2 Questions on Volvo 5.7 350

[wake4me]

Hello. New here and think this is great! I have two questions to ask the experts of iboats forums on a Cabureted Volvo 5.7L 350 that sits in a 1998 Four Winns Horizon RX.

First, is it better to remove the thermostat from the engine or is it frowned upon? I would think that it would help to keep the engine from over heating?

Second, I have 4 water drains on the engine. Two on the block (1 ea side) and two on the exhaust manifolds (1 ea side). Can you remove the drain plugs, replace them with a 1/4" brass or plastic nipple, then with 3/8" vinly/plastic hose and "y's" or "t's" connect all 4 drains into one hose that could pass thru the hull to the exterior of the boat near the main water drain plug? I think it would be nice to drain all water from the engine every time I pull the boat out of the water.

To add to this second question... Could the thru hull drain be left open at all times or would it need to be plugged while in the water? I'm not sure if it were left open would allow too much water to by-pass the cooling system?

 

[mkast]

Re: 2 Questions on Volvo 5.7 350

Engine was designed to utilize a thermostat.
You are describing what's called a "Single point drain".
Works great, except the drains in the block and exhaust manifolds get clogged with sand and debris.
Why would you want to leave the drain open while running?

 

[JoLin]

Re: 2 Questions on Volvo 5.7 350

Engine was designed to utilize a thermostat.
You are describing what's called a "Single point drain".
Works great, except the drains in the block and exhaust manifolds get clogged with sand and debris.
Why would you want to leave the drain open while running?

+1 on all points.

Your car uses a thermostat, too- does the t-stat make it overheat?

Ditto with the connected drains- when you drain the block and manifolds in the Fall you often have to stick something into the drain holes to clear out debris so the water will drain. Connecting them all together just makes that impossible to do. And, as noted... why the heck would you want to leave it open while running?

 

[Don S]

Re: 2 Questions on Volvo 5.7 350

First, is it better to remove the thermostat from the engine or is it frowned upon? I would think that it would help to keep the engine from over heating?

Keep the thermostat in, if you are having any kind of overheat at all, you need to check the raw water pump impeller. They should be changed every other year.

 

[Bondo]

Re: 2 Questions on Volvo 5.7 350

First, is it better to remove the thermostat from the engine or is it frowned upon? I would think that it would help to keep the engine from over heating?

Nope,... Don't even Think about it....
The motor would run Stone Cold which is stupidly Inefficient,+ due to the change in waterflows, it'd probably have Hot Spots causing all sorts a problems you'd never know about til it was Too Late....

Second, I have 4 water drains on the engine. Two on the block (1 ea side) and two on the exhaust manifolds (1 ea side). Can you remove the drain plugs, replace them with a 1/4" brass or plastic nipple, then with 3/8" vinly/plastic hose and "y's" or "t's" connect all 4 drains into one hose that could pass thru the hull to the exterior of the boat near the main water drain plug?

Ayuh,... Only if you want to Guarantee you'll have a Freeze Cracked block someday....
And, for your follow up question,...
See what I said above about Changing the Waterflows...

 

[wake4me]

Re: 2 Questions on Volvo 5.7 350

Thanks to all of you for the insight. I will definitely leave a thermostat in the engine. How about a lower temp thermostat though? I suppose that would be okay? I'm not having any issues with overheating, I just want to prevent it.

I am in the process of installing a new engine and that is why these thoughts have crossed my mind. I'm sitting here getting ready to put the new engine into the boat and keep thinking... ok, what else should I do that can't be done once the engine is back in place? I've replaced the bilge pump, which can't be reached... what else?

As far as the water drains. I had already thought about them getting clogged, but it wouldn't hurt to shoot a back-blast of air through them to clear would it? I also thought that if I just left them open I wouldn't have to put a plug in the "thru-hull" connector, but I see that it would be important to keep it sealed while in the water now.

I guess the biggest reason why I want to do the "single point drain" is becuase in the past I have noticed a lot of rust powder build up in the cooling system. I'm not usually one that is out on the lake every day and my boat sits more than it runs. So, I thought that if I could make an easy way to drain all the water from the engine every time I use the boat it would help to eliminate the rust issue?

Thanks again!

 

[JoLin]

Re: 2 Questions on Volvo 5.7 350

Draining the block after every use won't prevent or slow down rusting.

Putting in a lower-than-rcommended temp t-stat doesn't prevent overheating. Changing the water pump impeller every couple of years prevents overheating.

