Clark Pump Impending Failure?

[Dreaming Yachtsman]

Years ago a roving Spectra Rep and cruising friend told me that the differential pressures between the strokes of a Clark pump ideally should be less than 3 psi. Differentials on my pump have been less than 4 psid until just recently. During the last few runs of my Catalina model water maker the pressure readings on the "FEED WATER PSI" display have varied by up to 9 psid. The variations don't correspond exactly with the strokes of the pump as indicated by audible lugging of the feed pump, however, so I'm not really sure what's going on.

Furthermore, the sounds of the pump shifting directions are now quite different as well: one shift is short (about a half second) and the other is much longer (nearly two seconds) as I can best tell listening with a stopwatch. There is no apparent difference in the length of the strokes (about 5 seconds each).

Are these indications of an impending Clark pump failure? What indications would I see for such a failure? What are the implications of continuing to run the system as is (i.e. will it damage the pump and thus make any future repairs more difficult)? What, if anything, should I do to my Clark Pump?

[Bruce Beard]

Please take this answer in the spirit it is intended... I do not mean to be critical of you!

Why wouldn't you simply call Spectra and ask this question of their tech support people? I have found them to to be very willing to talk about my Spectra concerns at any time...

I am pretty sure your Clark pump is in fact failing as the symptoms are exactly what my pump had when it failed but the real experts work for Spectra. I would hate to find that after repairing the pump or replacing it the symptom remains...

[Kenomac]

Spectra will rebuild your pump to be good as new for only $425 at the factory and warranty the work. I just had two done this year. They come back as new.

[Dulcesuenos]

Call Halden marine Services in Florida, he is the East coasts Spectra Distributor and the best there is w spectra.

Sent from my LG-LS980 using Cruisers Sailing Forum mobile app

[Tellie]

Originally Posted by Dreaming Yachtsman

Years ago a roving Spectra Rep and cruising friend told me that the differential pressures between the strokes of a Clark pump ideally should be less than 3 psi. Differentials on my pump have been less than 4 psid until just recently. During the last few runs of my Catalina model water maker the pressure readings on the "FEED WATER PSI" display have varied by up to 9 psid. The variations don't correspond exactly with the strokes of the pump as indicated by audible lugging of the feed pump, however, so I'm not really sure what's going on.

Furthermore, the sounds of the pump shifting directions are now quite different as well: one shift is short (about a half second) and the other is much longer (nearly two seconds) as I can best tell listening with a stopwatch. There is no apparent difference in the length of the strokes (about 5 seconds each).

Are these indications of an impending Clark pump failure? What indications would I see for such a failure? What are the implications of continuing to run the system as is (i.e. will it damage the pump and thus make any future repairs more difficult)? What, if anything, should I do to my Clark Pump?

First, taking the pressure readings from the control panel are iffy at best on a Catalina. These are more of a guide than hard readings. The program is a bit slow to responded to the actual pressures created and by the time it could actually read it the Clark pump is on it's other stroke. The only real accurate way to discern the stroke difference is with the analog pressure gauge. Not all systems are equipped with a pressure gauge hopefully yours is. What you are describing is definitely an issue but not one that will further damage the Clark pump or make future repairs any more difficult. Slow shifts are a pressure issue and there can be several causes for this. Usually at this point it would be wise to consider sending this Clark pump back to Spectra for a re-build. It is well worth the $425 charge to do this. But understand that if either cylinder or both are damaged from excessive scoring they will need to be replaced and that is another $100 per cylinder added to the re-build.

Regular pre-filters changes are really important to any watermaker. By far the most damage causing thing I see occur to the main pressure pumps in all watermaker systems is failure to regularly do this simple routine maintenance. Pre-filters are the consumable part of all watermakers. It's amazing the lengths some sailors will go to to save a few pennies on a system worth thousands. Have a good supply on board and change them frequently.

Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators

[Dreaming Yachtsman]

Originally Posted by Bruce Beard

Please take this answer in the spirit it is intended... I do not mean to be critical of you!

Why wouldn't you simply call Spectra and ask this question of their tech support people? I have found them to to be very willing to talk about my Spectra concerns at any time...

I am pretty sure your Clark pump is in fact failing as the symptoms are exactly what my pump had when it failed but the real experts work for Spectra. I would hate to find that after repairing the pump or replacing it the symptom remains...

No offense taken but I posted here about this problem because I was in an outer Caye in Belize that didn't have good enough internet to support Skype calls and I don't have a telephone that works here. I knew Tellie would pick up on this as he has done several times in the past for me and many others with watermaker problems.

[Dreaming Yachtsman]

Originally Posted by Tellie

First, taking the pressure readings from the control panel are iffy at best on a Catalina. These are more of a guide than hard readings. The program is a bit slow to responded to the actual pressures created and by the time it could actually read it the Clark pump is on it's other stroke. The only real accurate way to discern the stroke difference is with the analog pressure gauge. Not all systems are equipped with a pressure gauge hopefully yours is. What you are describing is definitely an issue but not one that will further damage the Clark pump or make future repairs any more difficult. Slow shifts are a pressure issue and there can be several causes for this. Usually at this point it would be wise to consider sending this Clark pump back to Spectra for a re-build. It is well worth the $425 charge to do this. But understand that if either cylinder or both are damaged from excessive scoring they will need to be replaced and that is another $100 per cylinder added to the re-build.

Regular pre-filters changes are really important to any watermaker. By far the most damage causing thing I see occur to the main pressure pumps in all watermaker systems is failure to regularly do this simple routine maintenance. Pre-filters are the consumable part of all watermakers. It's amazing the lengths some sailors will go to to save a few pennies on a system worth thousands. Have a good supply on board and change them frequently.

Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators

Tellie,
Thanks for your reply. You confirmed my thoughts about the control panel pressure readings not showing real-time pressures because of processing delays. That was what I implied when I said "so I'm not really sure what's going on" in my original post.

My original analog guage failed several years ago and when I called Spectra to order a new one, they told me that they no longer install those guages nor do they have replacements for them.

I was hoping you could give me an outline to follow for repairing the pump because shipping into and out of Belize where we are currently located is not an easy process. I'll contact Spectra as soon as I can to start the ball rolling.

I faithfully change filters after 8-10 hours run time, more often if in "dirty" water. Per the Spectra Ops bulletin, I clean and dry them, then reinstall on the next filter change cycle. I clean the 5 micron filter first and see very little dirt in the wash water, indicating to me that the 50 and 20 microns are doing their job well.

Thanks for your help again.

[Tellie]

Originally Posted by Dreaming Yachtsman

Tellie,
Thanks for your reply. You confirmed my thoughts about the control panel pressure readings not showing real-time pressures because of processing delays. That was what I implied when I said "so I'm not really sure what's going on" in my original post.

My original analog guage failed several years ago and when I called Spectra to order a new one, they told me that they no longer install those guages nor do they have replacements for them.

I was hoping you could give me an outline to follow for repairing the pump because shipping into and out of Belize where we are currently located is not an easy process. I'll contact Spectra as soon as I can to start the ball rolling.

I faithfully change filters after 8-10 hours run time, more often if in "dirty" water. Per the Spectra Ops bulletin, I clean and dry them, then reinstall on the next filter change cycle. I clean the 5 micron filter first and see very little dirt in the wash water, indicating to me that the 50 and 20 microns are doing their job well.

Thanks for your help again.

