Thermostat

[rodbolt]

Re: Thermostat

but its still a wrong headed dumb arse method of testing. but shade trees are always right, I only get to see them after excessive damage has been done while the shadetrees and their bro-in laws wifes cousins hairdressers ex husband who worked on farm tractors has gotten done. T-stats are cheap. if suspect just replace it. rarely go bad in the fresh water and 99% of the time they either work or not. but while your testing and the cooling system is not operating correctly manifolds,risers, exhaust boots and pipes may be over heating and being damaged. the temp gauge does not monitor temps on these items just on the block water temp. so keeppoking and hoping, even a blind squirrel finds an acorn. if it was a biliards shot I would say shoot hard its a hard shot. just remember that cooling systems are noit voodoo nor black magic. a methodfical diagnoses and an understanding of the water flow is mandatory. always remember that it has to move all the water out that it moves in and air is a poor conductor of heat.

 

[Stan's Customs]

Re: Thermostat

First off we wern't talking about testing anything ...only that removing a thermostat from "an overheating system" can only help, not hinder anything. Simply to belay the theory one must run a thermostat under any condition......Actually boats run cool thermostats (140?) and the use of one is not nearly as critical as the need for one on a closed system in a hot climate.<br /><br />You are right Rodbolt this would be a dumb arsed way to test for overheating.. but if you are in west Texas with nothing much to work with in one our many isolated lakes and few tools....most mechanics would chunk the thermostat until you could get back to the shop. Possibly even exposing a bad thermostat and maybe the only problem in the process. I'll take my chances with an air pocket under those circumstances over a blocked thermostat.....still not talking about testing the system, even though there are many worse places to start that won't yield as much information that quickly a hundred miles from some place.<br /><br />Again troog...when coolant circulates continually without a thermostat in the summer the engine will over heat in some circumstances...in fact many circumstances. An example would be a gasoline powered motorhome or one ton truck pulling a heavy piece of equipment. These engines are working very hard and generating much heat....on a hot day the cooling system and the engine will heat sink.... to the point of overheating. Simply because the coolant does not remain in the radiator long enough to discharge the heat it is carrying. In my 23 year tenure in the Midland/Odessa oil field I replaced many an engine that the thermostat had been removed just because folks thought that it would make them run a little cooler in the extreme heat. Many times their systems were working properly just warmer than uusual on 100 plus days...so "hey let's remove the thermostat"....bad mistake. <br /><br />I still encounter this with large motorhomes that are running gasoline engines...they may run an hour or two at highway speeds before they heat sink, but without a thermostat but it "will" happen...at least around here in the summer.<br /><br />Now then...yes, run a thermostat all the time...period....if every thing else is up to speed. If you are "already overheating" in a boat, well you have my 2cents...

 

[TXTripper]

Re: Thermostat

Ok, now I'm confused. Stan are you saying that its ok to run it without a Thermostat or not ok to do it? Does anybody have a boat,(or had a boat) that they took it out? What happened??? I don't want to damage anything further, it was suggested to me to take it out, was that a bad suggestion? I plan on taking it our thermostat-less this afternoon- is that a problem? And I have had it in the shop since this problem started, they can't find anything. Its really annoying. Thanks again for the input fella's.

 

[Stan's Customs]

Re: Thermostat

What I have said is....taking it out will not hurt a system that is overheating......that's not to imply that it will help it. Just won't hurt....for a little while.<br /><br />Since you are not on the water and where you can, Put in a new thermostat "make double sure" the impellor is in good shape and then try it out. Still overheats...then you have a problem elsewhere. Blockage etc....Most Texas boats don't have scale problems like salt water boats do...maybe yours came from the coast. So pull a riser or drain plug, dig around a little , you'll find it if it's plugged with scale. <br /><br />Contrary to other post...I have seen thermostats stick once in a while, more than once. Most times they quit and stay quit...but not always, so be sure.....replace it.<br /><br />After that it could be many things...blockage, seeping headgasket, corroded fittings as Don S. suggested and so on... "Double check" the simple stuff and go from there...

