Marine thermostats

[TAPPED OUT]

Does anyone know how good those marine thermostats work and if they will work in sandy conditions. Some people said they would and the thermostat kit itself said it wont. Anyway I will be running my boat on the colorado river in big river and the strip. Should I use it or forget it?

[OverKill]

Does anyone know how good those marine thermostats work and if they will work in sandy conditions. Some people said they would and the thermostat kit itself said it wont. Anyway I will be running my boat on the colorado river in big river and the strip. Should I use it or forget it?
I run at Big River all the time. I just run the water straight in no thermostat, there really is no need for one there. IMO just forget it put the money to better use ( BEER ).

[TAPPED OUT]

Thats what I thought. I just have the water running off the jet into the pressure relief and then "T" ed to the block then I ran both lines out of the motor out of the housing. I got water for my headers off the intake I guess this might work out without the thermostat.

[Jetaholic]

Read this article about proper plumbing.
VERY GOOD READ!!!
Should make perfect sense.
http://www.performancejet.com/techtalkNEW.htm

[centerhill condor]

I bought the prv from that very site and drilled as indicated...I run year 'round and never got temp until I had this installed. Highly recommended and trouble free since installed. We have sand and silt and I haven't had a related problem.

[TIMINATOR]

We use the Rex Marine unit and install quite a few of them. Without logs to preheat the water you will never have much engine temp unless you restrict the hell out of it, and that causes an entire new set of problems. TIMINATOR

[Jetaholic]

I don't see how anyone can claim that there really is no need for a thermostat.
Lots of people claim "the colder the better...blah blah blah"...well...
First off...engines are designed to be ran at a certain temperature. For one, for all your clearances to be correct, the engine has to get to a certain temp for all the components to expand to their proper size for the correct clearance.
Second off...the engine has to be at a certain temperature for proper and adequate fuel burn...otherwise you're wasting gas.
And third off...without the thermostat...lets say you set your gate valve (which is not a very good temp regulating device since it will cut your water volume (the amount of actual water in the system) and make your heads run hot) for an idle of 180*. Then you hole shot, and all that cold water coming in will shock cool the engine down to 120-140. That's quite a difference and we all know what happens to metal when it is shock cooled. With the thermostat your temp will fluctuate between 160-190, which is way better than 120-180.

[riverbound]

Does anyone know how good those marine thermostats work and if they will work in sandy conditions. Some people said they would and the thermostat kit itself said it wont. Anyway I will be running my boat on the colorado river in big river and the strip. Should I use it or forget it?
I had one on my Spectra and boated Parker all the time, never had a problem with it, and as far as I know the current owner has it on there still.

[OverKill]

I don't see how anyone can claim that there really is no need for a thermostat.
Lots of people claim "the colder the better...blah blah blah"...well...
First off...engines are designed to be ran at a certain temperature. For one, for all your clearances to be correct, the engine has to get to a certain temp for all the components to expand to their proper size for the correct clearance.
Second off...the engine has to be at a certain temperature for proper and adequate fuel burn...otherwise you're wasting gas.
And third off...without the thermostat...lets say you set your gate valve (which is not a very good temp regulating device since it will cut your water volume (the amount of actual water in the system) and make your heads run hot) for an idle of 180*. Then you hole shot, and all that cold water coming in will shock cool the engine down to 120-140. That's quite a difference and we all know what happens to metal when it is shock cooled. With the thermostat your temp will fluctuate between 160-190, which is way better than 120-180.
OK so what if you have water injected headers???? As I was told if your running in sandy areas, you want that sand out of the motor ASAP no questions asked. An old school trick that works quite well is, take out all the insides of a thermostat and just install the frame of the thermostat. this will help regulate your water flow for good temp. and you can adjust your gate valves to whatever works best..
I hear what your saying about metal shock and poor fuel economy if the motor is'nt operating at spec. temp's. However Here in Arizona, when is't a 125 degrees outside, I want that water to the motor yesterday!!..:)

[Some Kind Of Monster]

A couple quick comments. Keep in mind I am not knocking a thermostat as I wouldn't mind running one myself that has been properly set up.
First of all, if you are worried about gas mileage, you shouldn't have a jet boat.
Second, A thermostat is not necessary. Gate valves are the age old solution to the problem and are sufficient. Mine is dialed in to run 155 at idle and 135 on the gas. My clearances are machined accordingly for the application, and oil temps are dead on at this setting.
Regarding sand, I NEVER start my boat in shallow water. Never never never. I understand that some of you run in the river so make sure you check your freeze plugs once in awhile as I have seen blocks that have become plugged with sand before. I would consider a sand strainer if shallow water is necessary for you.

