582 0verheating issue

[brilin_air]

Is the Bolly prop heavier than the Brolga ?

 

 

[pudestcon]

I don't suppose Rotax have quietly changed the port timing or areas? Could they have restricted the muffler to meet some whacky european noise standard? If the muffler bleed-off rate through the stinger has been reduced, it's a fair bet your pistons are too hot. Might they have tried to compensate by upping the compression? ...another sure way to increase temps.Yes, a long shot but we're getting desperate here!

Aw, heck. Give 'er a port job and knock up a set of 'spannies. That'll get er crackin' !

You are talking a language I don't understand Nong!!

 

I don't believe Rotax would be doing any development/improvement work on the 582 which is the same beast since 1999. I appreciate your suggestions though. I strongly suspect it is something simple I have missed, and to find it is a simple method of elimination. Which is why I am, and will be trying any and all suggestions that are reasonably practicable for me to do.

 

Here's another idea I only thought of last night. On the old engine the exhaust had a turned up outlet so the exhaust gases were expelled upwards, thereby missing the wing. The new exhaust just had a short straight stub which would expell exhaust gases straight onto the wing. So I cut the upturn end off the old exhaust and fitted it to the new one - length of upturn extension about 2" or 50mm. Have a look at the photo and tell me what you think.

 

 

Whilst you are looking at the photo take a gander at the radiator setup. A mate of mine - Runt we call him - has suggested I remove the overflow bottle from between the radiators as this could be causing an interrupted airflow to the radiators and engine. So I'll remove it next time I'm at the airfield.

 

Pud

 

 

[turboplanner]

Pud, the chamber tail pipe is (or should have been) tuned for diameter and length to maintain pressure in the chamber so the shock wave bounces correctly in time with the exhaust phase and scavenges the exhaust gases.

 

Diameter is more critical than length. If you've increased diameter, then power could be down, and it would pay to check the length compared with the original (I always work to +- 1 mm (In a curved pipe the length is the average length around the curve).

 

However, I couldn't see this affecting the engine so much.

 

Of all the posts TerryC's #8 looks the most likely to me since he had your problem exactly and fixed it.

 

Water temperature in a two stroke is the byproduct of other factors. I found on race engines you can cool them all you like but it's the hundreds of degrees in the chambers which count, not the tens of degrees in the water.

 

Two things will seriously add heat to the chamber:

 

(a) High engine load, which will also lower achievable rpm. (A boat left trying to push up on to the plane for too long, high headwind in top gear in a bike etc)

 

(b) Main jets too lean

 

I'm hesitating here to recommend you chage anything, mindful that the result could make things worst and blow a piston.

 

However, for (a) Terry C's suggestion will produce less load (providing as others have commented, you are using the same prop as him)

 

For the main jets, I'd pull them out and check the stamping on them and make sure they are the numbers shown in the Rotax workshop/service manual.

 

It wouldn't be the first time someone got two different jet sizes, or jets which were meant for some other Country or Application.

 

Having done those two things I'd be talking to Rotax for the solution rather than any of us because of the thousands of dollars at risk.

 

 

[brilin_air]

I am not too familiar with the design of this aircraft but there looks to be no shrouding for the radiators and the air would take the path of least resistance and wash around the radiator instead of being forced through it ? Maybe leave the bottle where it is and slightly deflect the radiators inwards to get more airflow through them.

 

 

[Methusala]

Pud, my exhaust is turned up in the same way as yours and has been on both engines. I don't think this will affect performance. My egt's show a difference of about 50deg C even though both carbs are jetted identically. Cht's are around 85-90 on full power but coolant temp doesn't go above 70. I have slight leakage of exhaust at the face between barrels and manifold I will try sealing this afternoon. Again my little addition to the thread. Don

 

 

[turboplanner]

The bend in the exhaust plays no part in power production, it's the operation of the chamber which is critical, so it's tube diameter and length which have to be checked.

 

 

[Tex]

My egt's show a difference of about 50deg C even though both carbs are jetted identically. Don

50deg C?

 

Just checking?

