Yesterday I did a line job off my boom pump, it didn't pump very well and kept plugging. The mud was also getting loose and then stiff. Time for new mud cups.. Every time i'd stroke reverse it would flood the concrete with water from the box. The concrete would go from a 4 slump to an 8. WTF contractor wasn't pleased, Blamed the RM driver. I guess i should have taken the blame.

I wont tell either

Who put to much water in, had to be the RM driver, Brian all jokes a side you pump pushes mud out not water if your mud cups are in need of replacing your water box would have been full of concrete surry.

Ed when the mud cups go bad, yes they do leak grout but when the pumps in reverse it sucks water out of the box in a big way. So when you loose water it goes into the concrete. On a small line job its quite noticeable to a trained eye. I must have lost 30 gallons per load.

Quite logic actualy. When you suck back you get a vacuum so the water gets sucked past the mudcups.

You reeaaallllly have to change your parts a BIT earlyer my friend ;-) (like half a year??   ;-)

Or maybe you've been pumping flat for a day without water in the box. Than they burn quickly...

You get vacuum every time the cylinders load while pumping, but maybe not as strong of a vacuum compared to sucking back on a plug? Put a half a package of slick in the waterbox to thicken the water to get you through until you can get a real fix. But be sure it's the white stuff, not the brown. Also to reduce the chance of it getting into the hydraulic oil, keep the water level below the bottom of the rod where it enters the hydy cylinder. I think this is good practice all the time, unless you as pumping super-slow.

you are kidding about keeping the water below the rods in the waterbox... right??? water won't go into the cylinders. the seals hold in hydraulic oil (under pressure) and there's a wiper there too. no water will pass those seals. think about it.

putzmeister actualy recomends to keep the waterlevel below the seals specialy when you start your job and the system is cold. those seals wear out to muddy. 

When the hydraulic-oil is cooling down it will draw water in to the hydraulic-oil from the waterbox.... And as Dipstick say , Putz recomend not to have water over the sealings and scraper over the night . They recomend to change them every 600 hour . And YEAS they wearout , when I didn't know better about the oil and sealings I was operating a Schwing 2525 longrock and after 2400 hour they was wornout and I had to change them at once , to much water in the hydrauli-oil . I had much over 2000 ppm of water in the oil , they stoped to count the level at 2000 ppm.

The seals are biased to hold pressure one way. When worn, water will be drawn in if it's above the seals, as will air, but air isn't nearly as bad of a contaminant. Even though it is likely only a minute amount drawn in, the cumulative effect is what causes the problems. And I certainly would want to minimize the amount of the chemical slick that may enter the oil. The brown slick is an abrasive, that's why I wouldn't recommend it as an additive to the waterbox. Thanks for the backup Dipstick and Vasa.

Not sure how true it is, but i was told that sermacs have two sets of seals one to keep the water in the box and one set of oil seals with a gap between them that allows the water to drain away if it passes through the seals! 

My old PUTZ on a hot day will shut down if there is no water in the box cause it make the oil hot so saying that water cools the rods and the oil, no water rods get extra hot.The other night we were pump 200 yards and every 75 yards I would check my water level cause it splashs out had to add more everytime.

It's like BigEd says to , the water cools the oil also . On some long bridge-pours I have a waterhose conected to the waterbox and have it running slowly with fresh water to cool the oil and clean water in the box . Lucky Phil more brand than Sermac has tried it with sealings with drainingholes for the water.... But they use to be clogged with cementslurry when the mudcups are wornout and start to leak.

I got new mud cups from CPR today. Haven't put them in yet. Yeah I waited too long.

Any good tips to putting them in? I know grease, and bolt on all the way to keep them straight.

Clean the entrance of the pump cilinders very very wel. I always use an old knive to get all the concrete of.

Use tyre greese. The one they use to put tyres on rims.

Has anybody ever tryed dry ice to cool the new cups and the excepting cylinder, I don't think it would hurt anything.

The rubber would get hard and not be able to flex enough to push into the cylinder. Besides it may get brittle and crack and break.

I know that you are thinking it would shrink so you could sweat-fit it, but it wouldn't shrink enough.

Mud cups have a larger diameter wedge at both ends to give a good seal for pumping pressure as well as the vacumm to load the cylinders.

Muddy your wrong you fill that box up completely and the vacuum it creates will pull water into your cylinders maybe not on a brand new pump but none of them stay new for long I have seen it first hand it happens.

b-alto it is possible to score the material cylinders with to worn out cups, not good then yor water box always leaks!