DIY sanden compressor install on a 535is

E28 technical advice asked and given! Troubleshooting, modifications and more.
klavender1
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Re: DIY sanden compressor install on a 535is

Post by klavender1 »

Measuring according to that link, it's .475". Which is near enough to .500" I guess. I'm using a digital caliper to measure. The actual nut size is .875" which is 7/8".

So I guess it is a #8.

I'm also going to get a 4th line made that goes from the firewall line to the drier. It seems to be a #6 on the firewall line side to a #8 on the drier side.
mnnguy
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Re: DIY sanden compressor install on a 535is

Post by mnnguy »

So I am looking to attempt this on my car, and was wondering if anyone would know what to do in this situation as my A/C low pressure line that comes out of the firewall has what I think are 2 fuel lines and the connection is almost all the way against the firewall.

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Has anyone dealt with this before? Because I have seen most cars having the metal line connection coming way farther out than what is seen here. I'm trying to figure out what would be the best way to run a new line with barrier hoses, but all I could think of is looping the fuel lines and making a new line starting from the connection all the way in the back. Or are these lines bypassable from the connections that are seen on the driver side?

Image
cek
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Re: DIY sanden compressor install on a 535is

Post by cek »

Those lines are for the fuel cooler. Many folks just delete/bypass it.
Mike W.
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Re: DIY sanden compressor install on a 535is

Post by Mike W. »

cek wrote: May 09, 2021 9:29 PM Those lines are for the fuel cooler. Many folks just delete/bypass it.
Quite true. However, there are a few of us who know why they put that fuel cooler in there. Twice I've been changing fuel pumps at the side of the road. Unusual conditions, some altitude, over say 2K feet, over 100, probably 110F and a long climb. Resulting in vapor lock and no fuel pressure. Chris K has run into it too. I'm not sure of the physics, but I suspect the fuel pump expands with heat. So much so it will no longer generate pressure. It runs, yeah, but if there's no pressure it doesn't matter. I would loved to have had one on my '85, 535i. The upside is both times, ~100 miles from Vegas in the summer I had a spare with me. Still not fun crawling under the car on vacation using the now removed wheel as a safety under the car while I'm wrenching in 110F weather, but it beats a tow truck, much expense and time.

Now if you're in most places, even say balmy New Orleans or Florida, where it feels hot due to humidity, but rarely tops 100, you probably don't have to worry about it. If you're like me and expect to take it anywhere anytime, you might think twice. Or do the intank conversion, I haven't heard of problems in extreme conditions with it, but I'm not sure.
Blue Shadow
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Re: DIY sanden compressor install on a 535is

Post by Blue Shadow »

Curious about the fuel level when the cooler is necessary. Would think that a full tank would need it less than a quarter tank. This might mean you could take your 85 on that run with a full tank and not suffer the problem.

Would not be hard to retrofit even using aftermarket piping on the cooling side and the stock panel covering the wiper motor etc
cek
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Re: DIY sanden compressor install on a 535is

Post by cek »

Mike W. wrote: May 10, 2021 12:43 AM
cek wrote: May 09, 2021 9:29 PM Those lines are for the fuel cooler. Many folks just delete/bypass it.
Quite true. However, there are a few of us who know why they put that fuel cooler in there. Twice I've been changing fuel pumps at the side of the road. Unusual conditions, some altitude, over say 2K feet, over 100, probably 110F and a long climb. Resulting in vapor lock and no fuel pressure. Chris K has run into it too. I'm not sure of the physics, but I suspect the fuel pump expands with heat. So much so it will no longer generate pressure. It runs, yeah, but if there's no pressure it doesn't matter. I would loved to have had one on my '85, 535i. The upside is both times, ~100 miles from Vegas in the summer I had a spare with me. Still not fun crawling under the car on vacation using the now removed wheel as a safety under the car while I'm wrenching in 110F weather, but it beats a tow truck, much expense and time.

Now if you're in most places, even say balmy New Orleans or Florida, where it feels hot due to humidity, but rarely tops 100, you probably don't have to worry about it. If you're like me and expect to take it anywhere anytime, you might think twice. Or do the intank conversion, I haven't heard of problems in extreme conditions with it, but I'm not sure.
I do wonder if the TRE/Wlabro single in tank conversion negates the need. FWIW, both Vlad & Maytag still have their coolers in place. Minerva never had one.
Mike W.
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Re: DIY sanden compressor install on a 535is

Post by Mike W. »

Blue Shadow wrote: May 10, 2021 4:39 AM Curious about the fuel level when the cooler is necessary. Would think that a full tank would need it less than a quarter tank. This might mean you could take your 85 on that run with a full tank and not suffer the problem.

Would not be hard to retrofit even using aftermarket piping on the cooling side and the stock panel covering the wiper motor etc
Made me look. I may be crazy but not that crazy, I only keep records like this for vacation. First time it had ~55 miles on the tank, second time ~80. Second time I could hear the gas boiling in the tank when I took the gas cap off. Weird.
cek wrote: May 11, 2021 3:22 PM
Mike W. wrote: May 10, 2021 12:43 AM
cek wrote: May 09, 2021 9:29 PM Those lines are for the fuel cooler. Many folks just delete/bypass it.
Quite true. However, there are a few of us who know why they put that fuel cooler in there. Twice I've been changing fuel pumps at the side of the road. Unusual conditions, some altitude, over say 2K feet, over 100, probably 110F and a long climb. Resulting in vapor lock and no fuel pressure. Chris K has run into it too. I'm not sure of the physics, but I suspect the fuel pump expands with heat. So much so it will no longer generate pressure. It runs, yeah, but if there's no pressure it doesn't matter. I would loved to have had one on my '85, 535i. The upside is both times, ~100 miles from Vegas in the summer I had a spare with me. Still not fun crawling under the car on vacation using the now removed wheel as a safety under the car while I'm wrenching in 110F weather, but it beats a tow truck, much expense and time.

Now if you're in most places, even say balmy New Orleans or Florida, where it feels hot due to humidity, but rarely tops 100, you probably don't have to worry about it. If you're like me and expect to take it anywhere anytime, you might think twice. Or do the intank conversion, I haven't heard of problems in extreme conditions with it, but I'm not sure.
I do wonder if the TRE/Wlabro single in tank conversion negates the need. FWIW, both Vlad & Maytag still have their coolers in place. Minerva never had one.
It might, but might not, but see my comment above. The pump was pumping, I could hear and feel it, but I would only get a dribble out of the supply line to the fuel rail. I didn't have a temp gun handy, but I'm sure the fuel temp after recirculating thru the engine compartment, in hot weather, with good working A/C, uphill, was high. And current reformulated gas doesn't even evaporate anymore, no telling what the good old stuff would have done, or maybe that's why they put the fuel cooler in there.
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