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Vacuum Pump replacement

Posted: Thu Sep 17, 2020 1:28 pm
by Stinger
I replaced my vacuum pump on a Maule MX-7-180A yesterday. The original lasted 26 years I think and 840 hours.
Bought an Airborne 211CC off Aircraft Spruce last week, luckily along with a vacuum pump wrench to qualify for free shipping (would be impossible to replace without one as I found out).

The nuts on the top two bolts are easy enough to loosen and back off, but the way it's designed the nuts can't be totally removed while the pump is tight against the housing, there's not enough of a gap.
The nuts on the bottom right (looking cockpit forward) needed the wrench and weren't too bad to loosen enough that my fingers could back them off.
The nuts on the bottom left were downright impossible. It almost forced my hand into doing a G5 replacement I've been thinking of for a couple years. Anyway, this one absolutely, positively, needed the vacuum pump wrench. However, there wasn't enough room for even a little movement with the oil filter blocking the rotation. So, I had to stuff some rags under the oil filter to make the removal as clean as possible and then remove it. Once it was out of the way, it was still difficult to remove the nuts on the vacuum pump, but at least it was doable.
Once all the nuts are loose, you can back them off some which will give enough room to pull back the pump to make room for the nuts to come totally off.

Make sure you remove the old gasket as well before putting on the new pump.

The process to get the nuts back onto the bolts for the new pump was even more of a pain then getting them off.
For all four, use a pair of needle nose pliers to get the washers on the bolts, that part is simple.
Again, that bottom left is the real issue. No room to hold the nut, spin it on the bolt, etc. I ended up taping the nut to the wrench to get it lined up with the bolt, then took a flat screwdriver to wedge between the nut and the pump, and then gingerly spun the nut onto the bolt. Spent about 5 tries without the tape with the nut falling out of the wrench each time, and then another 10 with the tape before I thought of the screwdriver to put pressure behind the nut, which took another 3-4 more of dropping the nut each time onto the floor and having to search for it to try again.
Top two bolts weren't much of an issue.
Bottom right was difficult as well (again, use the flat screwdriver to put pressure behind the nut so you can spin it onto the bolt). Making sure the nuts were tight was surprisingly difficult, no real good way to describe it, but the wrench will get caught up in motor mounts and hoses, and it's just frustrating.

Don't forget to put an oil filter back on.

All told, it took about 2.5 hours to make the replacement.

Re: Vacuum Pump replacement

Posted: Thu Oct 15, 2020 12:13 pm
by Allparg
Looking for the answer to removing and replacing vacuum pump on a 2005 M7-235 b4b5. My engine has the full flow adaptor for a spin on champion filter. Bottom left nut appears impossible without removing oil filter adaptor. Thought I would check here before going any further.???

Re: Vacuum Pump replacement

Posted: Fri Oct 16, 2020 2:55 pm
by Tomkatz
You need the vacuum pump wrench! Pretty much can't remove it with out the wrench. You will also find putting tape on the rear of the wrench to hold the nut in place when re-installing it will help greatly. Aircraft Spruce carries the wrench as does many others.

Re: Vacuum Pump replacement

Posted: Mon Oct 19, 2020 4:49 am
by drak130
All part,

I have the same setup as you (same motor and filter) and will be replacing vacuum pump this winter. I would be very interested in lessons learned when you are done. Some things need to be learned the hard way but I would rather learn from the experiences of others if I can.


Re: Vacuum Pump replacement

Posted: Mon Oct 19, 2020 11:20 am
by Allparg
I have done many pumps before and my usual tools were constricted... I posted for advice from those familiar with the Maule for any specific tricks... In the end it was the old standby, ”screwdriver and hammer method...” Now that that pump is gone upgrading to gi275’s.... pics to follow!