CMEP-OL bearings and questions...

Customer I'm working with bought a CMEP-OL from Ecogreen, now more than a year old so out of warranty. It started getting loud so I was called in to figure it out, pulled motor/pump assembly from frame, noticed fan was harder to turn that I thought it should be so I opened up end cap on the pump and saw 2 loose seals for the rod bearings, black dust and some grease on the bottom of the crankcase and after pulling the heads and cylinders off can definitely conclude its got a couple of roached bearings.

Looking at this thread, pages 3-4 https://www.icmag.com/ic/showthread.php?t=318744&page=4
It seems that BHOGart might have some better bearings for these units? Is BHOGart the only supplier of these or does someone have part numbers? Looks like they're closed on Sundays and nothing to be found on their website as far as CMEP rebuild parts.

I've seen a few mentions of people plumbing valves into the bottom of the crankcase to allow any residual butane out at the end of the run. I'm wondering if anyone has put a gauge on this valve to monitor just how much pressure we're seeing into the crankcase....would seem to me to be an easy way to monitor ring condition if you teed a liquid filled gauge into the line running out the crankcase before it sees a ball valve.

Thinking aloud there's some HC pump manufacturers that use a "pad gas" such as nitrogen, wondering if you put a regulator to keep some positive pressure in the crankcase it would slow ingress of butane into the vicinity of the bearings. I think some would inevitably end up in the butane tank as well but could be vented easily once the tank is chilled below 30*F so that any and all butane is in liquid form with a near-zero vapor pressure.

Another thing I noticed was some scoring on the cylinder walls. I noticed on the youtube video here: https://www.youtube.com/watch?v=pk1W9Ub0Xrk that he doesn't really do anything with the cylinder walls just slaps some new rings in. Thinking at a minimum I'm going to throw them in my lathe and hone them to a mirror finish before I throw a rebuild kit at the pumps top end. Maybe its the OCD machinist in me speaking but if the cylinder walls were as poorly finished as many other surfaces in this pump its a wonder that it lived this long still pumping butane...

Another thought I had, if a person made longer (taller) cylinder walls they could put a longer screw, spacer and use 2 rings instead of just a single one. If one of the rings was pointed out the the other was pointed in, it might do a better job of keeping grease washed out of the bearings from getting into the compression part of the cylinder and from there making its way into the butane tank.

More work than I think I have time for at the moment, but a big part of me wants to make a better piston/cylinder arrangement with a longer piston that has multiple rings and a proper wrist pin at the bottom of the piston instead of a piston which moves in the bore and IMHO, wears rings prematurely.

I took apart my CMEP-OL over the weekend as well, for the exact same reason. Squealing bearings. And, I'm wondering the same thing, can we get these "upgrades" that BHOgart's is using? Has anyone used a 2RS bearing, or is the resistance too much?

I did a little research on bearings, knowing not much about them, and it's also a shame that the manufacturer of the CMEP-OL didn't source perhaps a different style of bearing to go into these. There are other materials available that are more chemical resistant than rubber.

Ultimately a pretty simple job to get into one of these things. I will be posting pics of my tear-down, and re-assembly soon as well.

Gonna call BHOgarts today to see if they will divulge, unless I see it here first from learningta.

The bearings are not the problem. The issue is the crankcase being pressurized with butane. A small amount of butane gets dissolved in the bearing grease and when the pump is off, the butane starts to boil out pushing some of the grease past the seals. Eventually the bearings fail due to lack of lube. Only way to cure this is to vent the crankcase...

RB

Rickys bong said:

The bearings are not the problem. The issue is the crankcase being pressurized with butane. A small amount of butane gets dissolved in the bearing grease and when the pump is off, the butane starts to boil out pushing some of the grease past the seals. Eventually the bearings fail due to lack of lube. Only way to cure this is to vent the crankcase...

RB

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Well, my bearings have already failed so my bearings are a short-term problem to resolve and the long term fix will be venting the crankcase so that I can prevent/delay this in the future. Looking at other pump manufacturers it seems most have a dual-piston single cylinder setup to isolate the crankcase from HC fumes. I plan on putting a vent in the crankcase when I'm working on the pump again after the new bearings show up.

