asking for help on this overheating problem on Extreme

[flytech]

hello, i'm new to HF but have read many posts here. i noticed it's very MA dominant here which makes me a bit more confident in posting this problem:

pls help - i can't figure this out:

4-5 wks ago, fuel has been running through the MP2 of the OS91CspecPS more so than my other 90 (same engine/muffler). this is seen from the fuel spitting out at the muffler end. figured this may be okay sine i was already at around 1.5 turns out..

2 wks ago the MP2 started getting very hot after flights.

this past wknd, the muffler sounded very noticably louder than usual, i plugged the end slightly while running and it sounded like the loudness was coming from the engine.

also.. i noticed some strange chaffing right above the lower clutch assemby (aka 120-28). when pulling the engine i noticed all 3 dampeners (0546-6 and 0546-16) were toast (appear to be melted)

the engine had been running at decent temps throughout this time (usually by feeling around the pump and head area - though never sure without direct access to the backplate) except for the pipe which was often very hot. i tried richening it up and got up to 2 turns but it still came back very hot.

right now it can barely hold an idle and so i ordered front/rear bearings to replace and hopefully might be the cause of the loudness but do you think the perry pump on this PS is going bad? or what do you think?

engine is used and was told it rec'd the cat-eye mod.

any ideas you can point out? thanks in advance for any advice..

[WayneBrown]

Sounds as if the bearings are toast.
If you've been running with damaged dampers for a while, you may want to check the clutch bearings and starter shaft bearings as well. The dampers can explain the sounds, not the heat.

[capebob]

0546-6 is the lower collet and if that is melted looking then your fan was slipping and that would account for the heat. Also, I'm with Wayne in thinking that the engine bearings are bad and there is a possibility of the bearings in the clutch/starter shaft assembly should be checked.

Bob

[flytech]

great info, thank you both very much. do you think the worn engine bearings have anything to do with the over-heating muffler (i wouldn't think so) !?!? it seems coincidental but don't see the relation..

[DavidH]

Yes worn engine bearings can cause the muffler to heat hotter than normal. The worn bearings will usually cause the engine to run leaner, which in turns heats the exhaust hotter than normal.

The muffler is normally very hot anyways right after a flight. I have a few Hatori brands and MP II brands from letting the muffler touch against me right after a flight.

David

[flytech]

awesome, what a relief anyways. thanks, this place oozes with experience.

[capebob]

I have a few Hatori brands and MP II brands from letting the muffler touch against me right after a flight.

Hehehe! I have a Fury and a Stratus and with the muffler being on opposite sides I've managed to brand both legs more than once.

Bob

[flytech]

yikes..

well, it's looking more and more like i need to do a bearing replacement on the clutch assembly (part 120-28 - click below link for reference) which means it needs to be taken apart. i've never done one.. is there any tips on it? i'm sure it's no big deal..

also just a slight correction for later on-lookers. i mentioned 0546-6 above but after getting the parts from zoom's just now see that it's really 0546-3 "Pivot Ball/Isolators (New Style) which doesn't seem to be listed here http://www.ronlund.com/extreme/fe_engine.htm

thanks again all... :)

[capebob]

You're right it's no big deal, but you'll need some special tools. The clutch threads onto the shaft. To remove the clutch you need to either make a special wrench or modify MA's fan removal tool. Pad the jaws of a vice and place the pins of the clutch driver in the vice. Using either the tool you made or the modified clutch removal tool unscrew screw the clutch. A little heat with a heat gun will help here.

After unscrewing the shaft you will need to press out the shaft with a small press. After the shaft is removed there are two bolts to remove and then the bearing can be pressed out of the bearing block. A little heat will help here also.

To reassemble, clean all surfaces with acetone. I use a little Loctite 680 retaining compound on the bearing outer race, heat the bearing block with a heat gun and push the bearing in by hand. If you have to use a press for this operation be careful to only contact the outer race or you will damage the bearing. The two flat head screws are next installed with a little blue or green #290 Loctite. These screws should only be snugged up so as not to distort the bearing.

Next install the start shaft in the bearing using a bit of retaining compound. The clutch and washer are are next installed using the either the tool you made or the modified fan removal tool.

If this seems like too much you can send the assembly to MA and they will l repair if for you for a reasonable amount.

The tool that you need can be made out of a piece 1"X8"X1/8" aluminum. Drill two holes in the aluminum the same distance apart as the holes in the clutch, the closed holes not the holes at the end of the slots. Then install 4mm bolts through the holes. Either threa the holes at 4mm or back the bolts with nuts. I got my press at:
http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=6970&productId=35091&R=35091

Good luck with your project.

Bob