Jump to content

Cooling System Penta: Outdrive or through-hull?


Recommended Posts

I just purchased a 2005 190SSI Sport with a Volvo Penta 4.3 GL engine.  I'm a complete newbie (this is my first motorboat) so pardon the questions.  The sterndrive has the usual raw water intake ports as shown in the manual.  But the boat also appears to have a raw water thru-hull fitting and hose directly leading to the raw water pump. 

Questions:

1. Does the raw water come into the engine through both locations?

2. I'm on salt water and keep the boat elevated on a Jet Dock. To flush the engine, I have been attaching a hose to the Engine Raw Water Flush Attachment as recommended in the manual.  Do I need to close the valve on the raw water thru-hull fitting whiIe I am flushing?  What would happen if I just left the raw water thru-hull fitting open while flushing (recall, the boat is out of the water on a Jet Dock)

3. Does anyone know if the 2005 190SSI Sport came standard with this raw water thru-hull and on/off valve or could this have been added by the previous owner (now deceased).  The owner's manual makes no mention of the raw water thru-hull.  If it was added, what would be the purpose of having two sources of raw water simultaneously?  Is this common?

I've searched everywhere on the internet for the answers, but to no avail.  It's probably a dumb question, but appreciate any insight you might have.

Thank you

Raw Water Thru-hull.jpg

Link to post
Share on other sites

Do you have the full engine model number? There are 10+ different Volvo Penta 4.3GL’s. The model number should be 4.3GL-__ or 4.3GL__-__.

Awefully dirty bilge.

Can’t be 100% sure without confirming exact engine, but looks like an add-on.

Is it on the suction side, or a t-off the discharge perhaps to drain?

If on the suction side, +1 to Bt Doctor’s question. 

Link to post
Share on other sites

Thanks for all the responses/questions!  Here is some additional information to help solve the mystery

The specific engine is a Volvo Penta 4.3 GL-D (Engine# 401213366)

The thru-hull hose appears to lead directly to the raw water pump on the engine (not sure if it the vacuum side or the output side)

When I re-open the seacock valve after flushing it, I can hear residual water flowing out of the hull (I can't see it because my view is obscured with the hull on the Jet Dock.  But, I can hear it flowing from the bottom of the hull. So, I believe it is actually a thru-hull.

Also, I did an experiment today when I flushed it out with the hose port while on the Jet Dock.  1st I tried it with the seacock valve open, and when the hose was running I saw no water exiting the rear of the boat or exhaust while the engine was running (or before I started it.)   DANGER! DANGER!   So, I stopped that after 30 seconds and figured all the water must have just been going from the hose, through the pump, and straight out the bottom of the boat???  Next, I tried closing the seacock valve and flushing it.  Then I saw water flowing out the outdrive and the exhaust before and after starting the engine.  So the original questions still stand

1. Does the raw water come into the engine through both locations?

2. I'm on salt water and keep the boat elevated on a Jet Dock. To flush the engine, I have been attaching a hose to the Engine Raw Water Flush Attachment as recommended in the manual.  Do I need to close the valve on the raw water thru-hull fitting while I am flushing?  What would happen if I just left the raw water thru-hull fitting open while flushing (recall, the boat is out of the water on a Jet Dock).  TONIGHT, FROM MY LITTLE EXPERIMENT,  I LEARNED IT SHOULD BE CLOSED WHILE OUT OF THE WATER...RIGHT?

3. Does anyone know if the 2005 190SSI Sport came standard with this raw water thru-hull and on/off valve or could this have been added by the previous owner (now deceased).  The owner's manual makes no mention of the raw water thru-hull.  If it was added, what would be the purpose of having two sources of raw water simultaneously?  Is this common?

Link to post
Share on other sites

Thank you.

It’s not part of the original design. 

The raw water pump is below the main pulley in your picture. Please locate it. The barb and hose closest to the keel is the outlet to the motor. The barb and hose just above is suction (raw water). They are both are oriented slightly downward toward port, at the 7 pm and 8 pm positions. Follow these hoses and see which is attached to the “thru-hull”. 

Double check where the flush hose is attached. It should route to a t-fitting on the suction hose (inlet to the raw water pump; the suction side).

