Volvo 230A/SP Sea Water Problem

[CptCFI]

I just completed repairing a lot of items on my boat with help from these forums. Thanks.

The last issue is the Sea Water Pump. It has been completely overhauled. Everything is new and original Volvo except for the case. The case is deeply worn with .030in or so grooves on the cover and back (not on the surface where the impeller runs) but it was pumping water even with several vanes missing on the impeller prior to the rebuild.

If there is a leak causing it to not create a vacuum I'm thinking that would be between the sea water inlet and the pump. Everything after the pump should be under some sort of pressure. So an air leak causing a lack of suction must be either in the pump or before it. Does that sound correct.

Thanks.

 

[captmello]

Re: Volvo 230A/SP Sea Water Problem

yes, not uncommon to have an air leak in the water intake. What makes you think your sucking air?

Did you find all the pieces of the old impeller?

 

[bruceb58]

Re: Volvo 230A/SP Sea Water Problem

You can always put a clear section of hose in before the pump to see if any air is entering.

These drives are notorious for getting an air leak where the hose going to the pump threads into the drive.

If you sucking air when running on muffs, make sure you plug the small intake near the front bullet of the drive.

 

[CptCFI]

Re: Volvo 230A/SP Sea Water Problem

I did not think to 'reassemble' the impeller to make sure I had all the pieces. Oops. The sea water strainer though is downstream of the pump so any that got away should have been caught there. The heat exchanger has been removed and flushed. Last night I used the garden hose to flush the lines that were not removed.

Maybe the question I should ask is how much water should be coming out at idle? I am getting some flow through the system but it is less than I was expectiing.

This model doesn't do well on muffs so I'm using the large plastic tub method to submerge the intakes. The waterline is an inch or so above the top intake slot.

 

[captmello]

Re: Volvo 230A/SP Sea Water Problem

Ya know, after rereading this thread, It's not clear what is wrong.

Is it still overheating? Under what conditions???

 

[Don S]

Re: Volvo 230A/SP Sea Water Problem

The case is deeply worn with .030in or so grooves on the cover and back

You need a new pump. Those grooves are enough to cause an air leak inside the pump.
Most people don't understand how the impeller actually works, the impeller sets offset and the vanes squeeze down so the cavities between the vanes is very small on one side, and almost full size on the other side, this creates suction and pressure. If you have deep grooves and the open and closed vanes pass air/water between sides, less or no water will be moved.

 

[CptCFI]

Re: Volvo 230A/SP Sea Water Problem

Success of sorts. Based on Don's comments I went to try to measure the grooves. The are more like .007 than .030. While measuring I checked the width of the old and new impeller. The new one is .053 narrower than the old one. This measurement was made at the base where the rubber is molded onto the brass center.

Checked the part number molded into the part. They are the same.

Just for fun put the old one back in and with 4 missing vanes it still pumps a siginifanct amount of water.

Has anyone run into this before? (The new impeller came directly from Volvo, not aftermarket).

 

[CptCFI]

Re: Volvo 230A/SP Sea Water Problem

Thanks for your help on this. This thread can be closed.

The old part was bigger probably due to volume swell in the rubber. It was enough larger that it worked in the 'oversize' pump body.

I do not recommend this for everyone but we were successful in milling .003 off the cover to remove most of the wear there and .008 off the body to compensate for the wear in the back of the case. Reassembled, and it works.

Shakedown cruise showed normal temps 190-195.

 

[Bondo]

Re: Volvo 230A/SP Sea Water Problem

Shakedown cruise showed normal temps 190-195.

Ayuh,... That sounds awlfully Hot to me....

 

[bruceb58]

Re: Volvo 230A/SP Sea Water Problem

Shakedown cruise showed normal temps 190-195.

If this is a closed cooling system you are ok. if it is raw water cooled, you still have a problem.

 

[Don S]

Re: Volvo 230A/SP Sea Water Problem

230's all have closed cooling systems, and 190 to 195 is quite normal for them.

 

[CptCFI]

Re: Volvo 230A/SP Sea Water Problem

230's all have closed cooling systems, and 190 to 195 is quite normal for them.

Yes, it is a closed water system with a 180deg thermostat. Temp stable at 185 or so at idle. The 190 was after 10 min at 3200 rpm (going down the river).

I'll be replacing the sea water pump housing when I can afford it. This fix is temporary, I feel with with minimal risk.