Temperture Gauge - Sea Ray 180

[Sushiholic11]

Temperature Gauge - Sea Ray 180

I have a 1999 Sea Ray 180, and the temperature guage is reading 170 deg when running. I replaced the thermostat and the impeller but no change. I used a temperature gun pointed at the thermostat housing and it read a steady 145 deg while idling on the muffs, the gauge read 170.

My question is this, has anyone added a resistor in series with the gauge to "calibrate" the gauge? If it is a resistance meter then theoretically this should work, it would add some bias to the gauge.

I plan on trying it out with a potentiometer while running, set it so the gauge is reading the same as the gun then shut the engine off and while it cools I will compare the gauge to the gun to see if it is still accurate throughout the whole lower range. If everything works out I plan on replacing potentiometer with the closest stock resistor size.

Has anyone else done this?

Thanks.

 

[CliffA]

Re: Temperature Gauge - Sea Ray 180

i think you are 'chasing a ghost'....i believe the correct operating temp for your engine is 170* so it sounds like your cooling system is functioning properly.....your engine probably has a 160* thermostat installed....this means that the t'stat 'begins' to open at 160* and 'fully' opens around 170*.......the metal on the t'stat housing is pretty thick so it can dissipate some heat before it reaches the outside of the metal....that is likely why you are only reading around 145* with the temp gun....

it sounds like your engine is operating just fine so i would suggest you don't try and correct something when there may be nothing wrong to start with...

cliff

 

[Lazy Daze]

Cliff is correct. Everything is fine, leave it as is.

In addition to what Cliff mentioned about the "thickness of the t-stat housing" and "aiming the IR gun"... another variable is the exact spot that you aim the gun.

 

[Sushiholic11]

I just replaced the thermostat with a 140 deg, as per my shop's recommendation. I believe that 140 deg is the correct temp range for a raw water cooled 3.0. I understood that the 160 deg thermostats were for closed cooling systems.

The only way I can be sure of the water temp is to buy a cheap gauge for $35 and see what it reads.

 

[CliffA]

I just replaced the thermostat with a 140 deg, as per my shop's recommendation. I believe that 140 deg is the correct temp range for a raw water cooled 3.0. I understood that the 160 deg thermostats were for closed cooling systems.

The only way I can be sure of the water temp is to buy a cheap gauge for $35 and see what it reads.

i don't want to question your shop but i am very surprised at that....my understanding is that the 143* t'stats were used prior to the mid 1990's and then usually on engines that were used in fresh water and raw water cooled....i believe engines used in salt water prior to the mid 1990's with raw water cooling had 160* t'stats.....somewhere around the mid 1990's i thought Mercruiser went to 160* t'stats for all of their engines.....

if you have a 143* t'stat installed and the actual temp of the cooling water is in fact 170* you may have an issue with the cooling system...

cliff

 

[Lazy Daze]

I'd have to go back and check, but I'm pretty sure 160* is the correct one. Older, big blocks used a cooler stat - but I'm pretty sure yours uses a 160*. Well, that, and when I owned a '00 180 it always ran at 170*... and all of the other (hundreds, probably) 3.0L's that I've run also showed 170*.

Now, if you are POSITIVE that you put a 140* in there (what was stamped directly on it?), something is amiss and just "by luck" the gauge is actually showing the correct temp then.

 

[Sushiholic11]

I'm positive that it said 140 deg in the thermostat. I'm going to have to research some more as I'm finding people with both 140 and 160 temps in their 3.0 Mercruisers. Gotta love the Internet sometimes.

 

[Sushiholic11]

Ok, I understand the 140 deg is for raw water cooled engines that run in any salt water, as salt crystallizes above 160 deg. If you run in a lake 160 deg is perfect.

Now I still have to chase down the gauge issue...

 

[CliffA]

Ok, I understand the 140 deg is for raw water cooled engines that run in any salt water, as salt crystallizes above 160 deg. If you run in a lake 160 deg is perfect.

Now I still have to chase down the gauge issue...

yes, that is correct....i mistakenly had it reversed in my reply....

however if you have fuel injection the engine likely needs to run hotter than a similar carb'd engine.....

good luck...

cliff

 

[Lazy Daze]

Ok, I understand the 140 deg is for raw water cooled engines that run in any salt water, as salt crystallizes above 160 deg. If you run in a lake 160 deg is perfect.

Don't believe everything you hear/see on the internet. I'm calling baloney on this one. While there may be some merit to this in a lab, in reality there is not. It's more of an 'old wives tale' kind of thing. Merc has never recommended changing the stat because of the water you are in. The ONLY thing you're going to do by going to a 140* is to lose efficiency. ALL 3.0L's come from the factory with 160* stats in them and dealers DO NOT change the stats based on where the unit is used. That means every single 3.0L engine out there will have, regardless of what water it is in, a 160* stat in it (other than if an owner changes it).

In the end, do what you want and believe who you want to, but it'd be a shame to lose efficiency because "someone told me..." or "I researched the internet..." None is this is, in anyway, meant to be off-putting or crude towards you - just trying to give you honest information.

Now, why does the temp gauge read higher than it should? There are 'specs' for what a temp sender should read at various ambient temps. I don't know them offhand, but it shouldn't be too hard to find them. You can test the sender that way. It's just really strange that the gauge is 'wrong', yet reading exactly where it normally does, you know? I doubt there's anything wrong with connections or wiring, though, since temp is inversely proportional to resistance and extra resistance in connections/wiring would cause the gauge to read low.

 

[ZZ13]

My 3.0l in my 175 Sport came with a 160 degree and it reads 170 consistently. I have been running it in salt water for 6 seasons. I just flush all the salt out of there with a Salt Away clone (Salt Terminator) after every outing.

 

[blaster]

My 2001 180br had the 160° t-stat also. It read 180 on the gauge but when I would hook up a second gauge to the motor, it would read closer to 160°. I spoke with the selling dealer, Conestoga marine in Lancaster and they said " the 180's run hot". Even though the gauge ran hot I was confident everything was OK. I spoke with several owners of 98-2001 180 Br's and all of them read hot.

Cliffs right on about the temp. The 115 HP 3.0 used a 143° t-stat but the 135HP 3.0 used the 160° t-stat. The lower temp will reduce efficiency as Dennis mentioned and will also foul the plugs faster.