Why can't anyone seem to answer this question?

[WATERWINGS]

I have asked this before, but seem to get answers all around it without actually getting a right to the point answer.

Not taking away from anyones knowledge here, (cause theres tons of in on this site), but.................

If a Merc makes more heat the more water it dumps through the thermostats, (or washers) (like I've always been told), then why does the thermostat open when the temp guage goes up, and close back off after the temp guage goes back down???

Either I have always been mis-informed, or, there is more to it than I have been told..........does dumping more water make more heat, or dumping some, or NO water make more heat??

Thanks Ya'll

John

[Markus]

(My Mercury does not even have thermostats, but my Yamahas do, so here is my understanding of the topic)

The thermostats open to allow water into the water jackets of the cylinder heads. This will

1. Cool the heads
2. Make the water flow faster through the rest of the engine, cooling things down

So, in general, more water results in less heat, at least up to the flow permitted by the restriction created by the passages in the thermostats.

However, if the restriction from the thermostats/washers gets too low, the cooling system does not reach the intended pressure, which may cause the engine (or parts of it) to run too hot. That is what you see with too big washers.

[ON THE HUNT]

Fishin motor.From idle to the opening of the poppet valve the t-stats are regulating block temp to arond 145-155 deg.The block water gets hot they open allowing cool water to pass through the block.If its under the tstats temp they will stay closed holding the water in the block and will not allow any flow through the block until tstat opening temp is met or exceeded.

[redlight robert]

It was always my understanding that the t-stats held the water in the block for a substansial amount of time for the water to absorb an amount of heat instead of just running by it.
Pour a bowl of hot water, put your hand in it fast, now try it while holding your hand in it a few seconds, and see which way your hand removes more heat from the water! The poppet valves, I always thought were mainly a overpressure relief valve, whadaya think?

[ON THE HUNT]

Thats a secondary function of the poppet.We need heat in the heads at all times to insure the fuel mixes with the oxygen so it will burn,however we dont need the piston skirts running at 150deg. at 6000 rpm.So the worlds greatest engineers came up with the poppet valve which dumps block water when block psi reaches around 10psi reducing block temp to around 120 for sake of conversation.The heads are still being feed by a hot pocket of slow moving water sitting above #1,#2.

[Markus]

Redlight Robert, think of it like this: The cooler the water is, the more heat it absorbs from the engine. If more water runs through the engine, the water will be cooler and thus absorb more heat.

To use your analogy: Your hands will be cooler if you put them under the faucet with cool running water for 5 minutes than they will if you put them in a small bowl of water that initially came from the faucet, since after 5 minutes, your hands will have warmed up the water a bit.

The only reason you need pressure in the block is to make sure the cooling water gets everywhere it should. Other than that, pressure is a pure proxy for flow.

[B.Mac]

Too much water (volume/ pressure) dumping out the motor does not allow for adequete (efficient) transfer of heat from the water jackets/ heads due to the lack of (time) exposure to the heated casting ........ BUT Not enough water (volume/ pressure) dumping out of the motor does not allow for adequete (efficient) transfer of heat from the waterjackets/ heads due to the slower absorbtion rate of higher temperture coolant water and/ or air pockets. Therefore the need for T-stats or the correct size washer orifice to control/ balance the rate of the coolant flow.

I believe I understood the question but maybe not?
B.MAC:D

[Dark Allison]

So what size do you run in the summer and what size in the winter? I know no one changes thier thermostats for the seasons but what about their washers?

[Jacob]

If the water moves through the block to fast it doesn't absorb enough heat. If the water doesn't exit you block it will eventually become just as hot as combustion temperatures. the only thing that stops the water from gettin that hot is the metered amount of water that exits your block through a thermostat/ washer ( and the melting point of aluminium). It's all about allowing the heat to be disipated to the water and then the water exit the engine. Then there is that other point when the water stays in just the right amount of time then exits with a lot of you engines heat and doesn't allow you engine to retain some heat and it will idle like crap and create more wear. Well maybe not as simple as I wanted it to be. hope one of these explanations helps.

[Markus]

Too much water (volume/ pressure) dumping out the motor does not allow for adequete (efficient) transfer of heat from the water jackets/ heads due to the lack of (time) exposure to the heated casting ........


If the water moves through the block to fast it doesn't absorb enough heat.

That is simply not grounded in physics. The faster the water flows, the cooler the water that is exposed to the block, and consequently the more heat is transferred from the block to the water.

[Superdave]

The thermostats are NOT at the end of water flow like a car. The stats help to keep heat in the heads to prevent cold siezing. If you replace them with a washer you need to check head temp with a reliable thermometer. If you are running cold/hot you can regulate the temp with different size pee hole fittings.
Dave

[B.Mac]

Originally posted by Markus
That is simply not grounded in physics. The faster the water flows, the cooler the water that is exposed to the block, and consequently the more heat is transferred from the block to the water.

