water flow
 

when I purchased my boat the owner told me that he blocked off the outdrive from sucking water, so there is no need for ears ,all I have to do is run a hose into my seacock and I'll be fine. However when I drop in at the ramp in order for me to get flow I have to loosen the cap on my heat exchange to get flow and after that everything is fine other than I get my alternator covered with saltwater(goodtimes) But if my outdrive would suck water would that eliminate that problem? some one said its vapor lock and it happens a lot,doesn't seem right to me has anyone had this problem and is there a way to reverse the outdrive problem.

Re: water flow
 

I am not sure I understand what you mean when you say he blocked off the water flow. That does sound like a problem from where I sit though.

How does the engine cool when running?

Re: water flow
 

my motor is fresh water cooled ,plus it comes from my seacock. when I run the motor at my house I put a hose in my seacock which in turn gets pulled through my motor and comes out my out drive, But if I put a set of ears on the outdrive it will not suck water in because he blocked that off from taking water in , thats what i'm trying to explain I have no clue why he would do this I'm really not sure.

Re: water flow
 

I think I would be talking with a good mechanic and figure it out and fix it the correct way. Could it be the water pump that sucks water into the out drive is not working? I don't know, I have always run outboards, except a little 4 banger back in the mid 80's.

Re: water flow
 

The outdrive pump has nothing to do with engine cooling on a fresh water cooled closed system. The raw water pump takes care of the engine. The outdrive pump should be retained as it helps cool the outdrive and the hose at the top of the outdrive is cut and just squirts the water out. I have the same set up on my Sceptre w/260 Mercruiser and it works fine.

Re: water flow
 

doesnt the fresh water cooled just cool the engine but the exhaust sides are still raw water cooled thru the outdrive intake correct?

Re: water flow
 

NO! NO! NO! The impeller in the outdrive is what feeds water to the heat exchanger and in most cases, (if you have one) the raw water pump. If you don't have raw water pickups on the hull bottom, you desperately need good impellers in your lower unit. BTW, the outdrive has no need of cooling, it sits in the water.

Most fresh-water cooling systems use engine coolant just like a car, and in many cases, the engine coolant also cools the exhaust manifold. The raw water is injected from the heat exchangers into the exhaust risers after the exhaust manifolds, and then through riser to outdrive hoses.

However, there are still a lot of engines where everything after the cylinder heads going outward is raw water cooled. Most Mercruisers are like this.

I had a 255 Wellcraft SunCruiser with twin V6 stringer drives, and I have had a FishNautique with a Pleasurecraft inboard, and both used exhaust manifolds that were cooled by the closed cooling system. The OMC's actually used the exhaust manifolds as heat exchangers.

Re: water flow
 

I have seen this set-up before where the raw water pick-up is transferred from the outdrive to a thru-hull fitting with seacock. IF you think about it (and your outdrive does not need the water flow for internal cooling, it makes sense in that if you had an issue, you have a means of shutting the ingress of water via the seacock (i.e. a busted hose or fitting).

The set-up would make sense to me on an engine/drive combo like mine,
a 7.4L Merc with Bravo 1. The Bravo drive has no water pump; the raw water pump is mounted to the engine and is driven by its own belt. It would, in theory, be simple enough to install a 1.5" or 2" through-hull to feed the raw water. Also, if you saw the plastic fitting on the inside of the Merc transom plate that the raw water hose attaches to, which is typically below the water line at rest, you might give the thru-hull/seacock idea a lot of consideration.

Re: water flow
 

The alpha's have impellers, the Bravo's don't. When you say you loosen the cap on the heat exchanger, is that the fill cap where you put in coolant??? I'm not sure about that...??? But essentially you have a big upside down U shape with one end being the seacock intake, then up through the strainer (if you have one) through the seawater pump, through the heat exchanger, through the exhaust elbows
(the top of the upside down U), and then down through the Y pipe out the prop. Without some kind of vent at the top, it's airlockd when you drop it into the water so water can't make it up to the seawater pump to prime it. When you use a pickup on the drive it's easier for the seawater pump to prime. You could install a strainer in your raw water path (above the water line but below the top of the elbow) and prime the pump from there......

I'm at a loss for explaining why loosening the cap (if you mean the coolant fill cap) would affect it....

Unless you correct it I would expect seawater pump impeller life to be pretty short.... :(

Re: water flow
 

One more note....while the outdrives don't have explicit cooling, they do use the water flow for some cooling. In the docs describing how to install the blocking plate on the Bravo transom assembly to block off seawater flow, it describes how to position the hose so there will be some flow through the drive. I do long offshore runs with my Bravo and installed a drive shower that keeps it noticeably cooler.

Re: water flow
 

i dont know what type of drive you have but i have a volvo 280 that i did the same thing to. just blocked off the water passage through the transom assembly and ran hose straight from my impeller on the crank pulley (volvo penta) to a 2 1/4 thru hull clam shell w/ seacock... works great... if you think about it, that is the exact way albemarle and carolina classic riggs their jackshaft setups... not sure about your priming problem... if you have a good impeller that is belt drivin then it will supply water anytime the engine is running... now if the previous owner did this to an Alpha 1 setup then you have a problem.... the best thing that i can think of is to get the whole impeller assembly from a bravo setup and do it that way.. go to landandsea.com and get you a "universal" impeller assembly and do the conversion that way..... i cant think of anything that would make the engine "lose prime" besides a leaking hose allowing air into the system or bad strainer seal, bad hose clamps. first off start by finding whether or not you have the impeller on the engine... if so you shouldnt have a problem.... no regrets about mine

Re: water flow
 

I loosen the cap on the heat exchange where the raw water is not the coolant.And when I loosen it it finally starts to take the water from the seacock. Getting tired of trying to figure it out.so i'm gonna go with a 357 mag 325 horse and a bravo 1 drive, now she'll get up and go.what do you think of that? sound good or what

Re: water flow
 

That's a good package.......but the FWC will last a long time.... ;) I think you definitely have a loop that locks it up. I think there's a pretty easy fix for it though.....you have a hose from the heatexchanger going to each of the exhaust elbows. If you put a Tee in one of them and put a valve on it you can open the valve to bleed the air and the raw water will flow in up to the water line level which I think should be enough to prime the pump. I would make sure the valve is ablove the water line....and it doesn't need to be a very big valve since its only going to bleed air.