Weber DCOE Choke Pistons dont move.... - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 13 (permalink) Old 07-20-2017, 01:28 PM Thread Starter
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Weber DCOE Choke Pistons dont move....

Hi,
maybe somebody here can help me out?
I´m rebuilding two 40 DCOE Webers.
In one of the carbs the two Choke pistons stuck and i can´t move them at all.
Put in gallons of WD40 already. Tried to push and pull carefully but nothing happens.
Feels like they are welded in...

Any suggestions?

Many thanks in advance...!
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post #2 of 13 (permalink) Old 07-20-2017, 01:58 PM
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Try using the product named 'Kroil'. Much better than WD40 which isn't really meant for this situation. I can't think of any thing other than crud of some sort that would cause this problem. Did the carbs sit for a long time? Could be corrosion from moisture.
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post #3 of 13 (permalink) Old 07-20-2017, 02:20 PM
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Quote:
Originally Posted by Johnny105 View Post
Hi,
maybe somebody here can help me out?
I´m rebuilding two 40 DCOE Webers.
In one of the carbs the two Choke pistons stuck and i can´t move them at all.
Put in gallons of WD40 already. Tried to push and pull carefully but nothing happens.
Feels like they are welded in...

Any suggestions?

Many thanks in advance...!
As above. Find a good penetrant rather than WD40. You need to be patient . Sometimes nearer a week than a day. Eventually they will free off. I have had many carbs with seized accelerator pump pistons come to me, and sometimes I have had to soak them for a week before they'll move, but eventually they do move.
Don't be tempted to knock them out with a hammer or you'll mess up the brass and score the bore when they finally do move. Sometimes they've freed off in my ultrasonic cleaner when I've turned the heat up, sometimes they need the soaking.

Steve

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post #4 of 13 (permalink) Old 07-21-2017, 12:25 AM
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I had something similar when I tried to change the chokes on my DCOE 40s, with the carbs still on the car. A soaking with carb cleaner and a puller made up by a friend sorted me out. You can see how much crud had built up, causing them to stick in place.
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post #5 of 13 (permalink) Old 07-21-2017, 12:44 AM
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I was under the impression that he was talking about the cold start brass pistons rather than the choke tubes ?

Steve

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Last edited by GTA R; 07-21-2017 at 07:50 AM.
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post #6 of 13 (permalink) Old 07-21-2017, 09:16 AM Thread Starter
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Right Steve, it´s about the brass Choke pistons...
But thanks anyway malcolm1.

At least one of the two pistons went out in the meanwhile with the help of a fan.
The second seems really tough...
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post #7 of 13 (permalink) Old 07-21-2017, 09:40 AM
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Do NOT apply force! Bad things WILL happen. Spray liberal Gumout choke and carb cleaner in the slot of the spring retaining brass clip. Wait 24 hours. Push down with thumb pressure on the pump rod. It probably wont move. Then GENTLY tap DOWN on the rod witha light plastic or brass hammer. While doing this, hold the butterfly plates as open as possible EASILY. Avoid any force. The piston may sloghtly loosen at this point. Try to pull up on the rod. If the piston begins to move, spray more Gumout and let it sit overnight again. Eventually, it will move if you are patient. You will still need to completely remove the piston, rod, spring and retainer and clean, plus clean the cylinder bore.
It is also likely there is more gum partially or completely blocking the "catacomb" passages under the Weber that feed the pump circuit and the starter circuit. There are more complicated tricks to fix these. Unless you are familiar with Weber repair, you may be well of sending them to a known good Weber specialist. Many of the Webers I restore have SERIOUS damage caused by well intentioned DIY repair. This can be a costly lesson. Ruining good italian made Webers is not an option as new Italian replacements don't exist, and parts can be costly.
From my experience.


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post #8 of 13 (permalink) Old 07-21-2017, 10:49 AM
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Gordon, what you say is correct for the accelerator pump piston, Johnny 105 is talking about the two cold start pistons.

Steve

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post #9 of 13 (permalink) Old 07-21-2017, 11:58 AM
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Cold start is the same deal. Just use a punch for the downward motion AFTER removing the 2 screws and the mechanism off the back of the Weber. Otherwise the little arms on the gears on the mechanism break off. Not good. The same choke cleaner, but on these you can screw an "easy -out" into the hole down inside the enriching piston to rotate them. Once you get them to move, they come out.
The important part is that FORCE must be avoided, or it will cost you $.


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Last edited by Gordon Raymond; 07-21-2017 at 11:59 AM. Reason: add a sentence
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post #10 of 13 (permalink) Old 07-21-2017, 12:16 PM
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Quote:
Originally Posted by GTA R View Post
I was under the impression that he was talking about the cold start brass pistons rather than the choke tubes ?

Steve
Good point. I just googled Weber Choke/cold start piston.

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post #11 of 13 (permalink) Old 07-21-2017, 03:13 PM
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I've found that lacquer thinner does an amazing job dissolving gas residues. It may take a while, but be patient.

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post #12 of 13 (permalink) Old 07-22-2017, 08:34 AM Thread Starter
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So, finally the pistons are out! Heat helped best it in my case...
I´ve put the Carb in the sun for some hours and then gave it the fan again.
With the help of a 6mm wrench as a lever it went out.
But this second one sat really tight...

Thank you all for you help...!!!
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post #13 of 13 (permalink) Old 07-08-2018, 02:29 PM
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Thanks for this thread. I've got three DCOEs with 5 out of 6 cold start pistons seized.
It is possible to insert a small screwdriver into the hole in the barrel of the carb where the starter mixture feeds in. This allows you to apply a small pressure to the underside of the piston. The second and third piston came out after heating the carb to 150 degC in an oven (tolerant wife permitting). Numbers four and five took heating and then dry-ice poured into the inside of the piston from on top. Then came number six, which is when I Googled this post.
Lacquer thinners is a good tip and seemed to be making progress with removing gunk, but the suspicion was leaning towards corrosion, so out came the vinegar. Still no joy.
So, despite my reluctance, out came the eazi-outs. I cannot believe how hard I had to lean on the eazi-out. I was really worried about cutting deep into the thin wall of the piston (although the last resort was always going to be to drill the piston out and replace it anyway), but eventually she started to move. Now, the reason for this post is to advise you to try and remove the eazi-out at the first sign of movement, otherwise your next challenge is going to be trying to find a way of gripping the piston to get the eazi-out out of the piston!!! without scoring the outer wall of the piston.
Thanks to all above for useful thread.
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