Volvo 2002 mystery coolant leak

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G

Gricha

Hi all,

I have a Volvo Penta model 2002, 2 cylinder diesel with the optional fresh water cooling system. I've got a coolant leak that I can't for the life of me locate.

Quick facts: 1991 Beneteau, original engine w/5500 hours, not well maintained or used by PO past 2 years. I acquired the boat in March. The fresh water pump was replaced at that time. Coolant hoses were repalced about a week ago. Engine cools from both raw water and fresh water (closed circit).

I've replaced most all coolant hoses (the two coming from the overflow tank), the two from the air vent above the engine, the small one between the overflow tank and engine); I've replaced my raw water hoses, too (b/c they were suspect, but not leaking). The only remaining hoses (that I see) are two that go from the engine (just behind the water pump) to somewheres forward in the bilge.

The metal water pipes (behind the water pump) appeared to be dry on the outside (e.g. no leaks).

I ran my engine at idle for about an hour this morning before taking the boat out. Everything came up to temp/pressure as expected. I had a tiny drop (e.g. the size of a dime) of coolant in the bilge pan below the engine, directly below the water pump. When I put the boat in gear, ran the engine up to 2200 rpm to leave the marina, the high-temp alarm went off about 2 minutes later. Sure enough, all the coolant was in the bildge pan.

I ran my hand all over the collant hose and pipe connections, but nothing was wet. I felt all aroudn the water pump, only the slightest drop on the underside. I have no idea where this leak is coming from.

Before I get back to the boat next weekend and refill the system and run it up to speed while I observe it to see where the leak might be coming from; I thought I'd ask the collective expertise on the forum of other places to look, or possible other causes. Could there be a hose or pipe I'm missing? Does this engine have drain cocks for the coolant? If so, where are they?

Thanks in advance!
Gregg
 
Nov 28, 2004
209
Hunter 310 San Pedro
Mystery Coolant Leak

Greg, Based on your description I have an idea of where the problem might be. The best method to diagnose the problem is to pressure test your fresh water circuit. Not sure about Maryland , but here in Calif. several auto parts stores will loan/rent tools. If you have tester or have access to one pump the system to 15-18 lbs of pressure and you will see the leak. Most likely suspect is the fresh water pump. Perhaps a faulty pump, but since it was just replaced it may be the gasket.
By the way, the two hoses that go forward into the bilge are connected to your hot water heater.
 
Nov 6, 2006
10,215
Hunter 34 Mandeville Louisiana
Mystery Leak

Pressure testing, as Dennis suggests, is a great way to leak check without the noise and safety problem of working close to a running engine. The water heater hoses and their clamps would be something you’d want to inspect closely. Is the heater situated above the pan such that a heater hose leak would run into the pan?
 
Jun 4, 2004
17
- - Miami, Fl
Check hoses to...

Water Heater. When I was crossing the Gulf Of Mexico, my Water Heater came lose and chafed the hose as it enters the heater. Coolant was leaking out and causing over heating.
Good Luck,
MArc
 
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