In the meantime, don’t run the engine. Fixing an overheat typically ends up being expensive. 

Given the two experiments, I believe you’ll find this thing is t-d from the outlet hose.

If confirmed, it’s a drain and the engine should only be operated with the valve closed.

If it’s off the suction side, more investigation is required as there’s other modifications.

A picture or two further left and also down lower would help.

Good luck.

Link to post
Share on other sites
11 hours ago, Curt said:

the meantime, don’t run the engine. Fixing an overheat typically ends up being expensive. 

The mystery continues.  I followed the thru-hull hose with my hand (it was hard to get a photo) and it comes up to a T that feeds into the suction side of the raw water pump, NOT the output side.  The hose flush unit ultimately feeds into this same suction side as well (as expected).  So, it sure appears like the thru-hull is for sucking up extra seawater in addition to the two outdrive vents.  In aerospace, they call it redundant systems. 

So, is this a rare set up?  Not sure why they would do it.  The brackish river we are on isn't particularly dirty (just occasional seagrass floating around).  DOes anyone else have a set up like this or know of boats with this set up? 

Thanks to everyone for all your expertise and experience.  I'm quickly trying to get up on the learning curve

Link to post
Share on other sites

Typically redundant systems are designed and implemented in a way that doesn’t have the potential to create additional damage. In this case, if t-d off the suction side, it’s not redundant, dangerous and likely to cause damage. As you’ve learned, with the valve open there is no flow through the engine and out the exhaust. The exhaust needs cooled, otherwise parts melt and fail. Likewise, if open when out on the water, there will be no/reduced flow through the drive and inlet hoses. Both will lead to damage.

Yes, it’s rare. Probably a one of a kind.

Reason? We can only guess. 

In my opinion, you know what free advice is worth, never run the motor in the open position. Further, if not removed, wire tie the handle closed so it can’t be inadvertently opened.

Be real attentive to the motor and drive because these might have been damaged. The only logical assumption is flow through the drive, into the engine and out the exhaust (e.g. normal way) was compromised somewhere along the way and this concept born and installed.

Best.

Link to post
Share on other sites

I have the same setup on my 244.  Mercy engine and outdrive.   It came from Chaparral factory that way.   There is a T fitting that feeds outdrive and thru hull to raw water pump.   It is a Bravo 3.  Dealer was surprised when it came in that way which is how I remember.

Link to post
Share on other sites

Thanks @Curt, I'll try your advise and just keep the thru-hull closed all the time and keep a close eye on the water temperature.  I don't believe this set up is stock.  There is no mention of this setup in the owner's manual, otherwise, the flush instructions would have said to close this valve before flushing with hose.  Also, I do have the original receipt of the boat purchase in 2005 and there is no mention of an add-on. 

@Lestat, how do you use your set up?  Do you use both intakes simultaneously (out drive vents and thru-hull).  Do you close your thru-hill valve when flushing?

Link to post
Share on other sites

The OP has a Volvo Penta and this thing is not part of the motor build. Is it a Volvo or some other aftermarket or homemade solution? Yes, it's one of these. The discussion has migrated to a Mercury with a B3. For kicks, I did a search on the words "Mercury Bravo 3 with thru hull inlet". Take a look through this link:  http://www.boatered.com/forum/topic.asp?TOPIC_ID=131433. The pro group claims added water flow due to less than desired flow through the outdrive (the regular way). The con group claims a hotter outdrive as a result. I did the same search substituting "Volvo Penta" for "Mercury Bravo 3". Not nearly as much information. I'm neither pro or con, but have a concern that stems from water taking the path of least resistance and whether this has consequences to the motor and/or outdrive. Whatever decision you determine is right for you, please think it through so you don't cost yourself aggravation and money. Perhaps stopover or call a Chaparral dealer with the Hull I.D., motor and drive numbers handy. They will likely have more information.

Link to post
Share on other sites

Curt, thank you for the link on the Merc Bravo 3 thru-hull modifications.  Fascinating.  The more I think about this topic, this is my conclusion.  The vast majority of boat owners do not make this modification of adding a thru-hull for extra water.  So, if my boat isn't getting enough raw water though the  standard out-drive inlets, then I should first diagnose why that is happening in the first place.   So, I'm going to run it with the thru-hull closed and see what happens.  At least I don't feel all alone now with an unusual setup.

