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Cylinders turning pink?

astjp2

Registered User
Utah/Alaska
Ok, I am used to seeing exhaust leaks giving a brown or yellow dusting, but I have been working on 2 different aircraft and both have had cylinders where the paint is turning pink. Once has a full engine monitor and CHT's are reported as normal, the other has no monitoring and most of the head is turning pink on the upper surface away from any exhaust or intakes ports. So I have only ever seen this on these 2 airplanes, one is a 360 Lycoming the other is a 65 Continental. I almost feel that it is an indication of overheating and when I pulled the exhaust on the lycoming, the gasket was showing a good seal...so I am not sure how to proceed. Tim
 
Oh the Lycoming also has a bent exhaust pushrod on the number 4, so I get to clean the exhaust guide with a reamer next Saturday...Cylipinders came from overhaul last year and have almost 400 hours. Intake on the number 3, I pulled the spring and used some lapping compound because it was discolored and had evidence of blow by. The stem also had a large buildup of carbon/lead that I was able to scrape off. Fun times yesterday.
 
Stock Lycoming, rebuilt by a shop on the midwest. Actually they are ported and polished by some other shop when they were new 2,200 hours ago
 
So, I ran my O-200 for 20 years, never had a cylinder off. Overhauled it with new Millennium cylinders, 200 hours in all compressions were around 20 due to carbon/lead on exhaust seats and in guides. Didn’t change the way I ran it, can’t figure out why. Reamed all guides and lapped seats. We’ll see what happens going forward.
Sorry, don’t want to hijack your thread just thought I’d ask.
 
Here is a picture of the issue
 

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All 4 are discolored to some extent, front 2 are not as bad as #3&4, 3 had an intake valve leak that I lapped in and 4 has the pushrod that is bent. I will probably ream the intake guide on 3 and the exhaust on 4, there was a lot of buildup of crud on the #3 intake which I scraped off. I dont have the $3000 lycoming tool to check the wiggle, but I do have a set of pin gauges and ball hones...which is acceptable for the intake and a reamer for the exhaust.
 
On every Diesel engine I’ve overhauled the exhaust manifold/s gets a good coat of engine paint
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....they all turn pink.


Sent from my iPad using Tapatalk Pro
 
Were both of the engines cylinders overhauled by the same shop? If so, then perhaps it is just the paint they used which could not stand up to the heat?
 
2 different engines from 2 different parts of the country, the Continental came from the east coast and moved to New Mexico and now Nevada. The other engine came out of California.
 
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