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PCM 351W fresh water cooling (FWC) |
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Wilhelm Hertzog 
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Joined: June-14-2014 Location: Cape Town Status: Offline Points: 349 |
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 Posted: November-12-2020 at 6:35pm |
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Before realising there were air leaks in the raw water circuit I was thinking the impeller was to blame for my issues, so I ordered a new one. Because my bucket test results were far better after the air leaks were fixed (definitely emptied a 5 gallon bucket in less than a minute at idle) I never installed the new impeller. But I'll install it and see if that makes a difference.
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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Wilhelm Hertzog
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Joined: June-14-2014 Location: Cape Town Status: Offline Points: 349 |
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Posted: November-16-2020 at 4:03am |
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As I noted in this thread, my boat's ventilation system was totally butchered at some point. As part of this process, the front vents were sealed off, so it seems to me there is very limited flow of fresh air getting to the engine under normal operating conditions. Could improving engine ventilation improve engine temperatures in any meaningful way?
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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8122pbrainard
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Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Posted: November-16-2020 at 5:19am |
I really don't feel it would help the cooling problem. Have you double checked how you have the engine plumbed?
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Wilhelm Hertzog
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Joined: June-14-2014 Location: Cape Town Status: Offline Points: 349 |
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Posted: November-16-2020 at 6:35am |
Yes, I'm confident the plumbing is correct. I'll change the impeller and report back. |
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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Wilhelm Hertzog
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Joined: June-14-2014 Location: Cape Town Status: Offline Points: 349 |
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Posted: November-24-2020 at 2:01am |
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Below are pictures of my disassembled raw water pump. The impeller clearly is not in the best of shape anymore, so hopefully changing that will improve water flow/priming at low engine speeds.
Three questions I'd really appreciate some help with:
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11155 |
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Posted: November-24-2020 at 7:55am |
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To me, the cam looks good, it's symmetrical and can go in either way.
The O ring goes on one side of the plate and gasket on the other just like the diagram shows. Pete will probably say that impeller is good for another quarter of a century or so...........I'd replace it anyways since you're having cooling issues
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SNobsessed
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Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Posted: November-24-2020 at 1:11pm |
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The housing only goes together 1 way, as the holes are not exactly 120 deg apart. I would just scrape off the crud, put a new PCM impeller in it, & not look back.
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11155 |
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Posted: November-24-2020 at 5:54pm |
I think what you really mean to say is that the holes are indeed 120 degrees apart and the housing can go on 3 different ways but only one way works to have the suction and discharge facing straight up and down on a PCM pump bracket Wilhelm took some really good, clear pictures and you could measure the distance between the 3 holes and see that they're 120 degrees apart on the bearing housing, the impeller housing and the gasket.. Or I could mention that I just put one together 3 different ways
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SNobsessed
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Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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Posted: November-24-2020 at 9:28pm |
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OK sorry for bad info, it must be a different pump than I had. Mine would only go together 1 way. Maybe it was machined wrong but it is a fact.
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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Singlespeedy
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Joined: June-08-2018 Location: 83864 Status: Offline Points: 6 |
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Posted: May-23-2021 at 11:36am |
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Do you still have the lower thermostat housing R025004? Mine is cracked and I'm searching!
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Wilhelm Hertzog
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Joined: June-14-2014 Location: Cape Town Status: Offline Points: 349 |
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Posted: May-23-2021 at 3:01pm |
Yes I do - it is installed on my engine. It took quite a bit of searching around to get everything together for the fresh water cooling conversion I did in 2019. Rudy Solares at Marine Parts Guys eventually managed to get everything together for me (after a lot of to and fro with PCM from his side). Bottom line: I could not order R025004 as an individual part. PCM (via Rudy) eventually gave me one part number (RA025009) to order which included (or replaced) all of the following items:  My understanding at the time was that there had been a problem with the sealing of the thermostat in the thermostat housing, so the thermostat housing was redesigned and the old one (R025004) discontinued. I'm not sure of the part number for just the lower housing that was included in my RA025009, and whether the lower housing included with RA025009 will work with the old upper housing (R025009 or RB025009). I guess SkiDim or someone like Marine Parts Guys should be able to get the answer out of PCM for you (PCM doesn't like dealing directly with the public - they told me as much via Rudy).
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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Wilhelm Hertzog
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Joined: June-14-2014 Location: Cape Town Status: Offline Points: 349 |
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Posted: December-31-2021 at 9:31am |
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Wrapping up this thread: the impeller change did not change much as far as engine temps or bucket test results go. I've decided to live with the slightly high (by marine standards - but seemingly acceptable by automotive standards) operating temps.
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1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer
Do not go gentle into that good night. Rage, rage against the dying of the light. |
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Wilhelm Hertzog wrote: