DA 100 overheated cylinder heads

[FastnLow]

I had some repair work done on my DA after a crash. The service report had it running well at the end of the repairs on there test bench. I havent run it yet since getting it back (no plane). They mentioned to me on the phone that my cylinder heads were blue from over heating and that if I wanted to they could replace them or I could run the motor as is. Did I make a mistake saying no to the repairs? I was stupid not to ask at the time what effects the overheated heads may have long term. Opinions?

[Reza]

You should've asked if there was any loss of RPM due to that? If there was, then I think you should've had it replaced. DA normally doesn't recommend a repair if there is no need for it at all.

[3ddd]

running blue makes no sense at all.aluminum alloy doesn't turn blue from heat.da and 3w aluminum turns pinkish from heat and if you run it cooler it will go back to original color.if you are talking about the header pipes blue don't hurt them ether as long as you don't keep doing it

[en1]

My question would be did they replace the rings and or pistons, If there was no cylinder damage to the cylinder walls as the DA cylinder and head are all one piece, there should be no problem using them I would be more concerned that the rings have lost thier tension to the cylinder which can be caused by overheating and cause a loss of compression, If they said it will run that way, richen the high speed mixture and run it ....

[FastnLow]

According to the service report the engine ran 6170 rpm with a 25/12 3 blade,pefa exhaust. You are right 3ddd they look more pinky/purple than blue.

[flyin woodbutcher]

slight PINK is the sign of a well tuned/running DA. All mine start to show this after about 10 or so gals.

FWB

[3ddd]

look inside cylinder ports with a flashlight.if you see blueing in there then you have a problem.but i would mix 50;1 belrey or any good iol of your choice and tune it to max on topend and then detune it 300 rpm,set the lowend proper with almost no burrble at 1/3rd throttle and fly the hell out of it.it will ether be ok or you will notice a slow drop in rpm over time meaning the rings need replacing and are passing gas.da might have already changed the rings when they put back together,if so fly it

[FastnLow]

I think I will leave it be until it gives me a reason to get new heads. DA changed out one piston(worn out piston pin bore) but I don't know about the rings because they are not listed on the service record.I would assume they would change them but I'll get a hold of them tomorrow and find out.

[3ddd]

they probably did so i would run it like new for a gallon or two

[rcign]

This stuff gets better all the time...BLUE cylinders from heat ?
Pink cylinders ?
I just took a broken fin from a 3w cylinder and MELTED it with a Mapp gas torch...The molten mass never changed color, it's now solidified and still looks like it did before...No blue, no pink....
The person who said the cylinders were blue should maybe tell us poor uninformed masses how aluminum can turn blue....

[sensei]

	Quote: Originally Posted by rcign
	This stuff gets better all the time...BLUE cylinders from heat ? Pink cylinders ? I just took a broken fin from a 3w cylinder and MELTED it with a Mapp gas torch...The molten mass never changed color, it's now solidified and still looks like it did before...No blue, no pink.... The person who said the cylinders were blue should maybe tell us poor uninformed masses how aluminum can turn blue....

I don't know about any blue cylinders young fellow, but they sure will turn pink....

Bob

[RTK]

I was always under the impression that the pinking was from a solvent/agent used in the manufacturer of the DA cylinders. It was not intentionally used to make cylinders pinkish when hot, but that was a side effect. I could be all wet though.

[Temptation]

The cylinders on my DA 150 have a slight pink color to them, but rcign said that can't happen, so I must be color blind.

[3ddd]

i am surprised you would make such a statement rcign as you supposedly have alot of experience with engines.the blue is bs ,aluminum will not blue and molten aluminum when cooled will not be any thing but a dull color but a 3w or da cylinder will pink if the temps get too high.myself and countless others have seen this so i won't even argue this with you

[rcign]

I have seen the pink, so that's why I melted the fin...Didn't turn color at all....
If the color comes from a solvent, maybe the cylinders should be cleaned better after machining....The fin I had was from an old cylinder, maybe the solvent already turned pink and disappeared....
Maybe the 3W factory could enlighten us ?