Engine cooling system

[Lou_tribal]

Hello my fellow TFers!
Following some events last year I am in the process of modifying my engine cooling system. In summary, I currently have an engine oil cooler as well as a tranny oil cooler. I plan to remove the engine oil cooler, there is no issue in removing it, I did many hours of test run lat year and up here in our cool weather and water an oil cooler is not needed on my engine, and even better the engine reach a better warmer temp without it.
Long story short, currently the two oil coolers are in parallel on the water line right after the raw water pump ( so first in line). By removing the engine oil cooler I will have only the tranny oil cooler in serie in the line after the pump.
I was wondering if this can cause an issue with the water flow? I do not want to create a bottleneck in he cooling line by doing his.
To illustrate this description below is a schema of what I have and what I plan to get ( sorry for the poor graphics I am not an artist lol).



Any input will be much appreciated.

Thank you!

L

 

[steelydon]

I have a Cummins 6bt configured the way you are proposing. The coolers, oil, transmission or heat exchanger, are not designed to slow the incoming raw water flow. Of course we have all had to retrieve impeller vanes from the inlet side from time to to time but my experience has been the obstruction does not create a back pressure problem but limits water flow causing an overheat situation. I think the only thing you may notice is the raw water reaching the heat exchanger will be slightly cooler, a good thing.

Don

 

[jleonard]

It looks like you are getting a new tranny cooler that has larger inlet/outlet?
That will be fine if the sizing is similar to what you have now using both coolers.
If you are simply blocking off one side of the dual cooler, you may not have enough water flow.

 

[Lou_tribal]

It looks like you are getting a new tranny cooler that has larger inlet/outlet?
That will be fine if the sizing is similar to what you have now using both coolers.
If you are simply blocking off one side of the dual cooler, you may not have enough water flow.

No I will keep the same tranny cooler and indeed my concern is water flow restriction.

L

 

[sunchaser]

Of course we have all had to retrieve impeller vanes from the inlet side from time to to time Don

How often do you install new impellers and throw away old, both in terms of time and hours?

 

[twistedtree]

No I will keep the same tranny cooler and indeed my concern is water flow restriction.

L

If the raw water path in and out is unchanged, then it shouldn’t make any difference. I assume the raw water side is common to both coolers?

 

[Ski in NC]

Looks like existing rig has engine oil and gear oil coolers in parallel, so if you go to a single gear cooler with all the flow, there is the chance that flow will be restricted. But it might be ok in trawler service. Try it and if temps at engine and wet exhaust are ok, then it is ok.

If flow is too low and temps climb, just upgrade to a larger gear cooler. Not for more gear cooling, but for more water flow capability.

Agree that a sea water engine oil cooler in low load service with cold sea temp... that can keep oil too cool.

 

[Nomad Willy]

Lou,
I’ve been advocating getting rid of the oil cooler for years on underloaded engines.
But Sunchaser informed me that the oil cooler cools the oil by transferring oil heat to the cooling fluid. So one would loose that advantage by nixing the oil cooler heat exchanger. Have I got that right?

See my post #79 on Engine Loading.

 

[jleonard]

No I will keep the same tranny cooler and indeed my concern is water flow restriction.

L

Well you leave the raw water circuit unchanged and just remove the oil lines from the cooler and buy a fitting to hook them together to make a loop.
That way you'll have the same flow as you now have.

 

[Lou_tribal]

Another question related to my change. I am planning to properly rerouting the water lines so to avoid any kink or chafing of the hoses. Does anybody see any issue with using elbow fittings along the line to create clean elbows instead of just twisting the hose? What kind of fitting would you use? Note that I am in fresh water.

Thank you to help me to make it right [emoji4]

L

 

[Jeff F]

I'm pretty sure elbows restrict flow a lot compared to gentle bends. Probably a bigger restriction to flow than the trans cooler.

WRT your original question, I'd run it in series. If there's too much restriction in the trans cooler it'll show up as gradual overheating of the engine coolant at high loads. So you can try it and monitor temps as you did last year. I'd bet that there won't be an issue.

 

[Nomad Willy]

Lou,
Get the gentle radius elbows. Think they are called “long radius”. Bronze.
I put several or more in Willy. Mostly during the repower.

 

[RT Firefly]

Greetings,
Morning Mr L_t. I agree that elbows may cause restrictions in flow. Could you use wire reinforced hydraulic lines for your water supply? Although they will not bend in a very tight radius they will bend without kinking. Just a thought...

 

[kchace]

Also consider that every elbow adds 2 possible leak or failure points.

