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CMEP-OL owners...anybody actually seen the updated bearings?

Placed order for the latest and greatest bearings from Bhogart third week of February, told them my pump was down. I think the most basic of customer service would have been to tell a guy that they didn't *actually* have any of them in yet and they were still waiting on them to come over on a boat from China, but they took my card number and didn't fess up to being still waiting on them until I called about 2 weeks later, said they would have them "soon".

Sent an email Mar 10 asking if my order had shipped yet, no response whatsoever.

Called again last week of March, was told "the tech" dealt with all CMEP stuff but that he had bearings and they would "prioritize" shipping my order out.

I finally got infuriated enough on Monday that when I called and they STILL hadn't shipped yet, I told the person who answered the phone that this service was abysmal and that I was cancelling my order.

Has ANYONE actually received upgrade bearings from Bhogart or are they just vaporware?

Initially I placed an order with Bhogart because their bearing price was better then Ecogreen's, who wanted $81.25/ea for their bearings and didn't lie about how they were waiting on parts to arrive from overseas. Clearly that didn't work out so well. Since my customer didn't have a month and a half to wait around for Bhogart to get off their dead asses and ship what had already been ordered and paid for, we ended up installing some 6908ZZ's from eBay which cost a whopping $12/each shipped.

But I'm still curious for when the next time the bearings fail.

eBay is showing a US seller selling 6908 Zirconium Dioxide bearings with a PTFE cage for $143/ea shipped out of Anaheim. No shields, no grease.

There are Chinese ZrO2 bearings you can get for around $40ish shipped, same deal no shields or grease. At least a couple say that they are fine to use dry in "high vacuum environments" but no word on how long they will last if you actually do so.

I'm halfway tempted to try buying a pair of hybrid bearings with ZZ shields, stripping out the petroleum grease and replacing with something like Dupont Krytox 226. In which case the bearings will be $20ish dollars apiece but a tube of that grease is $26/oz shipped depending on how big a package you buy and which grade. That expensive grease is supposed to last well in vacuum environments though.

Just curious if anyone else has already got a set of the upgrade bearings from either Ecogreen or Bhogart and if so what they are actually like and how they are performing for you.
 

Rickys bong

Member
Veteran
Ceramic bearings probably won't help. The issue is a basic design flaw where the crankcase is pressurized from the pump outlet. The gas dissolves into the bearing grease under pressure and when the pump is shut off and crankcase pressure drops the gas boils out of the grease pushing a bit of grease out of the seals.

When this cycle is repeated many times the bearings will get dry and overheat.

I still think the best fix for this issue is to vent the crankcase. Drill and tap a 1/8npt hole and put in a fitting with a tube connection you can vent outside.
 

Gray Wolf

A Posse ad Esse. From Possibility to realization.
Mentor
ICMag Donor
Veteran
Ceramic bearings probably won't help. The issue is a basic design flaw where the crankcase is pressurized from the pump outlet. The gas dissolves into the bearing grease under pressure and when the pump is shut off and crankcase pressure drops the gas boils out of the grease pushing a bit of grease out of the seals.

When this cycle is repeated many times the bearings will get dry and overheat.

I still think the best fix for this issue is to vent the crankcase. Drill and tap a 1/8npt hole and put in a fitting with a tube connection you can vent outside.

Or through a bleed valve to the intake of the pump, so as to produce a gas ballast effect.
 
Ceramic bearings probably won't help. The issue is a basic design flaw where the crankcase is pressurized from the pump outlet. The gas dissolves into the bearing grease under pressure and when the pump is shut off and crankcase pressure drops the gas boils out of the grease pushing a bit of grease out of the seals.

I've been told that the use of ceramic or hybrid bearings will reduce noise. Haven't actually tested to see if the claim is real or marketing bullploppy.

That Dupont Krytox grease is supposed to be a lot more resistant to butane intake and loss under vacuum. A standard petroleum grease like the original CMEP bearings had will boil off under vacuum given enough time, and I know that in spite of the CMEP marketing, if you run it into vacuum pressure territory the crankcase will also be under vacuum (because ring blowby is a two way street). If you never ran the CMEP under vacuum I suspect you would get a lot more life out of the bearings.

I still think the best fix for this issue is to vent the crankcase. Drill and tap a 1/8npt hole and put in a fitting with a tube connection you can vent outside.

No doubt that would make it better. My only fear with that is that if the line is left open, with the inlet side of the pump under vacuum it would pull ambient air in thru the vent line and pressurize your refrigerant tank with a potentially explosive mixture of air and butane.
 

jswick93

Member
We just picked up our CMEP-OL from Bhogart. It took 3 months to get it fixed and brought to the closest bhogart store. I was charged $320, so as far as getting one repaired, the wait time isn't really worth the small savings unless you have got a backup pump. Having said that, it runs quieter than it ever has, even out of the box. Bhogart told me the new bearings are ceramic and that the grease contains a mix of ptfe to provide a longer life, but that they are still susceptable to the same issues as the original bearings. They said not to subject the pump to vacuum and that solvent/oil mixtures reaching the pistons and proper elevation of the pump along with condensing coils are the two biggest factors in pump longevity. Sorry if this is all already known.
 

Concentrated_

New member
I just received replacement bearings, we have 3 pumps that have gone down in the last month. Looking at the replacement bearings they seem better made than the stock ones, now to find a press to install them and get it running again. Sent the other 2 cmepols off to xtractor depot for rebuilds, and will be replacing the other pumps bearings and seals myself.
 

