Ragged Edge

[captddis]

water here is 90 degrees in the summer. have seen my canal at 91.

 

[Boss Lady]

What rpm do you cruise your boat in 90 degree water?

 

[captddis]

1850 to 1900 year round, blow it out every so often as well.

 

[Boss Lady]

Count yourself very lucky, or you have an extremely well maintained cooling system, and fresh engines. My 8v71Ns had temp problems in the Bahamas.

 

[captddis]

I take good care of my cooling systems and maintain dozens of other DDs. When they are maintained they do fine. I have people who run them at 2150 to 2200 and hold temp. The 6v92 TTA will run warm in the summer and could use a boost cooler, but 20+++ years later they are still going. While this go's against common wisdom, I do not put zincs in my cooling systems. They stay much cleaner that way.

 

[Genesis]

I had to tear Gigabite's raw water system down annually to keep it under control, and we have water in the bay here that reaches the high 80s to 90 in the summer time.

If you didn't, you had problems - serious problems - with attempting to run over 1800 RPM.

These cooling systems are simply inadequate for "tropical" raw water conditions and demand scrupulous maintenance or you WILL have overheating issues. It doesn't help that Covington thought that it would be a good idea to put the gear cooler on the SUCTION side of the raw water pump which has a somewhat-negative impact on total raw water volume under load (they're called "pumps" and not "sucks" for a reason)

BTW one way to get 10% more cooling system capacity is to run distilled water with inhibitors instead of "coolant." This is an approved cooling system fill (according to Detroit) and it results in about 10% more heat-removal capacity (Glycol has significantly less specific heat capacity than does water) but of course it cannot be done in areas where temperatures go below freezing, and if you don't maintain the inhibitor levels.......

I ran this way for this specific reason. Checking inhibitors every couple of months with a dip strip is trivial and overheating is expensive.

 

[Captned]

What inhibitors did you use?

Captned

 

[Genesis]

Fleetguard has a decent package available (at a decent price) made specifically for wet-liner diesels. Detroit also has them available (and theirs are in fact made by the same folks... )

 

[solanderi]

Genesis,

What do you think about the boost cooler (fuel return cooler) as insurance ? Besides breaking apart the cooling system annually and using distilled water w/ inx, are there any other bolt on coolers (like a bigger capacity H/E) that you could recommend ? Thanks

Greg
1985 45C
Hat Time

 

[MikeP]

"While this go's against common wisdom, I do not put zincs in my cooling systems. They stay much cleaner that way."

I don't use them (nor did the PO) in the RW pump and I have been wondering what good they really do in the HE since the engine is bounded (or should be) to the rest of the metals which are then, in turn protected by the external zincs. I'm certainly no expert on galvanic corrosion issues but I really don't understand their use in the engine itself.

This Pascoe article, as I understand it (which may NOT be the case) seems to support the notion that if the system is tied together, then the external zincs are providing the protection needed. Of course he also talks about the distinct possibility that the bonding system may NOT be up to snuff or may have deteriorated so as to be ineffective. But this can be corrected.

http://www.yachtsurvey.com/corrosion.htm

 

[Genesis]

Sol, the boost cooler was the "later generation" attempt to solve this problem. Its better than nothing.

If it wasn't so damn expensive I would have re-engineered the entire system. Ideally the raw water pump would not have the gear cooler in front of it, and that cooler would be LAST in line instead of first. This would require some MAJOR rework. Oh, and the primary H/E would have about double the capacity in terms of BTU exchange as the original design.

The problem with such a retrofit is the plumbing - that would be non-trivial. If you could manage to solve those problems and it didn't break you, it would be great. But when I owned Gigabite and looked into this the costs quickly got out of hand to the point that it started to get into the range of "you're nuts".

As a consequence I decided instead to go for the distilled water + inhibitors + anal maintenance and close attention to operating temperatures.

 

[captddis]

"While this go's against common wisdom, I do not put zincs in my cooling systems. They stay much cleaner that way."

I don't use them (nor did the PO) in the RW pump and I have been wondering what good they really do in the HE since the engine is bounded (or should be) to the rest of the metals which are then, in turn protected by the external zincs. I'm certainly no expert on galvanic corrosion issues but I really don't understand their use in the engine itself.

