RWC Excalibur 330 Limp Mode / Thermostat & Temperature Sender variation from manuals.

[PropMonkey]

Boat Details: 2002 Super Air Nautique with a PCM 330 Excalibur. The motor is raw water cooled.

This winter I replaced a failing water temperate gauge and decided to also replace all temp senders along with a new thermostat. I noticed two part variations from my current cooling configuration. The parts manual calls for a 160 degree thermostat and a plug for the intake temperature sender (R020003). My engine had a 140 degree thermostat and the intake temperature sender R020003 installed.

Here is what I replaced:
R020002 - thermostat housing
R020003 - intake manifold (parts manual indicates this should be a plug however my engine had this sender)
R020019 - ECT
R026002 - 160 Degree Thermostat
New Teleflex Vision style gauge 2002 from Nautique Parts PN:8235

This spring after new RWC impeller install I noticed the new water temperature gauge was reading high around 190-200. Checked temps around thermostat housing with an IR heat thermometer and temps where good, around 160-170 as expected. At this point, thinking faulty gauge.....

Our first trip to the lake the engine went into limp mode. Again, checked engine heat with the IR gun, 160 to 170 degrees... Oil pressure is reading ok on the gauge. My gut tells me to put the 140 degree thermostat back in and give it a try. However, I have some confusion on why there was a 140 degree thermostat installed in the first place as well as the extra temp. sender on the intake manifold (R020003).

I am wondering if anyone in the community could provide some clarity on this. I also have some additional questions.

1) I may have the wires mixed up between intake manifold sender and thermostat housing sender? Currently wired light green to thermostat housing. Tan to intake manifold. See attached photo.


2) Is there a reason my raw water cooled engine would have the intake manifold sender, indicated on the parts manual to only be for FWC engines?
3) What sender trips overheat limp mode?
4) Could my ECU / MEFI be programmed with a lower temperature threshold? (possible reason for the 140 degree thermostat?)

My next steps are to rule out oil pressure sender malfunction, double check temp senders are wired correctly and change the thermostat back to 140 degrees.

-J

[PropMonkey]

Solved!!!

The green wire is for a water temperature switch (R020014) or "Limp Home". The water temperature sender (R020002) and the water temperature switch look nearly identical.

The temperature switch is not called out in the PCM parts manual, temp sender R020002 is. So, I had a temperature sender putting out a signal, as senders do, which placed the engine in limp mode as if it was a switch for an overheat condition. If you have a RWC engine with the intake temperature sender R020003 for FWC engines (brown wire), the part installed in the thermostat housing (green wire) is a temperature switch not a sender. I would have never figured this out as the documentation does not exist. Thanks to the guys at SKIDIM for solving this. BIG help.

Wanted to share with with the community for what its worth. I cannot say if this was a factory configuration that ended up not being documented in the parts manual. Or, if somewhere down the road this was added by a previous owner.