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Old 31-05-2015, 08:22   #16
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Fuel consumption or efficiency improves as an engine reaches it's optimum operating temperature. The diesel prefers higher temps, as this improves the ring to cylinder wall contact or seal. Better compression, less blow by. The engineered temps of the manufacturer should be adhered to. Achieving this will be trial and error. A partial bypass may be necessary to reach the engineered temps for longevity of the engine. This would allow the thermostat to do it's job of maintaining engine temperatures.
Oh, less I forget, beware water intake obstructions.
Muscles, barnacles, plastic bags, twigs, leaves, etc.
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Old 31-05-2015, 08:31   #17
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Re: She lives!

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The diesel prefers higher temps, as this improves the ring to cylinder wall contact or seal. Better compression, less blow by. The engineered temps of the manufacturer should be adhered to.
The engineered temp of my Volvo is right about where it is now. It had a 140 degree thermostat as it was raw water cooled. Getting much above that is bad in a raw water cooled engine as the salt crystalizes and clogs up the cooling passages.

Since I converted to fresh water cooling I was looking to increase temp for the reasons you stated. My engine already has two bypasses in it, one is a complete engine bypass, the other is a thermostat bypass. The thermostat bypass is flowing enough water to keep the engine at the temps it is now, right about the point the original thermostat would just be on the verge of opening.

To raise temps higher, so that the 170 degree thermostat would do something, I would need to either increase flow through the engine bypass or restrict flow through the thermostat bypass. Unless the engine bypass has an obstruction in it (rust, scale from the system) I am not able to increase flow through that. I might be able to restrict the thermostat bypass in the thermostat housing.

Shawn
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Old 31-05-2015, 10:35   #18
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Re: She lives!

The crystallization of the salt is a concern that would cause me to consider a heat exchanger cooling system. A thermostat that doesn't open has no purpose. Shortened life, from excessive blow by and soot in the oil will get expensive. More so than a better mouse trap.

But, I tend to over engineer.

Fair winds.
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Old 31-05-2015, 13:20   #19
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Re: She lives!

"The crystallization of the salt is a concern that would cause me to consider a heat exchanger cooling system."

That is why I converted to fresh water cooling. My exhaust manifold water jacket was so clogged up it wasn't flowing any water at all. I actually haven't yet gotten that manifold to flow decently yet and that is after boiling it, soaking it in citric acid for days and going at it with a coat hanger. I ended up using the one on my parts engine.

"Shortened life, from excessive blow by and soot in the oil will get expensive. "

At this point I'm pretty sure the engine is running hotter than is typical for a MD7A, I'm on the verge of the red zone with the raw water biased temp. gauge. The engine is 35 years old, doesn't smoke, and starts within a second (with no glow plugs) so running within the temps it was originally designed for aren't a huge issue IMO.

I may get in there to see if I can raise the temperature further but that is a little offset by the fact that I may end up above the temp. rating of my fresh water impeller (55 degree C) and it will also raise the temp of the tranny above what is typical. For the impeller I have a thicker gasket in there to help offset the swelling from the additional heat. The tranny is the first thing out of the heat exchanger so it will receive the lowest temp. of the fresh water. I don't know what the outlet temp of the fresh water will be if the engine is running at 170 degrees. No matter what though it will be hotter than what is typical, the tranny was the first thing in the raw water cooling system behind the strainer. I want the tranny in the fresh water system as its water jacket is what tends to rot out first.

So far I've been running around 1600-1800 RPM. If I end up needing full power (2600 rpm) in some situation it is likely the bypass won't have enough cooling and then the thermostat will limit the temp rise.

When I open it up I may find that the engine bypass is partially clogged. If it is cleaning that up is going to raise the temp of the engine more as it will reduce flow through the thermostat bypass.

Shawn
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Old 31-05-2015, 14:27   #20
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Re: She lives!

I was thinking of a fresh water and antifreeze heat exchanger. Again, I tend to over engineer.
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Old 31-05-2015, 17:31   #21
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Re: She lives!

Yeah~ just today I was stewing about temperature gauges, or lack thereof, in my case. We were on a short leash today so went up for a few hours to tackle a few small items and I ran the motor for 20 minutes or so. Started immediately. Well, ya turn the key, hear 'er give one stroke, then a 2 second pause and it chugs to life without hesitation. She bangs like an old ass tractor until the RPM's get up but she sings so pretty when ya give 'er the juice. The bad part is there's no gauges. No tachometer. Just three red idiot lights in the cockpit for oil, water and voltage. I'ma have to address that.

I do know the temp never got above my ability to hold my hand on the cylinder head. The block was a bit uncomfortable but not bad. I figured around 140-150 on the block. Much less on the cylinder head. Water output was in line with the tiny impeller and looked good. I had de-scaled the thermostat housing while I had things apart and it wasn't that bad. Most of what was removed were thin layers of rust but it needed to be chiseled out. *fingers crossed*
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Old 31-05-2015, 18:13   #22
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Re: She lives!

