I have 600 hours on my 2015 R-25SC equipped with the Volvo D3 150i-G engine, the coolant temp was increasing while operating at higher RPM settings so I flushed/descaled the heat exchangers. I developed the following Volvo D3 flush procedure by modifying the Yanmar procedure developed by Mike Rizzo / Knotflying (thanks Mike).
Ranger Tug Heat Exchanger Cleaning Procedure For Volvo D3
This procedure uses the Ranger Tug raw water washdown pump to circulate Rydlyme through the raw water cooling system to remove scale/deposits from the reverse gear (i.e. transmission) and engine’s 3 heat exchangers. The procedure is not as difficult to perform as it may appear.
Volvo D3 Raw Water Cooling System Flow Path
This is the path that seawater takes through the Volvo D3 raw water cooling system, understanding the flow path will help you understand the flush procedure:
1) Raw water inlet (mounted on hull).
2) Seacock
3) Strainer
4) nlet hose wraps around front of engine and attaches to the reverse gear heat exchanger
5) Raw water pump
6) Turbocharger intercooler heat exchanger (starboard side of engine)
7) Engine coolant heat exchanger (port side of engine)
8) Tee fitting (¼ inch hose diverts some raw water to the stuffing box/prop shaft bearing)
9) Exhaust mixing elbow
10) Muffler
11) Exhaust/Coolant outlet
Material List (hose sizes are inside diameter)
6 feet ¾ inch hose
1 foot 1¼ inch hose
5 feet 1½ inch hose
5 gallon bucket
Containers to hold used Rydlyme & Water mixture
Tums (to test Rydlyme)
1 to 2 gallons Rydlyme
1 inch male pipe thread to ½ inch female pipe thread nylon reducer bushing
¾ inch barb with ½ inch male pipe thread nylon fitting
6 Hose clamps (3 for ¾ inch hose, 2 for 1¼ inch hose, 1 for 1½ inch hose)
Procedure
1) Close raw water seacock.
2) Remove the raw water pump impeller.
3) Replace impeller cover (without installing impeller).
4) Remove 1¼ inch raw water hose from inlet (port side) of reverse gear heat exchanger.
5) Inspect reverse gear heat exchanger inlet for debris (e.g. seaweed).
6) Disconnect the ¼ inch hose from the tee that supplies raw water to the stuffing box, either plug the end of this hose or
keep it above the water line.
7) Remove 1½ inch outlet hose from engine coolant heat exchanger (this is the hose that goes to the exhaust mixing
elbow).
9) Remove ¾ inch raw water washdown inlet and outlet hoses from the pump’s nipple fittings.
10) Place 5 gallon bucket behind the engine on the step pad.
11) Install 3 feet of ¾ inch to inlet of raw water washdown pump and insert other end into bucket.
12) Assemble barb fitting to reducer bushing.
13) Install 3 feet of ¾ inch hose to outlet of raw water washdown pump, install reducer bushing/nipple assembly to the
other end of this hose.
14) Install 1¼ inch hose to inlet of reverse gear heat exchanger, install the other end to the reducer bushing/nipple
assembly.
15) Install 1½ inch hose to the outlet of the engine coolant heat exchanger and place other end into the 5 gallon bucket.
16) Fill 5 gallon bucket with fresh water (not sea water)
17) Turn on washdown pump to flush sea water from the raw water cooling system
18) Repeat this step a few times to insure that the raw water cooling system is filled with clean fresh water.
19) Empty fresh water from bucket and add a gallon of Rydlyme, since the cooling system now has about a gallon of fresh
water in it you will end up with a 50/50 mixture of Rydlyme/water.
20) Circulate the Rydlyme/water mixture for a few hours.
21) If the Rydlyme/water mixture stops foaming take a small sample of the mixture and add a Tums tablet to the mixture,
if the sample does not foam your Rydlyme is depleated and you need to add more Rydlyme to the bucket.
22) When complete, flush the system with a few buckets of clean water until water exiting into the bucket is clear.
23) Clean the raw water washdown inlet screen.
24) Reconnect all the hoses as originally installed.
25) Replace the raw water pump impeller.
26) Open the seacock.
27) Start the engine and check for leaks.
