Suzuki thermostat keep or go?

[ob]

Re: Suzuki thermostat keep or go?

jimd,The only drawbacks I can see with running without a T/stat are <br /><br />1-slower warm-up time <br />2-engine not operating at or near its designed engineered temp. <br />3-depending on the pressure and flow characteristics of cooling system ,lack of water squeeze.<br /><br />On the older evinrudes I've owned if motor was run without complete T/stat assy;water pressure was reduced.Many local wrenches recommended if removing T/stat to simply remove the thermo portion and reinstall blank housing to act as a restricter incerasing waterjacket squeeze.It is this squeeze that enables the water through conduction to remove heat.May well be that your particular engines pressure and flow characteristics will allow you to run with entire assy.removed.

 

[DJ]

Re: Suzuki thermostat keep or go?

jimd,<br /><br />Yes, your engine can be harmed without the t-stat.<br /><br />Think of it this way. The t-stat keeps the water passages full of water, even when fully open. It is a regulatory valve. Without it, water may not reach or touch all of the spots on the cooling system that it needs to. Thus, you develop "hot spots". Slow moving water will absorb more heat that rapid water.<br /><br />The t-stat is not a compromise for differing climates.

 

[jim dozier]

Re: Suzuki thermostat keep or go?

djohns,<br />I am willing to believe what you said if you can describe how an open thermostat will do what you say. If I thought I knew the answer for sure I wouldn't be pestering everybody on this subject on the forum. On my engine the thermostat sits at the top of the engine, water is supplied from the impeller to the cylinder block walls and then the head cavities then up to the thermostat and out a 1/2 inch diameter hole after it leaves the thermostat, and drains the head and cylinders from the top, down a side slot in the head (not the head cooling passage) and out the bottom of the head. If the cylinder and the head fill with water from the bottom up, how can a restriction or lack thereof at the top prevent water from reaching the cylinders and head below. The previous problem on this head design was caused by a poor head gasket design that tended to allow salt and corrosion to plug the drainage slot which is after the thermostat and restricted flow out of the head (which is what got me inside of this engine in the first place. The new head gaskets have a long slot the length of the head which matches the head slot instead of 1 hole at the top and bottom in the gasket. The 1/2 drainage hole that exits the thermostat housing looks to be about the size of an open thermostat anyway. These cooling systems on an outboard are not pressurized like a sealed system in an auto enginge either. They run at ambient pressure + whatever the impeller can deliver.<br /><br />So describe to me how a free flowing system with a 1/2 inch restriction creates hot spots. Perhaps I have misunderstood the plumbing on my engine.

 

[DJ]

Re: Suzuki thermostat keep or go?

jimd,<br /><br />I'm not going to try to convince you. <br /><br />A restiction is a restriction, whether it be 1/2" or a foot. It is there to slow down the flow and make sure that every nook and cranny in the cooling system is full. Without it, water can possibly bypass areas.<br /><br />The same principles apply to automotive engines. Car/trucks run without t-stats frequntly have cooling and running problems.<br /><br />An engine with an even temp. throughout is going to be much more efficient.

 

[jim dozier]

Re: Suzuki thermostat keep or go?

Automotive engines recirculate their coolant and the temp of the coolant on the inlet side is determined by the ability of the radiator system to dissipate heat. The radiator has to be able to dissipate the maximum amount of heat generated by the engine and as a result may overdo it (cooling) when the engine is not working hard.<br /><br /> I wonder if the constant inlet temperature of the inlet (seawater) changes the comparison of boat engines to auto engines.<br /><br /> I don't know. I may stick a thermostat back in the durn thing just to placated everybody who says I should. Does silicone grease stay on a thermostat and help them from subsequent sticking? <br />Thanks to all who offered there 2 cents

 

[bossee]

Re: Suzuki thermostat keep or go?

Hi jimd!<br />Here is some info about thermostat from my Suzuki DT65 Service manual. Maybe it will be to some help.<br />Make sure the thermostat is mounted correctly.<br /><br />/Bo

 

[DJ]

Re: Suzuki thermostat keep or go?

jimd,<br /><br />I doubt silcone grease would stay there for more than a minute.<br /><br />The Suzuki 85 had cooling system issues from day one. It manifested itself in the head area.<br /><br />The new gasket was the fix for that.

 

[jim dozier]

Re: Suzuki thermostat keep or go?

Automotive engines recirculate their coolant and the temp of the coolant on the inlet side is determined by the ability of the radiator system to dissipate heat. The radiator has to be able to dissipate the maximum amount of heat generated by the engine and as a result may overdo it (cooling) when the engine is not working hard.<br /><br /> I wonder if the constant inlet temperature of the inlet (seawater) changes the comparison of boat engines to auto engines.<br /><br /> I don't know. I may stick a thermostat back in the durn thing just to placated everybody who says I should. Does silicone grease stay on a thermostat and help them from subsequent sticking? <br />Thanks to all who offered there 2 cents

 

[jim dozier]

Re: Suzuki thermostat keep or go?

