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25 hrs and still running hot.

Randy

Well Known Member
My IO-375 runs hot in OATs below 60F. This is on my RV7A with new engine from Aerosport with 25 hrs on it and the rings seem to be seated as oil consumption is hardly noticeable.

If this keeps up I am going to have trouble this summer. I have gone over my baffling again and again sealing up any places where air might escape before doing it's engine cooling duty. (Washer behind #3 rear baffle etc.) I verified correct routing of the oil cooler hoses so air should not be trapped in the oil cooler. Running 8432R oil cooler on modified RV10 firewall mount, feeding it with 4" scat off the rear baffle and have 4" butterfly valve to control the air flow, it is working properly. I even made special baffle wraps to fit the tapered cylinder fins on the ECI tapered cylinders, they wrap nicely against the cyl. fins forcing the air between the fins. Differential pressure from top of engine to behind the baffles is always above 10" WC, up to 14" WC at speed with EZ Cool flaps open. Air cannot escape through the upper cowl inlet ramps, they are sealed.

I had anticipated that I would need to partially close the oil air door except in the hot temps of summer, not so. It looks like I will need to keep my EZ Cool cowl flaps open whenever I run at full power, ( I think they are especially helpful on A models as the gear tubes block the normal air exit). Even with them open, at best power mixture setting, it will heat up above my limits.

I can easily control the temps by running way rich of peak, or lean of peak, but if I run at best power, even up above 8000', oil T will head up above 200F, and CHTs will climb above 400F. Both of those are temp limits I would like to keep in place. I know some people feel OK with higher temps than that, I do not, especially with OATs as low as they have been.

I am still running mineral oil for break in, maybe I will see improvement when I change that out?

Could I still be experiencing an extra warm engine due to break in after running it hard for the first 20 hrs? I hear that the Nickle Carbide cylinders generally break in pretty fast.

Possibly related, I am running dual PMags. I set them up for max advance of 26 degrees during the first 20 hrs. Now running A curve and this change did not appear to affect the engine temperatures. During those first 20 hrs I always had more than 24" MAP, and way ROP, trying to make sure I got a good break in.

I am looking for some feedback from others with similar engine configuration that might shed light on this business. Maybe it will get better after some more hours on it??

OK same subject but different: While inspecting for problems and thinking about the heat I look at the cabin heat valve, and see that when closed, it dumps that heat right into the back side of the engine area. The heater seems to work real good in the cabin so I am thinking I don't really need to be dumping that heat near the fuel pump and PMags. So I have this idea of ducting the hot air down closer to the cowl exit. Anybody tried that?
Maybe there is enough air flow back there to get that hot air out before it contributes to heating up items on the accessory case, but who knows?

Randall in Sedona
Maybe I should just keep flying it and try to be patient...
 
cabin heat

I thought of the cabin heat also and installed a engine soft plug in the tube to stop the air flow and it didn't make any difference. I will install a ez cool. There is just not enough outlet for it to escape. My 2 cents worth.
 
Hi Randy. I have an Aerosport IO-375 with Catto cruise prop, single electroair plus one mag, and full EMS on my 7A and also battled high CHT's at first. I learned to manage my temperature and can now get the most out of the engine and plane. I find climbing to the mid teens to cross the Rocks the most challenging scenario, not hot summer days.

I think temp is an issue because RV's have little excess cooling capacity/drag, the 375 stroker creates more power/heat than a 360, and because the nose gear fittings create exit interference for cooling air. I learned to manage CHT by:
-Detailing the baffle seals as outlined in previous posts. This did not help much since my seals were not bad to begin with.
-Blocking some of my oil cooler to bring oil temps up to 180-200. This helped bring down CHT a bit.
-Adjusting my flying to meet my engines needs. Once clearing 500 AGL, I cruise climb at 110 knots, make a small reduction to throttle setting, (it gets more even temps with the throttle backed off 1/4 inch) then make an initial leaning adjustment to 200 degrees rich of peak which increases power and smoothness. I then lean slowly during the climb, targeting CHT at 350-360
-I transition to LOP about 7000 with almost full throttle, or lower for local flights with retarded throttle. (My home field is 3360, so I don't often fly below 5000) Running LOP at 50-65% power dramatically reduces CHT. I could lean more, but like to keep CHT between 300 and 330 for cruise
-I added fixed louvers but keep them closed with duct tape most of the time. I open them up whenever I pack oxygen for long trips, and find they really help cooling up high. I like your cowl flaps better.
-the EMS has shown me how amazingly sensitive the engine is to mixture, power, and airspeed, I don't think I could own another plane without one. I set it warn me if I exceed 380 CHT, and use 400 as my personal redline. I only broke 400 once when I had to take off with best power from hot, high, un-mown strip with super cub style obstacles at the far threshold

PS. I love my IO-375. It continued to run smoother and cooler until after I hit 100 hours and now burns about 1 quart every 20 hours with 230 hours
Jay
 
What exhaust system are you using.
If you open the exit it will be a drastic change.
Search on this sight for high oil temps.

