Screwdriver test

rrlund

Well-known Member
Is it necessary to do a screwdriver test on the injection pump of an early Super 55 if it's been sitting? There's an auction coming up with a bunch of rough old Olivers on it. One's an early Super 55 diesel. I just saw the sale bill this morning,so I don't know the first thing about it other then it's rough.Don't know if it's been run,or if anybody has tried to start it or what the story is.
 
Any time an American Bosch PSB pump has NOT run more than six months there's a GOOD chance the first time the engine is turned the head plunger and/or plunger gear guide GU 903 WILL be broken. Then it's good luck time for finding parts. Last Massey-Harris 44 diesel I helped a friend with took three pumps to find enough parts to get one that worked..
 
You must be eying that auction up in Stanwood that Art Smith is auctioneering. Looks like there are a lot of items there. I'd like to go because they have a 770 parts tractor on there that has a 3pt. If it is the factory hitch, i'd really like to add that to my 770 since I have an aftermarket 3pt, but I've got other obligations that day.
 
Two things to check. You need to take the timing window off of the side of the pump. Inside this cover the governor control rod is attached to the control arm with a hairpin clip. Remove the clip and unhook the rod. Break the wire that goes through the 2 screws and remove the 2 screws so that the control unit can be removed. Check it to be sure that the control unit can rotate. I have run into several unit that were stuck, One was on a Super 88 with amounted picker and of course the picker was down. If this happens the engine will only run one speed. The other 2 were both on Case diesels. Now when you removed the control unit you will find a square block inside the pump. This block has a slot milled in it where the tang of the control unit slides into. Insert the tip of the screwdriver into this slot and don't use a long screwdriver. When you move the screw driver up and down that block needs to move freely. If not remove the pump with out turning the engine! Rich may do it a little different and he is welcome to chime in!
 
See John S. explanation on the control unit, and the internal plunger sleeve. Scary part is although these are good checks to do, I've seen plungers broken that had free-unstuck metering sleeves and control units too. But, still WELL worth the time it takes to check them. What I tell guys to do if they are unsure is to remove the pump as is, where is. Meaning DO NOT even set the timing!! I've saved several pumps WITH stuck parts, but NOT if they have been turned over..
 
Thanks John for the information on doing the screwdriver test this will definitely save a lot of pumps. Thanks again for sharing your wealth of knowledge on these old fine Oliver tractors.
 
Just thinking out loud here, but if so few people know about this, why isn't SOMEBODY making replacement parts?
 
Ya,that's the one. There's that consignment sale in Edmore too that day,but if it's a nice day I'll probably hook on to the trailer and head for Stanwood.
 
Good question. Used to be any American Bosch PSB part was available, even had a rebuilt exchange hydraulic head program for all tractors with the PSB pump. Now I cringe every time a PSB pump comes in for repair..
 
I've dodged a bullet twice on PSB pumps......5 years ago I bought a GVI MM diesel with a PSB pump that hadnt run in 20 years...We pulled it 5 feet and it was running...At that time I didnt know about the screw driver test..Recently I bought a Cockshutt 50 diesel with a PSB pump that hadnt run in 12-15 years..About 2 years ago a new owner pulled it to break loose a slightly stuck engine..He went no further with it...I bought it knowing the PSB pump could be damaged...I got very lucky and now have the 50 Cockshutt diesel running....
 
I did the same thing with a 30 diesel. Knew nothing about it and had sat for years. After the fact I learned about it and got a hold of a 570. That one got checked. Both ended up being fine.
 

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