Help needed - oil became grey tacky, water mixed? - Page 7

Lou_tribal · 08-05-2018, 06:48 PM

Just check the oil, level is good, oil is perfect clear as new, no visual trace of milky aspect, no smell other than new oil smell.
I think I am good.
One thing I noticed on the way back is that oil pressure was somehow lower than before. In the past with the oil cooler oil pressure was just above the 40psi mark, without oil cooler it is lower than 40, around 35 I would say. I guess this is due to an higher oil temp.
As this is in the normal range for the engine I think I do not have to worry (normal range at 1800rpm is min 30psi max 65psi).

L

ben2go · 08-05-2018, 07:40 PM

It sounds like you're good to go cruise before winter bite comes in.

BruceK · 08-05-2018, 08:52 PM

Lou, good progress, will you replace the oil cooler which seems to have been the culprit, or wait and see? There must be a reason one was fitted but,maybe you can get by without it. I`m sure those with real mechanical knowledge will comment.

Lou_tribal · 08-05-2018, 09:59 PM

I will replace the oil cooler, in fact both while I am at it, and I will reinstall them a bit differently so they are well supported and not just hanging by the hose.
I am thinking to add bypass valves so I can use or not the oil cooler depending of the need. I guess that most of the time up here it will not be needed and maybe even more a source of issue. Not sure it is good to run with a too cold oil, not an expert but if normal temp is somewhere around 85C I am not certain it is good to run with oil at 60C or less. Like you mentioned hope experts will chime in.
In the original (not marine) manual for that engine it is mentioned that for some usage an oil cooler can be fitted, like for stationary pump. In that case I guess that cooling is far less effective so the need.

L

ben2go · 08-06-2018, 01:03 PM

I am no expert but cold oil moving through an engine can turn into sludge. Also, cold oil doesn't help condensate to burn out of the engine.

Comodave · 08-06-2018, 01:06 PM

Glad you got it running clean. Congrats

Lou_tribal · 08-06-2018, 01:50 PM

Quote:

Originally Posted by ben2go

I am no expert but cold oil moving through an engine can turn into sludge. Also, cold oil doesn't help condensate to burn out of the engine.

This is what I think too would be nice to have confirmation from one of mech expert

L

Lou_tribal · 08-06-2018, 01:52 PM

Quote:

Originally Posted by Comodave

Glad you got it running clean. Congrats

Thank you, now I need to think about my new coolers setup. From my measurements today one (engine oil) is 6" long, one (tranny cooler) is 8" long but smaller in diameter. I will check what size exist and will think about how to make a proper support.

L

Lou_tribal · 08-06-2018, 07:36 PM

Questions about oil coolers:
1. I saw them made of copper or copper nickel alloy, what is the best? What is the difference (except what they are made with)?
2. Currently mine are connected in parallel on the water line, is it better to connect them in serie? Yes/no, why?
3. Is there any impact to use coolers of different size (length or diameter)?
4. How your coolers are setup/supported?

As usually I have a lot of questions

L

rochepoint · 08-06-2018, 07:47 PM

We use a Seakamp CuNi dual cooler on our Perkins, cools both the engine oil and transmission oil in one cooler.

Lou_tribal · 08-08-2018, 11:41 AM

I think I will go with 2 SeaKamp Cupro-Nickel oil cooler of same size, 2"x9" with 1/2" oil ports and 1"1/4 hose ports like this one:

Question now is should I connect them in serie or parallel. As they are in parallel right now I think to keep that the same way.

On oil temp/pressure subject, I checked the doc I have for the ground version of my engine and here some numbers:
Oil pressure at WOT: min 30psi max 60psi.
Oil pressure at idle (550rpm): min 12psi.
Max oil sump temperature: 250F

I was worrying about having the oil reaching 185F +-5F, but looks like I am still far from max temp!

One question though, what is an optimal oil temperature? too cold it may not be hot enough to cook potential moisture and may be too cold to get a good lubrication, too hot it will degrade (what temp oil start to degrade?).
If I measure the sump temp at 210 or 215 F should I start to worry?

L

kchace · 08-08-2018, 12:21 PM

I think an oil temp around 190 is pretty close to optimum.

Ken

High Wire · 08-08-2018, 12:35 PM

What weight oil are you using exactly? There is no thermostat to control oil temp.

Lou_tribal · 08-08-2018, 01:38 PM

I am using straight SAE 30 oil. This is the one recommended in the doc for the ground version of this engine (when external temp is ranging from -5C (23F) to +40C (104F)).

