Running bravo 3 out of water with no muffs

[metsfan3197843]

If I pull the input line off the pump and run the hose to the muffs, no water comes out of the line at the pump. If I have a helper bear hug the muffs and seal them up tight, I get water up to the pump. So the muffs sealing is part of my problem. I could try other muffs, and I intend to. But they’re obviously a variable and I’d like to eliminate it.

This is what has me concerned. This is prior to getting the new muffs that you say are even worse. I said blockage but meant restriction. As in you can get flow when you hold the muffs on super tight but not under normal pressure. Hope you get it worked out rather it’s an issue or just low water pressure or bum muffs

 

[nitsuj]

I am not sure if this has been asked but, did you have the same problem before changing the impeller? And if you did not, is it possible that you have the inlet and discharge hoses on the pump housing reversed?

It's not very obvious if they are switched.

I have never had a problem getting mine to work with the generic "muffs" I have.

I have also used a 5 gallon pail with water + anti-freeze mix suctioning with the pail sitting on the swim-step, after starting with the hose filled with water to siphon from the pail to the muffs.

I have a full-closed cooling system so all I had to do is get the siphon started and start the engine. At idle, it would drain that 5 gallon pail in less than a few min.

If you accidentally get the hoses on the back of the pump housing wrong, it will not suction water at all even if you fill all the hoses first.

Unsure. The impeller was trashed, like no vanes left. So i wasn’t trying to diagnose a flow issue, knowing there would be no flow with the fragged impeller. I didn’t notice this issue until after the impeller was replaced. I had thought that I could have the hoses mixed up. I’ve checked and double checked. My impeller housing has two marking “LH Out” and “RH Out”. My engine is left handed (I’m 100% sure about that). So I have the inlet from the drive going to RH out, and the hose that leads to the engine hooked to LH Out. I’m pretty sure that’s right. Don’t forget, this all started because I didn’t think I had flow, but may have been looking in the wrong place.

Let me ask this of the other bravo owners, because I still don’t have confirmation of my suspicions. When running on muffs at idle, should I see water coming from the prop hub? Should it be coming from the ports on either side of the drive near the transom? Should I have both? Is just one of the other a signal of a problem?

 

[metsfan3197843]

I can only speak for full closed cooling. That’s all you see in our marine environment. On my setup the only thing being supplied by the seawater pump is the PS cooler, the heat exchanger and then from there both elbows. My engine, manifolds and risers are cooled by the closed fresh water system. Sea water side mixes with the exhaust at the risers and comes out the bottom of the exhaust pipe via the 2 holes on the sides of the transom. Some water is still mixed with the exhaust and comes out through the exhaust boot or bellows depending on which style you have. I don’t notice much out of the prop but to be honest I only watch the two exit holes on the transom because that’s where 95 percent of my water flow exits and if I have flow there I’m fine. Hope that helps. I would think if you have an exhaust bellows you would see more water out the prop but that’s just an assumption as I’ve never been around a bravo that had one

 

[HT32BSX115]

I can only speak for full closed cooling. That’s all you see in our marine environment. On my setup the only thing being supplied by the seawater pump is the PS cooler, the heat exchanger and then from there both elbows.

And if you have a 7.4L engine, after the cooling water leaves the PS-Cooler, it goes to the OIL-Cooler., then to the heat exchanger.

If you do not have a heat exchanger (Raw water cooling) cooling water exiting from the oil cooler will then go to the T-stat housing, manifolds/risers etc

If there's one engine it should be left-hand rotation (Viewed from the back looking forward) This will also result in the raw water pump turning the same direction.

(hat-tip to the Late-Great DonS, may he RIP)

 

[nitsuj]

Thanks for all the info! Definitely left handed, it’s marked as such right on the engine, and in the manual. I’m raw water cooled, so no heat exchanger. What I still don’t know for sure is, on a raw water cooled engine, is it kosher if I’m only getting water exiting the transom ports. I suspect it’s ok as the few videos I can find that show a bravo idling seem to show them blowing water out of the transom and little or none out of the prop hub. My current theory is after I installed the impeller, I panicked when my wife said no water was exiting the prop and shut it right down. That’s when I started suspecting bad muffs, etc. When I should have been having her watch the ports on the transom. I plan to reinstall the drive tonight after I take care of a few other things and try the whole thing again.

 

[achris]

.... What I still don’t know for sure is, on a raw water cooled engine, is it kosher if I’m only getting water exiting the transom ports.....

Yes. It's to do with the design of the exhaust Y-pipe and the fact that at low revs/idle you aren't pushing a lot of water through the system. If you were to remove the Y-pipe and have a look at it, the passages for the idle reliefs (transom exhaust ports) is right at the bottom of the pipe. Until there is enough water flowing though the system to overwhelm those ports, that's the only place the water will drain from....

Chris..........

 

[nitsuj]

Big old update as if anyone cares. Flow is good. Got the outdrive back on tonight. I "primed" the system by filling it first. Fired it up and water flowed like the mighty Ohio river! I don't want to jinx anything, but I think I'm ready for another test splash!

 

[metsfan3197843]

Glad to hear it. Fingers crossed for you

 

[alldodge]

Don't know why there was an issue, and maybe we will never know. My motors (1 is B1 and other is B3) are drained completely for winterizing. In the spring, attach muffs and fire it up and water comes out without issue in 20 to 30 seconds (never timed it)

 

[nitsuj]

Don't know why there was an issue, and maybe we will never know. My motors (1 is B1 and other is B3) are drained completely for winterizing. In the spring, attach muffs and fire it up and water comes out without issue in 20 to 30 seconds (never timed it)

I'm reasonably sure the problem was combo of bad muffs and not knowing where to tell my wife to look for exhaust water.

 

[HT32BSX115]

I "primed" the system by filling it first.

Priming is not required at all. When the boat is sitting in the water, the pump and associated plumbing is below the waterline so it is self priming and fills with water when you're sitting in the lake..

The only time you would need to "prime" would be if you wanted it to draw water from a bucket under the drive. But, you'll NEVER do that. (and should never try either!!) It would never be necessary..... No stern drive will draw water from a bucket and it's the fastest way to destroy an impeller.

It might be possible to get it to work with an Alpha if you could fill the bucket (and the bucket could be tall enough) for the waterline to be above the drive mounted impeller.

Regular Flush Adapters (Muffs) work just fine. Only run idle (or slightly above) with the muffs too. No need to rev it up out of the water.