Impeller question

[wheelin]

VP AQ131A

Is there only 1 impeller on this? (sea-water pump) ..or is there 2?

I'm having an over-heating isasue at fast speeds on water

Thanks

 

[dubs283]

Re: Impeller question

i do believe there is only one raw water pump on that motor located either on the front shaft/harmonic balancer or a separate pully driven pump.

if the motor has a closed cooling system (green coolant with a heat exchanger) your problem may be more in depth than just an impeller

 

[Fun Times]

Re: Impeller question

Keep in mind, There is a classic problem with the older Volvo drives. Of course check and replace the impeller, but unless you find missing blades or permanently bent blades that might not be the problem.

The Volvo has the water pump on the engine and sucks the water up from the outdrive. There is a hose that goes from the transom plate to the drive. Your problem is might be the fitting on the drive that the hose connects to. What happens is either the fitting corrodes or the seal goes bad and leaks. When the boat is idling this fitting is below the water so it still sucks in water. When the boat gets up on plane this fitting is now out of the water and now sucks enough air so you don't get water to the engine and you overheat. Drop back off plane and you get water again and the engine cools down.



Take a look at the linked diagram. The fitting is item #1 and the seal item #2.

Good Luck.http://bpi.ebasicpower.com/mm5/apps...E=93&INAME=OMCVOLDiagrams/images/GLMOMC06-160

 

[jerryjerry05]

Re: Impeller question

If it's a 131 it's probably an 80s something, then there could be a bunch of culprits.You didn't fill out the profile so we don't know whether it's salt or fresh water.
1st,the manifold could be clogging(that would be my first guess)
2nd the heat exchanger is clogged.
3rd the water pump excentric cam is wore and not pumping at speeds.Fill out the profile or give all the info about the motor.J

 

[wheelin]

Re: Impeller question

Sorry about the blank profile...I wasn't aware I had one...lol...I usually just read the boards for info

1989 Bayliner 17ft AQ131A not much history on boat...my son bought it sight-unseen off craigslist...we never even thought to ask about it being in saltwater

I'm going to replace the impeller tonight and use clear hoses running to seawater pump and see if I can visually see a problem

 

[jerryjerry05]

Re: Impeller question

If it's pumping water then it's probably the manifold.They can look brand new and be so coroded they stop working.Take the rubber boot loose and see how bad the end of the manifold looks.If it's a stock manifold (Volvo)then it's probably OLD and needs to be replaced.J

 

[Maclin]

Re: Impeller question

As Boat Teck mentions, with these if it cools ok at lower speeds but wants to overheat on plane it is probably sucking air somewhere between the drive and the pump. The pickup hose and fittings on the drive are all underwater until higher speeds so the leak is underwater also, but at the higher on-plane speeds it is exposed and that is when the air leak shows up.

This problem also shows up on the engine flushers. The fittings and hose are exposed to air and are between the water intake grates and the raw water pump, and if they are compromised they can let air in and the raw water pump loses prime and has problems getting water on up to the engine.

Don S has a neat troubleshooting guide for Volvo cooling systems, it may be up in the sticky area or you can do a search as there are many recent posts where he has put in a link to it.

 

[wheelin]

Re: Impeller question

Keep in mind, There is a classic problem with the older Volvo drives. Of course check and replace the impeller, but unless you find missing blades or permanently bent blades that might not be the problem.

The Volvo has the water pump on the engine and sucks the water up from the outdrive. There is a hose that goes from the transom plate to the drive. Your problem is might be the fitting on the drive that the hose connects to. What happens is either the fitting corrodes or the seal goes bad and leaks. When the boat is idling this fitting is below the water so it still sucks in water. When the boat gets up on plane this fitting is now out of the water and now sucks enough air so you don't get water to the engine and you overheat. Drop back off plane and you get water again and the engine cools down.



Take a look at the linked diagram. The fitting is item #1 and the seal item #2.

Good Luck.http://bpi.ebasicpower.com/mm5/apps...E=93&INAME=OMCVOLDiagrams/images/GLMOMC06-160

The fitting (item #1) only had one bolt in it...i could see light thru half of it
where its supposed to seal....I installed a new bolt and put in the new impeller....We'll see how it runs today

 

[wheelin]

Re: Impeller question

SUCCESS......New impeller and new bolt and it runs like a top....
2 days on the lake with no issues
THANKS FOR THE HELP GUYS

 

[Fun Times]

Re: Impeller question

SUCCESS......New impeller and new bolt and it runs like a top....
2 days on the lake with no issues
THANKS FOR THE HELP GUYS

Good job