L

Chrisjs · 08-08-2018, 02:46 PM

It's been a few years since I sold the boat (Selene 47) but do not recall that there was an oil cooler fitted to the 280HP Cummins 6BTA. There was a transmission oil cooler but I am kind of sure that there was no engine oil cooler. I believe the engine oil relied on the main engine cooling system and did not have a separate cooler. The engine typically ran at 185F with no cooler. Even cruising in the Bahamas, engine temp stayed about 190F during normal running. Any idea why your engine would require the cooler?

Lou_tribal · 08-08-2018, 02:52 PM

Quote:

Originally Posted by Chrisjs

It's been a few years since I sold the boat (Selene 47) but do not recall that there was an oil cooler fitted to the 280HP Cummins 6BTA. There was a transmission oil cooler but I am kind of sure that there was no engine oil cooler. I believe the engine oil relied on the main engine cooling system and did not have a separate cooler. The engine typically ran at 185F with no cooler. Even cruising in the Bahamas, engine temp stayed about 190F during normal running. Any idea why your engine would require the cooler?

Absolutely no idea why. It was the setup when I got it. In the ground version manual they specify only that for some usage (same engine as been used for stationary generators, pumps, trucks and boat) an oil cooler might be installed. I guess that a generator or pump get less cooling so the reason but for me I am not sure I need one.
Maybe the one who fitted the engine in the boat was thinking that cooler was better? Or maybe it is the PO who thought it was a great idea? Not sure.

At the same time I would not want to make a mistake and cook the oil or worse the engine itself.

L

DavidM · 08-08-2018, 03:33 PM

Cummins engines do have an oil cooler but it is supplied by the engine's coolant system (a better approach btw as it eliminates over cooling) and is integrated with the engine so it may not be obvious.

Lou's oil cooler is typical of many marine engines. It is raw water cooled. Oil in high output engines (and Lou's isn't one of these) often sees much higher temps than the rest of the block or head such as from piston cooling nozzles.

I think in his case it is just a supplement to the coolant system. Lehmans, Perkins, Yanmars and many, many others have raw water cooled oil coolers.

On the question of parallel vs series installation, I would go with what was originally set up, ie parallel. Series might add too much pressure drop to the main system. It will also increase cooling, something you don't seem to need.

David

Lou_tribal · 08-08-2018, 03:42 PM

Quote:

Originally Posted by djmarchand

Cummins engines do have an oil cooler but it is supplied by the engine's coolant system (a better approach btw as it eliminates over cooling) and is integrated with the engine so it may not be obvious.

Lou's oil cooler is typical of many marine engines. It is raw water cooled. Oil in high output engines (and Lou's isn't one of these) often sees much higher temps than the rest of the block or head such as from piston cooling nozzles.

I think in his case it is just a supplement to the coolant system. Lehmans, Perkins, Yanmars and many, many others have raw water cooled oil coolers.

On the question of parallel vs series installation, I would go with what was originally set up, ie parallel. Series might add too much pressure drop to the main system. It will also increase cooling, something you don't seem to need.

David

Thank you David, indeed I was also thinking that a serie setup would play on the pressure so was not sure I wanted to mess with something else

L

Jeff F · 08-08-2018, 04:37 PM

I can't claim any real expertise on the series vs parallel but the series is common. I'd argue for series just because one could plug up and you'd lose the cooling capability for that unit without any real notice.

I also think you should continue to question the need for an oil cooler. You're not pushing that old motor hard, and there are good reasons why a higher oil temp (within reason) is good. I'd do more experimentation and observation before installing an oil cooler.

Ski in NC · 08-08-2018, 04:46 PM

185F oil sump temp means no cooling needed. 200-210F optimal.

Only concern is if you would ever need to hold engine at full power for an extended period.

If that was my boat, I would not install a sea water oil cooler. Not needed.

Almost all diesels above a certain size and hp have an oil cooler. Oil splashed from bearings hits bottom of pistons and picks up heat there. Common on little gennie engines (no cooler) for them to have 175F coolant and 195F oil temp. But that is fine.

High output engines have piston cooling nozzles and they absolutely need coolers.

It all depends on what the temp goes up to in normal ops.

I set up a little VW 50hp in a planing skiff. No oil cooler. First trip over two hours at 3200rpm saw oil pressure dropping. Hmm. Opened engine box and paint was bubbled on oil filter. That one got a cooler!!