Dometic T series macerator pump

NOGILLS2 · Nov 1, 2019

Hello all, I am looking for information to troubleshoot Dometic T series macerator pump. I replaced the duckbill valves, only to find the pump is not pumping. After a lack of information, I purchased a new pump and installed it, it is working fine. Only I am still not happy, I planned to rebuild old pump and keep it for a spare. Only I dismantled pump and cleaned and inspected it and found nothing, nothing appears to be broken, Bellows is good, o-rings pliable, so I plan to test pump tomorrow. But have been baffled that there is NO information on what to look for, or common problems. I expected to find bellows was cracked, but it is fine. Is there information out there? If so where? A lead would be much appreciated. I plan to introduce myself, after I post this.

Spinner · Nov 1, 2019

Try contacting Marine Sanitation and Supply in Seattle:

https://www.marinesan.com/Default.asp

Comodave · Nov 1, 2019

Peggie The Head Mistress will probably have an answer for you. You might send her a PM.

syjos · Nov 1, 2019

Did you put water into the pump or grease duck bills with Vaseline? Without water, the pump will sometimes not pump.

When the pump is on, does the bellows go up and down? If not gearbox is broken.

When reassembling bellows to pump, the lid O-ring sometimes get twisted or the one inside the bellows come out of the groove or gets pinched causing an air leak. The O-ring inside the bellows has always been troublesome during reassembly. Grease the O-rings with Vaseline real good and when inserting the bellows, push it on gently until you feel resistance, which is the inner O'ring. Make sure the bellows is square to the lid and push it on evenly all around with a quick push.. The goal is for the O-ring to go onto the lid squarely so it doesnt have an opportunity to squish out of the groove.

Grease duck Bills with Vaseline when assembling.

You can pressure test the pump by plugging the outlet and inserting air with an adapter. Use very little air pressure, 10 - 15 psi. Listen for leaks inside the bellows. A fine, invisible crack in the bellows at the seam can cause a leak. If you take the motor/gearbox off, you can dump the pump into a bucket of water to make small leaks easier to spot.

NOGILLS2 · Nov 1, 2019

syjos said:
Did you put water into the pump or grease duck bills with Vaseline? Without water, the pump will sometimes not pump.

When the pump is on, does the bellows go up and down? If not gearbox is broken.

When reassembling bellows to pump, the lid O-ring sometimes get twisted or the one inside the bellows come out of the groove or gets pinched causing an air leak. The O-ring inside the bellows has always been troublesome during reassembly. Grease the O-rings with Vaseline real good and when inserting the bellows, push it on gently until you feel resistance, which is the inner O'ring. Make sure the bellows is square to the lid and push it on evenly all around with a quick push.. The goal is for the O-ring to go onto the lid squarely so it doesnt have an opportunity to squish out of the groove.

Grease duck Bills with Vaseline when assembling.

You can pressure test the pump by plugging the outlet and inserting air with an adapter. Use very little air pressure, 10 - 15 psi. Listen for leaks inside the bellows. A fine, invisible crack in the bellows at the seam can cause a leak. If you take the motor/gearbox off, you can dump the pump into a bucket of water to make small leaks easier to spot.

Thank you, this is the knowledge and wisdom I have been looking for. I will take the pump apart and follow your suggestions. I will let you know what I discover.

Dometic T series macerator pump

NOGILLS2

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Spinner

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Comodave

Moderator Emeritus

syjos

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NOGILLS2

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