P38A Any tips for getting the EAS pump piston off its spline?

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Montyjohn

Montyjohn

Well-Known Member
Posts
241
Location
UK
I'm re-building my EAS pump as it's scored to hell. But I just can't get the piston off its spline.
I've removed the grub screw, and fully undone the screw under it (screw still in, but fully undone).

I've been tapping the thing, prying on the backside like a monkey and it just won't budge.

I was just about to see if I could replace the seal in-situ, but thought I best check I'm not missing anything obvious before the rest of the job is made unnecessary harder.
Thanks.
 
Would it work if u removed the compressor head and piston liner to change the seal

the more experienced members will be along to confirm if that will work
 
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I just use a medium flat screwdriver down between the crank & back of the housing. Wriggle & twist the screwdriver, and the crank should pop off the shaft. Then extract through the front where the silencer panel goes.



IMG_0494.JPG
 
pwood999 said:
I just use a medium flat screwdriver down between the crank & back of the housing. Wriggle & twist the screwdriver, and the crank should pop off the shaft. Then extract through the front where the silencer panel goes.



View attachment 309484
Click to expand...
This is exactly what I've been doing.
I'm a little nervous about being any more abusive with it.
I might spray some WD40 (not too much) down there, let it sit, and try again later.
 
Rubberknees said:
Try undoing the grub screw a bit further. I have found the odd few longer than you think
Click to expand...
I actually backed it all the way out to eliminate it as a possible reason, but couldn't quite get it out through its hole, so drive it back in one turn.
So I don't think this should be the issue.

I reckon someone put loctite on the spline because I'm now putting a lot of force on it and it ain't budging.
 
The shaft is not splined on any pumps & have seen.

Rather than WD40, get some proper penetrating fluid such as RP-90. You could also try a micro blow torch with flame turned down to minimum & slightly heat the crank around the shaft.

Failing that, take the brush plate & casing off the pump (careful not to drop it, or the magnets will shatter). Then put a chunky screwdriver by the sides of the crank to hold it steady. Turn the armature by hand so the shaft cracks the Loctite if that's what's in there.

Like these pictures.
IMG_0495.JPG
IMG_0496.JPG
 
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I've just finished getting the cylinder off and that took a huge amount of abuse to separate from the head.
I had the cylinder in the vice whilst I tapped and pried on the head and it took a lot of force to separate them.
Is this normal?
Just picking all the o-ring bits out now that are well and truly stuck in their groove (I think glued)

Does this sound like someone glued the sleeve to the head?

If this is the case, I'm going to try and replace the piston seal in-situ.
Hope I can still hammer that ring in place enough. Might be able to wedge somehting under the counterweight to take the strain.
 
I think this head might be junk. Unless I can find a solvent that works, the only way to get the ring out is to scrape out it with with a screwdriver. So far I can only get tiny pieces out and if I go any harder I'm going to gouge the head.

Why would you glue an o-ring in?

Grrrrr.
 
They probably used something on the cylinder and it got into the ring after assembly. Use a Stanley knife around it & gradually clear the o-ring slot. Replacement cylinder is part of the better kits anyway.
 
It's back together.
I found a needle worked the best for getting the crap out of the o-ring recess without scoring it.
Never did get the piston off. I think it's on forever.

Setting the piston seal ring home was pretty easy in-situ. Just place a washer under the counter weight before hitting it.
Getting the new cylinder on with the piston in-situ was a bit of a faff, but not too bad.

Before testing it was really had to turn the crank, I was worried it wouldn't have the power to turn, but it ran fine, lots of airflow.

Next time, I think I'll buy a second hand pump and refurb that.

Please don't glue your pumps together. It makes baby Jesus cry!
 
Montyjohn said:
It's back together.
I found a needle worked the best for getting the crap out of the o-ring recess without scoring it.
Never did get the piston off. I think it's on forever.

Setting the piston seal ring home was pretty easy in-situ. Just place a washer under the counter weight before hitting it.
Getting the new cylinder on with the piston in-situ was a bit of a faff, but not too bad.

Before testing it was really had to turn the crank, I was worried it wouldn't have the power to turn, but it ran fine, lots of airflow.

Next time, I think I'll buy a second hand pump and refurb that.

Please don't glue your pumps together. It makes baby Jesus cry!
Click to expand...
Was baby Jesus helping🫣👍
 
Montyjohn said:
I've just finished getting the cylinder off and that took a huge amount of abuse to separate from the head.
I had the cylinder in the vice whilst I tapped and pried on the head and it took a lot of force to separate them.
Is this normal?
Just picking all the o-ring bits out now that are well and truly stuck in their groove (I think glued)

Does this sound like someone glued the sleeve to the head?

If this is the case, I'm going to try and replace the piston seal in-situ.
Hope I can still hammer that ring in place enough. Might be able to wedge somehting under the counterweight to take the strain.
Click to expand...

No.

Getting the ring off can be a pain but if you just keep running a knofe around it then you can usually get a small screwdriver in and prise the locking ring off. I cannot see any advantage to using glue anywhere. Odd thing to do.
 
gstuart said:
hi @Montyjohn

hope u don’t mind me asking but did it work at all about removing the head please or was it alot of messing around

Just so I know for the future as of course wouldn’t wish to guide anyone in the wrong direction plse , many thks
Click to expand...
I already had the head and liner off when I was trying to get the piston off the shaft.
As mentioned above change the seal Insitu was fine in the end. Just a little tricky getting the liner on but otherwise straight forward.
To tap the ring on I recommend putting something under the counterweight to take the load off the shaft.
 
Montyjohn said:
I already had the head and liner off when I was trying to get the piston off the shaft.
As mentioned above change the seal Insitu was fine in the end. Just a little tricky getting the liner on but otherwise straight forward.
To tap the ring on I recommend putting something under the counterweight to take the load off the
Click to expand...

Good ur sorted
 
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