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| 5.7 GSi - Raw Water Pump https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=23415 |
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| Author: | YYZ-RC [ Sun Jul 21, 2019 8:48 am ] |
| Post subject: | 5.7 GSi - Raw Water Pump |
On the repair order for the spring launch the tech noted “sea water pump is pumping weakly and should be replaced”. This was noted at the time that the engine and drive oil were replaced (on land, obviously). I replaced the impeller last year and the boat consistently runs cool. I also replaced the circulation pump last year as well. Any suggestions on how I can verify if the flow is sufficient? If I pull a hose that runs to one of the manifolds, is there a typical flow volume I can measure for? I’m also confused as to why the whole pump would need to be replaced and not just the impeller. |
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| Author: | Thalasso [ Sun Jul 21, 2019 10:54 am ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
The low volume they claim might just be in the intake and not the pump? There is a plastic nipple going through the gimble housing. Could be blocked by debris If it isn't running hot i wouldn't worry about it Repair manual says to hold supply hose at T/stat at flame arrestor level. Run engine at idle You should have 1 inch head of water discharge. If less then 1/2 look for source |
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| Author: | TX H210SS [ Sun Jul 21, 2019 8:47 pm ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
Take a look at the grills on either side of drive unit....the ones you place muffs over. You should be able to see if they're clear inside. I did suck up some grass one time and had to remove the grills to clear them out. It's unlikely but only takes seconds to check with flashlight. To my knowledge that pump would be leaking if seals were bad. Still think it would be pumping fine as long as the impeller was good. |
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| Author: | skidaddytn [ Tue Jul 23, 2019 12:36 am ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
>sea water pump is pumping weakly and should be replaced As long as the impeller is good, I'm not quite sure how this could be? Make sure your temp gauge works by watching it when you heat up... if calibrated right you should see the gauge rise to ~170 or so and STOP. If in doubt you can put your hands on the manifolds. They should be warm/even hot, but they shouldn't burn the @#$% out of your hand. I've never sucked anything that blocked my intake but our lake doesn't have much grass/seaweed... Anything that fits through those holes will probably go all the way through and I agree you could probably see something at the holes if they are plugged... |
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| Author: | TX H210SS [ Tue Jul 23, 2019 5:46 pm ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
I may be preaching to the choir....but a good 15 dollar investment is an infrared digital thermometer....let's you quickly check temps on manifolds, risers, therm housing etc. Plus helps with the bbq pit and checking trailer hub temps during stops. Plus temp check on house ac vents. I've used the hell out of mine. |
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| Author: | YYZ-RC [ Wed Jul 24, 2019 7:54 am ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
Thank you. I have a infrared thermometer and everything is in check. Boat runs at idle at 160ish as per dash gauge and confirmed with IR. Never goes higher. There are no leaks anywhere; last season I replaced the circulation pump (which was leaking) and now everything is perfect. I guess what confused me most is why the note would say that the sea water pump should be replaced rather than saying "impeller should be replaced" but I'll ask the service advisor next chance I get. |
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| Author: | LouC [ Thu Jul 25, 2019 10:48 am ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
I've never taken apart a Volvo Penta raw water impeller/pump but I'd guess that they might feel that scoring on the interior of the pump might reduce pumping efficiency. When I've done the Cobra impellers on my OMC I can replace the wear plate, housing etc for about 40 bucks or so. Your engine temp should be between 160-175, it will tend to rise a bit after coming off plane, but should not go over 175. The exhaust manifolds and elbows should not get hotter than about 135-140 after coming off plane. At idle they should run at about 90-110*F or so. That Volvo pump is expensive at approx. $300 I think, I'd want to make sure it needs to be replaced before doing so. The dealer makes more money fixing things that way! I'd only replace the pump if it did not pump right with a new impeller or was leaking. |
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| Author: | skidaddytn [ Thu Jul 25, 2019 11:29 pm ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
I don't claim to be a raw water pump expert, but every one I've seen is mechanically driven by a spline shaft (be it either in the lower unit itself for older cobra drives, or driven by the serpentine belt of the engine for newer VP engine mount models). I can understand how one could leak if not sealed up right, but I have no idea how it could fail alltogether unless it was a bad impeller (rubber veins of the impeller damaged). Can this spline shaft actually get stripped and no longer engage a new impeller? Never heard of this happening, but I suppose it could be possible if maybe the wrong type of impeller was put on... but I would think this should be obvious when replacing the impeller. You should not have to hammer something that doesn't fit the spline in to place.... just sayin... If you have a newer model VP with engine mount you could also make sure the serpentine belt is not slipping on this accessory's drive wheel? Can the housing itself get damaged? From the rubber of the impeller, very doubtful unless someone put nails or sharp metal objects in there... Since your not having any trouble, you should just replace the impeller as indicated in the maintenance schedule for your drive or engine. Usually you can easily get twice as long as they recommend. I'm a firm believer in buying a NEW impeller (with new rubber) and not using one that has been allowed to age first (especially in an unconditioned hot environment where the rubber can stiffen or go bad). Another thing that causes the rubber veins to get torn early is to start them turning when DRY. If you reuse last years impeller after storing dry for many months, it is a good idea to at least add some glycerine or dish soap to it before going out on your first journey. Although once you take apart the housing, its only a small amount of additional effort to just put a new one in place. |
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| Author: | TX H210SS [ Fri Jul 26, 2019 11:18 pm ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
My guess it was a standard notation to replace impeller. The assumption the pump is bad based on exterior discharge is ludicrous. There's no wear plate on the VP system you have....the raw water pump seals may fail but that means water is leaking from it as water passes by the inner sealed bearings. Mine is dripping now and I'm set to replace impeller and o ring but it's not a bad pump...drops from the cap seal. Even if raw pump bearing seals fail...you can replace them with a complete impeller/bearing kit for 60 dollars. If its fresh water boat your good for 2 years...salt needs swapped yearly usually. While there is debate on need to fill system with rv antifreeze...the impeller lube is one reason I do this during winterization each year. I will say if you run the drive thru sand...that can likely shorten life of the impeller. Sand exposure can kick it but not instantly. I've swapped impeller every other year and they look new...I have the old ones in a box in case I never sell the boat....in want to show their condition which is something i as a buyer would appreciate. Based on what your saying...I would ask them why?....and if cooling correctly, go boating if no leaks. |
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| Author: | YYZ-RC [ Sat Jul 27, 2019 6:43 pm ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
Thank you all for the replies. I'll buy a new impeller now and keep it on the boat just in case, will install in the spring regardless. |
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| Author: | LUBA [ Mon Dec 20, 2021 7:45 am ] |
| Post subject: | Re: 5.7 GSi - Raw Water Pump |
Those raw water pump housing can be scored and may need to be replaced. I have twins and one doesn't pump as much -verified by pulling fuel cell cooling hose- at idle. Implellors have been changed and look perfect. I will be getting a new housing to fix. |
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