Follow the manufacturer's instructions, specifications and service schedule. Nothing you've suggested will make your motor last a minute longer, and second-guessing Volvo on the right parts might actually shorten its life. Volvo knowe a lot more about their drivetrains than you do.

Take care of it the right way and have fun.

 

[Bondo]

Re: 2 Questions on Volvo 5.7 350

Putting in a lower-than-rcommended temp t-stat doesn't prevent overheating. Changing the water pump impeller every couple of years prevents overheating.

Follow the manufacturer's instructions, specifications and service schedule. Nothing you've suggested will make your motor last a minute longer, and second-guessing Volvo on the right parts might actually shorten its life. Volvo knowe a lot more about their drivetrains than you do.

Ayuh,... I Agree,... You might find some Manuals for your rig up in the Adults Only section of this forum,...
Have a look,+ download whatcha need....

Btw,... Welcome Aboard,...

 

[slasmith1]

Re: 2 Questions on Volvo 5.7 350

If you are that worried and installing a new motor now is the time to consider adding a closed cooling system. I love I/O but I will never own one that has an open (raw water) system.

 

[wake4me]

Re: 2 Questions on Volvo 5.7 350

If you are that worried and installing a new motor now is the time to consider adding a closed cooling system. I love I/O but I will never own one that has an open (raw water) system.

Sounds like a good idea, but I'm not sure that I have any room for a radiator or coolant resivoir in the engine compartment. It is so packed in there I couldn't fit a high rise intake, let alone an aftermarket flame arrestor. I'm sure that it could be done, but not sure that it is something that I am ready to do at this point. That may very well be a project for next winter!

I went all last summer trying to figure out what was going on with my engine only to finally decide to just replace it. At this point, my main goal is to have a functional boat & engine come summer. Next winter will be my down time for modifications and performance upgrades.

Maybe someone already has posted a how-to on chaning to a closed cooling system, but if not I would be interested in seeing the steps and installation procedures.

 

[slasmith1]

Re: 2 Questions on Volvo 5.7 350

Sounds like a good idea, but I'm not sure that I have any room for a radiator or coolant resivoir in the engine compartment. It is so packed in there I couldn't fit a high rise intake, let alone an aftermarket flame arrestor. I'm sure that it could be done, but not sure that it is something that I am ready to do at this point. That may very well be a project for next winter!

I went all last summer trying to figure out what was going on with my engine only to finally decide to just replace it. At this point, my main goal is to have a functional boat & engine come summer. Next winter will be my down time for modifications and performance upgrades.

Maybe someone already has posted a how-to on chaning to a closed cooling system, but if not I would be interested in seeing the steps and installation procedures.

You can only install theese in a new engine after running raw water through it it is too late.

It doesnt take any significant extra space. If the boat is already apart it doesn't even take any extra time to install while you are re assembling your motor.
here is a link to a picture of one system.
http://orcamarine.thomasnet.com/image?&cid=3802&plpver=10&prodid=1022&itemid=1539

 

[wake4me]

Re: 2 Questions on Volvo 5.7 350

You can only install theese in a new engine after running raw water through it it is too late.

Why is it that you cannot convert to a closed cooling system after running raw water? Contaminants? In the past, on some older vehicles that I have owned... I have had radiator leaks. I would fill the entire cooling system up with tap water to make it home or wherever. Then, once the leak was repaired, I drain the water and replace with 50/50 antifreeze/water mix.

Just curious why you can't convert an engine that has been running on a raw water cooling system to a closed cooling system?

 

[slasmith1]

Re: 2 Questions on Volvo 5.7 350

Why is it that you cannot convert to a closed cooling system after running raw water? Contaminants? In the past, on some older vehicles that I have owned... I have had radiator leaks. I would fill the entire cooling system up with tap water to make it home or wherever. Then, once the leak was repaired, I drain the water and replace with 50/50 antifreeze/water mix.

Just curious why you can't convert an engine that has been running on a raw water cooling system to a closed cooling system?

the block isn't full of sand and rust possibly corrosion if you use it in salt. you will have problems forever with blockages in your heat exchanger.

 

[wake4me]

Re: 2 Questions on Volvo 5.7 350

the block isn't full of sand and rust possibly corrosion if you use it in salt. you will have problems forever with blockages in your heat exchanger.

Duh! I wasn't thinking about salt water. My boats have never seen salt water, so that wasn't on my mind. I can see how that could cause some big problems, but as far as fresh water goes... As long as you flush the system well I don't see why you couldn't add it on later. I have been doing some searching for the "add on" or aftermarket closed cooling systems. Seems a good way to go, but out of my budget at this time. The new engine has set me back enough!