rothfm
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- Joined
- Sep 26, 2006
- Messages
- 914
I’m an outboard guy (on the Iboats OMC forum) trying to help someone with a new-to-him boat. Although I’m a good outboard mech, not entirely savvy on these inboards yet, but getting there. Been reading posts all day-still looking for advice
I’ll write boat/engine spec’s below, and below that my IR temp readings and observations. Also attached is a copy of the water flow-diagram with some of my notes written on it.
Here goes:
Engine in question runs fine at idle and slow speeds, guage showing same as good motor at 160-170. We then do test runs at 3k rpm, and Stbd side slowely rises to around 190 after a good 5 min run. Slow down and it drops back to 160-170. No alarms.
Observations:
My thoughts:
Questions
Sorry this is so long, I want to be clear and provide concise information. Thanks In advance to those that have input.
I’ll write boat/engine spec’s below, and below that my IR temp readings and observations. Also attached is a copy of the water flow-diagram with some of my notes written on it.
Here goes:
- 1995 Searay Weekender 300 (30’
- Dual 1995 5.7L Bluewater MC inboards, full FWC and V-drives
- We have Maint records from 2007 from Past Owner, always serviced at same marine-very well maintained.
- Risers and mani’s done just about 5yrs ago. We are planning on doing them soon as they are due.
- Raw water impeller done 2013
- Unknown replacement date on the Circulation pump impeller.
Engine in question runs fine at idle and slow speeds, guage showing same as good motor at 160-170. We then do test runs at 3k rpm, and Stbd side slowely rises to around 190 after a good 5 min run. Slow down and it drops back to 160-170. No alarms.
Observations:
- Plenty of comparative(with good engine) water flow out the exhausts at all speeds.
- All IR gun temp readings match good side at idle and slow speeds.
- Only detectable are of difference is directly on the t-stat housing. Bad side at 3krpm shows 180-194. Good motor solid at 159-166. All other hoses, risers, manifolds, heat exchanger ends-all compare to the good engine.
- Strainers are clear.
- All fluids fresh and topped.
- No visible signs(Leaks, air in coolant etc….
My thoughts:
- Even though I don’t see it, possibly the exchanger output to Circ Pump is warmer than it should be, elevating the temps throught the process (again, I don’t see any marked difference to good engine). Exchanger efficiency issue?
- Possibly T-stat not opening fully restricting flow and increasing temp(provided input to Recirc pump at norm temp).
- Recirc pump impeller causing a lack of volume(again, not seeing much difference in all other areas).
Questions
- Riser input temps from the exchanger is cool(same on both engines) and risers are cool, hardly warm at all—is this normal?
- If my temps are elevated, wouldn’t I see that on the manifolds…all 4 are the same temp at all speeds.
Sorry this is so long, I want to be clear and provide concise information. Thanks In advance to those that have input.
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