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Thread: 084 Operating Head Temps

  1. #1
    Super Moderator Corky's Avatar
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    084 Operating Head Temps

    OK, so now that I'm up and running with the daily fishing and general cruising there's some questions...The max operating range for the 084 head temp is supposed to be 475*...And if I stay below 3000 rpms it'll hold steady for the most part around that temp...But with the circle s redrive I have the ability to run at 3700 rpms...And so far I can only do short bursts of anything above 3200 rpms or so without the temps heading north of 500*
    I'm not looking to be a speed demon on the river..And it stays on plane well below 3000 rpms even with two people and I have no issues what so ever with performance,weight,etc...I guess what I'm trying to do is add a little more durability at the upper rpm range for extended times like shooting through rapids,emergency situations and/or maneuvering without constantly looking at that darn CHT gauge...
    Yes I'm a worry wort and without that gauge I would never know there's a problem the engine oil temp gauge is steady at 175 but the heads tell a different story...And knowing just how easy it is to drop that valve seat out of the head from overheating makes me worry...
    Anyhow, here's my theory on how to possibly get those head temps down..

    1} install a larger oil cooler
    2} install the large capacity {1qt} oil filter
    3}add cooling fins to that oil filter

    As you can see it's all about the engine oil taking the burden of cooling the engine..
    Trouble is the oil temps really aren't that high at 175*

    Here's another round of possible mods :
    A} direct some of the air flow from around the operators seat directly to the heads but just how much is too much that it cuts down on thrust is anyone's guess..
    B}Add some type of head cooling fin extensions to get more head dissipation
    C}Have the head combustion chamber coated with a heat barrier coating to direct the heat out the header..
    D} And the over the top approach would be to somehow add water cooling between the head's fins..Be it some type of tubing with seawater being pumped to and from the system or even a direct water spray which would probably create serious heat related issues with hotspots..

    Any thoughts or other approaches from anyone ?
    Last edited by Corky; 09-01-2019 at 09:13 PM.

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  2. #2
    Member Bart's Avatar
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    Re: 084 Operating Head Temps

    after this last month of chasing my tail with trying to dial in my motor, I had cylinders 2 & 4 giving me fits, the exhaust coming off of #2 would get a nice cherry red if I ran it for over more that an idle... thinking it was the head, changed it out and then i dropped a exhaust valve seat on #4. go figure,...
    last night I opened up my motor and found out that cylinders 2, 3, & 4 were all a little large in the middle of the stroke. max clearance is listed at 2.995 and these were at 3.003 to 3.004,
    don't know if correcting this will solve the problem, but I sure do hope so.
    but seeing how I have an over abundance of parts coming in, I thought I would try something that I have read about on the Samba forum. "Connecting Rod Oil Squirter Mod"
    there are pinons all over the place on this one.
    the best one is that this will put more oil out into the crankcase, which could create a problem with windage...
    but you have a side clearance of min. .0060 to a max of .014 on each connecting rod, on the 084. and oil is coming out of this clearance already..."it is just not being directed"
    and if you got low of oil pressure, a person might want to look at the some tired bearings....

    I am looking at it as an attempt to direct more oil into the end of the piston to take away more heat. "I have noticed on all of the pistons that there is oil burnt on the backside of the crown, maybe a little more oil might help"
    some have claimed to have seen head temps be reduced from 50 to 100 degrees. For me, if this works, this would be a big plus..


    there have been a few connecting rods come from the factory with a notch built on them.
    and there are a few locations that they have been placed. I choose to make a notch on both sides close to the 11:00 position, angling it just past the wrist pin.
    the notches are about 1mm / .0395" deep and 2.6mm / .1055" across, I used a 3mm dia mill ball on the end of a dremel to cut it out.

    at the this time, and after opening up the case and seeing how tight everything is, this looked like the simplest thing to try.
    when I get the rest of my parts and pieces, and reassemble the motor, I will know if this is something to pursue..

    I am almost ready to un-bury my other 2a042 genset motor, that still has everything on it. And see if I can get it running just to see what the head temps are with the cooling fan and shroud in place. I just don't have a base of what to compare the head temps to... or what is normal...

    I was thinking of drilling and tying into the supply line that feeds the lifters, and use a spring loaded squirter, but with the throws on the crank shaft, there just is not much room for anything..
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    Last edited by Bart; 09-04-2019 at 11:57 PM.

  3. #3
    Super Moderator Corky's Avatar
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    Re: 084 Operating Head Temps

    You're right, there's not much room in there to get the squirters shooting in the right direction...Any oil is better than none...As long as you don't bleed it off something that needs the oil down the line...I'm wondering just how efficient a piston top thermal coating would be to try and keep the heat transfer to a minimum ??

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  4. #4
    Member Bart's Avatar
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    Re: 084 Operating Head Temps

    Quote Originally Posted by Corky View Post
    You're right, there's not much room in there to get the squirters shooting in the right direction...Any oil is better than none...As long as you don't bleed it off something that needs the oil down the line...I'm wondering just how efficient a piston top thermal coating would be to try and keep the heat transfer to a minimum ??
    you are right on that. the rod journals are at the end of the line for the oil flow in most motors. I am going to be real curious as to if these notches will drop my oil pressure. but from what I understand most of the oil pressure is determined by the clearance between the journals and the bearings. and it is forced out the sides. and you need the side clearance on the rods, to be within specs, to keep everything in line.
    if I have worn out bearings or abnormal clearance someplace, in the motor. the oil pressure will drop accordingly
    "the one nice thing about the spring loaded oil squirters, is that if the oil presser drops below 25 psi. they close. but I have read that a few are finding the tips when they change out the oil. so even if they come from the factory. there is a chance for them to get in the way and get knocked around."


    but at the moment I have 7 spare connecting rods. but having to open up the motor, again, well what else do I have going on this winter...
    but if this will bring down the temps. I would dance a jig..
    I see where you are getting frustrated on what and how to get rid of the heat, when you are at the upper end...
    one thing that i look back on is when I was operating my Cuyuna motor. It was used and still is being used in a few ultralight airplanes.. It has an pulley mounted fan that is always blowing air over the top of the heads. I never took a temp reading on them, but even after running hard, I could still put my hand on the top of the heads

    I was always wanting to hear one of my 042 motors run, now that I have a 12 volt starter and 2 spark plug thermocouples .. I may have to dig it out. for I am really curious now.. as to what the so called normal head operating temp is for these motors. and besides that what is one more project....

    just for my own piece of mind. when I get my motor back together, for this testing phase.. I am also looking at fabing up some thin gauge aluminum for a shroud. and using a couple of fans to blow air over the cylinder and heads. just so I have a back up plan. or I could just direct the air coming off of the flywheel better..

    as for the ceramic coating, all indications are that it should work, the main unknown, heat is energy, and if the heat is contained by the ceramic coating. what will be the cause and effect.
    if anything, I may send out one head & piston and see what happens. it would be 80 to 120 per cylinder plus shipping, depending on how much I wanted to do?? but that would give me some answers besides just thinking about it. and the nice thing it would take less than an hour, to swap them out. I need to get some more funding projects so I can play on these ideas.

  5. #5
    Member Bart's Avatar
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    Re: 084 Operating Head Temps

    Dang, I might have look into getting a couple of batteries and I will have a 5k generator. it started right up after sitting for more than 15 years..
    and the price was right. and it does generate some electrons. at least it ran a grinder...for a while. need to see what I could wire it up to, to give it a load and see if it really works.