Note: The Volvo D3 does not have internal engine zinks, if it did they would need to be removed because Rydlyme dissolves zink and aluminum.
Glen Wagner
Journey - R-25 SC powered by the 150 hp Volvo D3
Ranger Tug Heat Exchanger Cleaning Procedure For Volvo D3
This procedure uses the Ranger Tug raw water washdown pump to circulate Rydlyme through the raw water cooling system to remove scale/deposits from the reverse gear (i.e. transmission) and engine’s 3 heat exchangers. The procedure is not as difficult to perform as it may appear.
Volvo D3 Raw Water Cooling System Flow Path
This is the path that seawater takes through the Volvo D3 raw water cooling system, understanding the flow path will help you understand the flush procedure:
1) Raw water inlet (mounted on hull).
2) Seacock
3) Strainer
4) nlet hose wraps around front of engine and attaches to the reverse gear heat exchanger
5) Raw water pump
6) Turbocharger intercooler heat exchanger (starboard side of engine)
7) Engine coolant heat exchanger (port side of engine)
8) Tee fitting (¼ inch hose diverts some raw water to the stuffing box/prop shaft bearing)
9) Exhaust mixing elbow
10) Muffler
11) Exhaust/Coolant outlet
Material List (hose sizes are inside diameter)
6 feet ¾ inch hose
1 foot 1¼ inch hose
5 feet 1½ inch hose
5 gallon bucket
Containers to hold used Rydlyme & Water mixture
Tums (to test Rydlyme)
1 to 2 gallons Rydlyme
1 inch male pipe thread to ½ inch female pipe thread nylon reducer bushing
¾ inch barb with ½ inch male pipe thread nylon fitting
6 Hose clamps (3 for ¾ inch hose, 2 for 1¼ inch hose, 1 for 1½ inch hose)
Procedure
1) Close raw water seacock.
2) Remove the raw water pump impeller.
3) Replace impeller cover (without installing impeller).
4) Remove 1¼ inch raw water hose from inlet (port side) of reverse gear heat exchanger.
5) Inspect reverse gear heat exchanger inlet for debris (e.g. seaweed).
6) Disconnect the ¼ inch hose from the tee that supplies raw water to the stuffing box, either plug the end of this hose or
keep it above the water line.
7) Remove 1½ inch outlet hose from engine coolant heat exchanger (this is the hose that goes to the exhaust mixing
elbow).
9) Remove ¾ inch raw water washdown inlet and outlet hoses from the pump’s nipple fittings.
10) Place 5 gallon bucket behind the engine on the step pad.
11) Install 3 feet of ¾ inch to inlet of raw water washdown pump and insert other end into bucket.
12) Assemble barb fitting to reducer bushing.
13) Install 3 feet of ¾ inch hose to outlet of raw water washdown pump, install reducer bushing/nipple assembly to the
other end of this hose.
14) Install 1¼ inch hose to inlet of reverse gear heat exchanger, install the other end to the reducer bushing/nipple
assembly.
15) Install 1½ inch hose to the outlet of the engine coolant heat exchanger and place other end into the 5 gallon bucket.
16) Fill 5 gallon bucket with fresh water (not sea water)
17) Turn on washdown pump to flush sea water from the raw water cooling system
18) Repeat this step a few times to insure that the raw water cooling system is filled with clean fresh water.
19) Empty fresh water from bucket and add a gallon of Rydlyme, since the cooling system now has about a gallon of fresh
water in it you will end up with a 50/50 mixture of Rydlyme/water.
20) Circulate the Rydlyme/water mixture for a few hours.
21) If the Rydlyme/water mixture stops foaming take a small sample of the mixture and add a Tums tablet to the mixture,
if the sample does not foam your Rydlyme is depleated and you need to add more Rydlyme to the bucket.
22) When complete, flush the system with a few buckets of clean water until water exiting into the bucket is clear.
23) Clean the raw water washdown inlet screen.
24) Reconnect all the hoses as originally installed.
25) Replace the raw water pump impeller.
26) Open the seacock.
27) Start the engine and check for leaks.
Note: The Volvo D3 does not have internal engine zinks, if it did they would need to be removed because Rydlyme dissolves zink and aluminum.
Glen Wagner
Journey - R-25 SC powered by the 150 hp Volvo D3