[snake321]

good thing you mentioned the sand. I think that the gate valve temp. regulating system doesn't let the full water pressure through to clean the system of sand. I just pulled my 454 apart and there was almost 3 full large metel dustpans of sand in my motor. That's not counting what came out when I ran the hose through it 2 times.

[Jetaholic]

good thing you mentioned the sand. I think that the gate valve temp. regulating system doesn't let the full water pressure through to clean the system of sand. I just pulled my 454 apart and there was almost 3 full large metel dustpans of sand in my motor. That's not counting what came out when I ran the hose through it 2 times.
Exactly. It cuts back the actual amount of water flowing through the block, which can hinder being able to push all the sand out. I'll be running a water bypass valve to drop the incoming pressure to keep from overpressurizing the block, but I will have the same amount of water flowing through the block as you would with no gate valve...just not under so much pressure.

[Oldsquirt]

Exactly. It cuts back the actual amount of water flowing through the block, which can hinder being able to push all the sand out. I'll be running a water bypass valve to drop the incoming pressure to keep from overpressurizing the block, but I will have the same amount of water flowing through the block as you would with no gate valve...just not under so much pressure.
Pretty sure you will also see a drop in flow through the block, after all that is how the pressure drop is accomplished, bypassing some of the volume from the pump out your bypass line.
Best solution for you guys running in sandy, silty water is to occasionally flush the block. Just pull the block drains and run water through the engine from a garden hose.

[OverKill]

Pretty sure you will also see a drop in flow through the block, after all that is how the pressure drop is accomplished, bypassing some of the volume from the pump out your bypass line.
Best solution for you guys running in sandy, silty water is to occasionally flush the block. Just pull the block drains and run water through from a garden hose.
where are the (block drains) on a 454 Chevy???

[Oldsquirt]

Just above the pan rail, between the middle two cylinders.

[TAPPED OUT]

Okay I am going to forget the thermostat, and just build my motor clearances and tolerances for cold water conditions the way a jet boat motor should be built for and run that over pressure bypass. Remember if the motor is built right, the cooler the motor the more power you will recieve, also the gas will burn since you can advance the timming allot more without detonation. Thanks for the input.

[Aluminum Squirt]

I run a thermostat and I run in a little sand. Okay, I run my boat into sand bars occasionally to the point where I have to get out and kick it back in the main channel to get going again. Never had a problem with my thermostat. I run a pressure by-pass->through an oil cooler->into the block->through a Rex thermostat/bypass->dumped out the side. Dry headers. No doubt there is sand in my black but I have never had a problem with temp/flow, holds 180 for about 20-30 minutes of WOT, seems to work pretty good. The Kiwi's run a sand trap if you are really worried about it. I would take a serious look at running your motor at 160-180 with as few fluctuations as possible. These are automotive motors and they are designed to run at 180. I'm sure a little machining of your clearances will help but the factories put a lot of reasearch into making these motors run at 180, I think running them there makes more sense. There are a lot of things going on here besides your main clearances; there's metal expanding/contracting, fuel atomization issues, etc etc. I'll probably get flamed for this but I'd bet most of the 45-65 MPH recreational boats are running whatever system works, that's fine, its low stress. I'd bet he higher speed/HP/performance boats are running a little bit finer tuned system and are keeping their temps in the 180 range. There's a reason for this. But that's just my $.02-Aluminum Squirt

[squirt'nmyload]

First of all, if you are worried about gas mileage, you shouldn't have a jet boat.
.
LMAO

[pw_Tony]