I would like to understand this better please, could you elaborate? I've understood that by forcing too much coolant through a block too quickly, it does not allow for as efficient heat transfer of heat to the coolant, as the water molecules do not have enough time to "absorb" the heat energy. Now I'm speaking of the efficiency of heat transfer here not a firehose on a lower unit.......
Respectfully,
B.MAC:D

[WATERWINGS]

I just got an E-mail notification that Skip, (Talon 2.5) just replied to this thread, but I don't see it, so if I ask sometihing he has just answered, please forgive.

I ask this question because no matter what I've done all summer, I can't make anymore heat no matter what change I make, thermo's, poppet, jet changes.............

I can only assume now that it HAS to be something in the mid plates, but I have had them off, and I can't find anywhere that they could be dumping excess water, (causing water to flow through to fast)

But to bring the question back to its most simple form:

Should a nearly stock, (or any other Merc) make more heat if it dumps more water or less, (or no water)?

Or.........

If a Merc makes more heat the more water it dumps then why do the thermo's open only after the temp guages go up, (head) and why do they shut after the guages (head) go back down?

[Talon2.5]

this is a pretty crazy looking thread :D

i agree with 3 people who have replied as far as pulling heat

lemme give an example.........

take a hard boiled egg straight out of the boiling water and run fast cold water over it and hold your hand below the egg directly in the stream, the water is a "bit warmer" than before it went over the egg yet not pulling the heat out of the egg, just the surface, the inside is still damn hot

now take that pan of eggs off the stove, drain the hot water and fill it with cool water and let it sit for a few minutes, cold water got hot right? pulled the heat out of the eggs better than running water over it fast right, the inside of the egg is cooler than the egg in the scenerio above

the water running over it fast was not given the time to sit and pull the heat out of the egg

the motor in the winter needs the larger washer (high perf motor) so the water runs past and doesnt take the heat away from the cylinder that (when it's cold out) the motor needs

the motor in the summer needs the heat taken out more thoroughly so you slow the flow so it has time to pull the heat

the thermostat allows a stock motor to get up to optimum operating temp according to the manufacturer's intended use of said motor, they open when the "set temperature" designed into the thermostat itself, by the manufacturer to be installed in the motor they designed, for the use they intended it for, and the rpm they specify and dump the water, and restricting the flow to the desired amount designated by the engineers for the specific engine and it's intended use

we.....on the other hand never use a motor in it's intended purpose, we screw with them to get more power, more rpm, more speed and in that quest create more heat so we have to do away with reason and go for what works to keep the beast we created cool and not all beasts are born alike thus causing a "no set answer" effect on cooling

if ya move the water that pulls the heat out slower in the winter the motor runs better because the internals are "up to operating temp" when everything around it is cold and it needs that internal heat just as we do to survive and not get hypothermia

on the other hand in the summer if you can keep that water in longer it will pull that heat out so the internals dont overheat above catostrophic levels, just like we need to keep our internal heat down in the summer to not get heat stroke

no 2 motors are gonna be exactly alike in thier cooling characteristics (none that i have seen so far at least) and each individual has to cool thier motor as needed following the "standard guidelines" of the "cooling beliefs" of said hot-rodders changing what the engineers designed them to do thus going outside the normal cooling issues of stock motors

in short...........there is no wiz bam it works on every motor solution, to pull heat ya need the water to stay in contact longer, the thermostats stay closed to take a motor from stone cold to fully warmed up before they dump, the water thats being held back on warmup has to reach a certain degree the engineers pre-determine to be correct for a "warmed up engine" and that water being held once the same temp of the block does not promote cooling any longer, which the thermostats allow to be dumped letting in water that can now promote the cooling process of which the engineers of said motor used in the manner it was designed for can operate within the temperatures it was designed to without failure

your head hurt yet?

to cool the beast you have created also takes you to cool it in the best manner you can thats indigenous to the beast you have ;) ask questions and move forward never losing sight of your own thoughts of what it takes to cool YOUR motor :D

not all will react to the same cooling mods, however the setups will be similar on 1: stock , 2: mildly modified, 3: highly modified motors

if you have a motor built like john marles and used the same as johns, you will be best suited to run cooling like his tweeked as you need (if needed) to achieve the same temps
my motor is not gonna be cooled as well using his because my motor is not used in the manner he is using his

it's all relative yet segregated and again different but the same :eek:

how do ya like that **** :D

skip

EDIT: not a single one of my mercs have been the same, nor have they had identical cooling set-ups to get the same desired temps

tough subject at best :(

[ON THE HUNT]

Look at the tstat, T inside the brass button sticking out of the bottom of it is a small chamber filled with "wax".This wax expands and contracts with changes in block temperature to open and close the valve at the top of the thermostat.The brass button should also be stamped with its opening temp.So if you are dumping water through the poppet valve and the pockets of water above #1 and #2 never reach temp then the tstats wont open and the heads will be running dry.At idle water psi is lower than the tension of the poppet spring so it closes and the water is held in the block until it reaches tstat opening temp.When it opens water is then allowed to flow thru the heads to dump.I hope this helps...

