Squealing after impeller change

[JWUSER]

2001 Crownline 225BR with 5.7GXi. After performing end of season maintenance I was testing everything before putting the boat away. New oil, filters, impeller, etc. I’m getting a horrible screech from impeller housing. Impeller is OEM and installed properly. Engine idles well and maintains 175 degrees once warm. Screech vanishes when RPMs are increased and doesn’t even appear for the first 30 seconds or so of engine running. Once the screech appears it doesn’t stop until I kill the engine or rev it. New serpentine belt. I just ordered a new water pump but wanted to check to see if anyone else had an idea. Attached is a video of stethoscope pinpoint.

 

[cyclops222]

Bad serpentine belt. When it starts to screech . Toss a coffee cup of water on the belt and pullies. My car Honda needed 3 new different belts before a good one was found.
This is why no one should ever change a bunch of parts all at the same time. especially DIY and phony mechanics.
I still do 1 at a time.

 

[ESGWheel]

A “screeching belt” can come from one of several things:

• A worn (or bad) belt > like a bald tire, it will not grip but slip (and thus screech).
• Not enough tension on the belt > that causes it to slip.
• Too much of a load on the belt > even with proper tension an excessive load will cause it to slip.
• A pulley bearing or device that is belt driven making a noise that sounds like a screeching belt.
• A slightly too large of a belt > so the auto tensioner will not hold proper tension and thus it slips.

Since it’s a new belt, it’s possible the tensioner (while changing the belt) gave up the ship, but not likely. Use that breaker bar on it again as if changing the belt and see if it seems ok. In fact, just take the belt off in order to do the next step.

With the belt removed, turn all the pulleys by hand, and see how they feel (idler, water circ. pump, power steering, tensioner, alternator). If any feel difficult to turn or even “loose” address that problem.

I assume that your battery is up to charge and there are no heavy loads on the alternator due to stuff that might be on.

If all the above good, try a different belt as cyclops is suggesting. For my 5.0 GXi-E I have tried to find an alternative to the VP branded belt but with no success. Not sure if your 5.7 has a non-VP brand belt option and you did not mention what you used, but if going to replace your new belt with another new, suggest using a VP branded one.

 

[JWUSER]

A “screeching belt” can come from one of several things:

• A worn (or bad) belt > like a bald tire, it will not grip but slip (and thus screech).
• Not enough tension on the belt > that causes it to slip.
• Too much of a load on the belt > even with proper tension an excessive load will cause it to slip.
• A pulley bearing or device that is belt driven making a noise that sounds like a screeching belt.
• A slightly too large of a belt > so the auto tensioner will not hold proper tension and thus it slips.

Since it’s a new belt, it’s possible the tensioner (while changing the belt) gave up the ship, but not likely. Use that breaker bar on it again as if changing the belt and see if it seems ok. In fact, just take the belt off in order to do the next step.

With the belt removed, turn all the pulleys by hand, and see how they feel (idler, water circ. pump, power steering, tensioner, alternator). If any feel difficult to turn or even “loose” address that problem.

I assume that your battery is up to charge and there are no heavy loads on the alternator due to stuff that might be on.

If all the above good, try a different belt as cyclops is suggesting. For my 5.0 GXi-E I have tried to find an alternative to the VP branded belt but with no success. Not sure if your 5.7 has a non-VP brand belt option and you did not mention what you used, but if going to replace your new belt with another new, suggest using a VP branded one.

Thank you for the feedback. I did use an aftermarket Duralast belt from Autozone but it was the same part number as my original VP belt. I’ll circle back to that if the water pump doesn’t resolve it.

Prior to my post, I had already performed those tests you mentioned. All pulleys spun freely with no “wiggle” or play in them.

Will you take a look at the video I attached in the post and watch the water pump pulley? It doesn’t appear to be spinning at the same rate as the other pulleys. It even seems to hesitate at times. Again, when I put my stethoscope to that impeller hub the screeching will nearly hurt your ears. The screeching is certainly at the water pump whether related to belt or pulley bearing.

