Closed Cooling System on Port Engine Running Hot(ter)

tpenfield

tpenfield

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In the time being . . . Here are a few more pictures that I have yet to post.

Temperature gauges at the helm when the engines are idling and brought up to temperature.

IMG_7984.jpg IMG_7985.jpg

Here is one of the MEFI units (ECU) when I swapped them
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The check sum label which is used to verify the program within the ECU.
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IAC Valve . . .
IMG_7976.jpg

Fuel Pressure Regulator . . .
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Schrader Valve on fuel rail . . . the location of this valve makes it nearly impossible to check the fuel pressure while the engine is running . . . so I have done the 'static' testing with the fuel pressure gauge.
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Under side of fuel rail where the regulator goes. This design was abandoned after a year or two in favor of a design where the regulator was located off the rail in a more accessible location.
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It would be rather interesting if, after all of this fuss, it turned out to be the recirculating pump :facepalm:
 
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HT32BSX115

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tpenfield said:
In the time being . . . Here are a few more pictures that I have yet to post.

Temperature gauges at the helm when the engines are idling and brought up to temperature.

fetch
fetch


It would be rather interesting if, after all of this fuss, it turned out to be the recirculating pump :facepalm:
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Ted,
I really hate to say this after all the work you've done, but...........(assuming you've completely ruled out gage errors)

This more and more makes me VERY suspect of either the raw water side of the Heat Exchanger, AND/OR the coolant side of the engine running hot because IMHO, timing and/or fuel delivery simply couldn't produce enough heat at IDLE for it to overcome the T-stat or heat exchanger capability......
 
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tpenfield

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A little tidbit I just want to pass along . . .

I have the boat out for its first cruise after all the regulator changes that I did. Pretty much the same as before the port engine stays at about 170, and the starboard engine runs about 165 maybe a little higher 167. So at Cruz speech which is about 2800 RPM the engines are really not that far apart in terms of their temperature.

The real differences are the starboard engine stays around 150 at idle speed and then slowly clients to 165 when you go to cruising speed probably takes about three or four minutes to get to 165 . Where is the port engine is already at 165 after idling and immediately crimes to 170 but stays there.

Not sure if it is that significant but I thought I'd pass i the observation along in case anybody can try some insight from that
 
achris

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Can I suggest swapping guages and senders? Or had that already been done.
 
alldodge

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The real differences are the starboard engine stays around 150 at idle speed and then slowly clients to 165 when you go to cruising speed probably takes about three or four minutes to get to 165 . Where is the port engine is already at 165 after idling and immediately crimes to 170 but stays there.
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Ya know just this statement makes me think two things. First would be the pump housing or air leak on the port, may be an issue, and other is its not that big a deal with only 5 degrees difference on plane
 
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AllDodge said:
Ya know just this statement makes me think two things. First would be the pump housing or air leak on the port, may be an issue, and other is its not that big a deal with only 5 degrees difference on plane
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Idle coolant or raw water flow is possibly less than optimum compared to cruise RPM......
 
tpenfield

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Yes, gauges were swapped early on. I could do the senders, but that is s bit a bit tricky with the closed cooling.

So, at cruise speed ( 2500-3000 rpm ) there is only a 5 degrees. At idle speeds there is about 25-20 degrees difference
 
achris

achris

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tpenfield said:
...So, at cruise speed ( 2500-3000 rpm ) there is only a 5 degrees. At idle speeds there is about 25-20 degrees difference
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Engine circulation pump impeller looking a lot more suspect. IMHO.
 
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HT32BSX115

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tpenfield said:
Yes, gauges were swapped early on. I could do the senders,
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The above swap proved that the gages are not faulty, but didn't say anything about the senders. Senders are just simple thermistors potted in a brass "can"......... They usually shouldn't ever go bad.

Here's a great discussion on their operation. One thing you can do is measure the cold resistance of both "senders" when the both engines are completely cold. Assuming both engines are at the same "resting" cold soaked temp, both senders should read the same (or nearly the same) resistance when read with a good digital meter.

Connect to the center connection of the sender and shine up the hex bolt part with some emery cloth and connect the ground there when reading the resistance. The resistance will be highest when the temp is low.
 
achris

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For me, one big indicator is that Ted says the engine take so much longer to cool off after a run. A bad sender wouldn't effect that. That would tell me it's a flowrate issue. Either not getting enough raw water through the HE, or the volume of circulation of the fresh water side.

Chris....
 
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HT32BSX115

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achris said:
For me, one big indicator is that Ted says the engine take so much longer to cool off after a run. A bad sender wouldn't effect that. That would tell me it's a flowrate issue. Either not getting enough raw water through the HE, or the volume of circulation of the fresh water side.

Chris....
Click to expand...

Yeah, I was thinking the same thing before. It still wouldn't be a bad idea to get a baseline on those senders. I have never had one fail however......It always seemed to be a poor electrical connection.

I also think it's thermodynamics instead of electronics all along.......but I digress!(alot!)..........
 
tpenfield

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Just checking my recent posts, which I dictated on my phone. A few dictation and auto-correct errors, so my apologies if they read a bit rough.

Anyway, temperature difference is about 5 degrees at cruising speed, but 15-20 degrees at idle speeds. I would not be surprised if the recirc. pump were at fault. . . Might also be a combination of lean mixture and low flow on the closed cooling side.

The winds and waves picked up pretty good late afternoon and our way back to home port was going into it at about a 45 degree angle. We could only maintain about 10 mph speed through 6 footers. Lots of water spray, we all got soaked.

Engines were at 1600 rpm. The port engine ran 170 degrees, starboard was about 162 at that speed.
 
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HT32BSX115

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tpenfield said:
Just checking my recent posts, which I dictated on my phone. A few dictation and auto-correct errors, so my apologies if they read a bit rough.

Anyway, temperature difference is about 5 degrees at cruising speed, but 15-20 degrees at idle speeds. I would not be surprised if the recirc. pump were at fault. . . Might also be a combination of lean mixture and low flow on the closed cooling side.

The winds and waves picked up pretty good late afternoon and our way back to home port was going into it at about a 45 degree angle. We could only maintain about 10 mph speed through 6 footers. Lots of water spray, we all got soaked.

Engines were at 1600 rpm. The port engine ran 170 degrees, starboard was about 162 at that speed.
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Looks like you're pulling an "all-nighter"!! Isn't O-dark-30 there now?
 
mr300z87

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With the issues I am having with my stern drive engine I said the same thing. LOL Time to get an outboard
 
tpenfield

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I was going to get an OB boat last time around, but they are a bit more pricey than IO boats. Probably keep my eyes open over the next year or so. :). Grady White or Pursuit would top my list.
 
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