No water flow to raw water pump

[boybadone]

Hi there,

I have a cooling system problem. I am not getting any water flow through my supply pump. I have removed the inlet hose from my pump and there is no trace of water with muffs attached. While the the hose was disconnected I attached a garden hose to check for obstructions and had a good flow of water from lower unit intakes. I then sealed the intakes with tape to check for leaks and could not find any. I also removed the outlet hose from the raw water pump that supplies water to the thermostat housing both with muffs and in the lake- still no water.

I have done some work to the boat in anticipation of the upcoming boating season that I think is relevant:

-Removed outdrive and water tube nut. I did not replace water tube o-ring but instead used old o-ring with a bit of gasket sealing compound

-Replaced thermostat, temp sender and impeller. I did replace impeller o-ring, which I believe I installed properly but when referencing a raw water pump diagram noticed a small washer at the tip of the shaft that I did not replace nor did I see when I had the housing off.

I did a lot more work but I do not think it would be helpful to diagnose this problem. Any help would be much appreciated. I did not yet inspect the impeller again as it is a PITA to remove but I will take a look as soon as I get a chance.

2004 Larson 180sei
3.0GLM-B and SX-M

 

[bruceb58]

Re: No water flow to raw water pump

-Removed outdrive and water tube nut. I did not replace water tube o-ring but instead used old o-ring with a bit of gasket sealing compound

You always replace the o-rings. Did you replace the oblong o-ring between the pivot housing and the drive? Since you said you get no water even if the drive is in the lake, these are not likely your issue since the drive is submerged in the water.

You definitely need to look at the impeller. Change it if it has been more than 2 years since it has been replaced.

 

[boybadone]

Re: No water flow to raw water pump

If you are talking about the gasket in front of the oring I reused then yes, I did replace that one. It came with the bellows kit that I replaced. The impeller is brand new. I installed it just before I started the motor. I will take your advice tho and take a look at the impeller again. I just wanted to make sure there wasn't something else to check first.

 

[boybadone]

Re: No water flow to raw water pump

What about the washer in front of the raw water pump. It is number 3 in this diagram.

Seawater Pump 3.0GLP-A, 3.0GLP-B, 3.0GLM-A, 3.0GLM-B, 3.0GSP-C, 3.0GSM-C - 7744380 - Volvo Penta

 

[dypcdiver]

Re: No water flow to raw water pump

Several places to check, make sure that you have the hoses in the correct position. Make absolutely sure that the impeller is the correct one, as there are some slightly narrower ones about that will not pull a prime. The "o" ring that is on the body of the pump, make absolutely sure you have removed all traces of the old one, and lastly the seal may have gone (No. 5 on diagram) in which case remove pump and renew the bearing at the same time. Do a search on here and several posts about it, part numbers/sizes etc.

 

[boybadone]

Re: No water flow to raw water pump

Thank you diver, the impeller is genuine vp but I will still check. I double checked the hose and the inlet is on the top. I didn't have a problem with the gasket on the back of the pump before I winterized but how do I check it? What about that little washer?

 

[boybadone]

Re: No water flow to raw water pump

From what I have read if the still begins to go then the pump will still operate but leak. Is this correct?

 

[boybadone]

Re: No water flow to raw water pump

Sorry I meant seal, not still

 

[Thalasso]

Re: No water flow to raw water pump

My guess is you have a air leak somewhere . If the water coming to the raw water pump is ok and nothing beyond that then it's a air problem. You might want to check the raw water pump for the o-rings

 

[dypcdiver]

Re: No water flow to raw water pump

When my seal went it sucked air rather than water. I agree with Thalasso, sounds as if you are sucking air from somewhere. By sealing the raw water pump outlet to the Thermostat housing ie. pull it off at the stat and fold it or put a bung in it. Then fit muffs to the leg and pressurise the hoses, oil cooler and the pump then look for leaks around the system.

 

[vwbugman69]

Re: No water flow to raw water pump

Did you remove the old oring from the impeller housing? I struggled for two seasons of the pump not priming until I found it. It would only prime if I reved the engine to 2k rpm.

My raw water pump saga for reference

 

[boybadone]

Re: No water flow to raw water pump

Where did you find it? I did not see an old oring so I just assumed the last owner forgot it. Maybe that is my problem

 

[vwbugman69]

Re: No water flow to raw water pump

Where did you find it? I did not see an old oring so I just assumed the last owner forgot it. Maybe that is my problem

It was still attached in the housing oring groove. I learned that two orings are not better than one......

Funny thing is, I thought the last owner forgot it too, so I would check there again. It is a fairly deep groove. Also, that little cap kept falling off as well since there was more clearance with the doubled up orings. Maybe that is what happened to yours.

 

[boybadone]

Re: No water flow to raw water pump

I will definitely check the o-ring but I did not see a groove. You are not talking about the seal at the bottom of the shaft are you?

On another note, the washer at the end of the shaft still confuses me. Also, should the muffs have enough pressure to exit the hose at the pump when I remove the inlet side? It did not when I tried.

 

[bruceb58]

Re: No water flow to raw water pump

Also, should the muffs have enough pressure to exit the hose at the pump when I remove the inlet side? It did not when I tried.

It should. Put your water hose in that same hose and see if it exits the drive by forcing the water in the opposite direction.

 

[boybadone]

Re: No water flow to raw water pump

Thanks Bruce, I may not have explained properly in my first post but I already did that. Water exited the intakes on the drive. I then taped the intakes to check for leaks but did not find any. However, I may not have spent enough time looking.

 

[vwbugman69]

Re: No water flow to raw water pump

I will definitely check the o-ring but I did not see a groove. You are not talking about the seal at the bottom of the shaft are you?
.

No. On the housing with the inlet/outlet connections.

 

[bruceb58]

Re: No water flow to raw water pump

Thanks Bruce, I may not have explained properly in my first post but I already did that. Water exited the intakes on the drive. I then taped the intakes to check for leaks but did not find any. However, I may not have spent enough time looking.

I thought you may have done that but wasn't sure so had to ask

 

[boybadone]

Re: No water flow to raw water pump

Thanks bugman, I did not see any grooves on the housing but I only removed the housing. This time I will remove the entire pump assembly to take a closer look.

Since I know water flows from the pump to the drive why does water not make it's way to the pump? Bruce said water should exit the inlet hose at the pump with the muffs on but this did not happen for me.

 

[vwbugman69]

Re: No water flow to raw water pump

Since I know water flows from the pump to the drive why does water not make it's way to the pump? Bruce said water should exit the inlet hose at the pump with the muffs on but this did not happen for me.

It does not for me either.