At my wits' end - raw water pump issues

[rlwagens]

Desperately looking for some advice or someone to convince me that dropping $650 on a new raw water pump will finally fix my issues with my 2006 210.

Put the boat in the water, idled for a bit at the access, made the 2 minute drive to the lift and left it for the week, no issues. Took it out to ride and engine temp was sitting around 180-190 at idle but would drop to 160 with increase in RPMs. Finally started climbing to 200 so took it back to the lift. Took the impeller out, scarred but no fins were missing. Threw in my backup, never primed and got torched once I realized engine temp was gonna pass 160 but again, no fins missing. Have since been trouble shooting with a brand new impeller from nautiqueparts and local dealer. Unable to get raw water pump to pump water. Replacement thermostat already as a Hail Mary. Able to manually dump water through every major part of the cooling system. Boat runs fine with a hose and fake-a-lake, immediately disconnect hose and put inlet into bucket of water and unable to suck water. Checked all hoses, changed o-ring and bolt washers on raw water pump. Can even put inlet hose directly to inlet of water pump and disconnect outlet hose from pump and still no dice. Also no leaks when the system is filled with water. Ordered my last new impeller from nautiqueparts and plan to put sealant on the housing and see if it can suck from the bucket, but its such a simple mechanism it has to be a simple answer before buying an all new pump or taking it to a shop. 1000 hours on the boat but still seems too early for the inside to wear. Still smooth, no imperfections. No clogs/buildup anywhere (have taken every possible hose apart and inspected from the water strainer to the manifolds.

[Nautiquehunter]

Block off the hose coming out of the RWP remove the intake hose at the bottom of the bilge . Attach a garden hose to the intake hose and pressurize the suction side of the system . Look for water leaks . It will be easier to spot than vacuum leaks. PCM only on new impellers Nautique Parts only sells PCM.

[rlwagens]

Pressurized the system again with water today. Finally got a couple drip drips from the window on the bottom of the bearing housing assembly.... prior to blowing the plug off the end of the outlet hose. Cannot believe that a leak in the bearing seals that took that much pressure to just drip was enough to prevent the raw water pump from priming. But dealers are also all booked until June and also have no clue what else I could try so might as well try a whole new water pump. Will report back in case anyone else ever has this strange issue.


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[SilentSeven]

Has it always been this way since you've had the boat? Did this start after some work of some kind?

Is there any chance this engine has the type of external raw water pump that can be installed backwards? Backwards as in the pump is installed with the intake and outputs flipped and thus the pulley turns the pump in reverse? In know this is possible on a gt-40; unclear if this can occur on a later model PCM engine....

And just to reconfirm - you're sure there is no intake side vacuum leak so the pump is sucking air and not water....?

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[rlwagens]

I think it’s been 7 seasons now, always winterized and stored the same way. This was the first trip out of the year, but no work was done other than the usual maintenance.

No way to put these era pumps on backwards, and inlet on the bottom and outlet on the top so no physical way to switch hoses.

Have also just tested it with the long inlet hose directly to the inlet hose, bypassing the transmission oil cooler. Still nothing on the outlet side. Even when feeding water from bucket/fake a lake > hose > transmission cooler > elbow hose > water pump > outlet hose im expecting the system to lose pressure or find a leak or water in transmission oil or something. Spotless.

Again, such a simple mechanism, has to be a simple answer. I can’t believe it would be some hairline imperfection on the water pump that can’t be noticed with the naked eye. But I can’t find any other plausible explanations.


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[scottb7]

just a guess. but could it be that impeller looks good, but the rubber is spinning on the hub.

we just had this season that looked like it should have pumped but it couldn't quite make a good seal. replaced and good to go. also make sure that your strainer is tight.

but it was same as you on the hose with house water pressure it ran ok. but we had to replace the impeller.

[ESP]

Just a thought is it possible you have a hose that has collapsed internally may want to take them off and make sure there are no blockages

[dkimball]

I had issues with my 2003 Nautique 216 this year. I can never get the paper gasket that is sent with the pump to seal (way to thin in my opinion and you essentially have to have a new pump because any imperfection causes it not to seal) so I end of having to cut my own that is a little thicker from a sheet of paper gasket from any auto parts store. Does your pump have the paper or does it use the rubber O-Ring? I got it all together and working but noticed a small drip which I believe was from a hose but it was cooling and working fine. Adjusted the hose clamp and tightened it and the next time out it was not drawing much water and began to heat up. Tow back to the dock and checked everything over. It all looked good and there was water in the lines but I took the pump back off checked over the impeller drained the raw water strainer, tightened all hose claps but made sure they were square on the hoses first. I think that sometimes they can get tightened at a slight angle and not create a good seal on the hose. Put it all back together again (after fixing the kill switch which decided to stop working while trouble shooting the cooling issue) and it started drawing water right away.

I would readjust all of your hose clamps and make sure they are square and tight and just verify the impeller is spinning normally by turning the pump by hand when you have the cover off.

[jtryon]

food for thought even though it's a different engine than i have (mercury black scorpion 330): i had a priming issue last season after replacing the impeller as routine maintenance. everything appeared fine, no leaks, etc., but apparently the old impeller was still working fine because it had scored its profile into the side of the water pump housing. when installing a new impeller that didn't fit exactly the same, there was a gap in the housing that caused it not to pump enough water when idling. i replaced that side of the water pump housing and had no more issues.

[rlwagens]

New water pump (came pre assembled with o ring and impeller but also tried my old impellers) and old everything else and back to normal again. Could easily prime and get water to flow out of the outlet just by turning the pulley by hand.

My original guess was that something failed in the seals of the pulley housing, only other thing I can assume is that some tiny imperfections in the raw water pump were enough for it to lose the ability to prime.

But anyways, thanks for the suggestions everyone. Glad for resolution and to finally be back on the water.

FYI: for anyone trying to replace their water pump on the Excalibur, patience is a virtue to learn what order to put the bolts back on. Those bolts sure come off easy but will do everything they can to not thread back on haha.

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[Michael James]

I had issues with my 2003 Nautique 216 this year. I can never get the paper gasket that is sent with the pump to seal (way to thin in my opinion and you essentially have to have a new pump because any imperfection causes it not to seal) so I end of having to cut my own that is a little thicker from a sheet of paper gasket from any auto parts store. Does your pump have the paper or does it use the rubber O-Ring? I got it all together and working but noticed a small drip which I believe was from a hose but it was cooling and working fine. Adjusted the hose clamp and tightened it and the next time out it was not drawing much water and began to heat up. Tow back to the dock and checked everything over. It all looked good and there was water in the lines but I took the pump back off checked over the impeller drained the raw water strainer, tightened all hose claps but made sure they were square on the hoses first. I think that sometimes they can get tightened at a slight angle and not create a good seal on the hose. Put it all back together again (after fixing the kill switch which decided to stop working while trouble shooting the cooling issue) and it started drawing water right away.

I would readjust all of your hose clamps and make sure they are square and tight and just verify the impeller is spinning normally by turning the pump by hand when you have the cover off.

I would suggest Permatex make a gasket. The tolerances need to be tight on cap and impeller to allow no leak by of raw water. I went back and forth with this and making a gasket and found the gel works well, just my .02...