    I was not able to close the shroud all the way. the stock fuel lines were kind of rotten so I plumed in a little jug and hung it above it.

    but I am now seeing what a difference when the air is directed, compared to my 084 with a fan and no shroud, it is a night and day difference...
    these motor are meant to run at 3600 all the time. I will be adjusting it later to see what the head temps are at idle..

    but it ran for a good 10 to 15 minutes at 3600 RPM, and the #1 head was just a little warmer at 350, and the #2 was at 300.
    so I took the top of the shroud off, and with in a minute #1 jumped up to 400 and #2 went to 375. I put the top back on. maybe when I change the oil and do a little maintenance on it I will see how much more it will climb. but I really don't want to get above 450.
    couldn't close it all the way due to a fuel line on the #2 side. It took a few minutes for the temp to come back down. but it did.

    there is one other addition that I would like to do with this 2A042 motor, is to add an oil temp gauge and see what the operating oil temp is. . then add a oil cooler to it. and see what the difference is.


    all in all I was impressed for how easy it started and ran. sounded good. all I did was put my 12 volt starter on it. debating on whether to pick up 2 small lawn and garden batteries and keep it as a 24 volt system..

    so now I am back to the drawing board.
    I see the big difference that we have from the 084 being install on an airboat vs. small airplane.
    the airboat is using a pusher prop. there is a whole lot of air movement behind the fan. but not a lot in front...
    where on an small airplane the prop is a puller. so there is a lot of air movement going by the cylinders to keep them cool...

    so far in my testing of the 084 motor the flywheel fan was almost keeping up. I never ran it for more than 10 minutes at a time. and only briefly at anything over 2000 RPM..

    maybe when I get a prop on it, the air flow might be different??

    at least this has got me thinking and who knows what I will come up with?
    I am not saying to stay away from these motors.
    I am just trying to get more information out there, so we all can make good judgement calls on how we operate.

    a few lessons learned, I am glad I had some extra blue hose for the intake manifold.
    also, that little pulley on the front, KEEP your fingers away, it looks harmless. but it can wake you real quick... it wouldn't be so bad if it didn't have them dang notches on it. just glad that there was nothing major....
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    Last edited by Bart; 09-06-2019 at 08:39 PM.

  6. #6
    Super Moderator Corky's Avatar
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    Re: 084 Operating Head Temps

    You know, you might have just answered your own question...Even with the prop it appears there isn't enough airflow to sustain these engines for extended rpms...What if you added a set of fanblades on the front pulley to direct a constant flow of air over the heads ???

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  7. #7
    Member Bart's Avatar
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    Re: 084 Operating Head Temps

    Quote Originally Posted by Corky View Post
    You know, you might have just answered your own question...Even with the prop it appears there isn't enough airflow to sustain these engines for extended rpms...What if you added a set of fanblades on the front pulley to direct a constant flow of air over the heads ???
    thanks, for the location. I have been thinking about this mod, for the last year or so. just didn't know in what direction to take it.
    A few of the different ways, or ideas that I have been mulling over.
    A. have a fan on each bank
    B. one large fan overhead or in front.
    c. there are always more ideas..
    but everything was looking real bulky and not even smooth.
    i have 3 different fans that I had picked up over the years, and am glad that they haven't gone the way of the world.
    one from a polaris sportsman, another from a suzuki eiger , and a 15" one from dumpster diving...

    a single large fan looked the simplest. and I could even have it turn on and off per the temp of the motor...
    but when I looked up the specs for the 15 inch fan. I don't know the rpm, but it is rated at 2360 CFM. But when I seen the AMP draw of 22 amps.
    well then it finally dawned. MOUNT IT TO THE FRONT PULLEY. thanks for the nudge.
    I had a spacer made to install another missing tooth wheel, just in case, the magnets on the rope pulley would give me fits...
    it is for show only now. I will need to make one 4.5 " diameter to fit & center the fan to the pulley.
    I was looking at ways to dump the motor, if I do, then I will need to make a plate with a centering pin on a bearing to center the fan to the shroud....
    it is always something. but it would cut the extra depth from 3" to 2" hanging out on front of the motor....

    if is works, even with just a fan & fan shroud mounted to the rope pulley. sacrificing 2-3 inches of space, I think most of us could do this..

    as this progresses, I have a few friends that are tin knockers, and will reach out to them to help me fab up a shroud that will be streamlined and functional,

    with a shroud over the cylinders, I need to look more closely at how the stock shroud is designed. and where the air is dumped out at. and try to imitate that to some extent, the only difference is the air intake will be on the front end of the motor.

    in reality should not be impose to much of an air restriction for the air going to the prop..

    now I just need to order a couple of aluminum rounds, and have some fun..
    I had been entertaining the idea of just using the flywheel fan, but once I get the redrive finished, the flywheel will go back into storage..