[JR IN JAX]

The amount of cooling in a heat exchanger is determined by the following:
1. specific gravity of the coolant.
2. temperature of the coolant.
3 .temperature of the hot surface.
4. flow of the coolant across the hot surface.
5. turbulence in the flow to increase exposure of coolant to hot surface.

The temperature difference in the inlet and outlet [fluid]temperature is called "delta t". The greater the flow / turbulence, the lower the delta t and the more heat is transfered from the hot surface into more fluid.

The increased flow removes more heat since the temperature rise from inlet to outlet is less, so the leaving fluid is cooler [and picks up more heat]. The difference between the coolant and the hot surface is called the "approach temp".

P.S. I design heat exchangers for a living, so I hope this is helpful.
JR

[ILLandowner]

Come on guys, lets compare apples to apples here. In the Hard Boiled Egg senerio, if we took too pans of eggs, one of which was drained and filled with cold water (set aside...no water movement) and at the exact same time the other one was drained, a hole drilled in the bottom and a hose installed running cool water into the pan that kept the water level maintained to the SAME volume as the other one, your saying that with a constant flow of cooler water thru the pan is NOT going to cool the eggs faster than the one where the water temp is constantly increasing?:confused:

[ILLandowner]

sounds like JR IN JAX is saying the same thing I am, only with the tech talk to boot!

[ON THE HUNT]

Forget the eggs.Two pans one with a 1/2 inch hole the other with a 1 inch hole.Turn both burners on to the same setting let the water run to keep the pots half full.Measure the temp of the water coming out of the pan with the 1/2 in. hole.Its hot becuase it was exposed to the heat longer.The water in the 1in.hole pan will be colder becuase it was not incontact with the hot surface long enough to absorb any heat.Put a pot on your stove heat it to boiling temp,pour tap water in it wont boil instantly becuase it has not absorbed any heat.Hey we just figured out how to run across hot coals...kick azz

[ILLandowner]

Isn't the point what temperature the Block (eggs) are not what the temp of the exiting water is?

Maybe I should go back to only reading these here threads instead of flappin my jaws

[ON THE HUNT]

Yeah but were havin trouble understanding how the heat gets out of the combustion chamber and into the water.

[Dave S]

The speed the motor is turning is a factor also. The faster it is the less heat transfer to the walls. Merc put thermo's in for this thread.:D I drill a small hole in the thermo to have flow all the time, when it get's hot it open's .;) If your motor is realy COOLD, put a spill valve on it.

[Talon2.5]

hehehehe :D i knew you'd like it :D

i'll have the 3 egg omlete with hash browns, a side of ham and orange juice :cool:

[Markus]

From a thermodynamics stand point, JR in Jax pretty much explained it all. I will only add one thing:

I think the mistake people make, for example in some of the analogies in this thread, is that they forget that the volume of water in the engine is always the same no matter how fast the water flows.

Think of it like this: At any given moment, there is, say, 1 gallon of water in the engine absorbing heat. The faster warm water goes out at one side of the engine and cold water comes in at the other side, the colder that 1 gallon of water in the engine is, and therefore the more heat is absorbed from the engine.

Does this make it clearer?

[WATERWINGS]

Dave S,

I put 1/16 holes in my thermo's too, (I've tried everything, still can't make heat), but I did make to much heat last year when, (I found out after removing a new water pump) I noticed the rubber grommet was missing from the top of the the pump housing, causing me to not get all the water from the pump.

Is this what you mean by "a spill valve"?

Mabey I should remove that rubber gromet, to make more heat??????

[Dave S]

Some of the newer Mercs have a hose that goes from the top of block to the back side of poppet . At low speed, the water bypasses the block, more heat. As RPM and pressure go up, the poppet closes that route and goes thru the regular way. Some 150 2.0s also did it, but they have a hole in the block by the poppet that works the same way, just no hose. Are you sure that you don't have a miss-match of powerhead to adaptor? Are you sure that the rubber ring where the poppet seats is there? A thing I would do is drill a hole in the back of the coil plate at the bottom to dump water out, try different size pissers. That would bypass the block but cool the hot side of pistons in the V also keep the exhaust plate cold. The hose on top of block does the same but ex plate gets short changed. Hope this helps.:) MERRY CHRISTMAS

[WATERWINGS]

Hey Dave,

The rubber ring is in the poppet hole, (there appear to be two).

I have run with poppet, and without,

with thermo's and without,

with poppet and washers,

with no poppet and thermo's...................

I thought about running a "T" from the top of the block, with one going to the pressure guage, and the other dumping out of the cowl, would that help any?

As far as mismatched mid plates, how can I tell?

As far as I know, all my stuff is 2.4, and I know its not the old 175 two liter stuff, cause the exhaust holes are the small square ones.

Its possable that I am running a two liter 150 mid, but would it be mismatched with my '86-200 block?


If I drill the bottom of the exhaust plate and dump some there, what size hole, (for pipe tap) should I go with, and where at the bottom is the best place?

............."and what about Marylou?"

No, tell me more about the "spill valve", or is that what you mean by dumping at the exhaust plate?