Link to post
Share on other sites

Update:  Tonight I tried running the boat with the thru-hull closed, instead of open.  I was only running just above idle speed piddling around the "neighborhood."  The engine started to overheat in about 10 minutes.  So, at that point, I opened up the thru-hull.  The engine quickly and dramatically cooled off by 50 degrees in about 1 minute.  So it does beg the question of why the standard out-drive inlets aren't functioning properly

BTW @Curt outdrive is # 4202118793

Link to post
Share on other sites

That should be a single prop, SX. A guess, just a guess, the inlets are gunked up, and/or the hoses have collapsed. I’ve seen zebra muscles get up in there and clog things up real good also, albeit in fresh water lakes. No clue what lives in brackish waters. If I was working on it, I’d powerwash the engine compartment, pull the drive, disassemble, deal with what’s probably a long overdue gimbal service and then sort it out. Others will run with the valve open. Neither is right or wrong. Two sides to any coin. Be careful on the overheat. Motors hate it and it gets expensive. Be nervous north of 160-F, and before 180-F shut down.

Some other pointers. Pull your thermostat and check it. Put it in hot water. It should smoothly open at about 160-F. (I need to double check the spec. for your engine.) Also, pull and inspect or replace the raw water impeller. Finally, it’s surprising, but even a small air leak on the suction side will kill prime and flow. So, when you start inspecting hoses, o-rings and so forth, keep this in mind.

Link to post
Share on other sites

Thank you @Curt.  Great advise and wisdom.  Yes, single prop.  When I purchased the boat a couple of months ago, I took it to the shop for full 3-year service (because I know nothing about boats).  They removed the out-drive, drained it, and inspected it prior to filing back up with gear-lube.  So, hopefully, it isn't clogged.  In addition, they changed the impeller. Although the boat is in brackish water, it has always been elevated on a Jet Dock and never just sat in the water, so hopefully nothing too big was growing inside of it.  Nonetheless, something must still be amiss if it overheats with the thru-hull closed which is the standard set up for this boat (i.e. no thru-hull).

I'll definitely double check all the hoses.  Iv'e heard a common issue is people forgetting t0o tighten the hose fitting tight enough and overheating, so I've been vigilant about that.

When I pull the boat out for the season in Nov/Dec, I'll have the shop take a deeper look at all your recommendations.  I definitely need to learn to do all this myself eventually.

 

 

Link to post
Share on other sites

My Bravo3 has the raw water pump mounted on the engine.  Alphas have it in Drive.  There is still a hose from the outdrive that joins the thru hull hose at a tee and the output from that tee goes into the raw water pump.  I don’t have a drive shower and my outdrive has never shown any signs of overheating and when I have checked it out after a run, it is cool.  But mine is a Merc system and not a VP so the OPs could be plumbed different.

Link to post
Share on other sites
10 hours ago, Hatem said:

Which makes the OP's setup rather strange because obviously he's not getting any water to the pump from his outdrive since it overheated simply by shutting off that thru-hull valve.  So how is his drive staying cool?

It sure is strange. I wonder if a plate was installed. As to the drive, it's in the water and this is a lower horsepower and torque motor. The drive is okay just being surrounded by the water. Ideal, no. Okay, probably. I'd sure change drive lubricant each and every year on this set-up. I do on the normal set-up, but don't have to per the manual.

Link to post
Share on other sites
  • 1 month later...

As a conclusion to my original post, I finally tracked down the mechanic who added a scoop/thru-hull into the engine cooling system.   This was done because (as many of you already figured out), there was some type of clog that wasn't allowing enough water from the out-drive to cool the engine.  So, this thru-hull/scoop was installed as a cheaper way to get more water circulation through the boat.  Now, that I understand it, the boat has been running great all season.  I open the valve on the thru-hull when operating it.  When I'm done boating for the day,  I rinse the salt out of the out the engine on my JetDock by using the usual hose attachment while making sure to close the thru-hull valve. 

Link to post
Share on other sites

I should have re-phrases what I meant.   I have a closed cooling system so I am aware the engine would not drain.  What I meant to say was that if it was open and running on hose the water would drain out it and not circulate.  My bad.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...