 

[ESGWheel]

For ease of communication, we need to get some terminology straight. The pump that is at the bottom of the engine that you cannot turn by hand is the Raw Water Pump (RWP) also known as the Sea Water Pump. As you know this one is responsible for sucking in lake/sea water thru the outdrive and into the motor. And I think that is what you are referring to. The other pump above that is the Circulation Pump which, well, circulates water thru the engine. Not trying to be offensive, but terminology matters especially when there is more than one pump

I have watched the video several times and a couple of things:

(1) The speed of a rotating device in a video can be deceiving. It’s all about frame rates (of the video) and RPMs (of the device being filmed). I am sure you have seen videos of helicopters flying where the blades look like they are stationary or moving really slow. Additionally, that pulley on the RWP is directly connected to the engine’s crankshaft, so there is no possibility of the pulley ‘slipping’ as if some great load was holding it back. It is the “driving pulley”. Not true with the alternator as a contrast > it is a “driven pulley”. Imagine the load is so great on the alternator that the belt slips on its pulley > in this case the pulley will be ‘slower’ than it should be. Just not possible with the RWP pulley. So, I did not focus on pulley speed.​

(2) That you were using a mechanic’s stethoscope is to be applauded. That the “impeller hub the screeching will nearly hurt your ears” is your telltale. From above possible causes: A pulley bearing or device that is belt driven making a noise that sounds like a screeching belt. So, it’s a good bet you found it.​

You ordered a new ‘water pump’ which I assume is the RWP. Good. Can you please confirm that it was a RWP you ordered and which brand (OEM or Aftermarket)? There are folks that rebuild / sell reconditioned RWPs that can save you a few bucks. Here is one I have used with good success link. And once you get your new RWP in hand and changed out, I strongly encourage you to either (1) rebuilt your old one with a kit from them or (2) send him yours for a rebuild or exchange and have it on hand for a future need. Nothing sucks more then missing the boating season due to not having a replacement part when needed

Also, see this post no. 14 at this link for my go to places for getting parts.

Please post know how it goes and any additional questions. If a different issue, post a new thread. Thanks.

 

[JWUSER]

For ease of communication, we need to get some terminology straight. The pump that is at the bottom of the engine that you cannot turn by hand is the Raw Water Pump (RWP) also known as the Sea Water Pump. As you know this one is responsible for sucking in lake/sea water thru the outdrive and into the motor. And I think that is what you are referring to. The other pump above that is the Circulation Pump which, well, circulates water thru the engine. Not trying to be offensive, but terminology matters especially when there is more than one pump

I have watched the video several times and a couple of things:

(1) The speed of a rotating device in a video can be deceiving. It’s all about frame rates (of the video) and RPMs (of the device being filmed). I am sure you have seen videos of helicopters flying where the blades look like they are stationary or moving really slow. Additionally, that pulley on the RWP is directly connected to the engine’s crankshaft, so there is no possibility of the pulley ‘slipping’ as if some great load was holding it back. It is the “driving pulley”. Not true with the alternator as a contrast > it is a “driven pulley”. Imagine the load is so great on the alternator that the belt slips on its pulley > in this case the pulley will be ‘slower’ than it should be. Just not possible with the RWP pulley. So, I did not focus on pulley speed.​

(2) That you were using a mechanic’s stethoscope is to be applauded. That the “impeller hub the screeching will nearly hurt your ears” is your telltale. From above possible causes: A pulley bearing or device that is belt driven making a noise that sounds like a screeching belt. So, it’s a good bet you found it.​

You ordered a new ‘water pump’ which I assume is the RWP. Good. Can you please confirm that it was a RWP you ordered and which brand (OEM or Aftermarket)? There are folks that rebuild / sell reconditioned RWPs that can save you a few bucks. Here is one I have used with good success link. And once you get your new RWP in hand and changed out, I strongly encourage you to either (1) rebuilt your old one with a kit from them or (2) send him yours for a rebuild or exchange and have it on hand for a future need. Nothing sucks more then missing the boating season due to not having a replacement part when needed

Also, see this post no. 14 at this link for my go to places for getting parts.

