ETEC T-stat

[Max123]

Question for the Etec owners out there regarding operating temperature.

I took the boat out yesterday for a blast up to Pitt Lake, and noted some odd temperature readings. Keep in mind water temperature was ice cold in the Pitt.

I noticed that running up the river at normal cruising speed that water temperature reading on the gauge was around 95F, which seemed pretty cold. I realize that there is a pressure relief valve that opens around 2500rpm and lets in more water, but my recollection from the past is that water temp typically was in the 120F range. Possibly this was just extremely cold water temperature and nothing more.

Next, I noticed that at idle, engine temp goes to 150-160F, however at hull speed or off plane, temperatures would climb to around 180F. I didn't let it get any hotter than that (either sped up to open the relief which opens the relief valve and quickly cools the engine, or slowed down to idle/troll) , so I never actually triggered an over-temp alarm.

Firstly, water flow from telltale looked good and impeller was replaced last fall and had been tested once or twice already, so I would tentatively rule that out.

My assumption is that it is just a failed thermostat - but thought I'd check to see if this sounds like something else. I have two Tstats sitting at home in my parts box, so going to the throw them in next time I'm out there.

 

[sly_karma]

In normal ops with the engine warmed up, it will run hotter at low rpm than at cruise. There's just so much more water flow once the PRV opens. Off plane at 2000-ish rpm will see the highest temps since the motor is working relatively hard but only has the water flow through the stats to work with. So on the surface of it, your outboard appears to be behaving normally. The low idle temp is explained by low ambient water temp.

The PRV is triggered by water pressure. The water pump should generate 21 psi system pressure at around 2500 rpm and open the PRV. Monitoring water pressure while under way should tell if your pump is developing pressure appropriate to rpm range. It's also an easy way to observe an impeller weakening with time.

The stats are easily accessed if you want to test them. Pot of water on the stove and an instant-read meat thermometer will tell the story, but from your description they appear to be both working.

 

[Max123]

In normal ops with the engine warmed up, it will run hotter at low rpm than at cruise. There's just so much more water flow once the PRV opens. Off plane at 2000-ish rpm will see the highest temps since the motor is working relatively hard but only has the water flow through the stats to work with. So on the surface of it, your outboard appears to be behaving normally. The low idle temp is explained by low ambient water temp.

The PRV is triggered by water pressure. The water pump should generate 21 psi system pressure at around 2500 rpm and open the PRV. Monitoring water pressure while under way should tell if your pump is developing pressure appropriate to rpm range. It's also an easy way to observe an impeller weakening with time.

The stats are easily accessed if you want to test them. Pot of water on the stove and an instant-read meat thermometer will tell the story, but from your description they appear to be both working.

Thanks for the reply. I don't normally watch the temp very much so don't recall the typical normal range (I always mean to write this down on the dash) - but when I looked it up the T-stats are set for 150-160F, so when I started to see 180F on the gauge it seemed high (even though I was loading the motor up without tripping the PRV).

I'm going to pull them today and see what the deal is.

 

[ship happens]

The tstats on Etecs are 143 degree. Once that blow off valve opens the tstats are completely bypassed. That being said if the engine can sit and idle and keep temps between 150 - 165 then they are working like they should.

As @sly_karma stated, about water pressure. Correct. Guys who run long distance at 1200 -2000 can experience higher engine temps and even overheat fault. They make a lighter spring for the 60 degree etecs. Part number 352544. It's a 19 lb spring. Might solve your problem. Part # 5006465. Part number for the kit which comes with the diaphragm is part #5006465.

Can't remember but some of the later models came with the 19lb spring. So best to pull the cap off the valve and measure the spring diameter and length. The heavier 22lb spring is 2.31 in legnth with a wire Diameter of .092" +/- 002". Can easily measure it with a caliper.


That all being said, keep in mind that outboards with high HP don't like to be ran at 1200 -2000 all the time. On the etecs specifically right after 1200 ish is when they start burning more fuel and air. From idle till around 1200 is only timing advance. When the TPS bottoms out ontp the intake shaft around 1200rpm it's programmed to that voltage off the sensor and starts opening up the intake butterflies. The EMM knows that critical point because it's programmable. Which most mechanics overlook when first installed. 9 times out of 10 if you recalibrate it you'll get a different value. Hope that makes sense.