 

 

[Methusala]

Yes Tex, this afternoon my friend and I flew and at 50kts and 5850rpm the egts showed 523 and 552. This is 30 odd degrees but the difference can be up to 50 deg. Also, the rev drop at 3000 is about 120 on one mag and 230 on the other! All very curious. I hope that this information can be of use. The previous engine was a grey head that had done 700 or more hrs although it had been top overhauled twice. I only changed engines because I thought the blue head would be a safer bet. I'm running out of ideas, maybe measure compression for difference between cylinders next. Don

 

 

[turboplanner]

Two strokes are very sensitive to spark Don. If the highest temperature cyl is the one with the biggest rev drop, I'd almost be certain you need to do a test on the connections, wiring and coil on that side.

 

 

[SAJ]

You are talking a language I don't understand Nong!!I don't believe Rotax would be doing any development/improvement work on the 582 which is the same beast since 1999. I appreciate your suggestions though. I strongly suspect it is something simple I have missed, and to find it is a simple method of elimination. Which is why I am, and will be trying any and all suggestions that are reasonably practicable for me to do.

Here's another idea I only thought of last night. On the old engine the exhaust had a turned up outlet so the exhaust gases were expelled upwards, thereby missing the wing. The new exhaust just had a short straight stub which would expell exhaust gases straight onto the wing. So I cut the upturn end off the old exhaust and fitted it to the new one - length of upturn extension about 2" or 50mm. Have a look at the photo and tell me what you think.

 

[ATTACH=full]17296[/ATTACH]

 

Whilst you are looking at the photo take a gander at the radiator setup. A mate of mine - Runt we call him - has suggested I remove the overflow bottle from between the radiators as this could be causing an interrupted airflow to the radiators and engine. So I'll remove it next time I'm at the airfield.

 

Pud

G'day Pud.

I had the same problem with my silver head 582 T500 when I first started flying it. I had the smaller radiators on my 582 where as a friend of mine had the larger radiators on his and he had no problems with over heating. I mounted one of the small radiators my friend still had off his engine horizontal up under the gearbox and my overheating problem was gone, I also made up a flap that I could activate from the cockpit to cover the third radiator in flight if the engine got to cool, works great. If I knew how to upload pictures I would show you a picture of my setup.

 

SAJ

 

 

[pudestcon]

G'day SAJ,

 

To upload a photo click on the "Upload a File" box under where you type to submit a post - it's on the right side next to "Post Reply".

 

You need to ensure the photo file is small enough to be accepted. If it's too big you will get a red error message about the file being too big. Just resize the photo and try again. I'd be interested to see your setup.

 

Cheers,

 

Pud

 

 

[pudestcon]

Tonight I’ve been trying to get my head around where I am with the under revving and overheating issues with my blue head 582. Here’s where I’m at and what I’ll be doing next time I’m at the airfield….

 

Summary of known conditions in no particular order-

 

· Propeller. 12* pitch blocks on a 3 blade composite 68” Brolga prop, powered by a 582 blue head Rotax engine through a “B” reduction box 2.58:1 gearing. Propeller is second hand but in good condition. Number 1 blade weights 2 grams lighter than the other 2. Number one blade tracks 10mm to the rear of the other 2 blades at bottom centre of the propeller arc. No facility on this type of setup to adjust propeller blade tracking.

 

· Maximum revs 6200 WOT ever since brand new including during run in phase.

 

· Engine prone to overheating ever since new with temps wanting to climb through 80*c including during run in phase.

 

· The Bing 54 carburettor slides show synchronised and full movement through the entire throttle lever range. WOT position shows slide as wide open.

 

· Engine idles at 2000 RPM with vibrations felt until revs increased to 2200.

 

· Engine has 30 hours since new, as shown on electrically activated hour meter – true running hours possibly 27 or so.

 

· Tacho and water temp gauges are confirmed as reading accurate.

 

· Thermostat is confirmed as operating correctly.

 

· Enrichening circuits (choke) on the carburettors are functioning correctly with complete de-activation when levers returned to the ‘Off’ position. Engine starts with no trouble.

 

· All 4 spark plugs exhibit consistent tan/light brown colour, indicating correct fuel/air mixture.