 

[trog100]

Re: Thermostat

i would like this "air pocket" concept explaining to me as well..<br /><br />where exactly is this air coming from.. is someone saying that if the coolant is flowing too fast (not slowed down by a stat) some kind of air pocket would form..<br /><br />if the place the water comes in is below water and the place it goes out is under water.. where does the air come from..????<br /><br />surely we are not talking about a vacuum somehow being created somewhere in the coolant passages are we..??? cos if there aint no place that air can enter the only way there could be places without coolant would be a vacuum..<br /><br />trog100

 

[IdahoKid]

Re: Thermostat

My input would be this. You took the thermostat out to test it, and it looked fine. A thermostat should either work or not. This means you still have work to do, and need to solve the problem. Unless money is a huge contraint, I would still put a new thermostat in because you KNOW that's not going to hurt anything. If you can't go for a new thermostat, put the old one back in. Don't run without it. It's not going to do you any good. If there is a problem with the engine, at the best you will cover up the problem, and at worst, the problem will develop into something worse. You need to figure out what's going on. Like rodbolt said, it's not black magic. You just have to be persistant and figure it out. You've already solve d step one, determine if it's a stuck thermostat.

 

[rodbolt]

Re: Thermostat

trog<br /> when water is pulled from the sea at a vacum, remember the volvo is a crank or belt driven pump and not submerged on the lower like a merc or some OMC motors. the water can "boil" as low as 100 degress plus the turbulence around the case causing air bubbles. if you dont belive ask someone with a 90* looper jonnyrude that ditched the t-stats and lit the regulator on fire due to lack of water pressure at the top of the block. water under pressure tends to boil at a higher temp for a given sealevel. all basic 5th grade physical science. if I was sitting on the pond with a hot motor would I take the t-stat out? heck yea. sitting on the trailer? nope. I may take it out but I would install a new one. but I suspect either the riser passages clogged or the pump is worn, pump cam and end plates dont last forever even if ya do put an impeller in it. or most likly on a volvo the water outlet on the top of the fork assy or the water tube oring between the bottom of the water tube and the top of the lower unit. if the t-stat works fine idling odds are it will work fine running. the water requiements running out are higher than idleing, plus when idling the outlet and the oring are submerged but once on plane they are airborn.

 

[bigbrownbuku]

Re: Thermostat

i started in this field in a very remote location so i know about the back yard tricks and why and when you do them. so heres the remove thermostat trick if you think it will help. remove it and cut the supports that hold the core to the flange, replace the flange into the housing. this will at least create the same restriction as a fully open thermostat. again, your engine shouldnt get much hotter then 100 or so like this even when the water temp is around 70. beyond that find out why your engine is overheating.

 

[waterone1@aol.com]

Re: Thermostat

Sounds like cabin fever has once again struck Iboats......back to the original post...he has a boat that is overheating when running above idle. We are not talking about a sixty dollar part here....gas is now over $2.50 per gallon....replace the thermostat and move on....my guess is 25% this is his problem....lets eliminate this and find the real problem.

 

[rodbolt]

Re: Thermostat

I am kinda with waterone.<br /> if the stat is a few years old I pop a new one in it. if I spend 20 minutes setting up the test and testing it at 75 per hour ya bought a new one regardless. my guess from your description is an air leak on the suction side of the pump or a restriction at the riser. several easy quick tests are availble some in the book some from a working knowledge of what is happening.

 

[trog100]

Re: Thermostat

waterone1.. when someone comes up with an absolute statement that dont sound overly logical to me i will always question it.. i sometimes **** poeople off my doing this but i do learn things..<br /><br />the basic thing i am questioning here is a kinda common belief that coolant somehow has to be slowed down to do its job of cooling.. <br /><br />if it goes thru a radiator/heat exchanger too quick it dont have time to get cooled kinda logic..<br /><br />if it goes thru an engine block too quick it dont have time to cool the engine kinda logic..<br /><br />both these common beliefs are in essence utter nonsense.. he he he.. it dont stop em being "common beliefs" thow<br /><br />its all a circuit.. it goes round and round.. going round too slow might (will) cause local temperarure variations but going round too fast isnt possible.. it cant go round too fast if cooling is its job.. the faster it goes round the better and more evenly it will cool things..<br /><br />the job of stat is a simple one.. it slows down the coolant flow as and when needed to stop it cooling too much.. a stats one and only job is to bugger up the coolant flow.. without it the faster flowing coolant would do its job too well and the engine would run too cool..<br /><br />i fully accept the fact that in this case the overheating problem isnt caused by the stat.. stats are a bit like condensers.. they get replaced as a matter of course when there is bugger all wrong with em..<br /><br />how i would disagree with most is in the fact that i would leave the stat out untill the real cause of the problem is fixed.. i see no point whatsover in refitting a device whos sole job is to lessen/decrease coolant flow when and engine is suffering from too little flow anyway.. just on the principle that a good cooling system that is working correctly with more than adequate flow needs one is silly..<br /><br />a raw water cooled boat cooling system is still a circuit by the way.. the heat exchanger is just called the "sea"..<br /><br />find and fix the real problem by all means.. just leave the stat out till u do is all i say.. in an ideal world the problem would and should be fixed straight away.. in this world it sometimes isnt..<br /><br />thanks to rodbolt and benc for attempting to explain why (sometimes)u shoulnt run without a stat by the way..<br /><br />trog100

