Leaking Cold Start Valve

[mBdrvr]

Short question: How do  you disassemble the CSV spring and seat fitting for cleaning?

Long story:

My 1970 280SL is running rich due to what I believe is a leaking cold start valve (CSV). I also smell fuel while driving and find the dye that I put in the fuel tank is showing up in the head mixed with oil.

I tried to adjust the idle with the large screw on the intake during the "linkage tour". The higher than normal idle remained mostly constant no matter how I adjusted the screw.

I found a suggestion here that a leaking CSV could be the cause.

To confirm, I removed the CSV and sealed the port. The idle calmed down and was adjustable with the large screw. The CSV is the problem...

I cleaned it with carb cleaner and took it apart as best I could but I could not remove the spring and seat from the fitting as shown in the tech manual.

I reinstalled the CSV after cleaning with the original result.

Is the 1970 CSV different from other years or is there a way to disassemble the fitting?

Any help will be appreciated.

Thanks!

[Bshaunessy]

MBDRVr
  Interesting as I had almost the exact problem: leaking CSV.   Unlike yourself, I was able to disassemble and clean CDV and problem ( rich running from leaky CSV) went away.  Q? Perhaps you can disassemble again, totally, remove the valve and seat and polish both to seal properly? Just a suggestion as this was my Plan B if simple cleaning didn’t work.
  Plan C was to replace…several CSV's available E Bay.
  Other: could it be an electrical issue whereby the CSV is energized always / during normal running conditions?
 

[mBdrvr]

I took the CSV apart as far as I could and cleaned it with carb cleaner. After reinstallation the problem persisted.

I want to polish the valve and seat but can't figure out how to take the fitting apart without damaging it.

I'm attaching pictures.

Thanks

[BobH]

Hello Paul, the fitting you've pictured is the fuel line connection, the needle valve is inside the body of the main unit, have a look on here

https://www.youtube.com/watch?v=RIOq1wEe0Dk

[rwmastel]

Other: could it be an electrical issue whereby the CSV is energized always / during normal running conditions?

I think this should be tested.  Maybe it's not leaking, maybe it's just running?

[stickandrudderman]

With engine running: remove the 7mm hex head screw in the cold start injector assembly.
There should be no fuel present and you should feel a small vacuum at the exposed port.
If fuel is present then either you have a permanent 12v feed at the solenoid (disconnect the cable to see if the fuel flow stops (switch engine off so as to avoid a spark when disconnecting the cable)) or your needle valve is not seating.
They can usueally be repaired using valve grinding paste.

[mBdrvr]

Thanks for the responses.

I'll check these items again.

Paul

[mnahon]

Paul, your CSV is the later 'small diameter' CSV. The discussion in the technical manual, including polishing of valve seat, relates to the early 'large diameter' CSV.

In your CSV, the seal is accomplished by that spring loaded ball bearing you see in your third picture of the fitting. The fitting can't be disassembled. Try sticking something in to push the bearing off its seat and then soaking it in carb cleaner. Maybe try spinning the bearing to see if you can see dirt or corrosion on it.

If it's still leaking, you'd have to replace the fitting, but that's close to impossible to find on its own.

Best of luck.

[BobH]

You learn something new every day, i've popped this in the tech manual

Thanks

[stickandrudderman]

Paul, your CSV is the later 'small diameter' CSV. The discussion in the technical manual, including polishing of valve seat, relates to the early 'large diameter' CSV.

In your CSV, the seal is accomplished by that spring loaded ball bearing you see in your third picture of the fitting. The fitting can't be disassembled. Try sticking something in to push the bearing off its seat and then soaking it in carb cleaner. Maybe try spinning the bearing to see if you can see dirt or corrosion on it.

If it's still leaking, you'd have to replace the fitting, but that's close to impossible to find on its own.

Best of luck.

Good point!

[mBdrvr]

Thanks stickandrudderman! I thought something did match up.

I managed to push and hold the ball bearing in a bit and used an ultrasonic cleaner with a mix of ATF and Marvel Mystery Oil to try to clean it. I haven't reattached it yet. I'll post here when I have a result.

[mBdrvr]

Still no luck.

I'm going to seal off the intake port for the CSV and close off the fuel supply. I'll see if I can get along without a CSV until I figure this out.

[mBdrvr]

I removed the CSV leaving the air and fuel lines in place.

I loosened and pushed aside the CSV fuel line at the injector pump. I cut an old fuel line to about 8 inches.. I tapped an 8 32 thread at the cut end and inserted an 8 32 screw with Loctite to block the fuel flow.

I cut a piece of metal to cover the CSV inlet port on the intake. The I copied the screw locations from the gasket, applied some Form A Gasket and screwed it to the intake. The metal was too flimsy to make a good seal so I temporarily sealed around it with some silicone until I make a more sturdy cap.

I put a rubber plug in the air line to the CSV but I'm not sure this is necessary.

The car does not start as easily but a little pressure on the accelerator pedal gets it going. The temperature is about 70 Fahrenheit.

Most importantly, the fuel smell in the cabin is gone. I can now adjust the idle air at the intake.

So far the car runs pretty well.

I'm looking into an 12 volt valve that I can put in the fuel line and an injector that I can insert into my cap. That may be a good temporary fix until I can find out how to repair my small CSV.

[Bshaunessy]

Paul Greenblat
  There is a used CSV on ebay for $95 right now.  At only $95 , maybe worth a try!
https://www.ebay.ca/itm/126690580630?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=Id3blo7kSZS&sssrc=4429486&ssuid=EtSSplvvSsa&var=&widget_ver=artemis&media=COPY

[stickandrudderman]

That is an early version which doesn't fit the OP's car. Bargain though!

[BobH]

This one doesn't have the solenoid, but the valve might be ok

https://www.ebay.co.uk/itm/226000378961?chn=ps&norover=1&mkevt=1&mkrid=710-153316-527457-8&mkcid=2&itemid=226000378961&targetid=4584757337008491&device=c&mktype=&googleloc=&poi=&campaignid=431353847&mkgroupid=1298523655396099&rlsatarget=pla-4584757337008491&abcId=9301942&merchantid=87779&msclkid=4b607f6fb83511f0e2f0186596f4d110

[mBdrvr]

There's no guarantee that this used part works. I'm going to see if there's a way to fix the one I have.

Thanks!