Full FWC 357mag Alpha 1 gen 2

212rowboat

So.. title says it... thats what I have.  There is no through hull raw water pickup; just the foot. 

My drive is an SEI 116, their version of an alpha 1 gen 2... there is no difference i can identify between it and a merc... 

According to the chart I found the gen2 is a low pressure high volume as opposed to a high pressure low volume the gen1 was... its supposed to flow 20gpm at head pressure of 20psi. 

I read the full FWC system is too much for the alpha to handle without running hot...

Last night I ran hot... around 175 to 180... i hardly pushed it at all... i came home and dropped the foot and inspected the impeller.... it has very little hours but I just slapped this drive on after its been hanging in the shop for at least three years... 

Four of the six vanes are about to fall off... a fifth is torn a 1/4 way through.. the only solid one was deformed near the end... I've no clue how it was pumping anything.  

New one on and about to hit water again for another shake down run.  I'll see how much new impeller helps (I'm certain it will)... I'm hours away from a WOT run, though, and I won't be doing any extended cruising yet.... 

My question is.... has anyone ran a full FWC with an alpha and NOT had to punch the hull and run a belt or crank driven sea pump?  20gpm sounds like plenty... is it not? 

PickleRick

There is a company, I think mr cool that sells a full fwc kit for the merc alpha one.  Run her hard and report back.

A sbc isnt hot til she gets past 210 220...i personally like 190 200 tops.

reneechris14

I think the bravo3 seawater pump is around 20gpm at 3000rpm, i think that the alfa foot could handle it.

PickleRick

I dont think the alpha delivers the volume the bravo delivers.  I considered putting my volvo 290 crank drive pump on the alpha and seems the alpha foot would be too restrictive.  This was i boats recommendation, i didn't try it but i have all the rebuilt parts in my garage.  

212rowboat

It says 20gpm... i find that incredible through a 5/8" ID hose coming through the transom.... i guess I could do the math, as it's also said 20psi head pressure. 

I hit the alarm at around 180ish... took longer this time... 

I'm not certain the stat is a 160... i just can't recall what it was when it was installed. I know I've got a 160 and it may be good to swap it anyway.  

But.... I'll be going through the hull... will likely go with a crank driven pump... now, to figure out where to drill the hole. 

PickleRick

I thought the perk of running closed loop was to run the engine hotter, it was my impression fuel is better atomized when the engine is running around 200 degrees, especially on the newer vortec motors not so much the old carb motors.  

Ive only looked into closed loop cooling for a diesel conversion, never for an inboard

After some quick google searching seems 160 is the closed loop cooling thermostat of choice, i use that now and your target operating temp is 170 to 180.

212rowboat

If I could reprogram I would do so for a hotter stat, but I wouldn't want the engine compartment to see that kind of temp as the only drawback... it goes into guardian mode around 182 or so.  I've not had it above 190... I've actually not had it above 185... im dropping in a 140 stat as I type to see what it does before I punch a hole through the hull.... otherwise? Gonna add sea pump. 

212rowboat

Uh..... the stat that was in it.... came with kit and I'm not even sure I tested it (its in a neck that replaces the four way, and has its own temp sender... all I had to do was replace the neck bolts with studs and sandwich it in there.)... and... its a freakin'  195* stat... my wager, and I'm not a smart fella, is all will be well after the stat swap for a 140* stat.  

Btw... here is the impeller that came out of the foot: 

PickleRick

Hopefully that will keep her cool.  Why the 140? I thought 140 was used in salt water raw cooled engines to prevent crystallization.

212rowboat

Thanks @Alswagg... will give that path a look... i appreciate the insight. 

@PickleRick, good question... here is why:  I have 2 160* stats and one 140* stat... i also have several 195* stats from rebuilding a yj 240 not long ago... so... i snatched the 160's and headed to the kitchen........ neither work.  One opened but wouldn't close.  The other wouldn't open, I thought, and then it did at almost 200*.... i expected it to fail open, but it closed!!! It hit the trash along with the other one... i grabbed the 140 and it starts opening visibly at 142 and full open at 155ish.... closes, and re-opens again at 142.... so... its in the engine... all of them were Sierra brand (except the 195's... i don't know what brand the 195 that was in the FWC kit was, and I can't imagine why it was in that kit... "maybe" I did it, but I don't think I would have... )... 

PickleRick

The the 140 works go for it.  I once had a v8 with a 160 in it when i bought it. Once summer hit she would over heat .  the issue was the thermostat didnt close long enough for the radiator to properly cool and the coolant not was  in the block long enough to pull away the heat, those two issues didn't work well together.  Was only an issue at high speeds/rpms.  

Pulled the thermostat to check to see if it was sticking and found the 160.  Put in a 190 and issue went away.  Might have been a 195.  I didnt keep the v8 long before i dropped in a diesel.


With the sbc i could have baked a ham in the passenger floor board. 

212rowboat

what a simple thing turned PITA... 

the stat neck on that thing has two ports for sensors and a by-pass line... the sender fits just fine... the sensor, not so much... it DID fit with the 195* stat that came with it, but none of the other stats (Sierra) would fit.. the end of the sensor hits the stats spring/barrel.  

this disallowed the stat to sit in the machined recess... 

huhhhhhhhhhhhhhh.........

so... i relocated, in the end, the sensor... it's a $100 mercruiser part- i wasn't going to damage it unless i was going to get $100 of satisfaction and three days wait by destroying it.. it's with fortune i found a 1/2" MNPT bushing with a 3/8" FNPT passage in it, and i pulled a manifold plug about two inches from the stat neck (in pressurized coolant) and fit it just fine.  back. in. business.  

the temperature rises (dash gauge) to an estimated 170ish... it sits there butt cold on the water hose and muffs... i idled for half an hour, fast idling to 1200RPM for several minutes, and revved to around 3k for bursts- it stuck right there.  

i'll put it in the sound tonight and see what happens.  i feel better about it now than i have.  during the prolonged idle, the elbows never even got warm- which tells me it is flowing just fine.  now if raw water is in the exchange for enough surface and time remains to be answered- i'll find that out soon, but the elbows are a good indicator there is at least enough flow. 

212rowboat

Took a long time to get to operating temp... I'd guess 150 to 155 using Faria dash gauge.. ran around 4k rpms and 44ish... dropped to 3200 held for a while... found open deep channel and brought out of hole pretty hard for a new engine, and trimmed to 4k rpm again.... temperature dived, down to around 120 to 140ish and remained for a few full minutes and returned to the "velcro" 150-155 again... my "guess" is the cooling system burped air and filled the void with shot of coolant which cooled things down for that period... or... it passed something from the exhaust and started flowing properly. 

All good.. the FWC works on notta but the alpha gen 2 foot pump.