Plumbing an oil cooler onto the 4A084

[Papee]

Need, I don't know the answer to that. Is is better to have one than not? I would say better to have one, increased oil volume would be a plus in my opinion would help keep the engine temps down a bit. Maybe not noticeable amount but long term the cooler may be an advantage.

With only my seat of the pants gauge for engine temps I would say my engine gets hotter when I'm just idling around. I do know that since I have my carb problems I had in the beginning fixed it runs much cooler, sitting right by the motor you can feel the heat off it when it is hot after you stop. This and the smell of any oil on your motor causing that familiar burning oil smell. I've done the redneck temp test by seeing how long I can put my hand on it before it burns and I can tell you I have a harder time picking up my knife in the top of my tackle box once it lays in the sun. My tackle box has a clear top compartment.

I've been running and average of 6 hours a trip with a few stops to fish with no problems but an oil cooler is definitely in the near future. As long as the tubes in the cooler are at least the same size as the oil output and is installed correctly I would say a cooler is a benefit. I've not taken a lot of photos lately becasue you've all seen the river by now but I have been having a bunch of fun. The 4A084 is definitely a good choice for a mini motor as far as reliability and all around mini performance.

Maybe I can steal the wife's meat thermometer for some temp tests.

[buster]

Papee,

Hey, those infra red thermometers have gotten so cheap nowadays, that it hardly pays to be without one. I only paid about fifteen bucks plus shipping for mine on eBay, and it works great.

Wifey even uses it in the kitchen sometimes.

Dave

[chuckitt]

Here is a picture of the cooler we will use on Scorpy.
[attachment=0:2128ijl1]Oil Cooler 003.jpg[/attachment:2128ijl1]
Thanks, Chuck

[Duane Scarborough]

Hey guys,

My oil cooler / transmission cooler showed up today.

I had it cat scanned, and it came back 100 % approved.





Duane

[buster]

Duane,

Good one Duane, I got mine tuesday but I don't have "cat scanning" equipment. I hope it's ok anyway.

When I start my 084, the oil pressure gauge pegs out at 80 psi for a few seconds. From the picture it looks like your cooler has the slip on fittings. I hope that much pressure doesn't cause a problem with them.

Dave

[Duane Scarborough]

Buster,

I almost bought a 0-60 PSI mechanical oil gauge. The electric one is 0-100 PSI, but I was going to add a mechanical gauge as well. For "Just in case".

It sounds like I need to stick with 0-100 PSI gauges.

Part of why I bought this particular cooler was because of the slip fit hose fittings. It may have been a mistake, but the Scrappy Cat approves.

I know that you don't have cat scanning equipment in your home. Maybe you should consider it. Works great as a foot warmer on cold mornings.

Duane

[buster]

I took a few hours today to instal the new oil cooler.

My new "used" camera came in the mail today, so I figured I better try it out. I bumped the lens on my old one recently and it has not worked right since. I found the exact model on ebay, and got it for only $24. Sure beats the $140.00 I paid Walmart for the other one.

I'm not sure if the cooler is mounted in the right place or not, but I put it where my hoses reached.

I only had time to start it to check for leaks, but should get temperature results in a day or two..

Dave

[brlcla]

decent location.... it would get more air as it gets closer to the tips of the prop... most mount it at the top of the cage or the bottom of the engine stand at the tip of the propeller.... but you should have decent flow there...

[Duane Scarborough]

Buster,

As usual, you do nice work.

I wouldn't have chosen that location as my first choice, but then I can't see any problem with that location either.

After I think about it some more, I actually LIKE that location.

One of the "issues" that I saw on the Yahoo A084 forum (a long time ago) about oil coolers was that they don't seem to work well if you place the cooler much above or below the crankcase. I'm not sure that I completely bought into those arguments.... but they were there.

You've put it about at the same level as the crankcase. I can't see how that can create any oil flow problem. At least not because of the level of the cooler.

brlcla's comment was valid, to a point. You may get more airflow across the cooler if it was mounted a little further out. But, you'd likely disrupt the air a bit more if it was mounted way out there. But then, we collectively are not convinced that we even NEED an oil cooler on a 4A084. Is it a good idea? Probably.

I like what you've done. I especially liked the "I put it where my hoses reached" response.

That's what I had in mind anyway...

Thanks for sharing that idea,

Duane

[chuckitt]

I mount the oil cooler on the engine stand about center of oil cooler to center of prop blade. Being a pancake cage, your cooler should should work good there. Most all props are designed with about 11 degrees of helix in the blade. That should be about 11 degrees per ft. That should mean that the heavy air coming off the blade one ft from the tip of the blade would be about the same as the tip of the blade. Otherwords, the tip of the blade would be about 11 degrees less pitch than one ft in on the blade. Just trying to explain it to make it easy to understand. If you notice the big cup in the WaterWalker Maximus Blades, you will see how they used the strength of carbon fiber to make the column of air almost as strong close to the center of the hub as out at the tip.
You want have any problem mounting the center of the oil cooler close to the center of a prop blade.
Thanks, Chuck

[buster]

brlcla, Duane, and Chuck,

I'm glad you all agree my cooler mounting location is ok, even though my main reasoning was that I didn't want to spend more money on new hoses. Just the adaptors to hook them up already cost me about $25.

