osd9
New Member
It's the ECM..... 
Why engines are too sensitive to row water circulation?
- Thread starter Alex F
- Start date
- Oct 6, 2006
- 12,155
- Boat Info
- 1996 450DA
- Engines
- 3116 Caterpillars
There is no mechanical reason the clogged strainer will cause an rpm fluctuation....with one possible exception. I don't know if you have it or not, but some ECM programs have a limp mode where certain out of tolerance indications from sensors will cause the ECM to slow the engine down to a predetermined limp home speed.
But I'm hung up on the original question and your premise that engines are too sensitive to row (raw) water circulation. If your strainer is 25% full of grass it follows that you have a 25% restriction in cooling capacity. What would you expect if you put duck tape over 1/4 th of your radiator's exposed surface on your car? Would you feel that GM, Ford, Lexus, Honda, etc. are too sensitive to blocked radiators?
But I'm hung up on the original question and your premise that engines are too sensitive to row (raw) water circulation. If your strainer is 25% full of grass it follows that you have a 25% restriction in cooling capacity. What would you expect if you put duck tape over 1/4 th of your radiator's exposed surface on your car? Would you feel that GM, Ford, Lexus, Honda, etc. are too sensitive to blocked radiators?
- Feb 4, 2007
- 7,251
- Boat Info
- 1996 450DA, TNT, Caribe dink w/15hp OB.
- Engines
- 3126 427HP TD transmissions
I'm betting that it's just a coincidence. Tide, current, wind...
Alex F
Well-Known Member
- Nov 14, 2006
- 9,166
- Boat Info
- 2005 420DB with AB 11 DLX Tender, Raymarine Electronics (2x12" MFDs) with Vesper AIS
- Engines
- Cummins 450Cs, 9KW Onan Generator, 40HP Yamaha for tender.
Frank,
I only provided information based on my observation from the same events that took place at different time. I was thinking exactly the same that there should be ZERO performance difference and the only possible problem should be higher temp reading. The results are different.
Obsolutelly not. The engine performance is consistent every time I catch the eelgrass. It's the same on both sides, which in the way tells me that it's doing what it was designed to.
Sorry I don't have more detailed number readings at this time (I should have taken them down before posting), but I'll take note and will post them later.
I thought that someone might have the answer to the puzzle, but looks like I'll have to take Dave's advice and call Merc.
I'm surprized that it appears that I'm the only one that has this. Can anyone with similar package share their experience when they catch some eelgrass or sea weeds.
Last edited:
osd9
New Member
Alex:
I do see similar issues when I run over, and 'catch', a patch of eelgrass. I immediately hear the difference in the sound of the exhaust. I do, depending on the amount of eelgrass I catch, see my temps rise a bit and I do also notice a minimal degradation in overall performance of the vessel.
Like I said above, when this happens, I come off plane, reverse a bit and then continue on.
On my previous 330DA and 380DA I installed 'Barnagat Bay Strainers' on my mains. The pic below is during the install on my '98 330DA.
Notice that I cut out the stock strainers under the BBS screen. I did that to minimize the restricitons of waterflow.
I have not installed them on my 410DA.
I do see similar issues when I run over, and 'catch', a patch of eelgrass. I immediately hear the difference in the sound of the exhaust. I do, depending on the amount of eelgrass I catch, see my temps rise a bit and I do also notice a minimal degradation in overall performance of the vessel.
Like I said above, when this happens, I come off plane, reverse a bit and then continue on.
On my previous 330DA and 380DA I installed 'Barnagat Bay Strainers' on my mains. The pic below is during the install on my '98 330DA.
Notice that I cut out the stock strainers under the BBS screen. I did that to minimize the restricitons of waterflow.
I have not installed them on my 410DA.