As for satisfying others curiosity, I called both Bhogart and Ecogreen today, Ecogreen was closed so I left them a message. Bhogart claims they have "better" crank bearings. Cost $65/ea + freight but not listed on their website, either way ordered a pair of them and will find out later this week what they look like. Hoping that these are actually better bearings and not just the same series ones with better (metal) grease shields.

learningta said:

Well, my bearings have already failed so my bearings are a short-term problem to resolve and the long term fix will be venting the crankcase so that I can prevent/delay this in the future. Looking at other pump manufacturers it seems most have a dual-piston single cylinder setup to isolate the crankcase from HC fumes. I plan on putting a vent in the crankcase when I'm working on the pump again after the new bearings show up.

As for satisfying others curiosity, I called both Bhogart and Ecogreen today, Ecogreen was closed so I left them a message. Bhogart claims they have "better" crank bearings. Cost $65/ea + freight but not listed on their website, either way ordered a pair of them and will find out later this week what they look like. Hoping that these are actually better bearings and not just the same series ones with better (metal) grease shields.

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$65 a bearing......I so hope for that price they are ceramic bearings.

I dont have a cmep pump nor have ever rebuilt one but i do know a thing or 2 about bearings. The bearing number should be on the seal, then just measure.

Also, for replacement bearing on just about everything ive ever used bearings on....Ive used Boca Bearings in South Florida. Literally i have never found a bearing they dont stock or cant get on extremely short notice. I know there are tons of bearing companies in the US. The people at boca bearing have never failed me and have given me other options that have improved the functionality of many things ive replaced bearing on.

Id talk to a bearing specialist before dropping $65 a bearing.

killa12345 said:

$65 a bearing......I so hope for that price they are ceramic bearings
....
Id talk to a bearing specialist before dropping $65 a bearing.

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If they aren't ceramic bearings they are getting returned. I am willing to give Bhogart some business if they are actually selling upgraded bearings, if they are selling the same junk as the CMEP-OL was originally fitted with at that big a premium, believe me I'm going to raise a stink about it.

I have a local bearing house I'm consulting on replacement bearings for this pump but nothing definitive yet. There's more than one way to skin a cat I'm just very interested to see Bhogarts take and hear what Ecogreen has to say when they are open tomorrow.

learningta said:

If they aren't ceramic bearings they are getting returned. I am willing to give Bhogart some business if they are actually selling upgraded bearings, if they are selling the same junk as the CMEP-OL was originally fitted with at that big a premium, believe me I'm going to raise a stink about it.

I have a local bearing house I'm consulting on replacement bearings for this pump but nothing definitive yet. There's more than one way to skin a cat I'm just very interested to see Bhogarts take and hear what Ecogreen has to say when they are open tomorrow.

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$81.25 EACH for bearings from Ecogreen. But, they are waiting on parts from China.

Spoke to Mike at Ecogreen. He said that the earlier pumps (which I'm guessing this one is) were fitted with bearings that had black seals. Later pumps may or may not be fitted with red seals. Can't seem to find any indication of what seal color means (guessing it varies by OEM and forgot to ask who makes the new bearings) but he said that their improved bearings are lubricated with a PTFE-based grease which is more resilient to being boiled off after ingesting butane. I asked if they were ceramic and he said they were not. He also said that failure is inevitable once the top end leaks a sufficient amount.

I asked about venting the crankcase and he said they do not recommend it because it will interfere with the pumps explosion proof rating (which seems like covering their ass, the motor and all electronics are supposed to be sealed to keep them explosion proof and the pump won't comply with Div 1 ratings unless the OEM-fitted power cord is swapped with a jacketed line anyways as I'm to understand it).

Moving forward I'm going to see what the local bearing house has to say and what the bearings from Bhogart look like. I'd be surprised if we couldn't get a PTFE lubricated ceramic bearing with a better shield, I'm sure its just a matter of spending cubic dollars.

As for the crankcase I think I'm going to drill & tap the bottom of it for 1/8" pipe, and put a liquid filled compound gauge and a tee with a ball valve & check valve on it. That way I can use the gauge to monitor blowby and open the valve when the pump is done running at the end of use if it still has positive pressure. I figure a check valve is a good CYA in case the ball valve is left open, that way it won't be sucking air into the crankcase and pressurizing the tank with a butane/air mixture.