Rickys bong

Member
Veteran
That Dupont Krytox grease is supposed to be a lot more resistant to butane intake and loss under vacuum. A standard petroleum grease like the original CMEP bearings had will boil off under vacuum given enough time,

Not very likely. The vacuum levels this pump could achieve are not enough to get grease to boil.
Better lubricants for extreme applications like this are always a good idea though.

The piston seal really entirely a two way affair. It'll take pressure to push past the piston seal. I could be wrong, but I'd doubt it would pull much more than a few inches of vacuum on the crankcase.

My only fear with that is that if the line is left open, with the inlet side of the pump under vacuum it would pull ambient air in thru the vent line and pressurize your refrigerant tank with a potentially explosive mixture of air and butane.

Good point, but I doubt much would leak past under vacuum. Easily addressed by valving it and closing said valve when the inlet pressure nears zero.

RB
 
Not very likely. The vacuum levels this pump could achieve are not enough to get grease to boil.
Better lubricants for extreme applications like this are always a good idea though.

I've seen shitty greases in automotive applications (looking at you, Ford) turn to liquid at room temperature. Needless to say they weren't doing squat to lubricate ball joints anymore at that point. Under extreme use (heat + vacuum) I have no doubt a less-than-stellar grease will degrade. I may have used some hyperbole but I stand by the assertion, separating some part of a petroleum grease out by phase change is not doing what remains any help in actually doing what you bought it to do and keep your bearings' internal parts from galling against each other and falling apart shortly thereafter.

The piston seal really entirely a two way affair. It'll take pressure to push past the piston seal. I could be wrong, but I'd doubt it would pull much more than a few inches of vacuum on the crankcase.

I'll repeat that most of my experience has been automotive related, ever seen the amount of blowby present on a worn out 200k+ motor? If the pistons are exposed to an inlet pressure of -21 inHg and the crankcase is at 0 PSI at sea level there's almost a 10 PSI pressure differential between the crankcase and top of piston which only gets worse as the pump continues to spin. I suspect that you're underestimating the force present from that pressure differential and the amount of blowby on a CMEP with more than 50 hours on the clock. When I tore this one down there was a hell of a lot of scoring on the walls of the cylinders.

Good point, but I doubt much would leak past under vacuum. Easily addressed by valving it and closing said valve when the inlet pressure nears zero.

RB

I'd be interested to test it with a flowmeter to see how much it actually does, even if a person did just venting to atmosphere with air to avoid creating a potentially explosive environment. I lack the tools unfortunately.
 

Rickys bong

Member
Veteran
No doubt that would make it better. My only fear with that is that if the line is left open, with the inlet side of the pump under vacuum it would pull ambient air in thru the vent line and pressurize your refrigerant tank with a potentially explosive mixture of air and butane.

Thinking about it, there's an easy fix. Put a check valve with a 1psi cracking pressure on the crankcase so no chance of atmosphere entering. any pressure over 1 psi will vent, but nothing can flow back.

RB
 
I have the upgraded bearing, seems to be lasting longer... Not really too sure. I never run my pump under vacuum, so never had big issues and I usually take the pump in to get cleaned/rebuilt every 3-4 months of everyday use just in case. It does seem to be staying quieter longer but honestly hard to tell. I have not had the new ones replaced yet, when I do I will compare how they look with the old ones after the same amount of use. Next rebuild Im venting the crankcase as well.
 

Concentrated_

New member
I'm very interested in the venting of the crankcase, haven't found anyone who has done it yet though. Talked to Larry at xtractor depot about it but they have never done it. If someone has done it before I would love to hear about it, it seems like it could be vented in whatever spot for the most part that is easiest to fit your setup as far as venting the pressure/gas .
 
I'm very interested in the venting of the crankcase, haven't found anyone who has done it yet though. Talked to Larry at xtractor depot about it but they have never done it. If someone has done it before I would love to hear about it, it seems like it could be vented in whatever spot for the most part that is easiest to fit your setup as far as venting the pressure/gas .

I haven't done it yet, but mechanically it won't be terribly difficult. Unbolt motor & remove SS lines. Remove fan, remove front cover, drill hole in bottom of crankcase, tap with 1/8" tapered pipe tap & install a street elbow and ball valve (and maybe a check valve too)
 

Concentrated_

New member
Ya that's about what I figured, and after taking the first pump apart I'm pretty confident in being able to service them myself now. I found many different options for bearings online and they are very cheap compared to the cost from the service people. I purchased the shielded bearings from ebay for the main bearings and a smaller one for the back of the shaft, figured for 10$ and I'm already here might as well. The bearings I purchased are the same ones that xtractor depot are installing And he said it was the best ones they had found so far, so tomorrow I'm gonna re assemble the pump and see what happens.
 

CMEP Shop

New member
I've been told that the use of ceramic or hybrid bearings will reduce noise. Haven't actually tested to see if the claim is real or marketing bullploppy.

That Dupont Krytox grease is supposed to be a lot more resistant to butane intake and loss under vacuum. A standard petroleum grease like the original CMEP bearings had will boil off under vacuum given enough time, and I know that in spite of the CMEP marketing, if you run it into vacuum pressure territory the crankcase will also be under vacuum (because ring blowby is a two way street). If you never ran the CMEP under vacuum I suspect you would get a lot more life out of the bearings.



No doubt that would make it better. My only fear with that is that if the line is left open, with the inlet side of the pump under vacuum it would pull ambient air in thru the vent line and pressurize your refrigerant tank with a potentially explosive mixture of air and butane.


The new Gen 3.5 pumps have a release valve on the case.
 
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