Pump removal - direct drive

Hey all :slight_smile:

I just bought a used GX390 with a blown pump. I don’t care about the pump, just the engine. Thing is, I can’t get the pump off! I’ve changed over lots of these, but this one seems like it’s seized on the shaft.

Bolts are out, the pump moves left and right, but it just won’t pull off.

Any tips before I get the rubber mallet?


Penetrating oil and a pry bar on each side.


Thanks :+1:t2:

I’m about an hour into that :tired_face:

I’ve tried putting bolts through and pushing against the engine, but the alloy is too soft and it’s damaging the casing.

It’s moved a few mm, that’s all.

More lube…

Look for a set screw


Can you get this where you are?

If not, some people use an ATF and Acetone mix to break free frozen metal parts.

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Look at the side of ur pump… where it goes on the shaft. Look for s hole, or a slit and a small Allen head screw. Take that out …,some have them some don’t


As @Patriotspwashing was saying some pumps have a tiny set screw that will not let you slide the pump off. I’d check for that first before going the pry bar route.

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Thanks for all the help guys!

It’s getting there. Took the tank off for access. Used a whole tin of lubricant…

It’s moooved about a cm!

Oh wow, this is brutal.

I don’t have the right tools, I know - I’ve had to get creative. Don’t judge!

(I only used the spade to stop the damage from tightening the screws to use as a puller) oh the shame ha ha.

Now it’s stuck there. At least I can get more lube onto it directly…

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Your using a SFH instead of a BFH

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Hose down the shaft, pound the pump back on a half inch, let sit a bit, work it off a bit more.

I wonder if he could somehow chill the shaft so it shrinks the metal?

Maybe work it back and forth on it’s axis? The motor puts force on that key in one direction…


Phew. It’s off.

It was rusted on good.

Anything to do to the shaft before I put another pump on?

I was going to lightly sand it and the put some marine grease on it?

Thanks everyone :+1:t2:


Go on @florida_condo_cleani I’ll bite…?

Anti sieze would work better. Where’s the key?

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BFH = Big Fu***** Hammer

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I just have to say this. I know you’re from down under and y’all do everything bass ackwards but around here we use The Freedom Measurement System. I only tell you that because we have no clue what you mean by millimeters and centimeters and whatnot. INCHES! WE NEED INCHES AND FRACTIONS OF INCHES!


Replace that housing? Ohhh, that hurts to look at.

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Surely that can be saved? A steady hand and a sharp file? Or is that a no-no? I’ve never worked on anything but belt drives.

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It’s probably fine. File off the rough edges, but I would have sleepless nights with gouges like that. :alarm_clock:

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