Boomer
 
Randy,

Perhaps opening the exit by cutting forward 2 or 3 inches at bottom of cowl would help.

(The idea of opening the exit to facilitate moving more air is not without controversy due to increased drag, but it has always improved cooling for me which has to be accomplished to provide for reasonable normal ops. Nothing is free in this business)

The pipes and gear leg do block a part of the standard exit, opening the cowl forward does increase the exit area and air flow and improves cooling.
 
I ran the first 25 hrs or so with max timing advance at 26 degrees. When I changed over to the A curve with 35 degrees max advance at lower MAP, I saw no difference in the temps.

I do have two of the EZ Cool cowl flaps and I am sure glad to have them. However, if I move mixture to best power, with the EZ Cool flaps open, I can still watch the temps creep up to my limits of 400F CHTs and 200F oil T. Even up above 8000' this will happen.

I think those are reasonable limits, yes no?

Today I changed out the mineral oil for some Phillips XC 20-50 with a little Cam Guard thrown in. Maybe that will help a little. I have adopted the attitude regarding my operating temps that they are completely controllable via the mixture. I don't mind operating this way for awhile and maybe this engine just needs some more time. (It will get hot here in AZ pretty soon...)

Thread drift side note: My air speed was reading nearly 7Kts slow. I have flush mount static ports. Not wanting to dive in and drill out rivets etc. I have glued one half of a washer in front of each static port. I used the thicker washers, figuring if they make too big of a correction I may be able to put a tooth pick in the ports to protect them, and carefully grind down the thickness for adjustment.

So now I have two good reasons for a dawn patrol flight in the morning!

Randall
 
What is the CR of your engine?

I have an AeroSport Io-540 with 9.1 pistons, single Electroair and mag. It was spec'd as 20 degree timing.

I had a few issues with setting the Electronic ignition static timing. It was off by just 2 or 3 degrees (22 to 23 Btdc) as measured with the advance switch off. This had a substantial effect on CHT. Once adjusted to 20 BTDC as measured by the voltage output, I dropped temps by about 20F with or without the automatic advance switched in.

My conclusion is that with electronic ignitions, these engines are very sensitive to timing setup. Try dialing back your pmags to 20 BTDC and test fly again.
 
I reduced my CHTs by 25 degrees by blocking off the outboard sides of the cooling ramps.

It seems that the high pressure area was provided a huge outlet to the low pressure side by passing through the cooling ramps.

After damming the outboard sides, I now have confidence in my trip to Florida next month!

Have you done this already?

:confused: CJ
 
Try creating a custom curve on you EIC and knock the initial timing down one bump (1.4*) and see what that does for you..

Capping the max advance won't do much because in a high power setting, the timing should come down. Only during lower power settings, such as during cruise, will the P-mags advance.
 
Bill,

Thanks for the suggestion, I will try the custom curve as you suggested to see what that does for temps. As stated several times in this thread, I only experience these high temps at best power setting, and, when the timing advance was held to 26 degrees max, the temps still went high at best power mixture settings. FYI, I only go to best power mixture above about 8000' and then generally just to see if the temps are still going too high at that setting.

My inlet ramps are sealed and differential pressure from top of engine to back side is a minimum of 10" WC, up to 14" WC with the EZ Cool flaps open. Anybody want to share what their differential pressures are running? It is easy to get these measurements...

Changing to Phillips XC 20-50 from the break in oil did not seem to make any difference to my oil temps, but putting those washers in front of my flush static ports made a nice difference in my airspeed indications. Now reading about 2 knots fast, was about 7 knots slow, so I will thin them down a little and check again. Seeing the higher airspeed indications sure has a psychological impact.... at least on me:)

Another reality check I need to do is verify that my oil temp sender is telling me the truth. I will pull it and submerse it in some hot water of known temperature and compare the readouts.

Randall in Sedona
 
My IO-375 is 8:1 compression, another reason I think the temps should be running cooler...

You are right to track this down. Changing the timing will give you a datapoint. If it doesn't improve, it's either an airflow issue or just that a new engine runs hot. Keep collecting data.

One more thing. Despite the well known cooling problems called by cylinder fin flashing in the slots between the top and bottom spark plugs, the manufacturers have been slow to respond and this continues to need attention. Even my Lycoming cylinders had this problem on the Rocket, so some judicious filing/drilling was necessary.

On my RV-9a with ECI Cylinders, this single procedure reduced my measured CHTs by 30 to 40 degrees.

Good luck
 
Hey Randy,

As Bill suggested I too have been running a custom curve on my 0-360 for the first 80 hours or so. I'm running a normal A curve with a -1.4 offset. It really helped my CHT's to cool down a bit. I've not yet tried to go back to the non-offset A curve, but want to at some point to see how things change.

I also find that I need to keep the IAS up around 110kts or better in climb or the CHT's spike after a few min of climbing. It really heats up for me when I lean out to best power as I climb higher. So you're not alone there.
 