Thanks for your opinions guys,
Dave

[Papee]

Is it ok if I only partially agree? I hate to rock the boat.
As far as efficiency, the location is great but...
Where it is located it is blocking valuable surface area for air to the blades.
Sometimes I pick too much but I'd be willing to bet it is slowing your boat down.
This is not a big deal, I'm just adding fuel to the fire.

[buster]

Papee,

It's still a free country, so you can partially disagree if you must

My boat only goes about 25 mph anyway, so I doubt if it will make all that much difference.

While we are on that subject, do have you any idea why your heavy, DD boat will do 38 mph, while my smaller lighter belt reduction unit only tops out about 25? Could it be my GPS is different than yours, or maybe the river current helps you out? I've been wondering about that for a while

Dave

[n4wsp]

If you are checking your speed with a gps it only gives you your ground speed across the service of the earth. it is like flying a air plane with a tail wind. If your air speed is 100mph and you have 20mph tail wind your ground speed will be 120mph but your speed through the air will be 100mph. The same can be said if you are in a river with current and you are going down steam with a 10 mph current and your gps says you are going 40 mph. that will be your ground speed.to get your true speed you haft to subtract the current speed. the true speed will be 30 mph. In my river we always have current, my boat will run 40 mph down stream. Going up stream it will only run 35mph buy my gps. we normally have about a 5 mph current.

Steve

[Papee]

Buster the top speed I have listed is with my boat totally stripped down, no battery etc. Also best conditions like 3" of water. Another reason for my speed is my hull, I have 5 feet of almost flat hull, I have no chines. I also have a small step where the bottom material overlaps, it's not big but I do think it helps some. My top speed with everything in the boat that stays there is 32 MPH. My cruise speed is 27 MPH at 3000 rpm.

In most cases where I test for the speed the river flow isn't even worth the trouble to figure as in the one video where I show the GPS I am going across the river. I am uploading a video right now where I have a tail wind and got 34 mph with the wind and down stream. This was in about 3 feet of water. The gps video was also in a little deeper water. Between the rock ledges the current is only 2 mph tops this time of year.

[buster]

Papee,

I been thinking about it some, and I think the secret to your extra speed, more than anything else, is most likely the 3" deep water.

I remember in an old Aircat brochure, I read that their military model with the 180 Lycoming would do 58 mph in deep water, and 75 mph in shallow. Nuff said.

I can't think of any 3" water around here to test in, but I have been in water 1 ft to 3 ft., and it acts like a different boat there than in the deeper stuff.

Dave

[buster]

Ran the engine on the trailer about a 1/2 hour again today to test the oil cooler efficency. RESULTS? - Maybe I got too big of a cooler.

I did the same test before I hooked up the cooler, and the oil temp went to about 180 degrees.

Oil temp reading was taken just as the oil re-enters engine after going through the oil filter. The temp probe is in that big brass fitting I rigged up. See it in the first picture.

After hooking up the cooler, the temp would not climb above 125 degrees. Finally I coverd about 90 percent of the cooler, and the temp went right up to 150 degrees.

The question I have is, does anyone know what the ideal oil temp for for this location is?

I guess I could regulate the temp by keeping part of the cooler covered. That might be better than running too cold. Yes, I know Papee will think that will further impair my top speed, but that's the breaks, I guess.

Dave

[Duane Scarborough]

Buster,

At least it doesn't seem to be too small. Who'd have thunk that?

Rather than covering the oil cooler, you may want to consider only running part of the oil flow through the cooler. A simple way to do this would be to tee in a bypass. You could start with a simple bypass, so that roughly 50% goes through the bypass, and 50% goes through the cooler.

If that works for you, then you may want to install an adjustable valve (or maybe just an orifice) so that you can have some control of how much you bypass. Whether you want to throttle the oil that goes through the cooler, or the oil that bypasses would depend on what results you got with the roughly 50% setup.

Another choice would be that fancy thermostat that I sent you info on.

I do not know what the ideal temp would be.

Somewhere I read that you want the oil to get to "about" 180 degrees, (in the crankcase) so that moisture will boil out of the oil. (This was related to engines in general, NOT 4A084 specific)

I'd think that if you reach about 180 degrees in the crankcase, then 125 degrees wouldn't be a problem in the oil returning to the engine.

You've got that infrared thermometer. Get it up to running temp, and check your oil pan temp. Just an idea...

Duane

[David]

you said you have your oil temp sender reading after it goes through your cooler why not put it before the cooler

I would want it to run around 160 and no more than 180 JMO

[buster]

David,

Does that mean that the Max. oil temp for the engine should be 180 degrees?

I'll replum the lines tomorrow.

Duane,

How can the water in the oil boil off at 180 degrees? Last I heard, water boils at 212 degrees.

Dave