Please post know how it goes and any additional questions. If a different issue, post a new thread. Thanks.

No offense taken! I’m learning as I go and appreciate the free education! I did know it was called Raw Water Pump, but should have specified.

I did NOT know that the pulley for the RWP was driven and unable to “slip” so-to-speak.

I’m glad to see your link takes me to Raw Pumps as that is precisely who I ordered the remanufactured RWP from. I pulled the part number from Volvo Penta’s website (superseded twice now) but the RWP from Raw Pumps claims to be the right fit.

Now that I have removed the old RWP and see how simplistic it is, I’m still pretty uncertain of what was causing the screeching given what you said about the pulley being unable to “slip”. But, I’m still certain the sound was coming from the RWP. I put the stethoscope on or near just about every other component with no success.

Raw Pumps requested my OEM pump to be returned to them for refurbishing/core, so I won’t have a spare but hopefully this resolves the issue. I’ll update in a week or so when it arrives and is installed. Thanks again!

 

[Scott Danforth]

make sure the pulleys are all in-line (use a straight edge or use a laser pointer) get a new belt tensioner.

Will you take a look at the video I attached in the post and watch the water pump pulley? It doesn’t appear to be spinning at the same rate as the other pulleys. It even seems to hesitate at times. Again, when I put my stethoscope to that impeller hub the screeching will nearly hurt your ears. The screeching is certainly at the water pump whether related to belt or pulley bearing.

the pump can not stop spinning as its bolted to the engine crank. what you are seeing in the video is video shutter. most videos are taken at 30 frames per second. your eyes are flashing at about 22-24 frames per second. same phenomenon that makes wheels appear to be turning backwards at certain speeds.

you could also have a bad bearing in the pump. cost of a new pump is about $150. cost of rebuild kit is about $75

 

[ESGWheel]

Some follow-on thoughts for replacing the RWP.

Make sure you do not switch the hoses, easier to do than you would expect. Also given the age and this may be the first time the entire RWP is removed, the connecting hoses may have some rust scale on them where they clamp around the pump. It’s not that the hoses rust but rather the flaking off rust from the pump can stick to the inside of the hose where it was clamped around the pump feeds. Check this and if needed use a one of those green plastic scrub pads you may have in the kitchen. Do not use a wire brush. And lube up the hoses to install, water will work fine and make sure you are fully on and put the clamp in the middle. Look at the hose clamps as well, may be a good time to change and use a 316 stainless high quality one. Avoid the kind with the slots in them that the worm screw engages > they will cut into your hose over time. Attached is a catalog fm ABA on some good quality clamps to give you an idea of what to look for. And my process for tightening a clamp is to slightly over tighten it, back it off and then re-tighten.

 

[JWUSER]

It looks like I might just be an idiot after all of that. I decided I wanted to put the RWP back on and test without the belt on. As I was reassembling the pump on my work bench, I noticed a pancaked O-ring on the manifold. I remember not being able to find the old one when I replaced the impeller and assumed it had fallen off or disintegrated during pump removal (back before I knew you could raise the bench seat and was standing on my head to remove in a dark hull.).

Removed the pancaked O-ring, reinstalled with just ONE O-ring, left the belt off, no screeching. Tested 3 times for 2 minutes of runtime each.

Re-installed the belt. Tested 5 times for 2 minutes each. Zero screeching. Listened to the impeller with the stethoscope and can only hear what sounds like a rubber impeller spinning.

The impeller hub was snug and flush before but I’m guessing that somehow it was putting the impeller in a bind with 1 1/2 O-rings.

I’m normally a decent automotive mechanic but this one has me embarrassed. I’ve put the boat back in the garage and will plan to return the RWP when it arrives.

 

[Scott Danforth]

Or keep it on the shelf because the pump is a service item