    I know that I will be making a few drastic changes with notching the connecting rods, & now this fan. but if this can bring down the heat. the benefits will be great. I am just hoping that I can bring this all together.
    planning it out is the easy part. now another small project for this motor......

    it will be a month or more down the road, and I know some thing will change along the way. if any of you have any ideas, or thoughts that I may have over looked please let me know..
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    Super Moderator Corky's Avatar
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    Re: 084 Operating Head Temps

    yeah, the factory pulled the air up from the bottom so the original shields probably won't be of much use..
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    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



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    Re: 084 Operating Head Temps

    Quote Originally Posted by Corky View Post
    yeah, the factory pulled the air up from the bottom so the original shields probably won't be of much use..
    Corky, the motor fan pushes air into the shroud, and it exits for the most part at the back of the oil pan. there is a lever on the outside, where one can adjust the exiting flow of air depending on the ambient temp.

    in some ways I wish that I had access to a 084 shroud assembly, to use more than anything for a template, for the 2 valve covers. "at least I kept some of the shroud of the 042 that I dismantle. so at least I can get the right template for the valve cover.
    I ended up changing the oil in the 042 generator today, and ran almost 2 gallons of gas through it at max rpm. the the head temps stayed at 350 and 300 as before. and as soon as the top cover was lifted they climbed up to 400 in about a minute. and it took another minute to drop once the cover was put back on.
    so there is some engineering with the air flow. and I have a lot to learn...

    found out that most of my rebuild parts should be here Monday. once the motor is together. my first testing will be seeing how the notching affects the oil temp.
    was reading today about a lycoming motor that had the rods notch, and he needed a larger oil cooler
    I got this from 'VANSAIRFORCE.COM I have tried to copy the link, but it is not letting me. but the search was under high oil temp.
    he started out with this
    "Hello,
    I just installed a late model Lycoming with "piston oil squirters" and am seeing 205+ oil temperatures despite using a slightly larger than normal oil cooler. These temperatures are recorded at an outside temp of 30 degrees at 7,000 feet. Cruise at 10K feet / 21 degrees OAT yeilds 190 degrees
    My cylinders are a bit cold at 250 - 290 degrees but my oil is just too hot. I'm worried about trying to fly in warm weather with these winter numbers. The engine I replaced was too cold in winter and had to be shuttered.

    Someone mentioned that using the oil squirters case changes the motor from "air cooled to oil cooled"."

    this is the first time that I have seen any hard numbers poste, with notch connecting rods. it is making me curious as to what I will find.
    they also state that Lycoming's IO-390 operating manual is clear: Oil Temperature: The maximum permissible oil temperature is 235F. For maximum engine life, desired oil temperature is 180F.

    anyway I am finding some good information that I think is usable in this quest to keep our motors running better & longer
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  10. #10
    Super Moderator Corky's Avatar
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    Re: 084 Operating Head Temps

    OK , I had the flow backwards..I never ran mine out of the crate and just stripped everything off...I'm trying to understand why those 4 small shields were in place around the cylinder jugs {the springs were on the top so the shields were at the bottom}..I'm guessing it somehow directed the air from the bottom, through that small hole, and around the jugs..It's amazing the engines ran so cool with everything in place but get so hot without them..

