try a decent hydraulic shop. Where are you located?

I know the pressure is above 250psi, as I blew out brand new 250 psi hose on my first attempt to repair my SLS...

I think the original hose is rated around 1000psi. I replaced the blown hose with 4000psi steel reinforced Gates G6 hose, and never had another leak, so the pressure is under 4000psi.

You could get lucky at a PNP and find some close to new ones for cheeep.

Answer
 

The reason they are STEEL is road debris = sharp and/or abrasive trash..

This is a common issue I see on vegetable oil conversion cars, road debris = shredded plastic or rubber hoses..

FYI the SLS system can see pressure in the range of 650 PSI.

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I'm located on Long Island and luckily have a good hydraulic shop right down the road (Long Island Truck Parts). I'll take the old stuff out this weekend and head down there. I guess I'll probably end up going with some kind of metal line that they have, unless they recommend otherwise.

Thanks Whunter for the pressure rating. That's well under most of the high pressure hoses, as I suspected. And yeah, I can see road debris being a potential issue.

What is the OD of the steel lines?

The greatest concern is gathering fittings that will work with your car.

-4 ( 1/4" ID ) single wire 100R1AT hydraulic hose is good for about 3.200 PSI and is more flexible / smaller OD that 2 wire 100R2AT 5,800 PSI . ( This is the number of steel braid layers under the outer jacket.)

-6 ( 3/8 ) is 2,600 and 4,800.

Update: I replaced the steel lines and the system is holding and pumping fluid normally, so all good there. I used 1/4 inch line and had to bore out the fittings a bit to make them fit over it.

Ride height has not increased, so on to the next troubleshooting item...

Also, when driving yesterday I had about 250 extra lbs in the car and when I first added it the ride all of the sudden got VERY rough. Lasted for about 5 mins then back to normal.

I'll look on other SLS threads for advice but f anyone has thoughts feel free to share here.

Did you DIY it and did you use the Original Fittings?

Yes I used the original fittings. They just didn't fit the US line.

More details on how you got the fittings to work would be helpful for other members facing the same issue.

Of course!

So the OD of the line I got from the auto parts store is 1/4", but the ID of the fitting is a metric size slightly smaller than that (about 10 microns I think). So what you have to do to get the fitting to fit over the line is to just bore out the inside a little bit.

You could drill it - starting with a 1/4" and then going to a 9/32" and trying it until you get it to fit. But I happened to have access to a pneumatic boring tool so used that.

After that, fitting slid right on and I was able to flare the end and connect to the valve.

The size would have been 6 mm

I know this is an old thread, but..
 

What type of flare did you use?
I believe the stock flares are "bubble" flares, or reverse flares.

If that's what you did, how did you make them?

I'm facing the same issue.