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Little to no coolant in heat exchanger?
Liberty44140
Member Posts: 4,330 ✭✭✭✭✭
Launched my new to me 06 342 which has twin 350 MPI's today. Before running the engines I checked the exchangers on both engines. Port was nearly full of orange stuff but the starboard looked bone dry. Fired them up, started right up. Only ran for 4 min due to the stbd exchanger being dry, enough time for the fog smoke to die down. Looked in the stbd exchanger after shutting them down and the inside of the exchanger was wet so there must be some liquid at the bottom but still could not see any level of liquid. The good news is that the previous owner is obligated to make sure everything is ok even though the sale is closed so he will have someone look at it asap. I had a compression test done by a certified mechanic 3 weeks ago and they all came back good and within 4% of each other so I know that its not a cracked block or head gasket. They also plugged in the computer to both engines and all was well. 240ish hours on each engine, no major alarms. Wondering if the exchanger itself has a leak or a hose somewhere leaked it? Or could it be that when winterized they had to drain and forgot to re fill? Any thoughts?
07' Cruisers 390 (Previous Rinker's: 06' 342EC & 01' 310FV)
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PC BYC, Holland, MI
Those heat exchangers can get an air lock and require coolant. We put quite a bit into a friend's 2015 8.2 magnum in his new Rinker 290 - after the dealer had PDI'd it. We put in about a half gallon. The Mercruiser coolant is pre mixed. It burped some more air then we put in another quarter gallon. It ran all last summer without dropping at all.
If that doesn't do it there may be a pin hole leak in the tubing in the heat exchanger. You pretty much have to pressure test for that as a leak will get mixed with the cooling water and get shot out.
Fingers crossed that it is just some air that got in. How could that happen, you ask? Well, my friend, with a bit of a red face, finally admitted he had opened the reservoir up (cap off) when it was still too hot and a bunch came out. The bugger could have saved his buddies (me included) some serious crawling around time in his bilge if he had fessed-up to that sooner.
Where are checking for coolant? If you are simply pulling the end off the heat exchanger you won't see any coolant, the coolant runs through the jackets of exchanger I think, only thing you can actually see in there is water. Of course, I am describing my own, I suppose they could be different.
Make sure the overflow is full to the line, run engine till the air burps out, refill and go.
NAVYCTRC - I was looking down in to the exchanger. I removed the cap on top. The port engine had orange coolant to the top but the stbd had no liquid that I could see.
Do these engines just occasionally need a quart or two? With the low hours I cant think there is a major issue?
Checking your oil is a simple test too for water/coolant.
PC BYC, Holland, MI
Yes, your engine should be fine from what you and others have said have said.
So that likely leaves same air in your system requiring a fill-up of coolant.
Or, I failed to mention that a loose hose connection can let a lot of coolant out under pressure and I have seen that happen so check your hose clamps.
There could be a pin hole leak in a hose but you should see some evidence of coolant in the bilge - you might have to look under the engine.
I assume you have checked the removable ends (caps) of your heat exchangers to make sure they are on tight and don't leak.
After that, as BD suggested, its going to be a pressure test of your cooling system which is easy to do with a tester that screws onto your reservoir cap to check leak down.....fingers crossed.