When I take my coolant filler cap off (cold engine) coolant overflows and is clearly streaming in from the overflow reservoir hole. This didn't happen on our last boat- and I suspect it's because this overflow reservoir is higher and will drain into main reservoir when cap opened (our last boat's overflow reservoir was more or less level with the engine so not as much head pressure).
question: is this normal/unavoidable? Simply a gravity feed? I guess short of putting a valve in to close when checking levels it's unavoidable but just wanted to confirm that this is what everyone experiences and not indicative of an issue with my setup
thanks
Brad
—
S/V Escapade
2003 C36 MK2
Hull 2148
Standard rig/wing keel
Universal 35 BC
It's normal. You can check the level from the overfill bottle so their really isn't a need to open the cap on the engine.
Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B
You know, mine doesn't do that. My coolant overflow tank is also higher than my engine but I havent noticed it drain back to the engine if I remove the radiator cap. Now im curious.
"Nauti Seahorse"
2001 C36 MK ii. #2011
Well my coolant reservoir is below the level of the tank on the engine, as it is only there for overflow if engine overheats. Recall that this is a diesel engine, and does not work quite like a car engine. In several places in the instructions and manuals it is pointed out that the level of the coolant in the engine tank should be about 1 inch below the cap. If the reservoir is above the level of the tank level then it sounds like it is sucking coolant into the tank on the engine meaning that the level will be much higher than one inch below the cap. Sounds like some adjustment needs to be made in order to maintain the level at 1 inch below the cap.
Kevin Lenard
"Firefly"
'91 C-36 Mk. "1.5" Tall Rig, Fin Keel, Hull #1120, Universal M-35 original (not "A" or "B")
CBYC, Scarborough, Lake Ontario, Canada
I got curious after reading the comment about the location of the recovery tank and found these in the owners manual and technician manual. Per these books, the tank should be above the engine for proper performance. The filling instructions also are in one of the pics. Im not sure why it would be different in other years. Mine is a 2001. Brad, what year and engine do you have? I wonder if your cap has a Crack allowing airflow?
"Nauti Seahorse"
2001 C36 MK ii. #2011
I have a m35bc .. offhand not sure of the manufacturer year though the boat is 2003 so probably post 2001.
That's interesting, thanks for sending that info. It certainly makes sense that if you take the filler cap off, and there's a hose with head pressure it's going to briskly flow in to the manifold tank.
Interestingly, it doesn't seem to be a constant thing for me. Yesterday I emptied out all of the coolant, and treated the system with de-scaler, flushed and refilled with all new coolant. When I first drained the manifold, I expected the reservoir tank to empty out as well since I was draining it from the lowest point. But it didn't! I have no idea why it wasn't Freely flowing as the level of the coolant dropped. It was just a drop drop drop. The reservoir tank wasn't very full, just up to the low level so maybe it's not as much of a head pressure? Or, maybe I've got a piece of debris in my hose that's acting like a ball valve, sometimes it's a brisk flow and sometimes it's just a drop per second. That's the only explanation I can come up with.
S/V Escapade
2003 C36 MK2
Hull 2148
Standard rig/wing keel
Universal 35 BC