Help identify mystery hose on Penta

[senormechanico]

Originally Posted by jamhass

On our 2003t that goes to the hot water heater. Perhaps what you ID as a reservoir is the hot water heater?

Hot water does not need to be heated on my boat as it's already hot.

[Dave22q]

If the boat has fresh hot water, the potable water heater will almost certainly include coils which transfer heat from the engine coolant to the fresh drinking water. That's one hose in and one out from the water heater to the engine coolant supply. A connection from the coolant overflow tank to the water heater seems to make no sense.

[redbeard1]

Deblen – Thanks for the message. You mention there is no oil cooler on the 2003. Any ideas of how the oil is being cooled? Also, in case it helps, my boat does have the anti-siphon loop you spoke of. There is a hose that attaches about a foot after the raw water impeller, goes to my lazarette, does the anti-siphon loop, and returns back to the engine to attach to the heat exchanger.



Dave22q – Thanks. Agree my earlier message was a stretch. Reservoir coolant flow would not work. Trouble is, on my engine, the two holes that typically are used for supplying coolant to the water heater are not being used for that. Looking at the attachment, Part 21 on the circulation pump is closed with a bolt, Part 23 is filled with a temperature sensor for the thermostat. Next time I get to the boat, I’ll check for other possibilities.

[deblen]

Originally Posted by redbeard1

Deblen – Thanks for the message. You mention there is no oil cooler on the 2003. Any ideas of how the oil is being cooled? Also, in case it helps, my boat does have the anti-siphon loop you spoke of. There is a hose that attaches about a foot after the raw water impeller, goes to my lazarette, does the anti-siphon loop, and returns back to the engine to attach to the heat exchanger.



Dave22q – Thanks. Agree my earlier message was a stretch. Reservoir coolant flow would not work. Trouble is, on my engine, the two holes that typically are used for supplying coolant to the water heater are not being used for that. Looking at the attachment, Part 21 on the circulation pump is closed with a bolt, Part 23 is filled with a temperature sensor for the thermostat. Next time I get to the boat, I’ll check for other possibilities.

Good to hear you have the anti siphon.

The lube oil is cooled as it gravity drains back to the base sump. There is no special heat exchanger lube oil cooler on the basic 2003.

/ Len

[DougR]

When Pacific Seacraft installed the VP 2003 model in the Ericsson yachts they built, they located the engine coolant expansion tank in the cockpit locker to provide good access, but also because the house hot water heater was higher than the engine and they needed the expansion tank mounted higher than the engine to avoid air locks.

On the 2003 the normal coolant routing for hot water heaters was to exit the block either thru one of the fittings on the front of the cylinder head, or thru the fitting on the stb. side of the block near the alternator, the one you have shown. The coolant traveled thru the internal coil in the hot water heater and returned to the engine via the suction side fitting on the starboard ( outboard) side of the circulation pump, the fitting which you say is plugged with a bolt.

Normally the hoses/pipes which are attached to the suction side of the circ pump are:
- Coolant makeup hose from the bottom of the coolant expansion tank
- Hard pipe from the cool side of the heat exchanger
- Return hose from the house hot water heater
- Hard pipe from the front side of the cylinder head for engine block circulation before the thermostat opens

It seems to me that in lieu of running a return hose from the hot water heater all the way back to the circ pump, the builder put a T in the expansion tank makeup hose and returned the coolant from the hot water tank to the engine via the makeup water hose. This has obviously worked for many years, and shouldn't be a problem going forward.

DougR

[redbeard1]

DougR – Thank you. Your explanation makes lots of sense and seems to solve lots of loose ends. The large diameter hoses at the bottom of the reservoir always made me wonder. The hose that feeds the reservoir is thin. The hoses at the bottom of reservoir are 5/8 and ¾. If these latter hoses are sized to bring coolant through the heater then it makes sense they would be so large. I’ve updated one of my earlier attachments to reflect comments from you and some of the other posters. If I got any of the flows wrong, please let me know. In the Spring, I may get out to the boat and try to get access to behind the heater. If I do, I’ll update this posting with a confirmation.