Not having gauge would be annoying. Luckily on my setup I have oil pressure, water temp, amperage and a tach.

If you can hold your hand on the cylinder head you likely are no more than 120 degrees. You are cooling well, with raw water cool is good. Once you get a little too hot you are going to pretty quickly get a lot too hot as the system gunks itself up with salt.

Until you get a gauge in there the IR thermometers are great for diagnostics. If you do plumb in a sender/gauge be sure you have it in the head or exhaust manifold. My volvo has the temp sender in the exhaust manifold and the PO added a high temp switch (for a buzzer) as well. He plumbed the buzzer sender into the outlet from the thermostat housing, what went to the water injection point. That wasn't an effective place to add that sender as it was really just measuring the combined output temp of the engine bypass water as well as what went through the engine. When my manifold clogged up completely all water was bypassing the engine so that sender was never seeing any heat even though the engine was overheating.

Shawn
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Old 19-07-2015, 12:14   #23
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Re: She lives!

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Ain't life grand? Sounds like your oldie but goodie likes you guys. I have a vague memory of the 30' being the best sailing of the Lancers, had a different designer I believe. What's her name?
Enjoy.
Life is indeed grand these days! We've been spending every conceivable weekend working on various "issues". We managed to get her back to her home port but I'll tell that story later.

Her name's "Bon Aqua", french for "Good Water", of course. I loved the name out of the gate but it took a few weeks to grow on the Admiral and while I had visions of appeasing Neptune with a grand party, alas we now think it's a great name. *phew*

The designer was Lancer Yacht Corp & IIRC the founders were tightly associated with the folks that ran C&C back in the 70's. Having had a chance to inspect every nook & cranny, I like the design. Important chit is accessible, relatively. Hull to deck seam is very solid and toe rails are in perfect shape. 98% of the furniture inside is in perfect condition. I really believe she's spent most of her life tuggin on her dock lines, which I'm not unhappy about.
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Old 19-07-2015, 13:05   #24
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Re: She lives!

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The designer was Lancer Yacht Corp

I can't figure out how to edit so here I am quoting myself

What I meant to say is that the builder is Lancer Yacht Corp, the designer was Cutherbertson & Cassian. Apparently C&C was known to sell their molds. I've seen mentioned that the Lancer 30 & the C&C 30 were the same design.
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Old 19-07-2015, 13:08   #25
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Re: She lives!

Ok, so the test run was fine but whilst shaking her down I discovered the 25 gallon fuel tank was filled with about 10 gallons of water emulsified fuel and 12 gallons of black water/diesel/sludge. I enlisted some friends to assist with the process of emptying the tank into spare Gerry cans and hauled it all to a local recycler/waste disposal. I spent the next week or so repeating a tank treatment of 2 gallons fresh diesel hyper-treated with biocide/tank cleaner, suck it out & dispose of & reapply treated fuel. I did this four times, every two days. After the last treatment the fuel looked pretty good so I installed a see-through automotive fuel filter at the top of the tank, before the racor, to catch large particulate/slime that may still be present but I’ve ran through 30 gallons of diesel and there is only small black grit so far. *success*
While bringing Bon Aqua home, the forecasted W/SW winds turned into pure southerlies. We were headed down the ICW ‘tween Jacksonville and St Augustine & we threw the sails up for the first few hours we were on the St. John’s but once we hit the ditch it was in our face all afternoon. I found out this SB12 still has some cooling issues as extended motoring had to be done at low RPM or she was gonna blow. I recently picked an IR thermometer and I’m glad we had it. At the hottest point, after motoring at top speed for about an hour (or what I felt was top, about 75% off WOT) the exhaust elbow was 800F+ and the head was near 200F. FYI water volume out the exhaust looked acceptable; impeller is relatively new and recently inspected. So I backed off to about 50% throttle and temp dropped to 150F on the head, exhaust elbow was 400F-ish and I could see some steam in the exhaust. Water volume looked ok. To keep the head under 140F meant 20% throttle, tops. She produced a lot of soot which I assume is due to running at low RPM for nearly 10 hours… it slowed us down considerably but we did make it & we picked up a mooring at the municipal marina for a few days then motored an hour to pick up our slip where she’ll live for the foreseeable future.
She ran fine but is generating a lot of soot in the exhaust so I want to go through the raw water system and replace all rubber hoses. I recall there was not a lot of buildup in the thermostat housing but it is entirely possible a hose has collapsed. I do know I didn’t do anything with the mixing elbow… reckon I should clean that as well. I also think it would be wise to have the raw water pickup cleaned. It's time for a bottom scrubbing anyways.
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