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Cruise Actuator Fix # 2

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
Well, now my cruise control has died again. I tried my own advice and this time it didn't have any affect. I took it apart and tried bending the little bars out to make better contact but that didn't help either. I then took the whole electrical part off the round diaphram. and lubed the big o-ring between the two halves. I didn't expect it to work but I was shocked to find that it did. The symptoms this time were about the same as last time. It would slowly lose speed after running for a few miles. I suppose what was happening was the o-ring was getting pulled into the diaphram and causing a vac leak. Next time this happens I will just replace that o-ring since its now got 174K miles on it and is no doubt dried out and shrunken a little. hope this helps you folks that are currently experiencing troubles.

In this pic I have an arrow pointing to the screw that I recommend that you DON"T take out or you'll have a bunch of small loose parts to deal with. Remove the two that hold the plate to the plastic part of the diaphram on either end of the metal plate. You can just leave the diaphram attached to the car.

regards
.
.
lone73
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cruiseActuator02.JPG
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
Lone73 I read your post and ran right out to the garage. I removed the actuator from the servo. The O ring I found was sealing an ovel hole between the actuator and the diaphram. I grabbed my axle grease and did as you suggested. I have a question. When you removed the actuator do you remember seeing the diaphram spring covering part of the hole that the actuator mates with? Next I went out to give it a try and now I don't have anything;help :hb :BDH
 

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
John,

By "nothing" do you mean it doesn't work at all???

Yes, the edge of a big spring is visible in that slotted opening, seemed to be kind of blocking the opening to me. I think its supposed to be that way.

I'll bet your problem was the o-ring all along but now you've induced something else...electrical maybe? Those connetions that are in that pic I posted would seem to be a weak link to me. Try prying gently out on them like I'm showing in the pic. Thats probably a better way to ensure contact than just cleaning. You didn't take that screw out did you? End up with parts all over the place?

Check to see that the vac lines are in good shape and back on the proper connectors. If you don't find anything I'd take the solenoid assembly back off of the diaphram and make sure the o-ring didn't get dislodged during reassembly.

Good luck
 

ddick9366

Member
Joined
Feb 25, 2007
Messages
24
Location
Greenwood, IN
Corvette
'94 Polo Green Convertible
Cruise Control Trouble Shooting

John,

Having recently pulled my cruise control apart for cleaning and bench checking as Lone73 suggested, I did notice that the spring inside the vacuum area was indeed visible, so based on what you saw with your system, I would venture a guess to say that yours is normal.

ddick9366
 

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
I'd check the o-ring again, and those connections as stated above. Failing that you might try replacing the o-ring. Sounds like the diaphram is leaking in air when the cruise is actuated - not building vacuum.
good luck
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
I played with the "o" ring again and was able to get the cruise to work intermittently. Went looking for a replacement "o" ring and discovered that this is not an ordinary "o". It is flat on the side that mates with the actuator and rounded on the side that seals against the servo. Needless to say everybody looks at me with a dazed look and says not available need to replace the whole unit. What do you think of my using a little blue silicon on the seal? Oh I have not checked GM yet to see if I can get the "o" ring, (fat chance there):v ;help
 

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