8.1 Merc coolant reservoir MT

[grayzone]

Went to the boat today. It's been stored, indoors cold storage, since Sept./13. Noticed the port side (8.1 Merc) coolant reservoir was empty. Looks to me like the amount that's in the bilge is the amount that was in the reservoir tank. It was a particularly brutal winter here, -40 C for a good stretch. It is still 0 C / 32 F and below, most days, slow Spring arrival. I checked the dipstick, there is no antifreeze in the engine oil.

My questions are:
1.what side of the engine is the frost plug on and if I popped one, how much anti-freeze should be in the bilge?
2. Any other ideas on where to look first?
3.What would be the first steps to start diagnosing this?

 

[carterchapman]

Did the plastic reservoir tank crack?

 

[grayzone]

Did the plastic reservoir tank crack?

don't think so

I'm going back in a couple of days hoping to find something obvious but not serious

 

[my3sons]

These cold winters cause the coolant to contract, then when it warms up (all the way to 0 C / 32 F degrees, it's still a 60 to 70 degree swing) it creates pressure in your system. The hoses and fittings contract and expand also from the cold, and some coolant can leak out at the hose fittings. I had some coolant on top of the cylinder head last weekend when I visited the boat in storage. I traced it to the coolant hose at the thermostat housing. It was not snugged up the way it should be, and the pressure in the system was causing a seep. It never leaked last fall. It is something that we just don't normally think about, but when I took the pressure cap off the steel coolant tank, the coolant burped out of there like I was taking the cap off of a hot engine. The 8.1 I used to have use to leak coolant out of the heat exchanger/crossover gaskets every winter due to this. It never leaked out as much as you are describing, but you should check around those gaskets and coolant hose connections before going further with thinking the worse. Good luck.

 

[Henry Boyd]

The 8.1/496 engine coolant tank has barbed nipples. These fit into a manifold with rubber grommets on the top of the engine. During the winter everything contracts and if the right conditions line up, the tank leaks though the mounting point.

We went though this for several seasons where I thought the issue was just contraction of the fluid and lack of memory as to how much was in the tank at haul out. Then a couple of seasons ago the yard put the drain plug back and I found a puddle of Dex-cool under the engine.

Henry


Sent from my iPad using Tapatalk HD

 

[jdsrv300]

As suggested, I would check and tighten all hose clamps, look for drips, then refill the system. If you need to check further you can go to a large Auto parts store and rent what is called a "cooling system pressure tester" that will pump air into the cooling system. If the guage on the tester maintains it's pressure your OK. If not, then you need to look further.Good Luck.

 

[grayzone]

Finally got back to the boat to finish checking the leak out.Looks like it leaked from a hose clamp that was a bit loose.

Lots of people in our storage area experiencing the same thing.Were launching Thursday so that will be the final check but I feel confident everything is ok.