No exhaust water - help!

[Momosailor]

I have a Westerbeke 4107 with a Walters V-Drive. I pulled out the v-drive to replace it. Prior to doing so, my engine exhaust system ran normally.
Here is what I know about the raw water side of my system: after water goes through the raw water intake, it goes through a strainer, then through the v-drive, then to the water pump, then to an oiler cooler, heat exchanger and then finally through a transmission oil cooler before it goes through the exhaust manifold. After installing the new v-drive, I have had no exhaust water. The intake is not clogged, the strainer is not clogged, water moves through the new v-drive with ease. I checked the impeller, which appeared fine, but replaced anyways. The pump appears to be spinning the new impeller just fine. Any ideas? My raw water strainer bowl is filled but not draining when the engine is running. Seacock is open.
When I replaced the v-drive, all the water in the exhaust system emptied into the bilge, as the connections to the v-drive are the lowest point in the system...could all the air in the system be preventing the pump from priming?
Any thoughts?
Thanks!!!

[SkiprJohn]

Yes to your question. Try filling the system from the top even if you have to pull a hose to do it. It could also be a collapsed hose between seawater intake and the pump somewhere. Make certain nothing is in the way that could block the water from coming into the strainer.

Let us know if that works. There wil be more input I'm certain.

[Oceanride007]

Must get as much water on suction side of Pump with seacock shut use the above mentioned hose, once you get suction side closed up, give it a run, if no luck do the same again this time open a connection on disch of pump and check for water flow.

I has a similar problem on on a superyacht one time turned out to be a Anode that let go and precisely lodged itself in a flexible hose. I found that out by reverse flush.

Oceanrider

[laika]

Originally Posted by Oceanride007

open a connection on disch of pump and check for water flow.

Oceanrider

Agreed..easy check to narrow down which side the problem is on. No worry about overheating engine in idle during this.

After a launch, impellor change, etc., I sometimes have to briefly disconnect the raw water pump discharge with the engine running to prime the pump. Otherwise the pump will just keep pushing air through.

[mikefossl]

Is the plate covering the impeller worn or scored? If so, use some wet/dry sandpaper on a plate of glass to clean it up. A small leak may be a problem with air but work fine when primed.

[Ziggy]

My raw water pump sometimes fails to prime also. A bit of silicone grease on the impeller fixes it. If you don't have silicone grease, try dishwashing detergent.

[atoll]

Originally Posted by laika

Agreed..easy check to narrow down which side the problem is on. No worry about overheating engine in idle during this.

After a launch, impellor change, etc., I sometimes have to briefly disconnect the raw water pump discharge with the engine running to prime the pump. Otherwise the pump will just keep pushing air through.

+1 sounds like an air lock in one of the oil coolers,exhaust back pressure will also stop water flowing.

[cheoah]

Originally Posted by atoll

+1 sounds like an air lock in one of the oil coolers,exhaust back pressure will also stop water flowing.

Like atoll says, make sure you check the exhaust

[Momosailor]

Thanks everyone - filling as much of the system upstream of the pump as possible worked to prime it. Really appreciate the help!

[SkiprJohn]

So everything ok now? I love the Perkins versions of those engines.

[sailorchic34]

I should note that it is quite possible to install a new impeller, where looks like it is seated, but that it will not pump. The front face of the impeller must make contact with the inside face of the pump body. But I found out it that it is possible to leave a small gap, which causes the vanes to not seal to the front face.

My test is to take the intake hose and with the outlet hose off, blow into the intake. If you can blow pretty freely through the pump, the impeller is not seated all the way. There should be just a little leakage of air on the discharge, if the impeller is fully seated.

Its a great test to do before buttoning everything up.