This Pascoe article, as I understand it (which may NOT be the case) seems to support the notion that if the system is tied together, then the external zincs are providing the protection needed. Of course he also talks about the distinct possibility that the bonding system may NOT be up to snuff or may have deteriorated so as to be ineffective. But this can be corrected.

http://www.yachtsurvey.com/corrosion.htm

Mike,
I do dozens of cooling system services a year. Over the years it has been my observations that the systems with no zincs stay much cleaner and I can not cite one example of exchanger failure that a zinc would have prevented. The white scale that plugs exchangers and coolers comes from the zinc not salt as people think. Ever wonder why Northern Lights, Man, the Onan MDL3 and 4 never have cooling system problems? They have no zincs. I only install them when requested. Dave

 

[MikeP]

The first time I pulled my HE I found a lot of gunk that looked to me like zinc particles. It was my first inkling that they weren't doing a good thing there...

One thing I thought about that would serve both purposes if necessary, was removing the upstream zinc from the HE, leaving the downstream one in place. That way, at least the zinc gunk would be leaving the engine directly as opposed to ending up in the HE fins. In my opinion, a good bit of the engine zincs deteriorate just due to friction of the water, NOT due to any electro-issues.

But my plan is to remove both Zs from each eng when I de-winterize in a couple of weeks.

 

[Walter P]

Since my engines will probably be replaced anyway, I think I'll give it a go and run naked with no zinc "protection". I have 6/92's and they are very sensitive to overheating. Leaving them out may actually help...... Thanks guys

Walt

 

[solanderi]

Hey Mike P,

Now that I reread your initial response, I think that I would be very happy with a 5 degree cushion if all it took was a finned oil sump and a fan. Of course until someone actually did it, we would not know if we could get a full five degrees from a working (read that as 1900 rpms) 692, right?

Another random attempt at a solution short of a Genesis redesign is as follows. Just like there are engine oil block heaters, why not engine oil block coolers. A metal thin walled non-corrosive hollow container molded to fit the bottom of the motors essentially surrounding the oil sump. To this an intake and an outflow for cold water. The cold water could be made by a freeze plate and the flow made by a small pump.

This system could be activated for those long summertime runs across shallow warm water (Bahamas Bank, Biscayne Bay, the Keys stc). Does this sound like a whole lot of extra hardware and a waste of time and money ? Maybe an engineer / mechanic type can run with the ball from here.

Greg
1985 45C
Hat Time

 

[Genesis]

There isn't enough heat transfer via this method available to matter.

What you need is to get more heat transfer capacity out of the COOLING system. Cooling the oil won't do it.

 

[MikeP]

Totally agree with Karl - There's a LOT of cool air moving by a finned oil pan in a car. Trying to get that much COOL air (not boat engine room air) moving past a boat sump is neither workable or worthwhile given the limited benefit.

I suggest you pull all the coolers/HE and visually inspect them and dip them in DDs recommended solution - Muriatic/Oxalic acid/water. I can't recall the proportions at the moment but it is listed in the DD service manual. The usual cautions re acid and it's use apply.

When I did this several years ago, my WOT temps dropped from 194 to 180-185 with the same tstats in the engine. After you pull/clean the coolers manually, you can periodically flush them in place as Karl has described in earlier posts. When you pull them you may be surprised at the junk in the HE obstructing the flow - zinc particles, silicone gasket sealer squeezeout (Don't get me started on silicone sealer...), pieces of rubber impellors, etc. That's why it's important to visually insect them every few years.

Of course, once youve pulled/inspected/cleaned them, it is not so vital to do it again because you can keep track of what you've done and it's possible consequences. If you put in a new impellor and the old one was ok (no missing rubber), it's safe to assume that there are no rubber particles in the HE. On the other hand, if a blade is missing...you know where to find it. Same if you have replaced something in the upstream side and used too much silicone sealer...

 

[solanderi]

Mike P,

Are you okay with running at 185's ?

Greg
1985 45C
Hat Time

 

[MikeP]

I'm very happy to run at 185 and frankly would like the engine to run at that temp all the time but at my normal cruise at around 10Knots, the eng water temp never gets above 165 which is too cold for efficient burn. Maybe someday I'll actually change the stats to something warmer as I have been threatening to do for several years...

 

[solanderi]

I put a call in to Tony Athens and they want to have their Detroit specialist check out my question and advise me. I definitely respect their opinion....it will be interesting to see what they recommend.

Greg
1985 45C
Hat Time