Engine Temperature Issue

[teachercop]

New to us, 2016 RZX Raptor 6.2L 440. 215 Hours, running it daily at Lake Havasu, 115° with Lake water 89°. Engine temperature has been operating at 155-160°. Sunday towards end of day, cranks will not start. We were at the slip so we managed it in. Next day, go out a couple runs won't start, sit for 5 minutes starts. I see engine temp at 118°. Bring in, unable to locate an Indmar thermostat, at suggestion of service I get an O'REILLY 160° tstat. Run today at 140°.

Confused..

Sent from my SM-G960U using Tapatalk

[Zackdogg]

I have the exact same boat, and can tell you that mine runs pretty much always at 160°, +\- 5°. I’ve never been out in quite that much heat, but maybe like 105°, so not incredibly far off, and in water temps up to about 85°. The engine temp seems to stay pretty consistent regardless of ambient or water temps. The only time that’s ever changed, I got a code that my sea strainer was clogged, and it got up to about 180°, before returning to normal, shortly after.

The only time I’ve ever had issues with it dying, our fuel pressure was low, but it was throwing codes, and the check engine light would come on. Guessing you aren’t experiencing that?

Sorry, I know that answer isn’t a ton of help, but maybe knowing that 160° is where it should be helps a little. I haven’t looked for the T-stat, as I’ve never had any issues, but should probably know where it’s located. If you don’t have a better answer by the time I get home tonight, I’ll see if I can find it.

Good luck with it. My first 2 seasons with this boat, I had quite a few bugs to workout. It’s been a good boat after I figured them out, but it was pretty frustrating for a few years.


Sent from my iPhone using Tapatalk Pro

[freeheel4life]

teachercop I'm a bit confused how the no start condition lead to a thermostat swap. Ones not really related to the other. Also, how long had the engine run when it was reading 118*??

Zackdogg Tstat is on top the engine Bank 2 side ish up front. Round bubble/dome with single hose coming off it.

[Zackdogg]

teachercop I'm a bit confused how the no start condition lead to a thermostat swap. Ones not really related to the other. Also, how long had the engine run when it was reading 118*??

Zackdogg Tstat is on top the engine Bank 2 side ish up front. Round bubble/dome with single hose coming off it.

I figured someone would know, and you were at the top of my list of guys that it would be. Sounds about like what I’d be looking for. I was with you on the 2 not being related, which is why I mentioned the fuel pressure and codes thrown. I wasn’t sure if a high temp would shut it down, but couldn’t imagine a scenario where a low temp would.


Sent from my iPhone using Tapatalk Pro

[teachercop]

Thank you for various responses. Today's notes

Ambient has been 105-120° depending on an Arizona Monsoon. Water 85-90°.

Boat temp guage was running 118-120°. I changed Tstat and then used IR temperature gun which read 157° at the thermostat hose while boat guage read 120°. Wish I used gun before tstat swap.

Yesterday, threw 'Fuel Pump Relay Open
Code.' We continued to surf and boat shut down unable to restart, towed to ramp.

Last night installed new fuel pump relay, today returned to Lake, at beginning of day boat guage 120° with gun reading 157° at Tstat hose. Continued to operate, as day went, temperature guage increased to 155-160° with no codes displayed.

Like it never happened.

Have no idea what tomorrow will bring.

I may have a back up thermostat and Fuel pump relay on hand...

Sent from my SM-G960U using Tapatalk

[freeheel4life]

teachercop great follow up info!! All the smaller relays are the same besides the larger starter relay. Won't save you A$$ getting off the water but if you swap relays from the IGN or Fuel Pump slots and end up with the same error codes you know you have a harness/wiring issue or ECM issues. Sounds like a bad relay was the no start issue tho

FYI the coolant sensors are under the intake manifold and threaded into the head. Before you jump to a sensor failure diagnostic just remember that with a good impeller it takes a while to get to that 155-160 range and thermostat to open. Sit at idle and watch ECT creep up and see what temp it goes back down. If you watch you should see what temps the tstat opens within a few degrees on the screen. Sounds like you may be jumping the gun and worrying about coolant temps before tstat ever opens

[teachercop]

Additional
118-120° temo guage reading was during/after 6-7 hours on the lake with ballast/surfing, boarding. We have accumulated over 60 engine hours in July at Havasu. The boat had been running 155-160° flawlessly. When I drew concern the guage should have been reading the 155-160°. I should have verified with my IR gun prior to thermostat swap, I perhaps prematurely determined the thermostat was remaining open.


Sent from my SM-G960U using Tapatalk

[Bamer]

[mention]freeheel4life [/mention] what’s ECT?

Since they are swapping t-stats, They should be careful about getting air in closed cooling section too…right?


Sent from my iPhone using Tapatalk

[Zackdogg]

I’m thinking Engine Coolant Temp.


Sent from my iPhone using Tapatalk Pro

[freeheel4life]

[mention]freeheel4life [/mention] what’s ECT?

Since they are swapping t-stats, They should be careful about getting air in closed cooling section too…right?


Sent from my iPhone using Tapatalk

Zack nailed it. Engine Coolant Temp.

As far as airlock in cooling system I've typically only had it happen after coolant goes low due to either a heater pump/hose leak or an overheat. Once it's low if you just try top off via the degas bottle it will stay airlocked. To solve it without a vacuum bleeder/fill tool you pull the thermostat and top off the coolant thru the tstat housing until block is FULL and then just put tstat back in and top off degas.