No problem I don't mind helping at all. Sometimes shipping parts back and forth can be an issue and many times can get expensive as we cruise around the world. First, I'm not sure who told you that pressure gauges for your Cat300 are not available but we certainly do have those gauges for your system. Not all new Spectra systems come with the analog gauge but all systems can easily have them fitted. What you are describing with the Clark pump certainly sounds like a pressure issue. If it is the cylinder or piston not making the proper seal then they would need to be replaced. But in the top block section of your Clark pump are the annular rings. If you listen closely to the Clark pump and hear a hissing noise it is possible one of the annular rings have cracked. It is possible to dissasemble the top block and remove the annular ring and inspect it for a hair line crack. If one is discovered, simply turning the annular ring around and installing it the opposite way it came out might solve the problem until you can get a new replacement ring. If you hear no hissing sounds and the pump is asymmetrical the most likely cause is a bad check valve. Like all things mechanical, pumps do get tired over time even with the best of care. When I see these problems the best answer is usually sending the pump back for a re-build simply because if you are having one issue, because of a well used pump, chances are good something else will pop up perhaps sooner than later. If you don't have it already I can send you the information on the Clark pump and the annular rings. Just let me know.

www.HaldenMarineService.com

[Dreaming Yachtsman]

Yesterday afternoon I restarted the system which displayed essentially the same symptoms described in my first post. I listened to the upper block for hissing per Tellie's recommendation above, a symptom of a cracked annular ring. There is some but I have never listened to the pump closely before so have no basis for comparison. I measured the actual output of the pump at about 9 gph, which corresponds to the digital readout on the control panel and is only slightly down from the normal 10 gph I usually see. The stream from the sample valve on the product line displays the same strength of stream on both strokes and shows no discernable difference between the "spurts" when the stroke reverses or from what it has been in the past.

Unfortunately, when I clamped the brine hose as suggested by Clark at Spectra Tech Support, I may have broken something else because the control panel alarmed, displayed "System Stalled", and shut the unit down. I tried to restart it but it stalled and shut down again. That really ruined my evening.

I have submitted an application for an RMA to ship the pump to Spectra per Clark's suggestion but have not heard back from Spectra yet. I plan to remove the pump and disassemble the upper block, looking for obvious problems. Who knows? I might get lucky.

[Kenomac]

If you have the time it's well worth the effort and money to send the pump back to Spectra for the rebuild. I just sent them a ten year old pump that looked like junk, it came back looking like band new with a factory lifetime warranty. Turn around time was two weeks which included shipping time.

[Dreaming Yachtsman]

Just to close out this thread, I finally received the remanufactured Clark pump after the typical customs fiascos 3 weeks after sending it off to Spectra. After installing it, I had only one leak on a high pressure fitting that I had not tightened enough. Fixed that problem and the system is now working like a champ. The Clark pump makes a much louder thump at the stroke change but since it's working well, I'm OK with that.

Belize wasn't a bad place to be stuck waiting for the pump to come back and was definitely much easier to ship from and to than San Blas Islands in Panama would have been.

Thanks to everyone who recommended the Clark pump overhaul. It was sound advice and now I know to do it every 4 years.

[Tellie]

Originally Posted by Dreaming Yachtsman

Just to close out this thread, I finally received the remanufactured Clark pump after the typical customs fiascos 3 weeks after sending it off to Spectra. After installing it, I had only one leak on a high pressure fitting that I had not tightened enough. Fixed that problem and the system is now working like a champ. The Clark pump makes a much louder thump at the stroke change but since it's working well, I'm OK with that.

Belize wasn't a bad place to be stuck waiting for the pump to come back and was definitely much easier to ship from and to than San Blas Islands in Panama would have been.

Thanks to everyone who recommended the Clark pump overhaul. It was sound advice and now I know to do it every 4 years.

We can't close it out quite yet. If your Clark pump is shifting harder than you think it should, check the pressure in your accumulator tank. It should be around 60psi. If not a standard bicycle pump will do. Sometimes you can play around with the pressure a bit and this will soften the shifting.

Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators

[Dreaming Yachtsman]

Tellie,

I'll check the pressure after I return to the boat in October.

Thanks again,