The high temperature outside is 13 degrees. But I’m jonesing to get started on the car repairs. I’ve made a list of things to do and checked it twice. Today’s task is to remove the convertible top motor. This is quite possibly one of the easiest things in the car to remove. So easy that I don’t need to post any pictures. Besides, it’s cold out. I don’t want to operate a camera if I don’t have to.
Here’s a summary of a guide from the service that is going to rebuild the motor for me. There are four things that go wrong with convertible top pumps. Based on reading this, it’s a good idea to check the voltage to the pump from time to time. The pump should draw 30-35 amps when in operation. If it is drawing more than that, it’s time to repair or replace. The four problems are:
1) The pump operates erratically when the switch is activated. The armature in the motor is shorted out. Another symptom of a bad armature is a worn-out top switch. Components in the switch melt because it is designed for a maximum 40 amps, and a shorted out motor will draw over 100 amps.
2) You press the top switch and nothing happens. The brushes in the motor are worn out. Or mice got into your car and chewed through one of the wires leading to the motor.
3) The top only works in one direction. A check valve in the pump is shot.
4) The motor works normally but the top doesn’t. There’s a leak somewhere. That’s why your car smells like old transmission fluid.
No matter what you have a busted motor that should be replaced ASAP.
This procedure will work for any GM “A” body made between 1968 and 1972.
Tools you’ll need:
- A pry bar. Use the one for your spare tire jack. Unless you are Mr. Bungle and never bothered to replace it when you bought the car and the jack was missing.
- ½” box wrench
- Rags
- Wire ties
- #3 Phillips screwdriver
- Flag tape. You can get this at any hardware store. It is your friend for marking hoses, wires, and anything else that you’re not going to remember the proper location for.
- Sharpie
- Soapy water
- A new set of rubber mounting bushings and fill plug. These cost about 10 bucks from parts suppliers or eBay. Get two plugs because you’ll need one for the:
- Handy Dandy Dr. Fisher convertible pump bleeder tool. I’ll update this when I get around to re-installing the motor.
- A couple of soda bottles. Make them 2-liter. If you don’t drink soda, buy a couple of 2-liter soda bottles and pour a couple for R.E. Olds.
- A 50oF or above day. You’ll need to operate the top, and it has to be warm. This is an arbitrary number, born of one of my dad’s two rules about owning a convertible: if it’s over 50 you drop the top. For the record, the second rule is: you own a convertible because sometimes you have to put the top up.
Do this with the top in the raised/up position. It’s a hydraulic system, so the position of the top shouldn’t matter for servicing the pump. Having the top up gives you room to work, and you may need to raise the pump when you bleed it. If the top is down you have no clearance. And you’re fucked if you’re outside and the weather turns foul.
1) Disconnect the battery. This goes without saying. Mr. Bungle may skip this step. Mr. Bungle may also have some nerve damage from repeated electrical shocks.
2) Clean out the trunk. Remove everything including the trunk liner. You don’t want to get everything soaked with fluid. This is an excuse to get rid of all that crap that accumulates in your trunk. And it gives you room to work. Unless you’re Mr. Bungle. In that case, knock yourself out. Literally.
3) Lift up the well liner. This is the black vinyl bag that separates the trunk compartment from the passenger compartment. When down, the top folds into it. If you’re like me, you use the well liner to store the emergency jacket. What’s the emergency jacket? That’s for when you get the first nice spring day and you decide to take a quick spin with the top down. Only to realize that when it’s 52 degrees out, going 30 MPH with the top down is pretty fucking cold.
You won’t need to remove the bag. Just lift it up at the seams like you are turning it inside-out. I tucked the corners behind the piston rods to hold it up out of the way.
4) Remove the top motor. You should now have a clear view of the top motor. Unless you were doing this when it’s cold and you were running the car inside the garage to warm the place up. In which case you’re dead and still reading this and that should creep you out. The motor is held in place by three rubber acorn bushings. Use the pry bar to lift the motor, making sure you are NOT tucked under the reservoir cap, which is the coppery part of the motor. That thing is soft and you’ll bend it or puncture it if you are not careful.
Convertible top motor, removed from car. The copper-y part on the left is the pump reservoir. The aluminum part in the center is the pump. The steel part on the left is the motor. The bag underneath is a poor food choice.
The guide that I read said to use the soapy water to lubricate the bushings so they pop out easier. My pump motor was the original motor.* Those rubber bushings were original. Only they weren’t rubber any more. More like some crusty material that once was rubber. They crumbled. This is why you bought the bushing kit, right?
5) Remove the hydraulic piston hoses from the pump. There are two sets of hoses: one for lifting, one for lowering. Use the flag tape to mark which hose is which so you don’t reverse them. Unless you’re Mr. Bungle. Then use the Sharpie to correct the label on the top switch.
Using the ½” box wrench, remove each set of fittings. Because of the check valves, very little fluid should leak from the pump. Wrap a rag around the fitting and use the wire tie to secure the hoses to the frame. If you keep the fittings elevated they won’t leak fluid.
6) Drain fluid from the pump. Put the #3 Phillips in the divot of the rubber fill plug and work the plug out of the motor. Unless you have the factory tool for removing this plug. But you don’t have it. So just use the screwdriver. In my case, the plug met the same fate as the acorn bushings. No matter, you remembered to order the replacement bushing and fill plug kit, right? Now just pour the fluid out. It’s going to be either Type “A” transmission fluid**, brake fluid, or (if the pump has been serviced at least once in it’s life), Dexron transmission fluid. Either way, it’s going to smell kinda funky if it’s been in the pump for decades. Drain the fluid into one of those soda bottles. Use a funnel. I shouldn’t have to say that but I will. You should get 6-8 ounces of nasty, smelly fluid out of the pump.
7) Replace/rebuild the pump. If you haven’t already decided what to do, now is the time to decide. If you are impatient, you’ve probably already got a replacement pump. That’s cool. I like to rebuild or repair original components whenever I can. Since my pump is the original pump I’m opting to have it rebuilt. If I’m happy with the job I’ll plug the rebuild service when I’ve finished the installation.
Which motor do you need? As I understand it, they’re all kinda universal. But if you want an exact match the part number is stamped on the motor cover. There’s also a serial number stamped on the pump casing. At least that’s where it was on mine. If you send yours out for a rebuild, record the part number and the serial number so you know you’re getting your old pump back. If you do the rebuild yourself, it looks pretty easy. The hardest part would be rewiring the armature. I’m lazy and I’m paying someone else to do the work. Kits for rebuilding the pump/motor are readily available.
The part number for the motor is found on the motor casing. All GM top motors start with “5044”.
The rest of this will have to wait. The way things are going with the weather I won’t be able to finish this job until May 2014. When I update I’ll talk about flushing the old fluid from the pistons and bleeding out the motor.
*How did I know it was the original pump? It had an old label on it to remind the person who services the pump to only use Type “A” transmission fluid.
**Did you know a major ingredient in Type “A” transmission fluid was whale oil? Yeah, GM was killing Shamu so people wouldn’t have to learn how to drive stick.