 

[novicetech]

Re: Thermostat

Trog, not to say that you are wrong, but take a lit match or lighter and run your finger through it really fast, your finger will not get burned.It will not get burned because it does not absorb the heat. Now take that same lit match or lighter and run your finger through it slowly, your finger will get burned because it has time to absorb the heat. The water flow through a raw water cooled motor is the same way, if it flows through too fast it does not have time to absorb as much heat from the motor.

 

[rodbolt]

Re: Thermostat

just remember that removing the t-stat really proves nothing since now the package is not run as designed. all it proves is there is a problem. could be the t-stat could be someplace else.

 

[trog100]

Re: Thermostat

novicetech.. u are right if all u do is pass it thru once.. u are hitting the nail right on the head.. the longer it takes to pass thru the hotter your finger gets.. he he..<br /><br />but imagine quickly moveing your finger in and out of the flame say half second in and half second out.. imagine doing it twice as fast say quarter second in quarter second out.. half in half out is the key here.. your finger gets just as hot however quick u pass it in and out the flame..<br /><br />take a boat engine.. u have engine hot.. sea water cool.. if u pass enough cool sea water thru that hot engine both will equalize and both will be at the same temperature.. this aint the desired idea with an engine but it is what would happen if enough cool sea water was bunged thru an engine.. the sea being the bigger of the two opposing things would win out and the engine would end up at sea temperature.. in reality the flow thru a boat engine aint powerfull enough to bring the engine down to actual sea temp.. but it could be.. its all about the amount of cool water that passes thru that hot engine here.. there aint no shortage of nice cool water in the sea.. but however much water u bung thru that engine it could never get cooler than the actual sea temperature.. the job of a stat is to permit just enough and no more cooling water to pass thru the engine to bring the potentially too cool engine engine (rest of cooling sytem working as it should) up to whatever temp its best to run it at.. it also serves a secondary purpose of causing the engine to warm up quicker.. it does this by shutting the coolant flow off completely from the actual "cooler".. which could be the sea or a radiater/heat-exchanger..all three serve exactly the same function.. during this period it does permit coolant flow around the actuall engine itself (the coolant heater in this case) and in a car thru the car heater which from the engines point of view would be a cooler (mini radiator) but from the point of view of your feet a heater.. he he<br /><br />the fast warm up in a boat aint quite as important as it is in a car.. the boat dosnt do as many short cold start trips as the car does.. and it dont need heater/demistors kinda stuff to be going as quickly as possible..<br /><br />and rodbolt u are perfectly right about the package not working as it should..<br /><br />but if one part of the cooling package (lets call it part 1) is designed simply to over cool as it is.. and the other part of the package (lets call it part 2)is designed prevent part 1 from functioning quite as well as it should.. every thing is hunky dory.. he he<br /><br />but when part 1 is dysfunctional to the point of under cooling.. u really dont need part 2 to fight it..<br /><br />its simple really.. part 1 is designed to over cool in most circumstances.. part 2 is designed to control part 1.. if circumstances change so that part 1 aint over cooling.. part 2 becomes of negative value.. <br /><br /><br />imagine a world where the sea temp was 140 degrees.. the desired engine temp 140 dregrees.. all u would have to do would be to pump enough sea water thru the engine and both engine and sea temp would equalize and end up at 140 degrees.. u certainly wouldnt need a stat and fitting such a (restrictor) device wouldnt serve any usefull purpose.. only a negative one..<br /><br />from my 140 degree coolant (sea/lake) temp idea.. its also quite clear that in really hot places maintaining that rather cool 140 degree engine temp could be a problem come whatever.. a more powerfull flow system would probably be needed..<br /><br />there is another test here as well.. if a car or a boat runs hotter in summer than it does in winter.. part 1 of a cooling system aint doing its job properly.. that is over cooling..<br /><br />most folks think this is how things should be but it isnt.. its a sign that part 1 is struggling to cope with ambient conditions.. in fact its probably the first sign that your pump or passageways (radiator/exchanger are not passing enough coolant and will soon need attention.. <br /><br />trog100

 

[Don S]

Re: Thermostat

Forget about all the physics of heat exchange, there is all kinds of text books in libraries and information on line for you to learn how heat is exchanged in the engine and heat exchanger, but the qustion here is if he needs a thermostat.<br />The answer is YES!. Without it there will be hot spots in the engine. Quite normal on engines without a thermostat. Of course that hot spot may not be at the temp sender, so you won't notice it.<br />It's a Volvo AQ125 4 cylinder engine and without the temp running about 185° or 190° when warmed up it just flat won't run worth a nickle. The engines don't have chokes, so without the stat it would take forever before you could even operate it even in 90° water.<br /><br />So there is 3 reasons to have a stat. Anyone care to list the reasons to run without one..... and being to cheap to buy one isn't a reason.

