New boat owner and new Sterndrive installed, cooling questions.

[almstsobur]

I got a nice deal over the winter on a 1990 boat that was in really good shape, except the motor was worn out, ready to go. I grabbed it at a good price and looked to replace it.

Anyway long story short, it?s a 1990 boat with a 4.3L Merc, Alpha one- gen 1 outdrive. I had a brand new 2005 4.3L ?I think? designed for a Bravo put in the boat (I say designed for a Bravo because it does have a pulley based sea-pump) The Mechanic who put it in said they needed to use my old exhaust system and motor mounts only, the rest was the all new hardware. After doing some reading I think I have come to the conclusion that maybe more should have been done on this type of swap, I have read that the Alpha one-gen one pumps are not designed to cool a newer setup motor (something about high/low flow and volume)? I?ve also read that the thermostat housing is different, and I?m not sure what other things might be different.

Can anyone tell me if this was done properly? Is there is anything I should look for or change? I know according to my onboard thermostat that the boat does not sit at 160 degrees, it seems to go above that and fluctuate quite a bit. Having never owned any boats in the past I assumed this was somewhat normal, but now I?m beginning to wonder if I have a cooling issue? I would really hate to burn up this brand new motor, it wasn?t cheap at all.

Any help or tips on what to look for would be greatly appreciated.

Thanks!

 

[Don S]

Re: New boat owner and new Sterndrive installed, cooling questions.

Post some pictures of your install, plus post the Mercruiser serial number of your new engine.
With that, we can make a start at figuring out what's right or wrong.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

The SN# is OW331349 Says March 2005.

Thank You for any assistance, much appreciated.

 

[cr2k]

Re: New boat owner and new Sterndrive installed, cooling questions.

May have to do with the fact that your circulation pump is operating in a reverse rotation from your previous engine.

 

[Don S]

Re: New boat owner and new Sterndrive installed, cooling questions.

The pump is designed to run either direction, but for your setup, you need to have the hoses hooked up as shown in the image below. I see you have the plastic pump housing. It doesn't take but second with no water to destroy the impeller and the housing.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

Where is the cooler hose headed to? It's not a fresh water system (not closed loop, it pulls river water)? Infact, I kind of thought the Alpha One outdrive (gen 1) was the only pump working and the sea-water pulley pump was just for looks with my setup. I will have to take a close look, but I only recall 1 hose coming off that pulley pump. I really want to make sure I have things right now, because I have a SEI 106 on the way this week as well.

See, I got a bit of a deal on the motor, kind of knowing it wasn't exactly right, but assuming they knew what they were talking about. A local marine shop changed ownership and this brand new 2005 motor was in inventory, the new owner wanted to sell it, get it out of inventory. He had a craigslist add for it and I called, asked if it would work for my setup, they said they could "make it work, sure" So I paid them to do just that, but I'm not sure they did the cooling system the correct way, as I describe in my first post after doing more reading.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

Long story short, I went from a 1990 4.3L Alpha one Gen one motor and outdrive to a 2005 4.3L Bravo motor (I think) with still a Alpha one Gen 1 outdrive.

 

[Don S]

Re: New boat owner and new Sterndrive installed, cooling questions.

The problem is, we have no clue how the drive cooling water is plumbed, where the intake for the engine mounted pump comes from or any of the plumbing for the cooling system. Since it's not OEM, without being able to see all the hoses and where they run to and from, and what happens between the transom shield and the drive for water. It's just impossible to say if anything is right or not.

 

[Pete104]

Re: New boat owner and new Sterndrive installed, cooling questions.

You can't have 2 (supply) pumps in 1 cooling system... That sea-water pump would suck the guts out of the Alpha pump!
You must now make the engine a Alpha, not sure you can. Or put a pick-up in the hull. That wouldn't be to terrible!

Your mechanic didn't think o'that?:facepalm:

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

You can't have 2 (supply) pumps in 1 cooling system... That sea-water pump would suck the guts out of the Alpha pump!
You must now make the engine a Alpha, not sure you can. Or put a pick-up in the hull. That wouldn't be to terrible!

Your mechanic didn't think o'that?:facepalm:

If I understand the mechanic correctly, I think he did something to disable the pulley pump, its really just a place holder for the belt, I think. So what else would be different or wrong? I mean any reason a Alpha one gen 1 drive can't just feed this motor like it did the last one? I think that's my question ... do I need to swap the thermostat housing, or add the T- coupler from the older style? Also, would that pulley pump work if I did a closed cooling system, is that a viable option? I'm really not sure what my options are to get it it right, I really have no clue what the difference is between an Alpha and a Bravo from the motor aspect. I read another post though that concerned me ... however, something along the lines of the gen 1 Alpha was high pressure low volume and the Gen 2 is the opposite, thus it doesn't work right.

 

[Pete104]

Re: New boat owner and new Sterndrive installed, cooling questions.

