Adventure2660
Recruit
- Joined
- Jun 20, 2017
- Messages
- 1
Hi,
I have a 26 ft Cruisers Inc. Vee Sport with twin 1989 Merc 3.7LX 4 cylinder engines with Alpha 1 outdrives. The starboard engine has always run at a higher temperature than the port. Last season the starboard was running at 180 degrees and sometimes even up to about 190. The port always runs consistently at 150 degrees. These are temps while cruising at 3200 rpms. This season, the starboard engine is running up at 190 degrees and triggering the overheat alarm, which is when I shut it down and head in on the port engine.
I have tried a few things to diagnose the cause as follows:
1. Checked the exhaust manifold interface to the riser. I replaced the manifold 2 years ago with a used part because the original one had corroded. This looked fine and I reassembled with new gaskets.
2. Replaced the thermostat.
3. Replaced the Temperature sensor and over-temp alarm switch.
4. Inspected the inside of the heat exchanger, which doesn't show any obvious signs of clogging or build up.
5. Swapped the water intake hoses between the port and starboard engines and ran at 3200 rpm. Both engines behaved as I described above. I think this tells me the outdrives are pumping enough water as there was no effect in swapping them between the engines.
6. Compression test all cylinders : 160, 145, 150, 155.
6. Tested the closed coolant system with a pressure pump / gauge on the filler cap of the riser. I tested at 17psi and saw the pressure drop down to 16 psi over about 10 min. I did the same test on the other engine and it behaved about the same. I disconnected the sea water inlet & outlet hoses from the heat exchanged and watched for overflow while pressure testing the closed coolant side and saw no overflow.
Other symptom is that the starboard engine is losing coolant. If I fill the riser to the bottom of the filler neck and run the boat for a few miles there will be a loss of coolant in the riser when I check after it cools down. The coolant level drops by about 3 inches in the riser. One thing here has me confused. The coolant overflow recovery bottle is full of coolant to the very top. After running the boat and letting it cool down, the overflow is still max full while the riser is down by 3 inches. I would expect the coolant to flow back out of the overflow into the riser. Does this tell me something?
Any other suggestions on what to check?
Thanks Allot.
Dave
I have a 26 ft Cruisers Inc. Vee Sport with twin 1989 Merc 3.7LX 4 cylinder engines with Alpha 1 outdrives. The starboard engine has always run at a higher temperature than the port. Last season the starboard was running at 180 degrees and sometimes even up to about 190. The port always runs consistently at 150 degrees. These are temps while cruising at 3200 rpms. This season, the starboard engine is running up at 190 degrees and triggering the overheat alarm, which is when I shut it down and head in on the port engine.
I have tried a few things to diagnose the cause as follows:
1. Checked the exhaust manifold interface to the riser. I replaced the manifold 2 years ago with a used part because the original one had corroded. This looked fine and I reassembled with new gaskets.
2. Replaced the thermostat.
3. Replaced the Temperature sensor and over-temp alarm switch.
4. Inspected the inside of the heat exchanger, which doesn't show any obvious signs of clogging or build up.
5. Swapped the water intake hoses between the port and starboard engines and ran at 3200 rpm. Both engines behaved as I described above. I think this tells me the outdrives are pumping enough water as there was no effect in swapping them between the engines.
6. Compression test all cylinders : 160, 145, 150, 155.
6. Tested the closed coolant system with a pressure pump / gauge on the filler cap of the riser. I tested at 17psi and saw the pressure drop down to 16 psi over about 10 min. I did the same test on the other engine and it behaved about the same. I disconnected the sea water inlet & outlet hoses from the heat exchanged and watched for overflow while pressure testing the closed coolant side and saw no overflow.
Other symptom is that the starboard engine is losing coolant. If I fill the riser to the bottom of the filler neck and run the boat for a few miles there will be a loss of coolant in the riser when I check after it cools down. The coolant level drops by about 3 inches in the riser. One thing here has me confused. The coolant overflow recovery bottle is full of coolant to the very top. After running the boat and letting it cool down, the overflow is still max full while the riser is down by 3 inches. I would expect the coolant to flow back out of the overflow into the riser. Does this tell me something?
Any other suggestions on what to check?
Thanks Allot.
Dave
