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Engine Question

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dabear

Joined: 21 Jan 2011
Posts: 92
Location: Warrenton, VA

Posted: Mon Aug 15, 2016 6:53 am Post subject: Engine Question

Yak Folks,

Note: I don't have a CJ6 anymore.



But I know someone who just over temp'd his engine.  For about 5 min the 

CHTs in 4 cylinders were over 460F/420C and 2 reached 489F.  The engine 

is now running rough on the ground.  He is not flying it until fixed.



So, what is the consensus?  OH the whole thing?  Replace the Cylinders?  

Throw it in the trash and buy new?

Bear

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pa3arw(at)ziggo.nl
Guest

Posted: Mon Aug 15, 2016 7:16 am Post subject: Engine Question

In my humble opinion as a European I believe that 460F is NOT 420C but: 238

degrees...that is a lot different than 420C... 

I have had that as well and it gave no problems what so ever. According to

our engineer what happens after a "real" high cilinder head temp is that the

valve sockets are severely damaged and an exceptional high consumption of

oil will be the result. If that is not the case have the compression checked

and fly on....assuming that the 238C is correct, which is not an exceptional

temp. There is no stronger engine than the M14P.



Fly safe.



Hans O.

Op 15-08-16 16:53, DaBear(at)damned.org <dabear(at)damned.org> schreef:



 	  Quote: 	
		   

 

 Yak Folks,

 

 

 Note: I don't have a CJ6 anymore.

 

 But I know someone who just over temp'd his engine.  For about 5 min the

 CHTs in 4 cylinders were over 460F/420C and 2 reached 489F.  The engine

 is now running rough on the ground.  He is not flying it until fixed.

 

 So, what is the consensus?  OH the whole thing?  Replace the Cylinders?

 Throw it in the trash and buy new?

 

 

 Bear

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dabear

Joined: 21 Jan 2011
Posts: 92
Location: Warrenton, VA

Posted: Mon Aug 15, 2016 7:32 am Post subject: Engine Question

yes, sorry mistype... 464F/240C

On 8/15/2016 11:15 AM, Hans Oortman wrote:

 	  Quote: 	
		   



 In my humble opinion as a European I believe that 460F is NOT 420C but: 238

 degrees...that is a lot different than 420C... 

 I have had that as well and it gave no problems what so ever. According to

 our engineer what happens after a "real" high cilinder head temp is that the

 valve sockets are severely damaged and an exceptional high consumption of

 oil will be the result. If that is not the case have the compression checked

 and fly on....assuming that the 238C is correct, which is not an exceptional

 temp. There is no stronger engine than the M14P.



 Fly safe.



 Hans O.

 Op 15-08-16 16:53, DaBear(at)damned.org <dabear(at)damned.org> schreef:



> 

>

> Yak Folks,

> Note: I don't have a CJ6 anymore.

>

> But I know someone who just over temp'd his engine.  For about 5 min the

> CHTs in 4 cylinders were over 460F/420C and 2 reached 489F.  The engine

> is now running rough on the ground.  He is not flying it until fixed.

>

> So, what is the consensus?  OH the whole thing?  Replace the Cylinders?

> Throw it in the trash and buy new?

> Bear

>

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wlannon(at)shaw.ca
Guest

Posted: Mon Aug 15, 2016 8:33 am Post subject: Engine Question

Replace or overhaul the two high temp cylinders.   If overhaul, ensure the 

cyl. is checked for out of round, correct choke etc., and pistons NDT 

inspected.

Five minutes is a very long time at 254 deg.C.

Operating range for the Huosai is 120 to 230 deg.C,  normal cruise in the 

range of 150 to 170,   T/O and climb 170 to 200.

Unlike  P&W,  Huosai does not give a short term Max. allowable.  The P&W 

limit is 260.



Being Canadian I no longer recognize or understand that other strange (may I 

say goofy?) means of describing temperature.



Cheers;

Walt



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GeorgeCoy

Joined: 02 Dec 2010
Posts: 310

Posted: Mon Aug 15, 2016 8:46 am Post subject: Engine Question

It is my understanding that the severe overtemp can cause the interference fit between the aluminum head and the steel barrel to fail in the future. I recommend replacing the cylinders. We have seen this in the past.

George



--

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pa3arw(at)ziggo.nl
Guest

Posted: Mon Aug 15, 2016 9:19 am Post subject: Engine Question

I apologize Bear..I thought it concerned a M14P but you were talking about a

Housai....Forget what I said with exception of the conversion into

Centigrade... 



Hans O.

Op 15-08-16 16:53, DaBear(at)damned.org <dabear(at)damned.org> schreef:



 	  Quote: 	
		   

 

 Yak Folks,

 

 

 Note: I don't have a CJ6 anymore.

 

 But I know someone who just over temp'd his engine.  For about 5 min the

 CHTs in 4 cylinders were over 460F/420C and 2 reached 489F.  The engine

 is now running rough on the ground.  He is not flying it until fixed.

 

 So, what is the consensus?  OH the whole thing?  Replace the Cylinders?

 Throw it in the trash and buy new?

 

 

 Bear

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Lancer

Joined: 21 Apr 2016
Posts: 30
Location: Cairns, Australia

Posted: Tue Aug 16, 2016 5:11 pm Post subject: Re: Engine Question

The first place I'd start with is to do a compression test or a leakdown test. That will give you a good idea of the sealing ability of the rings/valves etc



Following that, pull the cylinder that is showing the least compression/highest leakdown and inspect the piston, rings and cylinder to see if the piston has been galling the cylinder (swollen too much and started scraping the cylinder wall). Next remove the valves and inspect them and inspect the valve seats for burning and to see if they have become loose in the head. There is also the possibility the head could start leaking where it screws onto the cylinder and I'd inspect it for signs of leakage. 



Repeat in order of next lowest compression/highest leakdown 



Then it becomes a matter of economics as how to proceed from there. if you need to replace 9 cylinder kits it could very well be a better option to start looking for a replacement but I wouldn't do anything until I checked first. It could be there is only a few damaged cylinders and could be a viable repair option



Regards,



Lance

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