You still haven't put up a serial #! Not sure why your guy insisted on old manifolds. Cost probably. You in salt water?
So, using those manifolds with an alpha drive, plumb it like an alpha. Requires a hose. The hose from transom to P/S oil cooler.
If he just pulled the impeller, he ought to be shot. You can't change the thermostat with those risers. Alpha & Bravo differences are cooling system, aside from EFI vs carb.
Alpha 1 pump is pressure with low volume & GEN II is a volume pump. It moves more water. With the way I think he has it plumbed, the pump is pushing the water about 6' further than it should with a MAJOR obstruction in way. The sea-water pump.

I really try to get him back, eliminate the hoses to & from the sea-water pump. Install the correct hose from the transom fitting to the oil cooler. This take about 41/2' of hose out of the system. Leave the sea-water pump the way it is for now. You can use this for a "closed cooling system" if you decide to go that way!

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

The SN# is OW331349 Says March 2005.

I posted the SN on the post with the pictures. OW331349

The motor had the Bravo Manifolds on the motor he had to remove them, so I'm not sure it was a cost issue, maybe fitment in the engine compartment?? No Salt water at all, nor do I plan on any, ever. I did put 13 Hrs on the new motor over the winter, it seemed to run and not overheat, but the temp gauge was erratic, not stable and it did get hotter than I would expect at times. I will be taking the outdrive off to replace it on Thursday, will that allow a view that could help identify anything? I would love to just do what needs to be done to get it the best possible "right" solution as I put it back together this time. AT this point I am not sure he didn't use the correct hoses, unless you see something that tells you this? I'm sorry I'm not more help, I'm mechanically inclined enough that I have rebuild car motors before .. I'm just clueless on boat setup's. Trying to learn as I go.

 

[Pete104]

Re: New boat owner and new Sterndrive installed, cooling questions.

Sorry, missed the S/N.
There is no difference between Alpha & Bravo exhaust manifolds.
The Bravo drive use the sea-water on the engine to supply cooling water. The Alpha (which you claim to have) push the water to the engine. The actual supply pump is in the drive. Any pics with drive won't do much good but take couple anyway.
The hoses on the sea-water pump, where do they go? Are they attatched to anything? You have an P/S oil cooler, portside down low. Get a pic of that. Straight back middle of engine just behind the distributor, get a pic of the transom plate.
When you say "hotter than expect", how hot?

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

It would get up near the 200F range from time to time. I am thinking at this point my best bet is likely a thru-hull and sea **** setup for the pulley pump and engine and just allow the Alpha intake to cool just the outdrive (not sure where the output water would go??). Thoughts on that? If you think that's a good plan ... can anyone advise on size, brand and type of Thru-hull? I was looking at them, but so many options. Not really sure what I need.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

Is this the type of thing I am looking for?

http://www.iboats.com/Intake-Strainer/dm/*******.338788507--session_id.464645994--view_id.237503

 

[Pete104]

Re: New boat owner and new Sterndrive installed, cooling questions.

If you went with the closed cooling, yes you would need that.

I/we want to see what you have as it stands.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

If you went with the closed cooling, yes you would need that.

I/we want to see what you have as it stands.

Okay, I will take more and better pictures and have a better idea of how it's setup tomorrow when I take things apart. I will post more pics.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

Sorry I didn't get back to this thread sooner, we had foul weather until today, just got the new outdrive installed. I took a look at the routing (really had to get pictures back there) It looks to me like the feed from the Alpha outdrive goes directly into the Bravo pulley pump, then everything else is as it was, through the power steering etc. Does that sound like an issue? Also, from what I can tell on the water hose, it will break 200F pretty easy at idle but drops down to the 180 ballpark with throttle.

 

[Pete104]

Re: New boat owner and new Sterndrive installed, cooling questions.

That's pretty much what I thought. The temp variation proves it. The pump in the Alpha can't move enough water.
You need to install the molded hose from the transom plate to the oil cooler. I assume the oil cooler came with the NEW engine! No doubt about it, making the Alpha pump (new style or old), they weren't designed to push water an extra 5 feet! The hose you want is maybe 15 inches, 18 tops. Alot shorter.

 

[almstsobur]

Re: New boat owner and new Sterndrive installed, cooling questions.

I'm not sure I fully understand the solution here. So I set it up how it was, from the Alpha to the oil cooler. Then what happens with the pulley pump? Also, isn't the Gen 1 alpha the wrong type of water pressure for the Bravo motor (low volume, high pressure, wrong thermo housing? ) Also, does that pulley pump not assist the Alpha to get the water the 5 ft length, or no?

How are the Bravo's setup on a new boat? Do they use a thru-hull pickup? If so, I am willing to do that if it's the correct fix, but I am unclear how I implement both, keep the Alpha cool and feed the Motor the appropriate water pressure. I'm willing to spend some money to get it right, lord knows I've spent enough, a lot better then burning a new engine up.

No sure if you were being a bit facetious with your "NEW" comment, forgive me if you weren't but it was new for sure. I bought it in the Mercruiser crate, all paperwork, all the new tags still attached, the warning stickers, the tie on the oil cap, manual, registration, everything. After I bought it I decided later to have them install it, when I realized it was not an Alpha motor and I wasn't sure how to get it to work right ... that's when they claimed they could do it no problem.