 

· EGT gauges at 6000 RPM read 1100* identical on both cylinders.

 

· Engine runs on Caltex unleaded 91 Ron fuel at 50.1 mix with Castrol Active 2T 2-stroke oil.

 

· Air cleaners were brand new with the engine and are in as new condition.

 

· Carburettors were brand new with the engine and have not been altered in any way, or checked for synchronisation apart from visual inspection of slide operation on both carburettors.

 

· Exhaust system was brand new with the engine and has been slightly modified. Where the gases exhaust to outside air a 50mm long (or thereabouts) curved pipe has been added to direct the exhaust gases away from the wing skins. See photo in post # 52

 

· The 2 part radiators are the smaller version radiators from the old grey head 582 installation. New radiators were not purchased with the new blue head 582 engine.

 

 

Things to check when next at the hangar-

 

· Remove overflow bottle from the radiator coolant circuit to check if there is airflow interference from the bottle interrupting airflow around the radiators and engine. See photos.

 

· Fully inspect and check carburettors set up – All jets and needles, float levels, position of needle clip retainer in needle groove, position of white plastic retainer is above needle clip, pneumatic synchronisation of both carburettors, and full throttle slide movement (again).

 

· Fit larger test radiators on loan from Riley to ascertain benefit from larger radiator capacity.

 

· Check ignition pick up gap and timing of ignition.

 

Is there any other checks I should do at the same time?

 

Pud

 

 

 

 

 

[robinsm]

Do you have the bleed tube attached to the front top of the head on the 582 (going back into the radiator). There may be a large air bubble sitting there if the tube is not in place causing the overheating issue. Do the egt's vary in flight or is that a static reading.?

 

 

[pudestcon]

Do you have the bleed tube attached to the front top of the head on the 582 (going back into the radiator). There may be a large air bubble sitting there if the tube is not in place causing the overheating issue. Do the egt's vary in flight or is that a static reading.?

The bleed tube is attached from top of the engine head to a 't' piece in the 1/4" horizontal pipe connecting the 2 radiator halves at the top. In the photo post #62 you can see the black tube connecting from the cylinder head to the 't' piece.

The EGTs vary in flight depending on what RPM setting I am using at the time. I don't have EGT readings at the different RPM settings for you though. I can tell you they are always consistent on both cylinders.

 

Pud

 

 

[facthunter]

Does the last part of the throtle opening make much difference to the revs?

 

When you reduce to cruise power what happens to the EGT?

 

Have you tried it without the thermostat? ( I'm not suggesting that you leave it out long term). Nev

 

 

[pudestcon]

Last part of throttle movement has no effect on revs, and when reducing from wide open throttle there is no reduction in revs at first. There is full movement of the slide to the end of the throttle stick movement though - give or take a few millimetres.

 

The EGTs reduce a little I think - not a definitive answer here because I need to check to be sure.

 

I haven't tried it without the thermostat for 2 reasons - the thermostat is operating as it should, and removing the thermostat also removes the gasket seal. The seal is provided by a purpose moulded 'O' ring that attaches to the thermostat and engages in a rebate. To run without a thermostat would require making up a temporary gasket. I think there are a few things to try before that though. I'm leaning towards the overheating being caused by the smaller radiators - some people are probably saying this is a 'no brainer' and should have been tried first. Just remember I have only recently become aware of the larger size radiator requirement, and will try this out at the next visit to the hangar.

 

Pud

 

 

[turboplanner]

A few mm make all the difference - the slides should be wide open (checked visually) - you may just have a slight throttle cable adjustment to make.

 

 

[pudestcon]

A few mm make all the difference - the slides should be wide open (checked visually) - you may just have a slight throttle cable adjustment to make.

We will see TP, next time I'm at the hangar all things suggested here, if at all possible, will be tried. We will get to the bottom of the issue(s) sooner or later.