Oh and regarding the cylinder walls he said he uses a 220 grit sandpaper and a mini lathe to polish them up. Didn't have a tolerance he could give as far as max size, though I'm sure going too wide would wear rings prematurely. Personally I think 220 is a bit low I will probably polish to a bit finer polish than that. He said the big thing was to get any major/deep gouges cleaned up as they will cause blowby.

A couple of points: Ceramic bearings won't solve the problem since they need lube too. Shielded bearings generally don't have seals. Shields are non contact dust shields meant to keep dust out of the bearings and lube in.

There are two types of seals, RZ and RS. RZ are light contact which means they bare touch for minimal rotating friction. they will also allow gas to get past. Type 2RS have contact seals on both sides and will be the best off the shelf solution. There are others, but none are designed to seal gases from the bearing grease.

http://www.skf.com/ca/en/products/b...l-bearings/sealing-solutions/seals/index.html

http://www.gobearings.com/shields.htm

Your best bet is still venting the crankcase and even better putting a fitting in the vent hole and plumbing it outside. That way there's little chance of gas leakage indoors.
Put a flowmeter (rotameter) on it rather than a valve. That way you can monitor blowby flow.

Even if you bought Vastly improved bearings any leakage from them is hidden and you won't know they are leaking grease until they get noisy. Grease that leaks from them likely will get into your butane stream and you won't know it.

RB

Seems like your still going to lose the grease, whether the gas is vented out of the crank case, or allowed back into your loop. It's also kinda B.S. this pump originally had a non-food-grade grease to begin with, and now PTFE? Teflon is carcinogenic. I realize PTFE is a common material found in extraction systems, but Damn there has to be better martial out there to use. Wish I would have not bought this pump. I wouldn't have if I'd known about all of these issues.

Dabbles said:

Seems like your still going to lose the grease, whether the gas is vented out of the crank case, or allowed back into your loop.

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Bearings are a wear item, just a question of how long they take to wear out given your application, I just think its a bit ridiculous that none of the retailers that are selling these pumps and rebuild kits for them are listing bearings on their website as well.

It's also kinda B.S. this pump originally had a non-food-grade grease to begin with, and now PTFE? Teflon is carcinogenic. I realize PTFE is a common material found in extraction systems, but Damn there has to be better martial out there to use.

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I agree that the non-food grade grease is bad news, teflon is carcinogenic but chances are a lot of people are exposed to way more teflon due to cookware than they will be from an extractor. If the crank case is vented hopefully nearly all the grease that is lost from the bearings goes out the vent line and not into your product or butane tank.

Wish I would have not bought this pump. I wouldn't have if I'd known about all of these issues.

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Ditto, I'd advised a Haskell but cost of the Haskell and a big enough compressor to run it to capacity was prohibitive at the time. That may change given the headaches with this pump.

Rickys bong said:

A couple of points: Ceramic bearings won't solve the problem since they need lube too. Shielded bearings generally don't have seals. Shields are non contact dust shields meant to keep dust out of the bearings and lube in.

There are two types of seals, RZ and RS. RZ are light contact which means they bare touch for minimal rotating friction. they will also allow gas to get past. Type 2RS have contact seals on both sides and will be the best off the shelf solution. There are others, but none are designed to seal gases from the bearing grease.

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I should've taken pictures but when I pulled the cover off this pump both outside bearing seals were loose and bouncing around on the crankshaft. At which point, even without the influence of the solvent gas, any grease still remaining is going to be flung out into the crankcase by centripetal force. What happens after is irrelevant, because at that point its no longer lubricating the bearings.

Now, chicken-or-the-egg question would be did the seals on the original bearings pop loose because the bearings were going bad, or did the bearings go bad because the seals popped loose from boiling grease (either due to vacuum pulled on the grease or solvent entrapment)?

For those trying to picture the above here's a good visual with some more options: http://www.astbearings.com/bearing-closures.html

I'm away from the shop and dismantled pump right now but makes me curious if its possible to get those crank bearings with type TTS seals, and also what the max temp those bearings get to when in operation.

Your best bet is still venting the crankcase and even better putting a fitting in the vent hole and plumbing it outside. That way there's little chance of gas leakage indoors.

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Thats my plan

Put a flowmeter (rotameter) on it rather than a valve. That way you can monitor blowby flow.