Thanks Bo for the diagram. Your 65hp looks a little different than my 85hp but the principle is the same. My return slot would be on the far left of your picture not down the center. My thermostat sits on top and is inserted vertically. Because it is also mounted offcenter it appears to only go in one way. I had to rotate and diddle with it just to get it in the hole.<br /><br />As Djohns has pointed out I am told this engine had some overheating issues which I am hopefully on top of. We'll see. Maybe I'll buy a dozen thermostats and put a quick release thermostat housing with a bungee cord to hold it down on it. What's the temp rating on bungee cords anyway?

 

[Boatist]

Re: Suzuki thermostat keep or go?

Jimd<br />The thermostat is there for a reason. I do now know your motor but do know two cycles in general.<br />The reason for the thermostat is to get engine up to tempature it is designed to run at.<br />When fuel enters the engine the fuel and oil are mixed together and enters the bearing/crank area thru reeds.<br />What is supposed to happen is fuel should heat up and vaporize and leave the oil behind to lube the bearings.<br />If engine is running cold this may not happen and instead the liquid fuel and oil would wash the oil out of bearings.<br />Piston expand as they heat up, too hot and engine seizes, too cold and piston is loose and get piston slap.<br />Either way not good for your engine. Cold engine oil does not burn right. Get more carbon and fouled plugs.<br />Thermostat should keep engine at correct tempature and motor running well.<br />Thermostat do fail but at least on my engines had them stick open or debree hold them open more than they stick shut.<br />Again I do not know your engine but on some engines can install the thermostat wrong way, make sure it is right.<br />If you really think Suzuki put it in there to make motor cost more leave it out but don't sell it to me.

 

[jim dozier]

Re: Suzuki thermostat keep or go?

Boatist,<br />I never meant to imply during any of my rantings that Suzuki or anybody else puts thermostats in the enginges just to run up the cost and make more money. I know why they are there. If I was engineering an engine to be sold around the world for salt and freshwater in varied climates I myself would specify construction with a thermostat. I would also admonish the user to check it frequently and replace if necessary in the manual to cover my company's butt because they apparently fail alot. My original question which has been answered more or less was whether in a warm climate you needed to keep the thing. I am going to put a new one back in (it only goes one way) and if I have more troubles I'll go from there.<br /><br />Is the internet cool or what?

 

[jim dozier]

Re: Suzuki thermostat keep or go?

Just a quick note on my thermostat problems. After contacting Brownspoint.com to order a new thermostat I find that there are 3 listed. 42deg C (108deg F) for the 85hp (mine); 50deg C (122deg F) for the 75hp; and an optional 60deg C (140deg F). I bought a cooking thermometer and measured the opening temp on the one I removed. It was the 60 degree optional one for what I presume is an Artic climate. Then I tested the one I had replaced in September. It was the 50 degree one for the 75hp model which has the same engine block as the 85hp. So my engine has had the wrong thermostat for some time now. Also interesting is that the correct one for my engine has an opening temperature only 20 degrees F above the average summer water temperature here in St. Petersburg.<br /><br />Never hurts to double check the parts you buy does it?

 

[ob]

Re: Suzuki thermostat keep or go?

If I read you correctly,the average summer water temp in St Petersburg is 102 degrees F?Must be some poor dissolved O2 content and lots of hardheads. Is this near a powerplant condenser discharge?

 

[jim dozier]

Re: Suzuki thermostat keep or go?

OB,<br />No I was trying to say that the correct thermostat for my engine which opens at 108 degrees F is only 20 degrees above the average summer temperature in the Gulf of 88 degrees.<br />(88+20=108)

 

[ob]

Re: Suzuki thermostat keep or go?

I see. I thought you were going back with the 122F that you changed in Sept.The mention of the 75 and 85 block being the same must have thrown me off.

 

[fridays]

Re: Suzuki thermostat keep or go?

I've been selling Suzukis for 20 years.First, is the check valve with the spring installed between the head and the block? You should have seen it on the left side when you had the head off. If its not there, that's your problem, because water is not making it to the top cylinder with the thermostat in place. Without the thermostat you get more flow and it cools ok now but will probably overheat in the Summer. If the check valve is in place feel free to run it without the thermostat. Your sea temperature in Fla is warm enough and you will never notice a difference, We have commercial customers who have run their motors for years w/out thermostats

 

[jim dozier]

Re: Suzuki thermostat keep or go?

Thanks FridayMarine,<br />The check valve is in place and the motor is running good.

 

[spete]

Re: Suzuki thermostat keep or go?

Not to beat a dead horse but ... I would want my motor to run the way it did from the factory ... with all the pieces.<br /><br />A) motor overheats with thermostat in<br /><br />B) motor runs fine without thermostat<br /><br />C) "problem" thermostat removed is tested and opens at temperature specified for your motor<br /><br />Conclusion: restriction of flow or cooling capicity lost somewhere up or down the line. <br /><br />Thoughts: <br /><br />What if it's a weak or misinstalled impeller that sends enough water at low speeds but not enough at WOT?<br /><br />Blockage that's overcompensated by increased water flow<br /><br />Bad sensor