Vincentc
Legendary Member
- Joined
- Jun 3, 2008
- Messages
- 1,514
- Status
- OWNER - I own a Hatteras Yacht
- Hatteras Model
- 43' DOUBLE CABIN (1970 - 1984)
Lilly Marie developed an overheat issue a few weeks ago. The starboard engine usually goes no higher than 165 degrees however it got up to 185.
I assumed the impeller needed replacement; but when I pulled it, there was no apparent damage. Since its been probably 6 years since I flushed the raw water system I suppose the problem was with the heat exchanger.
After consulting the web site for a reminder of how to do it, I purchased Phos-foe and gathered up components from the garage.
After some study the small heat exchanger at the rear of engine near the sea water intake looked like a good start end point and the hose connection near the heat exchanger at the front of the engine, which leads to the exhaust discharge looked like the other start/stop point.
I gathered up the following:
5 gallon bucket
2 gallos phos-foe.
1 brass 3/4' nipple which fits into the rear pencil zinc opening for the small heat exchanger
10 feet 3/4" clear vinyl tube
A combination of fittings to reduce the 1 1/2" ID hose connecting to the raw water discharge
to the exhaust down to a 3/4".
A 500 gph Rule 12v pump.
hose clamps
plastic nipple to fit over the discharge to the dripless stuffing box.
Go through the RW system, remove the pencil zinc plugs, check for remaining zincs (none) and clear the openings from residual zinc material. replace brass zinc plugs.
Remove the Heat Exchanger endplates and note the residue including several stopped passages.
Removed the raw water pump impeller and replaced the cover plate.
cover the discharge fitting to the dripless stuffing box and clamp.
close the thru-hull for the seawater intake
Insert the reducer assembly into the discharge hose and connect a garden hose, then flush the RW system with fresh water.
Cut the vinyl tubing into 5' lengths, attach one tube to the pump discharge and to the nipple screwed into the small heat exchanger.
Insert the reducer assembly into the discharge hose, connect a garden hose and flush system with fresh water and observe stuff coming out of rear HE plug.
Mix 2 gallons phos-foe with 2 gallons water, attach pump to tube leading to exhaust water hose and run tube from nipple on rear HE to bucket.
Connect pump wires to battery, and watch water flow through tube into RW system and out back into bucket.
After about 20 minutes reverse tubing so that acid solution runs through system in the opposite direction.
Reverse direction again after 20 minutes and allow it to be pumped through again.
The acid solution foamed impressively and turned from green to almost black.
When I disconnected the tubing I discovered a few oak leaves sticking out of the rear HE outlet. No idea where they came from.
Brought home the acid solution and poured it out on the gravel driveway. Found a fair amount of debris and sand like sediment.
Once I get the new impeller installed, I hope to report that this took care of the overheat.
I intend to post photos, not only for your review but as a means to refresh my memory for the next time.
I assumed the impeller needed replacement; but when I pulled it, there was no apparent damage. Since its been probably 6 years since I flushed the raw water system I suppose the problem was with the heat exchanger.
After consulting the web site for a reminder of how to do it, I purchased Phos-foe and gathered up components from the garage.
After some study the small heat exchanger at the rear of engine near the sea water intake looked like a good start end point and the hose connection near the heat exchanger at the front of the engine, which leads to the exhaust discharge looked like the other start/stop point.
I gathered up the following:
5 gallon bucket
2 gallos phos-foe.
1 brass 3/4' nipple which fits into the rear pencil zinc opening for the small heat exchanger
10 feet 3/4" clear vinyl tube
A combination of fittings to reduce the 1 1/2" ID hose connecting to the raw water discharge
to the exhaust down to a 3/4".
A 500 gph Rule 12v pump.
hose clamps
plastic nipple to fit over the discharge to the dripless stuffing box.
Go through the RW system, remove the pencil zinc plugs, check for remaining zincs (none) and clear the openings from residual zinc material. replace brass zinc plugs.
Remove the Heat Exchanger endplates and note the residue including several stopped passages.
Removed the raw water pump impeller and replaced the cover plate.
cover the discharge fitting to the dripless stuffing box and clamp.
close the thru-hull for the seawater intake
Insert the reducer assembly into the discharge hose and connect a garden hose, then flush the RW system with fresh water.
Cut the vinyl tubing into 5' lengths, attach one tube to the pump discharge and to the nipple screwed into the small heat exchanger.
Insert the reducer assembly into the discharge hose, connect a garden hose and flush system with fresh water and observe stuff coming out of rear HE plug.
Mix 2 gallons phos-foe with 2 gallons water, attach pump to tube leading to exhaust water hose and run tube from nipple on rear HE to bucket.
Connect pump wires to battery, and watch water flow through tube into RW system and out back into bucket.
After about 20 minutes reverse tubing so that acid solution runs through system in the opposite direction.
Reverse direction again after 20 minutes and allow it to be pumped through again.
The acid solution foamed impressively and turned from green to almost black.
When I disconnected the tubing I discovered a few oak leaves sticking out of the rear HE outlet. No idea where they came from.
Brought home the acid solution and poured it out on the gravel driveway. Found a fair amount of debris and sand like sediment.
Once I get the new impeller installed, I hope to report that this took care of the overheat.
I intend to post photos, not only for your review but as a means to refresh my memory for the next time.