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Any suggestions for one?

Even if you bought Vastly improved bearings any leakage from them is hidden and you won't know they are leaking grease until they get noisy. Grease that leaks from them likely will get into your butane stream and you won't know it.

RB

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Absolutely. Part of me is thinking about ditching the cooling fan in this pump (IMHO I'd rather see more power devoted to pumping and power an external explosion proof fan to cool the heat exchanger and cylinders), at that point wouldn't take much to weld a fitting for an airtight sight glass so you can see whats happening with your pumps bottom end. Would answer some questions anyways.

Have you received the new bearings from bho's yet? I ordered a pair too. We'll see!

Dabbles said:

Have you received the new bearings from bho's yet? I ordered a pair too. We'll see!

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Tracking shows it as there but my day job shipped me out of state and haven't gotten the chance to open it yet

Dabbles said:

Have you received the new bearings from bho's yet? I ordered a pair too. We'll see!

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You order from Bhogart? Those shitheads won't have anything to ship you for least 2 weeks. I got home expecting to have a package from them on my doorstep, no package called for tracking and was told nothings shipped because nothing has arrived from the OEM. Would have been real useful information the day I placed my order over a week and a half ago now.

learningta said:

Tracking shows it as there but my day job shipped me out of state and haven't gotten the chance to open it yet

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This is probably confusing and it doesn't look like I can edit it...got my packages confused, this tracking was for a shipment from Ecogreen with my pump rebuild parts, which was shipped the next day and arrived shortly thereafter. Bhogart sent me an order acknowledge but never followed that up with a tracking no for my bearings, because they hadn't shipped because they're still on a boat from China or something.

bearings

bearings

Been reading a few of the threads here.
First: Full Ceramic bearing do not require lubricant. They are perfect for using in these pumps. You will never get grease contamination of your gas if you use full ceramics. I sell NSK full Ceramics for 110 each. contact me.

2nd: do not vent the crank case because you will no longer have an explosion proof pump. Instead make sure to monitor the temperature of your pump. When you notice recovery times go down, turn off pump and let cool for 2 hours. Have a second pump ready and that is cold. You are getting blow-by and that is how the case get full of gas.

3rd, make sure your pump is above the top of your recovery tank and coil. this will make sure you are only pumping gas and no liquid.

4th, I recommend never heating gas to higher than 110 degrees. Even if you are making clear. This is extremely dangerous and will increase the amount of work that will have to be performed to keep it working properly. IE: higher temp crash the pump sooner.

++++++++++++edited to remove terms of use violation+++++++++++++

CMEP Shop said:

Been reading a few of the threads here.
First: Full Ceramic bearing do not require lubricant. They are perfect for using in these pumps. You will never get grease contamination of your gas if you use full ceramics. I sell NSK full Ceramics for 110 each. contact me.

2nd: do not vent the crank case because you will no longer have an explosion proof pump. Instead make sure to monitor the temperature of your pump. When you notice recovery times go down, turn off pump and let cool for 2 hours. Have a second pump ready and that is cold. You are getting blow-by and that is how the case get full of gas.

3rd, make sure your pump is above the top of your recovery tank and coil. this will make sure you are only pumping gas and no liquid.

4th, I recommend never heating gas to higher than 110 degrees. Even if you are making clear. This is extremely dangerous and will increase the amount of work that will have to be performed to keep it working properly. IE: higher temp crash the pump sooner.

If you have any questions, or parts needs please contact me at Rob@CmepShop.com

website should be up and running over the next few weeks as parts arrive.

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HAHA...$110 for each ceramic bearing....i figured a bike shop would get in on this. Advertise the right way with the forum. Still cant get over $110 each bearing.

Only a roadie would say something like this....LOL

CMEP shop, mind giving us specs and pictures on these bearings? For double or more what anyone else is getting for them I have high expectations.

Do you have an online storefront or offer any other products for the CMEP pumps?

How and where exactly do you expect us to monitor the temp of the pump? Explain to me if I'm wrong, but more blowby means less gas compression (thus the slow recovery times), and that would mean less temperature delta between inlet and outlet lines, not more. The parts which would get hot from spewing out their grease would be internal to the crankcase and I don't know how anyone is going to attach a thermal probe to crankshaft rotating at 1800 RPM.