 

[Nomad Willy]

kchase,
Yes but a wide radius elbow also only has two hookups.
But if the velocity of the fluid (and if it’s viscosity is low enough) the tight 90 elbow would be fine. But in our apps in the engine compartment wide radius elbows are just a bit more expensive. But better.

 

[Lou_tribal]

Thanks guys will look into this. The issue I am trying to solve is getting a nice hose routing without hose kinking. The PO often choose the shortest path that is not always the best for the hose.

L

 

[Brooksie]

You will be increasing the restriction by removing one of two coolers in parallel. This may or may not make a difference in your cooling depending on required flow rate but the water will flow more slowly.


If you don't run your engine hard you may get away w/o an engine oil cooler but by rights you need an engine oil thermostat. They are not expensive and will keep your oil at a constant/correct temperature.

 

[kapnd]

I’m not a cold water expert, but I would be hesitant to altogether remove the engine oil cooler.
How about moving it into the coolant loop where it can be regulated by the thermostat?
Oops, just looked at your diagram again, could you redraw that to include hose sizes and inlet/outlet sizes of coolers?
There may indeed be an issue there, though you could easily circumvent that by replacing the removed cooler with a suitable length of straight tubing.

 

[Lou_tribal]

Hose from the pump is 1"1/4, then at the parallel split hose is 1"1/4 at the tranny oil cooler and 2" at the engine oil cooler, then out of the parallel setup hose is back to 1"1/4 and into the engine exhaust manifold.
Removing the oil cooler is not an issue in itself, I ran without it (oil bypassed, but still in water line) last summer and at cruising speed (1800 rpm) engine temp difference is minor, oil is warmer but in normal usage range which is not a bad thing. Only difference I noticed is a lower oil pressure, what is logic with a warmer oil that is more fluid.
I am thinking to replace the cooler with a bypass and a valve, if I see that engine temp is rising due to flow restriction I would be able to open the valve to get more water flow, just in case.

L

 

[Ski in NC]

One option for oil cooling is a sandwich plate that goes between engine and filter. It has a bimetalic tstat that directs oil to cooler above a certain temp.

I used one on a VW 1.6 diesel on a little planing skiff. I ran it at 3200-3400rpm with no oil cooling. Started seeing low oil pressure after a long run, opened engine box and filter had blistered paint!! HOT!!! I put the sandwich and oil cooler on and it worked well. Available from auto parts places. Can't remember the brand.

Lou, I don't think you need oil cooling as your last season demonstrated. If IR gun on filter is below 220F, you are good to go. Better hotter, really, up to a point.

And yes, oil pressure will be lower with higher oil temp, but that is ok.

 

[Northern Spy]

One option for oil cooling is a sandwich plate that goes between engine and filter. It has a bimetalic tstat that directs oil to cooler above a certain temp.

I used one on a VW 1.6 diesel on a little planing skiff. I ran it at 3200-3400rpm with no oil cooling. Started seeing low oil pressure after a long run, opened engine box and filter had blistered paint!! HOT!!! I put the sandwich and oil cooler on and it worked well. Available from auto parts places. Can't remember the brand.

Lou, I don't think you need oil cooling as your last season demonstrated. If IR gun on filter is below 220F, you are good to go. Better hotter, really, up to a point.

And yes, oil pressure will be lower with higher oil temp, but that is ok.

I think I have one of those in my shed at home. Pretty sure it fits a PH8A if you are interested.

 

[kapnd]

With your 1 1/4” raw water pump outlet, a 1 1/4” cooler is pretty much standard procedure. The 2” oil cooler might have actually “robbed” raw water from the trans cooler, as fluids like to find the path of least restriction.
Make sure that the entire raw water system from intake grate through the exhaust elbow is clean and free of restrictions before making any judgements regarding flow.

 

[Xsbank]

Lou, I’d be tempted to put a small keel cooler on the hull, plumb the trans cooler to cool with the engine coolant and use the raw water pump to merely cool the exhaust, similar to a couple of Gardner’s I’ve seen. I hope I understand the dilemna.

 

[Lou_tribal]

One option for oil cooling is a sandwich plate that goes between engine and filter. It has a bimetalic tstat that directs oil to cooler above a certain temp.

I used one on a VW 1.6 diesel on a little planing skiff. I ran it at 3200-3400rpm with no oil cooling. Started seeing low oil pressure after a long run, opened engine box and filter had blistered paint!! HOT!!! I put the sandwich and oil cooler on and it worked well. Available from auto parts places. Can't remember the brand.

Lou, I don't think you need oil cooling as your last season demonstrated. If IR gun on filter is below 220F, you are good to go. Better hotter, really, up to a point.

And yes, oil pressure will be lower with higher oil temp, but that is ok.

Thank you Ski, I would have freaked out to see the filter paint blistering lol

L