I reset my pmag just two degrees and got a large temp Delta...
It is a critical adjustment... might try it.
 
You are right to track this down. Changing the timing will give you a datapoint. If it doesn't improve, it's either an airflow issue or just that a new engine runs hot. Keep collecting data.

One more thing. Despite the well known cooling problems called by cylinder fin flashing in the slots between the top and bottom spark plugs, the manufacturers have been slow to respond and this continues to need attention. Even my Lycoming cylinders had this problem on the Rocket, so some judicious filing/drilling was necessary.

On my RV-9a with ECI Cylinders, this single procedure reduced my measured CHTs by 30 to 40 degrees.

Good luck

Hi Vern, Could you explain this procedure?
 
ECI cylinder procedure?

Does anyone have a detail description of this process, see below? Thanks, Gary

You are right to track this down. Changing the timing will give you a datapoint. If it doesn't improve, it's either an airflow issue or just that a new engine runs hot. Keep collecting data.

One more thing. Despite the well known cooling problems called by cylinder fin flashing in the slots between the top and bottom spark plugs, the manufacturers have been slow to respond and this continues to need attention. Even my Lycoming cylinders had this problem on the Rocket, so some judicious filing/drilling was necessary.

On my RV-9a with ECI Cylinders, this single procedure reduced my measured CHTs by 30 to 40 degrees.
 
Does anyone have a detail description of this process, see below? Thanks, Gary

I think what Vern is referring to is the casting flash in the fins just outboard of the spark plug hole. Very visible in this photo:



Use a series of thin and small round files, or whatever abrasive you can fit, to open up the narrow slots to the full width of the rounded area at the ends of each slot. Tedious work for sure.
 
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High oil temps

Did my maiden voyage over a year ago and had high oil temps. For a year I followed these threads and did all the things everyone suggested. New baffle seals, RTV around them and anywhere else air could escape, new cooler, Anti splat cowl flaps, remote mount oil filter (with cooling fins) and even split the rear heater 2" scat line to blow on the filter. Tested oil temp sensor in boiling water and replaced it anyway. At this point I relocated the oil temp sensor to where it should have been all along on the adapter instead of the engine. At least Air Wolf filter relocation kit specifies to do this with their adapter, others probably do also just don't have paperwork.

Different engine but AeroSport Power IO-540, worth a try... good luck
 
2nd oil cooler sure helps!

To recap, my setup is IO-375, low compression, RV7A, EZ cool cowl flaps, vernatherm removed and oil plunger installed. I have checked all the normal things to check to trouble shoot high oil temps and finally put 2nd cooler in, somewhat out of frustration, and partially as an experiment to see if it would at least temporarily solve the problem, and it did. In fact I would say it did more than I expected since the oil is partially cooled before getting to the 2nd cooler the temp delta and thus cooler efficiency is not as good.

It does seem a little weird to have a 4" hole behind #4 and another 3" hole behind #3 in the rear engine baffle feeding to the coolers, oh well, for now it is a workin!

Anyway, against the advice of most anybody I talked to about my oil and engine temperature issues, I finally installed a 2nd oil cooler, and I like the results.

The 1st cooler is the 8432R dual pass cooler fed with 4" scat on RV10 firewall mount. The new 2nd cooler is an inexpensive Positech P2000C model (I think I got that right), 6 row cooler.

I have adjusted my oil pressure to run at the Aerosport specified 80 PSI at 180F and 2400RPMs.

The new cooler is mounted on the passenger side to engine mount tubes, and fed with 3" scat.

Before my temps would shoot past 200F very easily and when I tried to live with a limit of 220F I learned that the oil temps would not stabilize below that temp either.

I have oil squirters on an IO-375 so there is reason to expect about 20F increase over an engine without the squirters I am told by the tech rep at ECI.

So the results are that I can now keep the oil temps under 200F in normal flying conditions and do so fairly easily. I use the 4" butterfly valve on the first cooler to bring the temps up as needed. It sure is nice to actually use that valve for a change! It works great and the results of adjustments can be seen fairly quickly on the engine monitor. Our OATs have fallen in the last week so I have not had the chance to check it out in high OAT conditions but the difference from operating with one cooler is significant.

I am not really recommending that others take this route. As Dan H said on a previous post, something must be whacked in my install. This does at least give me another data point to learn from and I really like being able to run my engine at best power setting for long periods of time if I want to. Before the 2nd cooler I basically had to run lean of peak or way rich to keep temps where I wanted them.

Perhaps I will make a better air feed situation to my first cooler to see if I can improve things enough to eventually remove cooler #2, but for now it is letting me move on to the next big phase, paint. I had held off on this in case I needed to get some outside air to solve the problem.

If as reported, the 8432R drops oil pressure 15 PSI, and a normal cooler another 3 PSI, I may now have an 18PSI or so pressure drop across my two coolers.

I need to study the oil routing diagrams more to fully understand the effect of the pressure drop issue. Perhaps for another post...
 
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