2013 115 Optimax Cooling System

[KiloTango29]

Hey guys, I’ve heard there are some resident Optimax experts here so I joined to post some question about my new to me 2013 115HP Optimax. Model number is 1115D73HY. Serial is 1B934109. I put it in the water for the first time today and just a dribble came out of the indicator hose. I only idled it and only for 30-45 seconds at a time to troubleshoot. The owner said a new water pump was installed in 2020, so I assume a new one is in order. Any tips on this since I don’t have a service manual yet? What service manual do I need? Also, any other items in the cooling system I need to address/inspect? Anything fuel/air related. This motor only has 200 hours on it, so more sitting than running. But in very good shape. Any tips/tricks/advice is much appreciated!!

[SilverFox579]

Welcome KT!

The Optimax cooling system is critical for the engine and the air compressor. Water pump service interval is annual or 100 hours whichever comes first (same goes for spark plugs), so I strongly recommend replacing both before running your engine further. At the same time, ensure the compressor strainer and telltale hose are both clean and free of obstructions.

One of the best investments you can make is a genuine Mercury service manual (availble in paper only) and highly recommend one if you plan to service it yourself. I would also highly recommend a Smartcraft device of some kind so you can monitor critical engine parameters - SMARTCRAFT Options

There are great FAQ sections at the top of the 2.5L & 3L forums with a treasure trove of Optimax service recommendations and advice, much of which applies to all Optimax engines irregardless of displacement. There is a topic for servicing the 1.5L water pump in the 3L FAQ - 1.5L (75-125hp 3 cyl) Optimax Water Pump Replacement

That should get you started, the pros here can assist if you need more.

[JOE54]

^^^^^^ +1

[KiloTango29]

Thanks for the reply guys! This is my first Mercury, so I’m getting familiar with the systems etc. Previously an older OMC guy and currently 30HP Etec. So a bit of a learning curve but a lot of similarities within the DI two strokes. I will definitely get a new impeller installed and check the system for any blockages. From what I can tell on my engine which is a 3cyl, the path of water travel is: water pump, block, through the strainer, compressor, fuel rail, the out the tattle tell. I will do my best to troubleshoot before I get a service manual, but didn’t want to miss any critical steps.

Spark plugs will also make the list for swap out. I’ve read about some oil filters, is this a critical part to change? I’m looking into the SmartCraft system for monitoring as I’m basically flying blind on temp/pressures as of now. Any other must check items or tips are greatly appreciated. It seems these engines can be delicate, but a thorough understanding goes a long way.

[EuropeanAM]

There's actually three branches of water flow involved. Strainer, compressor and telltale are one branch. Block and thermostat, black and poppet valve are the other two.

No telltale = Air Compressor Overheat.

As suggested- start at the source and get your water pump replaced, as well as any other outstanding Annual Maintenance Items.

[KiloTango29]

Thanks again for the information guys! Just wanted to give a quick update on my cooling circuit troubleshooting. I tried the easiest fix of running some weed eater line into the tell tale line. Found some bugs that made a home, purged the lines out. Backed into the water close to home and had a strong stream from the tell tale line. I still plan to replace impeller, plugs, filters etc since the motor sat a while, but feel I can wait until I get a service manual. Is there a source for service manuals you guys can recommend that support the forum vendors/sponsors? Also, I wouldn’t mind overhauling the fuel lines. Sources that you guys recommend? Like I said, I’m new to Mercurys from ETecs, so new suppliers/vendors etc. I’m also curious as to what SmartCraft gauge I would need for a more detailed breakdown of my engines health. Is it an easy plug and play install? Thanks again for the info and knowledge!

[EuropeanAM]

Sherm's Marine & European Marine support the forums (see Sponsors List forum for a complete list of sponsors).

[SilverFox579]

Buy all my service parts from European Marine, top notch service.

[KiloTango29]

Thanks again guys. You’ve all got me off on the right foot. This forum is amazing, the info in the sticky’s is phenomenal. I have one more cooking related question. I’m wanting to get the vessel view app and Bluetooth module for my engine. I’m assuming its compatible from what I’ve read. And I’ve read you can get h2o pressure with the right sensor (read the forum on adding digital pressure sensor). On my engine it seems I have the grey tube that is connected to a sensor, and that sensor is plugged into the harness. The only issue is the other end of that grey tube is coiled up with a plug in the end not tapped into a water jacket. Was this an optional thing from Mercury? Any insight?

[EuropeanAM]

Water pressure is STANDARD on the Optimax. If not connected, you WILL get faults.

Most engines had a "tee" in the line between the block and the sensor- providing a coiled-up gray tube that had a red plug in the end of it. That was a ready-to-rig connection point for ANALOG water pressure.

[KiloTango29]

Thank you for the info Don. This helps my understanding of my engine immensely. I guess I couldn’t see the tee as it runs behind the coil packs. So for the Vessel View all I should need is the Bluetooth module and the smartphone app? Then I’ll be able to monitor water temp and pressure?

[KiloTango29]

After doing some more reading, I think I’m getting confused on the Analog vs Digital senders. So if I’m correct, my engine now has a pressure “switch” for alarm purposes. The digital sender is what the Vessel View needs for a readout. I saw the write up on installing one. Part number 8M0059531? Is the harness capable of plug and play with the digital sender? Sorry for all of the questions! But thank you for all of your help.

[EuropeanAM]

ALL Optimax product came equipped with, and monitored, water pressure (block pressure). Looking up or referencing information for 4-stroke models is simply confusing you.

STANDARD FEATURE ON ALL SMARTCRAFT COMPATIBLE OPTIMAX PRODUCT.

[SilverFox579]

Thank you for the info Don. This helps my understanding of my engine immensely. I guess I couldn’t see the tee as it runs behind the coil packs. So for the Vessel View all I should need is the Bluetooth module and the smartphone app? Then I’ll be able to monitor water temp and pressure?

Everything you need to see on an Optimax is provided by the PCM and displayed on a Smartcraft device.

The most important parameters for any Optimax are water pressure and coolant temperature, rpm and battery voltage are nice too. I have a Mercmonitor interfaced via N2k to my MFD and get full screen data - water pressure, coolant temp, rpm, battery voltage, speed via GPS, and real time fuel consumption, which by the way, is accurate to within 2%.

[KiloTango29]

Thank you for the clarification gentlemen.