SX-M Transom Shield Water Tube Replacement

[vwbugman69]

I began to troubleshoot my raw water pump cooling issues this afternoon so I do not have to rev the engine to prime the pump every time I put the boat in the water.

See my thread from last summer detailing some of the steps and frustrations I encountered on this issue:
http://forums.iboats.com/volvo-penta-i-o-inboard-gas-engines-outdrives/still-not-pulling-water-drive-559923.html

from my experiences last summer, I believe I have it narrowed down to several possible causes:

1) transom shield water tube
2) raw water pump

I tried to eliminate the transom shield water tube by seeing if I could pull a vacuum from the raw water pump inlet tube to the pivot housing inlet (the drive is off) using the mightyvac I got at advance auto. I taped of the big plastic nut and hooked up the mightyvac to the pump inlet hose. Nothing.

I disconnected the hose from the transom water tube and was able to pull and hold a vacuum in the hose itself.

I next taped of the water tube and tried to pull a vacuum from the pivot housing - Nothing, which leads me to believe the water tube is the culprit.

I have looked at the drive manual and have some questions regarding its' replacement.

1) How does this water tube seal in the transom shield? Looking at the parts diagram, All I see is the water tube itself, #3, but no oring/gasket/seal? Transom Shield SX-M - 7746050 - Volvo Penta

2) The parts diagram makes it look like the water tube attaches to the transom shield from the interior, but how does it go through the transom shield and where does the hose (#4) connect to it?

3) When replacing the water tube, does the pivot housing or gimbal ring need to be removed or is is possible to leave them on?

Thank you for all your help!

 

[dypcdiver]

Re: SX-M Transom Shield Water Tube Replacement

Have you replaced the shaft seal on the raw water pump? You mentioned a drip from the weep hole, there should not be any, if water can get out air can get in!

 

[Don S]

Re: SX-M Transom Shield Water Tube Replacement

Are you sure the one you linked to (This one) Transom Shield SX-M - 7746050 - Volvo Penta is how your water hose is set up? If so, then the hose itself has the seal on the end.

The earlier style had a tube that went through with a grommet, and the hose clamped on the other end. Look at this one. Transom Shield, Early Version SX-M - 7746040 - Volvo Penta

Both are SX-M

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

Have you replaced the shaft seal on the raw water pump? You mentioned a drip from the weep hole, there should not be any, if water can get out air can get in!

The drip was from the circ. pump and not the raw water pump.

 

[Don S]

Re: SX-M Transom Shield Water Tube Replacement

Did you ever overheat the engine?

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

Are you sure the one you linked to (This one) Transom Shield SX-M - 7746050 - Volvo Penta is how your water hose is set up? If so, then the hose itself has the seal on the end.

The earlier style had a tube that went through with a grommet, and the hose clamped on the other end. Look at this one. Transom Shield, Early Version SX-M - 7746040 - Volvo Penta

Both are SX-M

Yes, the one you linked is how mine is setup and what matches the drive manual.

Does that grommet ever fail and should be replaced now if I am replacing the water tube?

How involved is it to change the water tube out?

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

Did you ever overheat the engine?

It did overheat one time this past summer.

 

[Don S]

Re: SX-M Transom Shield Water Tube Replacement

If the grommet leaks, water will get into the boat. It won't allow air into the cooling system. That's not to say that the tube itself couldn't be cracked or have a hole in it. But the grommet has nothing to do with it.

How involved is it to change the water tube out?

Remove the hoses from both ends, remove the two bolts, and pull it out from inside the boat.

 

[Don S]

Re: SX-M Transom Shield Water Tube Replacement

It did overheat one time this past summer.

There is a big rubber grommet inside the drive that seals the water tube. If it's burned up, you would get an overheat when on plane only. It would be underwater at idle and low speeds. But on the muffs, it would allow the pump to suck air.

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

The issue is not after being on plane. With the boat still attached to the trailer and having the entire outdrive submerged, the pump will not pull any water, which leads me to believe the water tube to be bad.

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

Remove the hoses from both ends, remove the two bolts, and pull it out from inside the boat.

Do I need to remove the pivot housing to be able to get to the hose clamp? There doesn't seem to be a lot of room with the drive turned full to starboard to get a wrench in there.

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

UPDATE: Removed the water tube and was able to successfully hold a vacuum through it, so that is not the problem.

That leaves just the pump - Would the shaft seal be defective even if there is no water leaking out of the weep hole? Or am I looking at buying a brand new pump?

The impeller and housing was replaced last summer.

 

[Don S]

Re: SX-M Transom Shield Water Tube Replacement

Does the faces of the pump base and inside the housing show a lot of wear? Wavy surfaces? A worn out pump will act like that.

 

[aerobat]

Re: SX-M Transom Shield Water Tube Replacement

would it not be an idea to pull the hose of the raw water pump outlet and fire up the engine for a short time to look if it gives a good shot of water ?. if yes its not the pump but somewhere after the raw water pump. if not its the pump or a clogged / shot passage between the drive and the pump.

 

[vwbugman69]

Re: SX-M Transom Shield Water Tube Replacement

would it not be an idea to pull the hose of the raw water pump outlet and fire up the engine for a short time to look if it gives a good shot of water ?. if yes its not the pump but somewhere after the raw water pump. if not its the pump or a clogged / shot passage between the drive and the pump.

I had tried that last summer and the pump did not pump any water. The only way to the pump to prime was to rev the engine to 2k, It would pump fine after that at all rpm ranges and there were no cooling issues at idle or on plane.

 

[dypcdiver]

Re: SX-M Transom Shield Water Tube Replacement

Remove the raw water pump, 3 x Allen bolts. Replace seal 827247 and check the bearing at the same time and if it is bad buy a new one from a car spares place or where ever.
See this post http://forums.iboats.com/volvo-pent...-behind-5-0-gxib-impeller-housing-540929.html
Then go and enjoy your boating.