Closed Cooling System on Port Engine Running Hot(ter)

[tpenfield]

I would think that 15% less flow should still allow the thermostat to make up the difference....... .........you could have some debris or sand in the water jacket around the cylinders. Mine had *some* after only 122 hrs....

Rust can mix with sand and/or other debris. This is where FORD VC-9 or Cummins Filtration "Restore Plus" might loosen and remove that stuff if it's present, then you can flush it out.

Another thing to note, based on my earlier testing of the thermostats is that they are wide open at 170. So, I can assume that the port engine thermostat runs wide open all the time whereas the starboard thermostat does the open and closing thing based on the engine load, etc.

Still not sure if the 15% difference in flow would account for the symptoms that I have been seeing, but we probably have only 1 more outing with the boat this season. Then I'll have time to go through the cooling system in October.

 

[alldodge]

Not a fluid or thermodynamics guy, but slower water flow would allow more heat to transfer and reason for higher temp increase coming out.

 

[tpenfield]

Yes, I'm not sure how to evaluate a slower flow of sea water. I would think that the whole system would run hotter. My IR temp testing showed 5 degrees hotter, but the closed cooling side is running 15 degrees hotter.

I ran at about 2600-2800 rpm on the way back from the vineyard. The starboard engine ran 163 ish and the port ran 170 ish. Once I get up in the 3K rpm range the engines run at the same temp per the gauges.

 

[achris]

How hard would it be to swap the HEs?

 

[tpenfield]

How hard would it be to swap the HEs?

Not too hard, probably a 2 hour job. What are your thoughts in doing that?

 

[achris]

Just isolated and eliminating.

 

[tpenfield]

Just isolated and eliminating.

I did the flushing and de-scaling of the port H E. I have not done the same on the starboard H E, but could also do that as part of the swap.

 

[nola mike]

Why not test the flow progressively closer to the drive to see where the bottleneck is? Doing that before and after the HE would be easier than swapping.

 

[tpenfield]

Why not test the flow progressively closer to the drive to see where the bottleneck is? Doing that before and after the HE would be easier than swapping.

I could do a similar test, but take the sea water from right before the H E, instead of right after. That might tell something about the H E's and if there is a restriction or if the difference in flow rate is consistent even before the H E's.

 

[nola mike]

I could do a similar test, but take the sea water from right before the H E, instead of right after. That might tell something about the H E's and if there is a restriction or if the difference in flow rate is consistent even before the H E's.

Right. And you can keep going backwards from there until you find the restriction.

 

[tpenfield]

Right. And you can keep going backwards from there until you find the restriction.

In total, there are 3 places where I could get a decent test of the flow.

1) After the H. E., which I did
2) Right before the H. E., which is next on the list
3) Right after the sea water pump and before the 2 coolers.

Those are the 3 'easy' places to get a good flow test, as I can connect a hose to those points in the cooling system pretty easily and use my timed 5 gallon bucket method.

So, those additional tests might be on the check list for my next outing, which will be a couple of weeks out.

 

[tpenfield]

Not a fluid or thermodynamics guy, but slower water flow would allow more heat to transfer and reason for higher temp increase coming out.

My thermodymamics books are safely stored in the attic, so that will not be a bother to me

But speaking of thermo . . . now that I have some water flow data, and using the temp readings that I took previously, I can calculate the BTU rate coming out of each engine. 1 BTU = 1 lb of water raised 1 degree F

So, if I do the math and assuming salt water, I get

Stbd Engine: 9.1 gal/min, 8.54 lb/gal, (93-69)F temp increase overall from all coolers . . . (93-78)F from main heat heat exchanger

Port Engine: 7.5 gal/min, 8.54 lb/gal, (97-69)F temp increase overall from all coolers . . . (97-78)F from main heat exchanger

So . . .

Stbd: 1,865 BTU/min overall, 1,165 BTU/min from the H. E.

Port: 1,793 BTU/min overall, 1,216 BTU/min from the H. E.


So, these numbers are not all that far apart. The port HE is actually taking a bit more heat out of the coolant that the stbd HE.

 

[Fun Times]

Both engines idle around 625 rpm +/-

The starboard engine has 20% greater raw water flow through the open side of the cooling system based on this test, which exceeds the difference in rpm between the 2 engines. The starboard engine was tending to idle in the 640 rpm range and the port engine idles in the 620 rpm range when I did my Diacom testing.

Being stock MPI engines, the idle should be 600 RPM with a slight fluctuation using the Diacom. Your starboard engine is your issue here, not your port. Install a new thermostat that matches your drilled out portside thermostat and all should become more evened out....Even if they don't even out 100% exactly, you still have an issue on the starboard side.

Also be sure both engines TPS's are closing completely and are very close in range % & voltage wise.

 

[tpenfield]

Thanks Fun Times I will have the off season to get things sorted out. I agree the starboard engine is too cold at idle and not settling into the specified idle speed.

 

[HT32BSX115]

My thermodymamics books are safely stored in the attic, so that will not be a bother to me

But speaking of thermo . . . now that I have some water flow data, and using the temp readings that I took previously, I can calculate the BTU rate coming out of each engine. 1 BTU = 1 lb of water raised 1 degree F

Just thinking about opening my old Engineering Thermodynamics textbook gives me an anxiety attack!!

 

[achris]

I'm still concerned as to why you aren't getting sensor readouts from the Port engine. You've swapped the ECUs and the 'fault' stays with the port engine. Suggests a problem in the wiring somewhere. :noidea:

 

[tpenfield]

I'm still concerned as to why you aren't getting sensor readouts from the Port engine. You've swapped the ECUs and the 'fault' stays with the port engine. Suggests a problem in the wiring somewhere. :noidea:

I am getting data from the MEFI as you recall. The master/slave relationship was the thing that stayed with the starboard engine. Supposedly, there is a connector that needs to be pulled on either engine to make them operate independently from a controller perspective. I have not done that yet, but could do that in the off-season.

 

[achris]

. Supposedly, there is a connector that needs to be pulled on either engine to make them operate independently from a controller perspective. I have not done that yet, but could do that in the off-season.

Sorry, I thought you already did that... My mistake.

 

[tpenfield]

Update:

The boat is coming out of the water for the season on Tuesday, so I will continue my diagnostic/repair work on the hard. The Admiral and I took the boat over to the marina one harbor north of us to do and end-of-season pump out. Always want to make sure that gets done

I can always tell when the boat is ready to come out of the water and get prepped for winter . . . stuff starts breaking. This year it is the bilge pump. Lots of rain the past couple of days and when we got out to the boat, the bilge high water alarm was sounding. The bilge pump is not working so I had to pump the bilge out manually I was worried that the alarm had run down the battery, no telling how long it had been going off. Fortunately, the engines started. :thumb:

No rain in the forecast between now and Tuesday . . . I'll just add a new bilge pump to 'the list' . . .

 

[alldodge]

. I'll just add a new bilge pump to 'the list' . . .

Maybe two seems they never last long