So I need to barge in. I have a 460 with a Berk on it and I've changed my headgaskets twice already. The gaskets didn't even appear to be blown though? I was talking with another experienced jet boater that had the same set up and he told me that the berk pushes 90psi into the motor, which a BBF can't handle. He told me to regulate the water for engine temp and so water doesn't get into the motors.
You guys ever heard of BBF's holding the pressure from the pump? Thanx

[OverKill]

So I need to barge in. I have a 460 with a Berk on it and I've changed my headgaskets twice already. The gaskets didn't even appear to be blown though? I was talking with another experienced jet boater that had the same set up and he told me that the berk pushes 90psi into the motor, which a BBF can't handle. He told me to regulate the water for engine temp and so water doesn't get into the motors.
You guys ever heard of BBF's holding the pressure from the pump? Thanx
Ya know I believe this is a question for Squirtcha? He has a BBF with a Berk setup. I believe he has some photos of his plumbing setup also. You might want to PM him and ask what his numbers are. JMO:idea:

[Jetaholic]

So I need to barge in. I have a 460 with a Berk on it and I've changed my headgaskets twice already. The gaskets didn't even appear to be blown though? I was talking with another experienced jet boater that had the same set up and he told me that the berk pushes 90psi into the motor, which a BBF can't handle. He told me to regulate the water for engine temp and so water doesn't get into the motors.
You guys ever heard of BBF's holding the pressure from the pump? Thanx
This is why you should run the water bypass pressure regulator valve. It will drop the incoming pressure to about 12-15psi.

[pw_Tony]

This is why you should run the water bypass pressure regulator valve. It will drop the incoming pressure to about 12-15psi.
Yea but have you had troubles of water gettin in the oil from the pump?

[Jetaholic]

I personally haven't no...when my boat was running it had a gate valve to control the pressure, but a gate valve also limits your water volume at the same time.
With a water bypass regulator your water volume will stay the same, just under a lot less pressure.
12-15psi is perfect for any engine. 90 would be way too much pressure and you would overpressurize your block, ending up with water in the oil and blown head gaskets.
If you run the water bypass valve along with a marine thermostat, you will end up with a block under much less water pressure that runs between 160-190 degrees.

[Aluminum Squirt]

I think Jetaholic has it right. A pump can put out way too much pressure for a motor, well over the 90 lbs mentioned before. Most cars run under 20 lbs (thus the 20 lb release radiator cap). I don't know of too many gaskets that can last under that kind of pressure, leading to blown gaskets and water in the oil at the very least. Gate valves shut the flow down so much there is very little volume, leaving some cooling issues when running hard. A bypass valve lets it get full flow at 12-15 psi (or whatever you set it at) and bypasses everything beyond that pressure overboard. That leaves full flow through the motor and good cooling and no blown gaskets or water in the oil. This is a separate issue to the thrmostat. The thermostat keep the water in the motor and keeps the motor at a designated temp, usually 180. In my mind these are separate devices that do separate things. When you try to do it with gate/ball valves you are making a compromise somewhere, either in pressure/flow or cooling. This is an age old debate and I'm not quite sure why, it looks pretty simple to me. I'm sure there are plenty of people making gate/ball valves work, but to me it looks like a compromise, and maybe not the best solution for a high performance application.
On a related note, I make sure that all of my system after the by-pass does not get any smaller. What I mean is that at each junction or enterring the motor, or leaving the motor, I make sure to use either the same size line, one step bigger line, or two lines of the same size. To me, this makes it so there is no chance of pressure building after the by pass. By continually adding either line diameter or number of lines, there is no chance of making a 'choke point' in the system that builds additional pressure in the system. I end it with two water dumps. At idle, its just trickeling water out the dumps but the temperature stays perfect at 180 due to the thermostat. At WOT the dumps are flowing pretty good but I know everything is working because my by-pass is holding the pressure down and the gauge says my temp is 180. I put my dumps just behind me so I can reach back and feel the water come out. That way I can feel that #1 the water is flowing and #2 that the water is warm and I'm ready to roll.
This thing has been beaten to death. Maybe we can just make it a sticky thread and everybody can post their solutions for the newbie's. To me, sand doesn't affect the by passes, regulators, or thermostats and running gate/ball valves is asking for trouble in anything but a lower performance family cruiser. I'm sure there are some people out there making the gate/ball valves work on fast boats but I think a better solution is a regulator or by pass with a thermostat. Even better would be a closed system with a heat exchanger but thats a little heavy for most of our applications-Aluminum Squirt

[snake321]

I buy all of that, but how do you keep up enough pressure to keep sand washed out?