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  11. #11
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    Re: 084 Operating Head Temps

    thinking of a way to get a visual look inside the crankcase while the motor is cranking... to see it there is any difference in the oil coming off the rod bearings with the notches that where cut...
    at the moment I am seeing 2 options.
    with it on its tail. I could use a piece of hose connected to an oil source. put a piece of plexiglass on the bottom of the case to keep the mess somewhat contained...
    and another tube to the drain coming from the pressure relief valve..
    turn it over with the starter motor. and take a short video of what is going on. before the oil covers the plexiglass.
    the starter motor cranks the motor over at around 200 rpms. with no spark plugs, and 10 second bursts, it might be just enough....

    or option B
    find a inline pump. connect it to the oil return port coming from the oil filter. pressurize the line and see what is going on as i slowly rotate the crankshaft...
    this way, I don't have so many moving parts. and a little more control if anything goes south. (just don't have a pump, to pressurize the galleys) yet..
    copied the last 2 pictures from an earlier post http://miniairboatassoc.com/forum/sh...stem-questions
    where I marked out the oil flow, in an 042 motor.

    don't know if either of these 2 ideas would work, but I would like to see if the notching makes any difference with getting more oil to the pistons, besides just reading about it...and with the motor still somewhat disassembled. it wouldn't be to hard.
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    Last edited by Bart; 09-14-2019 at 01:59 AM.

  12. #12
    Super Moderator Corky's Avatar
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    Re: 084 Operating Head Temps

    I was thinking of something like a cheap inspection camera...I've got one that could fit in the oil pan plug but I'm wondering just how much oil is being thrown around for either of our ideas...And just how long even that clear plexiglass would stay clear enough to see any improvements..

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  13. #13
    Member Bart's Avatar
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    Re: 084 Operating Head Temps

    well, at cranking speed it does make a mess. I was thinking of using the oil pan off a 2A042 and just bolt it to the bottom half, and at least see the top half...
    but only the middle bolt on the back matched up. so there went that idea..
    picked up a gallon of tractor hydo/tranny fluid, wanted it thin enough that the electric fuel pump would push it through..
    took my fuel pump out and plumbed it to the (OUT) port at the top of the block. where it would skip the pump and go straight to the block galley ways.
    tomorrow, I may just plumb it straight to the intake tube feeding the oil pump.... (still have almost 2 quarts left. and need just a little more oil on the floor...)
    and cranked it over with the starter... with no plugs, the crank rpm is between 160 and 200.
    I don't have the editing stuff, or didn't know how to find it.. to put a part in slow motion..
    there looks to be a lot more oil getting slung on the lower half, but all the oil from the upper part is draining in opening at the center. and falling onto the crank, and it did make a mess....
    but I could see streaks of oil going out. I will have to up load a video to my computer and see if I can slow a part down to see it in more detail..
    so here is a video
    https://youtu.be/CPHLTKdLv0I


    on an other note I picked up a couple small garden batteries, put back the 24 volt starter, plumbed the fuel line through the shroud on the 2A042. then wheeled it outside and gave it a good cleaning...
    started it up, and with all the shrouds in place, I was seeing around 275 to 290 on both cylinders..at full throttle.

    now just need to finish putting the 4A084 back together and see if the notching really did anything. my 2 new heads came in today. so maybe in a little......
    Last edited by Bart; Yesterday at 02:12 AM.

  14. #14
    Member Bart's Avatar
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    Re: 084 Operating Head Temps

    so I just had to pump some real oil through it and see what it would look like. not as messy as yesterday, but I plumbed it to the oil pump this time.
    I could see some streaks of oil going places. but at low rpms, & upright. it doesn't make for a good test, but at least I am seeing the general idea behind it.
    so here is tonight's video. it is a little longer and I took time to explain what was going on.
    https://youtu.be/oBg3jHWyRTY

    all in all, this has been a fun & learning experiment. as you look at the video. at one part ( about 1:49 into it.) I am looking at the # 1 piston. right below it you can see goobious amounts of oil being flung right below it coming off the #2 connecting rod, I am almost thinking, a person should have the same amount going on the other side also. into the back of the piston. it is just harder to see it with the glare from the cylinder and piston skirt.
    Kind of getting excited, man I am glad I took the time to test it this way...
    Last edited by Bart; Today at 02:02 AM.

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