Volvo TAMD71B Overheating at High Revs

[Aquafennatic]

I´m having issues with my Starboard engine which I need help with. It overheats under load at about 2000RPMs and will quickly cool down when I reduce RPMs. It appears to be getting worse over the last couple of seasons. I´ve replaced the Seawater pump, cleaned the Seawater side of the Heat Exchangers and After Coolers. Cleaned the Reverse Gear Oil Cooler. Checked the Sea water path including the Thru Hull valve, Sea Strainer, Exhaust Elbow and all engine pipes for blockage. The antifreeze is new on the freshwater side and I´ve replaced the Thermostat, however I haven´t looked at the circulation pump or cleaned the freshwater side of the Heat Exchangers. Below you´ll see a chart of the temperature in degrees Fahrenheit. This test was conducted at the dock. I´ve noticed that the difference in the temperature of the antifreeze before & after the heat exchangers on the starboard side is only 20 degrees at high revs thus I´m suspecting it´s a sea water flow issue at high revs. The temperature of the Starboard engine that are indicated below is higher when the vessel is under load. (The gauge reads 200 degrees at 2000RPMs under load). Can anyone recommend next steps based on what you see below ...

1500 RPM 2200 RPM
Measurement points Port Star Port Star

Before Seawater Pump 73 73 73 73
Before Heat Exch 1 76 79 74 80
Heat Exch 1 Cap 79 79
After Heat Exch 1 81 82 83 113
Heat Exchanger 2 Cap 79 107
After Heat Exchanger 2 85 88 85 132
After Cooler 1 Cap 79 118
After After Cooler 1
After Cooler 2 Cap 79 117
After After Cooler 2 78 86 128
After Oil Cooler 80 88 127
Exhaust Elbow 83 85 86


Into Heat Exchanger 158 173 152 176
Into Circulation pump 101 113 105 156
Thermostat Housing 167 178 165 179

Please let me know if you'd like me to send you a more readable version of this table.

 

[volvopaul]

Have you checked the exhaust Elbow, they corrode inside and at the outlet , take it off look at the exit they corrode and block the outlet flow . Your results seem to indicate a stall. Simpler way is to sea trial and place your hand on the pipe from the sea water pump to first cooler , it should be cold if it's flowing well, a blocked part will warm the water as it dissipates the year inside the heat exchanger.

 

[Aquafennatic]

Have you checked the exhaust Elbow, they corrode inside and at the outlet , take it off look at the exit they corrode and block the outlet flow . Your results seem to indicate a stall. Simpler way is to sea trial and place your hand on the pipe from the sea water pump to first cooler , it should be cold if it's flowing well, a blocked part will warm the water as it dissipates the year inside the heat exchanger.

I've tried to insert a remote camera into the Exhaust elbow and it seemed to be OK although it was difficult to maneuver the camera thus perhaps I missed the issue. I'll remove the Exhaust Elbow to see if that exposes the issue.

Thanks

Mike

 

[Aquafennatic]

VolvoPaul was right ... The exhaust elbow is clogged. I'm looking at replacing the elbow, however the Volvo part # 864950 has been discontinued. It appears that Volvo part # 3830988 is available however I'm not sure what the difference is between the 2 parts. Does anyone know? Is there any way to clean the existing part?

Thanks,

Mike

 

[volvopaul]

Yes you get a flange that bolts to the turbo a clamp and an elbow , better idea as you can set it to any angle . Well done , you can clean it between the metal gap to improve flow .

 

[Aquafennatic]

Yes you get a flange that bolts to the turbo a clamp and an elbow , better idea as you can set it to any angle . Well done , you can clean it between the metal gap to improve flow .

VolvoPaul - It was easy to clean the carbon off the stainless steel within my exhaust elbow and it's in good condition thus I don't need to replace the elbow. (Part 864950). I was cleaning the flange and what looked like a gasket broke off the end of the flange. I put everything together and when I started the engine I get a lot of exhaust leaking from between the elbow & the flange. Is there a gasket between the exhaust elbow & the flange? If not I'm assuming I'll need to replace the flange. Does this make sense?

Thanks,

Mike