fishingdan
Lieutenant Junior Grade
- Joined
- Feb 12, 2005
- Messages
- 1,045
1991 era 4.3lx Mercruiser Alpha One (boat history shows a rebuilt engine installed in 2000 with only about 50 hours since). Boat is a 1991 Cobia Monte Carlo 198ES.
Bought the boat spring 2008. In general, the boat is in great condition and runs well.
I have only had the boat out once this season (fortunate to be busy at work...). In the second half of last season, I noticed the temp gauge was showing that the boat was running warmer than I would have expected.
Prior to the first outing this season, I did normal maintenance including changing the water pump impeller, wear plate, etc. First time changing one on an I/O, but I have always owned merc outboards and have a bunch of experience changing them.
On first outing, I watched the temp gauge and it showed 190-200 during most of the outing. I had some time over the weekend to poke around. I read on iboats about the steering oil coolers and how blockages can occur there if an impeller breaks apart. The impeller that I removed had some splits in it, but didn't appear to have any missing pieces. Just to be sure, I thought I would attempt removing the inbound hose. Once I found the cooler, I quickly realized that there was no way I was going to be able to get to it (under the port engine mount - who's brilliant idea was that?). I figure I'll save this for a time when really know there is a blockage.
I was walking around the marine parts store today and saw a mercruiser t-stat kit. Not knowing the history of the part in the boat, I picked it up and replaced the t-stat tonight. While I was at it, I explored a bit (found those check balls I was reading about) and then moved on to test the boat on the muffs.
Unlike previous running on the muffs, I watched the gauge closely while monitoring the hose temps (now that I know which hose does what) with my hand. I was actually able to determine when the t-stat opened. The gauge climbed up again to 190'ish and I decided to pull out my new infrared thermometer. I took readings all over the place. In general things seemed more normal than the dash gauge was reading.
After about 20 minutes of idling, I found that the tops of the exhaust manifolds were in the 165 (give or take 5) range near where the manifold meets the riser. The risers themselves were cooler (135-140ish if I recall). The base of the temp sensor in the t-stat housing (and the immediate surrounding area) was about 165 while the gauge was reading 190+ at the time.
Are these temps ok? They are certainly not near 200 degrees noted on my dash gauge.
Thanks
Bought the boat spring 2008. In general, the boat is in great condition and runs well.
I have only had the boat out once this season (fortunate to be busy at work...). In the second half of last season, I noticed the temp gauge was showing that the boat was running warmer than I would have expected.
Prior to the first outing this season, I did normal maintenance including changing the water pump impeller, wear plate, etc. First time changing one on an I/O, but I have always owned merc outboards and have a bunch of experience changing them.
On first outing, I watched the temp gauge and it showed 190-200 during most of the outing. I had some time over the weekend to poke around. I read on iboats about the steering oil coolers and how blockages can occur there if an impeller breaks apart. The impeller that I removed had some splits in it, but didn't appear to have any missing pieces. Just to be sure, I thought I would attempt removing the inbound hose. Once I found the cooler, I quickly realized that there was no way I was going to be able to get to it (under the port engine mount - who's brilliant idea was that?). I figure I'll save this for a time when really know there is a blockage.
I was walking around the marine parts store today and saw a mercruiser t-stat kit. Not knowing the history of the part in the boat, I picked it up and replaced the t-stat tonight. While I was at it, I explored a bit (found those check balls I was reading about) and then moved on to test the boat on the muffs.
Unlike previous running on the muffs, I watched the gauge closely while monitoring the hose temps (now that I know which hose does what) with my hand. I was actually able to determine when the t-stat opened. The gauge climbed up again to 190'ish and I decided to pull out my new infrared thermometer. I took readings all over the place. In general things seemed more normal than the dash gauge was reading.
After about 20 minutes of idling, I found that the tops of the exhaust manifolds were in the 165 (give or take 5) range near where the manifold meets the riser. The risers themselves were cooler (135-140ish if I recall). The base of the temp sensor in the t-stat housing (and the immediate surrounding area) was about 165 while the gauge was reading 190+ at the time.
Are these temps ok? They are certainly not near 200 degrees noted on my dash gauge.
Thanks
