Water circulation problem

[track coach]

OK, new boat owner and new to forums, however here goes. I have just aquired a 1977 Glastron V-174 Bayflite. It has a Volvo-Penta 130 engine (AQ 130D/280) Possible serial # 7856/133568? with a Volvo 280 outdrive. I was able to start the motor but was not drawing any water through the sea water pump. I removed the cover plate to the pump and found the impeller turning (I assume at the correct speed). The impeller also looked to be in good shape. I blew through the suction line out through the outdrive and found no blockage. I did not let the motor run long enough to see if the T-Stat would open because I did not want to cause damage to the impeller. Am I correct in the fact that water should always circulate through the impeller regardless of engine temp? If I am correct in these assumptions, any ideas where to look/test for next.
Thanks for any/all help.

 

[Don S]

Re: Water circulation problem

Yes, The water from the pump circulates through the exhaust any time the engine is running.
Did you plug the secondary pickup hole in the bottom of the drive? You should when running on muffs. Also make sure you have plenty of pressure and volume at the hose.

 

[track coach]

Re: Water circulation problem

I did not know that there was a secondary pickup hole, however I used a large cooler filled with water that the outdrive sat in. Would that hole matter at that point?

 

[Don S]

Re: Water circulation problem

No, it wouldn't matter if the drive was in water, but the water had to completely over all of the pickups holes, or it would suck air. You may need a new impeller. They should be replaced every other year as preventive maintenance.
A very popular problem with those drives is the water hose connection on the drive. The corrode away inside the hose, look solid but suck air.

 

[track coach]

Re: Water circulation problem

It looks like there is a connection at the top of the outdrive held on by 2 bolts. If the bolts are removed, will that allow me to pull the tube inside the drive up and out to inspect? or do I have to disassemble the outdrive to remove the tube?

 

[sqbtr]

Re: Water circulation problem

Take the hose off the water neck to check the neck, they may look good but be corroded from the inside. That tube you're talking about is pretty robust and not likely leaking, requires drive removal to R&R. There is an o-ring between the tube and the lower unit that can be replaced by dropping the lower, but, that's getting way ahead of ourselves. Check the neck first

 

[track coach]

Re: Water circulation problem

Ok, Thanks for alll the info, I will try those ideas out tonight and update in the morning.
BY the way, is it safe to hook a hose right to the input of the water pump from a bucket and run another hose out of the water pump into another bucket to see if the impeller is running at the right speed and suction? or will damage occur to the lower drive doing that?

 

[am_dew]

Re: Water circulation problem

Ok, Thanks for alll the info, I will try those ideas out tonight and update in the morning.
BY the way, is it safe to hook a hose right to the input of the water pump from a bucket and run another hose out of the water pump into another bucket to see if the impeller is running at the right speed and suction? or will damage occur to the lower drive doing that?

You can't damage the lower drive but you do risk overheating your engine. I would just attach the hose to the input side of the pump, then start the engine and then check to see if water comes out of the exhaust port on the outdrive as well as monitoring the temp gauge to make sure it does not overheat.

 

[wellcraft19]

Re: Water circulation problem

If attaching the hose "hard wired" to the pump, water pressure in the hose being much higher than the impeller ever would generate, I'd advise against it. Use muffs (but ensure there's enough water flow), or drop the drive in a bucket, and let it suck "normally".
Of course, all the while monitoring flow and temperature.

 

[PiratePast40]

Re: Water circulation problem

The raw water pump is positive displacement so a hose hookup on the suction side isn't going to hurt anything. Excess water will just run out through the outdrive. You still need to replace the impeller and verify there are no air leaks on the suction side but it's a very simple way to run the engine without the muffs or a tub of water. You can get a radiator flush fitting at an auto parts store. If you have a water strainer, that could also be a source of the air leak.

 

[wellcraft19]

Re: Water circulation problem

By attaching hose directly ("hard wired") on the latest "true" Volvo I-4 engines, you risk pushing out the seals in the raw water circuit.

Looking at the picture, I see an older Volvo engine with nipples and hose clamps. On the later models they are just "push" fittings, and they are a tad sensitive to pressure. It really does not take much to create a leak, so I just want to flag for caution when hooking up the garden hose.

 

[PiratePast40]

Re: Water circulation problem

By using a setup like I've shown above, you can slightly pressurize the suction side by holding the muffs tight, blocking the hose hole, and plug the weep hole in the skeg. When you do that, leaks on the upper and lower o-rings of the water tube, the beaded gasket of the water neck, the water neck fitting, the hose, and all the fittings up to and including the strainer, will be easy to spot. You won't be able to hold the muffs very long by hand so you'll want to have an extra pair of eyes to look for leaks. Just be aware that the water neck and it's beaded gasket are know leakers so it's best to look carefully there. Don't expect to see water squirting out, it'll probably just be a few drops or a little stream.

As for the engine in the picture, that IS a later model AQ130D and is typically paired with the 280 outdrive. The D has some minor differences with the "red block" B20's. It's the B20 E or F casting and has an 8 bolt vs 6 bolt crank, has slightly different big end bearings, and some have a smaller thickness upper piston ring. This block was used on the later fuel injected, B20 automotive engines.

As for getting water past the pump, I guarantee you, you're only going to slightly pressurize the system for a few seconds. There will be so much water squirting in your face that you won't hold it very long and it's not full water hose pressure anyway. As for the push-in fittings, those are on the discharge side and you're not pressurizing that if you have the impeller in place. I also agree that you do not want to hook a hose to the discharge side of the pump.

 

[wellcraft19]

Re: Water circulation problem

Was more raising caution if connecting "directly" to the "sucking" side of the pump, with no "relief" out through the normal water uptake route (seen people do that).

 

[kevincave]

Re: Water circulation problem

read all the threads in this forum on overheating and you can see all the various problems that can cause problems......