Glastron175SX
Cadet
- Joined
- Jun 6, 2012
- Messages
- 8
I have a 2000 Volvo Penta 3.0L (I'm at work and don't have the serial numbers) that was overheating for the past few months. I just solved the problem last night, and since this forum has been such a huge help to me over the past years I thought I would post my experience so hopefully it can help someone else.
About 2 months ago, engine started to overheat only under a load and above 2500 RPMs. Impeller looked great. Back flushed all hoses and all were clear. Ripped out old, crusty thermostat and replaced with new one. Took it out for a test and it still overheated the exact same way (OK at low RPM, but overheat over 2500RPM or when on plane). Read a few forums and learned that it could be sucking in air from the intake hoses by the outdrive gills when on plane (so leak is under water when not on plane and sucks in only water), or it could be a clogged riser/manifold. I unbolted the riser, thought I had cleaned it out and all looked good, bolted it back on, checked all fittings in outdrive to ensure there was no rust or corrosion on nipples. Took it out for another test. Still overheated.
So, I took off the riser again just to make sure I didn't miss something. And this time, it was very apparent that I had (after looking at schematics of the riser online). The inner jacket (the outside layer within the riser for cool water, I'm guessing) was so clogged with crap, sand and crust that it had looked like it was solid cast iron itself. I grabbed my flat screwdriver and poked around until it punched through and realized that it was clogged to the rim (on both ends, the intake side of the riser as well as the exit side). Overall, it took about an hour or two of a good cleaning, rinsing and re-installing with new gaskets. Took the boat out last night and ran at WOT, the temperature never reached over 160 degrees. Absolutely thrilled to not hear that alarm after a few minutes. Anyway, my lesson learned and I hope you have a much shorter time to resolution than I did on my overheating problem. Happy boating!
About 2 months ago, engine started to overheat only under a load and above 2500 RPMs. Impeller looked great. Back flushed all hoses and all were clear. Ripped out old, crusty thermostat and replaced with new one. Took it out for a test and it still overheated the exact same way (OK at low RPM, but overheat over 2500RPM or when on plane). Read a few forums and learned that it could be sucking in air from the intake hoses by the outdrive gills when on plane (so leak is under water when not on plane and sucks in only water), or it could be a clogged riser/manifold. I unbolted the riser, thought I had cleaned it out and all looked good, bolted it back on, checked all fittings in outdrive to ensure there was no rust or corrosion on nipples. Took it out for another test. Still overheated.
So, I took off the riser again just to make sure I didn't miss something. And this time, it was very apparent that I had (after looking at schematics of the riser online). The inner jacket (the outside layer within the riser for cool water, I'm guessing) was so clogged with crap, sand and crust that it had looked like it was solid cast iron itself. I grabbed my flat screwdriver and poked around until it punched through and realized that it was clogged to the rim (on both ends, the intake side of the riser as well as the exit side). Overall, it took about an hour or two of a good cleaning, rinsing and re-installing with new gaskets. Took the boat out last night and ran at WOT, the temperature never reached over 160 degrees. Absolutely thrilled to not hear that alarm after a few minutes. Anyway, my lesson learned and I hope you have a much shorter time to resolution than I did on my overheating problem. Happy boating!