[1968Droptop]

I personally will be installing a by-pass system (and a t-stat) on my new High Flow Dynamic's built engine before heading out on the water this year. NO WAY can any engine handle the kind of pressure a jet pump puts into it.
I think by having properly sized lines, the volume of water going through the block will help extract sand.
I've also read that having sand in your block isn't the end of the world. Sand and water mix easily, and as long as the sand in your block is wet with water, it can keep things cool. Most of the heat generated buy your engine is at the top of the cylinder, not down at the bottom where the sand deposits. As long as your block isn't completely full, you'll still have water flowing in the critical areas, the top of the cylinders and the heads, to keep things cool.
If sand is a real big concern, then why not buy a high quality sea strainer ? A good one will set you back about $300. These unit are easy to clean anywhere, and I've heard they do a decent job of removing sand.

[patrolman808]

As far as pressure goes, don't the pistons produce more pressure than the jet pump? 90 pounds seems alot less to me than the compression produced inside the engine. Seems to me the head gaskets should hold up to some pretty high water pressure...am I wrong?

[pw_Tony]

As far as pressure goes, don't the pistons produce more pressure than the jet pump? 90 pounds seems alot less to me than the compression produced inside the engine. Seems to me the head gaskets should hold up to some pretty high water pressure...am I wrong?
Well I know more cylinder psi is between 105-110psi. I don't know what compression ratio that calculates out to though

[snake321]

but only intermittenly on the compression stroke.

[patrolman808]

but only intermittenly on the compression stroke.
Yea, but that is happening repeatedly on every cylinder. The maximum pressure the engine is going to produce n/a is steadily there inside the cylinder on every compression stroke.

[Aluminum Squirt]

Cylinder pressure and water pressure couldn't be any different. Cylinder pressure is high but its been engineered for with many bolts surroundeing the cylinder and the gasket is designed for pressure around the cylinders. Additionally cylinder pressure is predictable and does the same thing on every stroke. Water pressure can get very high (ask one of the experts, but I think it can exceed cylinder pressure if precautions are not taken, at least on a high perf pump). And there are other places that water is flowing where nothing has been engineered for high pressure, like through the intake manifold. This is frequently soft aluminum, few bolts, and a cheap fiber gasket or just silicone. Water pressure can also rise and fall unpredictably, hammering these gaskets into destruction with a pump that is loading and unloading. In the white water, we hammer our pumps with countless loads/unloads creating very high pressure spikes.
As far as sand goes, its going to be there unless you just boat on the lake. The by-passes/regulators.thermostats etc should be fine with some sand, just take some precautions by flushing your block periodically. If you are really paranoid, add a sea strainer or make your own little sand trap with some fine mesh in it. I think a lot of sand stays suspended in the water and goes through the entire motor causing no problems. I aslo agree with 1968DT, sand in the block is not causing huge problems until you either fill the block or let it heat/dry so many times that it turns into a cement like substance. If you are using a by-pass or regulator set up, its easy to replace your freeze plugs with expandable rubber plugs, making sand flushing easy with a hose. Just make sure to carry a couple of extra plugs. With the pressure regulated or by passed, the plugs will stay where you put them. Makes winterizing a snap too-Aluminum Squirt

[Jetaholic]

I'll add to Aluminum Squirt's post. To answer your question regarding cylinder pressure vs. water pressure...
You're dealing with 2 different mediums. Inside the cylinder you are compressing air.
In the water jackets, you have a liquid under pressure.
Air can be compressed, but you cannot compress a liquid.
Basically, the engine can handle air under high pressure, but not liquid under high pressure.
Make sense?

[pw_Tony]

Hmmm I understand now. So knock my psi down to bout 15 psi should be ok? And I was wondering somethin else. I'm knew to the blown boat scene. Should I run my boat cooler to try and help keep the blower cooler? 180 sounds good for N/A but should I run mine like 140?