Top goes down but not up

[94CSC]

The top on my 94 goes down fine but will not come up. Prior to it not coming up at all it was very slow and then one day just stopped. The top shop put a new pump in it and is still experiencing the same issues. He said neither of the cylinders appear to be leaking but that would be his next thing to replace. He did mention binding but I don’t think that’s a problem as I am able to get the top up if I assist it with the motor running. Maybe the cylinders can go bad without leaking. He mentioned there is fluid coming out of one side of the pump but not the other. Not exactly sure what that means. Has anyone experienced this? Any advice on what steps to take here?

[55trucker]

Vert top cylinders are nothing more than double acting hydraulic rams.

Pressure is applied from one or the other ends port, if the internal valve is allowing fluid to pass by it in one direction it will do so in the other as well. There doesn't have to be an external leak.

Going down is easier than going up. I take it when the top was serviced the entire system was flushed & tested for fluid flow in Both directions?

 

[94CSC]

What he is telling me, if I remember correctly, is that fluid flows in one direction but not the other. That’s what made me think it might be the cylinders. 
I’m going to call him again tomorrow to confirm the system has enough fluid and all air has been purged. 
The shops been doing this forever so I’d think they’ve done these things….

[55trucker]

You certain that the plastic shutoff valve on top of the pumps manifold is completely open?

[94CSC]

No im not, he didn’t mention that at all. One more thing to ask about!

[94CSC]

Do you think it could be bad cylinders?

[55trucker]

Sitting here?

 

Do not know, one has to test them 1st before condemning them.

A good bleeding is #1 on the list to do, because the cylinders do not lay flat & one end is usually above the pump assembly getting the air out is critical.

 

[94CSC]

Fair enough! Is the best way to get the air out to cycle of the pump over and over?

[55trucker]

Read this article provided from the GM manual, altho older GM ragtops the process is still the same, the bleeding process is not difficult, just some time & few needed basic tools to do the bleeding.

 

 

https://www.chevelles.com/threads/convertible-top-bleeding-and-filling.113945/

[94CSC]

Great stuff, I’ll read through it. I’m going to have him-

Double check fluid level

Check that the valve is all the way open at the top of the pump

Confirm the air has been purged

Bleed entire system 

 

[94CSC]

Just spoke to him. He says this pump does not have a shut off valve at the top of the manifold at all. He said that he has bled the system as well. Time to find another shop.

[55trucker]

I'm loathe to throw money at a problem without diagnosing the issue 1st, pull out the rear seat assembly & the side trim panels, with the top up & fastened at the windshield can you get at the cylinder's upper heim joints to disconnect them from the top frame structure.

Now go thru the  up/down process again, do both cylinder react properly, move freely & do not bind anywhere?

[94CSC]

I’ll have to give that a try. Haven’t had the time yet. 
Detailed it though!

[55trucker]

That's a nice clean car......

want to come up & do mine?.........the arthritis is a *bitch*

[94CSC]

Ha! On my way!

[94CSC]

Ended up being the cylinders. Second shop replaced them. First shop threw a pump at it-wasn’t the issue which is frustrating. But all fixed now!

[kinger_13]

Does anyone know if there is a kit to rebuild these two cylinders or the pump, just curious if there was I would love to get part number so I can order them to redo my parts