Pud

 

 

[facthunter]

The fact that the last bit of throttle makes no rev difference means the load ( Propeller) is too much for the engines torque. Can you borrow a proven prop.? Just because the prop is a such snd such and the blocks are set at a certain angle is not enough. This will hilight the possibility of the engine being down on power., and will check if the prop is the problem. IF a prop does a certain ststic revs on one motor and not as many on yours, your engine is down on power..Nev

 

 

[Blueadventures]

We will see TP, next time I'm at the hangar all things suggested here, if at all possible, will be tried. We will get to the bottom of the issue(s) sooner or later.Pud

Hi Pud

Firstly I'm no expert on this aviation application of the engine. You may have done the following already, as the temp and rpm units may not be calibrated an electrical gremlins could be some of the problem; have you got temp readings from say a laser temp gun and checked rpm with a handheld sensor device (you would have to put a white or shinny marker on a prop blade to get a reading. (Even local aero modelers or drive shaft engineering people may lend you one, not likely, but may do.

 

What's the climb out and cruise proformance like, forgetting for thirty seconds, what the guages are displaying.

 

Hope this is of some help. Not being current with your replies totally, apology in advance for any confussion I have about this matter.

 

Cheers

 

Mike

 

 

[pudestcon]

The fact that the last bit of throttle makes no rev difference means the load ( Propeller) is too much for the engines torque. Can you borrow a proven prop.? Just because the prop is a such snd such and the blocks are set at a certain angle is not enough. This will hilight the possibility of the engine being down on power., and will check if the prop is the problem. IF a prop does a certain ststic revs on one motor and not as many on yours, your engine is down on power..Nev

Could no extra revs also be attributed to no extra capacity (fuel) from the carburettors - I'm thinking main jets too small or blocked, in effect, governing the engine? I'll keep your idea in mind Nev. Thanks.

Pud

 

 

[pudestcon]

Hi PudFirstly I'm no expert on this aviation application of the engine. You may have done the following already, as the temp and rpm units may not be calibrated an electrical gremlins could be some of the problem; have you got temp readings from say a laser temp gun and checked rpm with a handheld sensor device (you would have to put a white or shinny marker on a prop blade to get a reading. (Even local aero modelers or drive shaft engineering people may lend you one, not likely, but may do.

What's the climb out and cruise proformance like, forgetting for thirty seconds, what the guages are displaying.

 

Hope this is of some help. Not being current with your replies totally, apology in advance for any confussion I have about this matter.

 

Cheers

 

Mike

Thanks Mike, all of what you mention has been verified as far as correct gauge readouts for RPM and water temps. I believe the climbout and cruise performance is ok, certainly no marked change from the training T500 I did my endorsement in. My T500 cruises at around 55kts 1 up with 5200 revs on the tacho.

Cheers,

 

Pud

 

 

[pudestcon]

The fact that the last bit of throttle makes no rev difference means the load ( Propeller) is too much for the engines torque. Can you borrow a proven prop.? Just because the prop is a such snd such and the blocks are set at a certain angle is not enough. This will hilight the possibility of the engine being down on power., and will check if the prop is the problem. IF a prop does a certain ststic revs on one motor and not as many on yours, your engine is down on power..Nev

The last bit of throttle making no difference to the revs could also be caused by the carburettor not releasing more fuel too, couldn't it Nev. I'm thinking main jets too small or blocked main jets. This would have the same effect as "governing" the engine wouldn't it? I'm not sure I can get hold of a propeller to try what you suggest but it's a thought I will progress a bit further along the elimination process. Thanks Nev.

Pud

 

 

[SAJ]

G,day Pud.

 

Here are a couple of photos of my radiator setup, the push pull handle on the left of the dash is for the radiator flap.

 

With your tracking problem, I was told in my early days when flying a skycraft scout that if your prop was out of track you could put a shim of some sort behind the blade that was back, seeing as you only have one blade out of track you should be able to put a shim behind it to push it forward.

 

My engine only rev,s to 6000 WOT has done ever since ive owned it, I thought that was the norm until I was told I should be getting about 6500 to 6700. I have 15% pitch block and my carbies are good, Ive never worried about it, it gets of reasonabley quick, climbs out ok, cruises at 50 kts indicated at 5400.

 

SAJ

 

 

[SAJ]

Pud I hit post reply befor I had put the photos in, having down trouble down sizing photos, when I work it out I will send them to you.

 

SAJ