 

[trog100]

Re: Thermostat

reason number one don..<br /><br />"Without it there will be hot spots in the engine"<br /><br />u make an absolute statement.. however u dont explain the why of it.. can u do so.. else it becomes meaningless.. dogma consists and thrives on absolute statements without reasonable explanations..<br /><br />"It's a Volvo AQ125 4 cylinder engine and without the temp running about 185° or 190° when warmed up it just flat won't run worth a nickle. The engines don't have chokes, so without the stat it would take forever before you could even operate it even in 90° water."<br /><br />reasons two and three only apply in certain circumstance.. low ambient sea temps.. u live in the cold north i assume.. and again only if the rest of the cooling system is doing its job of over cooling as it should..<br /><br />and the latter part of your (take ages to become opperative) would only apply if the rest of the system was doing its job properly.. and also even if partially true would take second place to the more important task helping the engine not run too hot.. thow how hot would be too hot where a boat engine is concerned is open to debate.. they can probably run hotter then the manual says short term without too many problems.. they cant exactly lose their coolant like a too hot car engine could.. i am talking raw water cooled here..<br /><br />expain to me don.. why would removing the stat from an engine suffering from other coolant flow problems cause local hotspots... or any engine for that matter..<br /><br />as for listing the reasons/circumstances to run without one.. i have tried.. i might have failed but at least i have tried.. he he<br /><br />trog100

 

[halffast]

Re: Thermostat

Originally posted by trog100:<br /> reason number one don..<br /><br />"Without it there will be hot spots in the engine"<br /><br />u make an absolute statement.. however u dont explain the why of it.. can u do so.. else it becomes meaningless.. dogma consists and thrives on absolute statements without reasonable explanations..<br /><br /><br />trog100

trog100<br /><br />We think alike. I always question 'conventional wisdom' when the premise seems illogical. I too, fail to accept 'because' as a reasonable argument.<br /><br />But here's an argument I can accept.<br /><br />The water passages are not in series. That means all the water does not flow through every passage. There are typically a number of parallel passages of differing sizes, each having differing restrictions to flow. Adequate flow to every passage may require some restriction at the outlet.<br /><br />To visualize this, consider water running out of a open garden hose just spilling on the ground. A small pinhole in the hose a few inches from the end wouldn't be noticable unless you tried to block the flow at the end.<br /><br />Half Fast

 

[Don S]

Re: Thermostat

First of all trog, I'm not going to play your theory game with you and your Half Fast friend, and play engineer and try to explain the "WHY" of every post on this board. The guy want's his engine to cool properly.<br />The fact is, if you have to remove a thermostat to get the engine to run cooler, you haven't fixed a damned thing. All you have done is covered up the real problem with a Bandaid fix which WILL show up again in a short amount of time.<br />If he puts a new stat in there and it still overheats, then the rest of the cooling system isn't working as designed. It's just that simple. And until the REAL reason is found for the overheat problem, it's going to be a problem. Or, as some would like to see, covered up so it doesn't show.

 

[rodbolt]

Re: Thermostat

I am with ya Dons.<br /> I dont design them I just fix them. sometimes the shade trees muck it up but its ok, nothing they can break that I cant fix, although copious amounts of cash are sometimes needed when the 100 dollar muck up turns into a 3000 dollar repair.

 

[waterone1@aol.com]

Re: Thermostat

Is it time to start a new section on here called "debate to death" ? It is utterly rediculous that 4 days later and 38 posts later we are still talking about whether or not to replace a fricking thermostat. If we were talking about an intermittant problem with a $1,000 ECM, that might be a different story....this is a thermostat. The fact that Don, Laddies, crazy Charlie, Rodbolt, Tommays and myself have all agreed on something....that either means that the end of the world is here or.....REPLACE THE THERMOSTAT AND MOVE ON.....there is a real problem yet to be diagnosed (most likely)! I think that I speak for most of us....we would like to help this guy get his boat running right, before the snow starts to fall again. TXTRIPPER, replace the t-stat and tell us what is going on.