[learningta]

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.

[Dabbles]

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.

[Rickys bong]

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

[learningta]

Originally Posted by Rickys bong

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

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.

[killa12345]

Originally Posted by learningta

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.

$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.

[learningta]

Originally Posted by killa12345

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

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.

[Dabbles]

Originally Posted by learningta

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.

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

[learningta]

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.

[learningta]

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.

[Rickys bong]

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.

https://www.skf.com/ca/en/products/be...als/index.html

https://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