1986 Bayliner Capri Raw Water Pump Question

[R Wallerr]

Hi, I recently posted a question regarding cooling system problems about 3 weeks ago. Long story short: I have run my entire cooling system for blockages, debris (including imploded impeller), acid bathed the heat exchanger, removed, cleaned and reinstalled the exhaust manifold. I discovered that I have little or no water coming through the raw water pump.

I rebuilt it recently including a new seal, impeller and cross-piece. The interior of the pump showed no signs of scarring and had no debris in it. The cam also looked to be in good shape also. The impeller is a "worked in" fit and the spines seem to flop proplerly. I lubricated everything with glycerin. Again, it draws little or no water.

I removed the intake tube and ran the engine. I put two fingers across the intake port and there was no suction at idle speed and very little at higher rpms. And yes, the impeller is turning proportionately to the engine rpms.

The body of the pump appears to be in excellent shape. I even tried a thicker gasket for the cover plate. I'd hate to replace the pump if the solution is something simple. Any thoughts you might have would be greatly appreciated.

I can attach photos of the inside of the pump if you like.

Thanks,

Rick

 

[jerryjerry05]

Re: 1986 Bayliner Capri Raw Water Pump Question

If all is working well and the pickup system isin't allowing in air(rear seal or the out side hose is bad).
The cam in the pump might be worn out.They are replaceable.Post some pics of the inside of the pump.
Try this: unhook the rubber hose from the rear of the engine and fill it with water.If the water pump or seal is bad it will leak.Try blowing air into it with your mouth to force the water. Those pumps(I think we are talking about a Volvo) should pump a lot of water. Take off the outlet side of the pump and start it (hooked to water) see how much it pumps.
The drive has a 1/2in hole on the bottom that will need to be plugged or it will suck air.J

 

[cr2k]

Re: 1986 Bayliner Capri Raw Water Pump Question

Another issue with older Volvo's is the way the water is routed to the pump. It is sucked through the drive and the pivot bushings. When the bushings wear it will suck air, more so on plane then at idle.

If this is your case the easiest fix is to locate a place in your bilge where you have room to work and install (on raw water hose side if possible) a scupper or hull intake as close to the center line of the hull as possible and facing forward. Also install a seacock with this then route this to the intake on your sea water pump. This eliminates a lot of distance the water has to travel to get to the pump as well as any issues between the pump and intake on the drive.

A simple tee fitting above the seacock with a hose fitting (and a way to cap or plug it) will give you an easy way to run on a garden hose too.

I have done many of these and they solve to problem very nicely.
Just remember to open the seacock after you run it in the driveway.

 

[R Wallerr]

Re: 1986 Bayliner Capri Raw Water Pump Question

Interestingly enough, I pulled off the rubber intake hose where it connects to the outdrive. I stuck a water hose in it and started it up. It blew all kinds of water out through the exhaust. It was great! I reconnected it to the outdrive and started it up. No water again.

I like you're solution but I have a question: Was the pump actually working properly or was it the pressure from the garden hose?

If the pivot bushings are bad I assume that requires dismatling the outdrive. It also makes sense to because my last trip my boat was fine up to 3000 rpm but overheated at higher rpms so I'm guessing it is the pivot bushings.

Thanks guys.

 

[jerryjerry05]

Re: 1986 Bayliner Capri Raw Water Pump Question

Those bushing are something that is RARE to leak.Not saying it can't , just rare. Before taking apart your drive, check all other possibilities.Plug up the hole in the bottom of the drive,duct tape the muffs to the drive then turn the water on full blast if the bushing are leaking then it will show then.Then do the other tests.
If it seems a lot of water is comming to the hose then it should throw all it's getting out of pump.The pump cam when it's worn won't look like its worn.It's just a lot thinner.J

 

[R Wallerr]

Re: 1986 Bayliner Capri Raw Water Pump Question

Hi Jerry and cr2k,

If something "rare" is going to happen, it will happen to me! I covered the water intake and the 1/2" hole on the bottom of the outdrive with duct tape. I then pulled the hose off of the intake tube to the pump. I put a garden hose inside and turn the water on gently. All of the water poured out of the outdrive around the pivot bushings. Not just a little bit...all of it. It was like nothing was there. I guess it is pretty obvious that it is the pivot bushings.

Again, this makes sense. Apparently they have been slowing going out for about the past year. Below 3000 rpm I was ok temp wise because I was only going around 10 mph and there was enough water around the top of the pivot bushings to allow some water to be sucked in. Once I increased my speed the water would pull away from the transom and I couldn't pick up any water at all resulting in overheating. When I stopped or slowed down, enough water returned around the outdrive to quickly cool the engine back down.

You guys are Brilliant!

I am not going to pull my outdrive. They are just a little over my head. I think I am going to take cr2k's advice and re-route the water intake from the outdrive to the hull. The brass intake tube is 7/8". What size scrupper do you recommend? Larger? What type of hose do you recommend? Is bilge hose too light and subject to collapse or is heater hose material better?

Thanks again guys!

 

[jerryjerry05]

Re: 1986 Bayliner Capri Raw Water Pump Question

Reinforced hose,prefrebly wire reinforced.Bigger is better when you are dealing with water delivery.You might want to think about a strainer too.I know you have one on your motor but more is better.That way it won't colapse(hope I spelled that right).Your water pump has enough suction to suck regular bilge line flat.Bilge pumps expand the hose the pump will suck it flat.Good luck,J