912 overheating after maintenance

Nick wrote:

Hi Jeff,

The front two cylinders 1&2 are still wrapped.

The mechanic said we can remove the wrap. They have been wrapped for the last 5 years atleast. 

Will these high temps harm the engine? It looks like I’ll have to fly the plane at least 1 hr to a rotax mechanic.

Wrapping exhaust pipes/headers is not for the benefit of the engine as such (& is against Rotax recommendations).

Wrapping, a form of heat shielding,  is usually done to protect other structures/systems from the exhaust heat.

I have found that home made heat shield, using automotive exhaust wrap, silicon glued to one side of builders soft aluminium flashing (from any hardware store), can be employed to protect vulnerable pipes (use double wrap safety wire to secure in place) and even silicon glued to the inside of the engine cowling adjacent to exhaust pipes - works extremely well.

Cut aluminium to size/shape with industrial scissors. Cut strips of exhaust wrap to suit (best if wrap a bit short on all sides). Apply liberal amount of high temperature silicon to one side of aluminium and one side of exhaust wrap strips. Press glued sides together. Leave to cure at least 12 hrs. Can be rolled/formed/trimmed to contours/tubes etc.

If going around a pipe or similar - secure with double wrap safety wire,  in at least two positions (more for longer shield)  before twisting tight. 

If fixing to inside of cowling, use isopropanol/paint thinner/etc to remove all grease from area to be protected - apply liberal amount of high temp silicon and press/form your shield to contours - leave 12 hrs to cure.

If he didn't have this overheating issue before the maint. then the cause can easily be because of the maint. and he should take a hard look at anything the mechanic did and not necessarily try to find some new cause.

Nick,

Regarding flying your plane 1 hour to the mechanic with these temps, check your aircraft and engine operating manuals for the limits.  I believe Rotax lists the limits for the F series engine as follows:

Max oil temp : 285 deg F

Max coolant temp : 248 deg F

Max CHT : 300 deg F.

So technically it looks like you would be in the limits with the temps you reported, but it’s a personal call.  It’s not fun to fly a plane that you know has something going on.  

The mechanic had installed DCPR8E

rotax calls for DCPR7E

Havent flown it since swapping the plugs.

Changing the spark plugs didn’t fix the temp issue.

reading through lots of posts on overheating seems like almost everyone is reporting some issue with the cooling system.

I’m going to determine if the water pump is working properly. Check hose clamps and make sure there aren’t any unplugged vac lines. 

I know the mechanic had removed the radiator and oil cooler to test them for leaks. How can we eliminate this as a possible cause?

I there a method for purging air out of the cooling system?