How to Winterize: risers specifically

[blamtro]

Bought a new closed cooling 383 mercruiser stroker with the single point drain. However can not figure out if the exhaust risers need draining. I have poured through the manual and interwebz but nothing specifically calls out draining the risers. Ive opened the drain plugs and emptied the raw side of the heat exchanger but want to avoid freeze damage to the risers. Help?

 

[blamtro]

Here is the engine info: Engines383#: 8M0136295 Sn: 1G701432, 1G701433

 

[Fun Times]

Engine part number 8M0136295 comes with Factory Fresh Water Cooling System that protects the engine block and exhaust manifolds.

So with that the risers are raw water cooled only and if you live in an area that gets pretty below freezing often and for long periods of time, your safest bet would be to address the risers of ensuring the water gets out and consider adding some marine winter grade antifreeze for added protection as the gasket between the riser and manifold is fully blocked off....Water on top, antifreeze below...

I'd probably say that In this/your case due to engine model, adding some antifreeze to the top side of the gasket area of the riser ought to help make you sleep better on those colder nights.

See the 2 notes for item # 12, https://www.mercruiserparts.com/bam/subassembly/32008/16414/170

Here's your parts guide for your engine serial number for future use if needed, https://www.mercruiserparts.com/383-mag-stroker-bravo-1g400000-up

Your engine details,

383 Mag MPI STROKER (350 Hp) with Factory Installed Freshwater Cooling (#8M0136295) | PerfProTech.com

Buy 383 Mag MPI STROKER (350 Hp) with Factory Installed Freshwater Cooling (#8M0136295) from PerfProTech.com. This is an OEM "Original Equipment" MerCruiser, (6.3L) 383 Stroker Bobtail Engine equipped with Factory Fersh Water Cooling System that protects the engine block and exhaust manifolds...

www.perfprotech.com

Hope this helps, good luck.

 

[tpenfield]

I have a closed cooling system on my engines. I usually run AF (-100˚ F) through the raw water side to protect all the nooks and crannies that water may reside, such as the sea water pump, oil coolers, HE, exhaust elbows. Then drain the HE as an extra measure.

You can assume the single point drain allows for proper draining, but just in case . . .Running AF through the raw water side is probably the best way of protecting the raw water side of a closed cooling system without disconnecting a whole bunch of stuff.

 

[blamtro]

Update: we’re supposed to get down the teens in a day or so. Went out to the boat, disconnected the hoses feeding the risers and pulled out about 10-12oz total of raw water in total from the 4 risers. The starboard risers had effectively no residual water, would say it was 6oz from each port riser. I have a short 3 inch section of clear PVC tubing at the end of the shopvac hose so I could watch if water was coming out as I hit each hose.

Looks like I need to add this to the winterize protocol or put in a tee with a drain for each riser to make this faster in the future.

Will likely make a brass Tee with drain to put in each riser hose.

I poured this out of the shopvac and because it was very close in color to the dexcool merc uses, stuck it in the freezer to make sure I didnt have a leak from the closed side of the system. If it wasnt water, wouldnt have froze.