earlwb

You can still examine your ruined glow  plugs more closely using a jeweler's loupe or something to see what the coil element looks like. Duke Fox's article above explains what to look for.

My rule is, if I pull the crankshaft out of a model engine, I then replace the crankshaft bearings too. it doesn't matter if the bearings were just replaced either.

Sport_Pilot

There is no need to remove bearings to see if they are good. First make sure it is clean of all dirt or congealed oil. If so then they should feel smooth. Second check radial play, Try to move the crankshaft from side to side, they should be a little radial play, a lot means a worn or poor fitting bearing. Next remove the glow plug, with no fuel, and a small prop and a fresh starter motor battery turn the engine as fast as possible, you should hear little to no bearing noise. Then run the engine, you should hear no bearing noise that is audible over the engine noise.

I suspectgyour bearings are good, no need to spend money on new bearings. Some people here would replaceeverything every time they have a chance. I guess it depends on what rock's your boat.

airraptor

My Feedback: (66)

Replace the bearings they are only 15 dollars.

you have the engine out and torn apart why not do some minor work on it.

Also can you take a very clear picture of the top of the piston and the chamber on the head?

Also since you have it apart why not clean the baked on oil off the case. run it in antifreeze in croc pot set on high for couple of hours.

new bearings, new ring and cleane case = almost new engine.

Sport_Pilot

I have only had trouble with two bearings. The first lasted a couple of years, their replacement lasted a year. So for, for me, original bearings last longer than replacement bearings. So sorry, I will not spend even 15 dollars when I know a good bearing when I have the bearing in front of me. That is to say I really don't know from posted pictures, no matter how good the pic.

freakingfast

My Feedback: (3)

You guy's are gona laugh, but once I puled some bearings that were rough, only to realize I didn't have those sizes on hand but I had to fly an event the next day. I noticed the balls were OK, only the races were bad when turned and pushed to one side but not the other. Sooooo, I turned it around and re-installed it planning to replace it ASAP. The darned thing lasted a surprisingly long time.

No, I don't recommend this, I got away with it once.

Basil Yousif

My Feedback: (3)

The way I apply the RTV is I put a thin layer on the muffler and let it dry. After it forms a solid gasket I install the muffer. I noticed in the past when I just put the RTV on the muffler and attatched it all of it just squirts out the side and your left with metal on metal.

1QwkSport2.5r

I assemble my mufflers with the rtv wet and snug the screws tight. The rtv fills the low spots if any and seals it up. Never a leak. Just gotta get the surfaces clean.

Sport_Pilot

I agree. Metal to metal contact is not bad, in fact the engine head has metal to metal contact and needs no gasket, it is just smoother. Many engine mufflers are the same way, when new they provide sufficent seal with no gasket, but loose mufflers, handling with no muffler, and poor sealing surface on aftermaket mufflers will ruin this. In that case it is better to put the RTV on wet and tighten up the muffler then wipe off the RTV around the joint. You most likely will not have a smooth enough gasket surface if you let it dry.

airraptor

My Feedback: (66)

If you look closely at the pics provided the head looks like it has little tiny nicks in it. Are they nicks or just something else? looks to me like the bearing is going or had a piece broke off of it.

Also Sport pilot why not change them now and rering it? The engine is 4 yrs old.

Sport_Pilot

4 yeas old isn't a requriement to overhaul an engine, in fact that is almost new. I have one engine that is 30 years old. I have never torn it apart, never used afterrun oil and it works fine. I suppose many here would tell me the bearings are bad if I posted a pic of them here, but they are not, its just castor oil stains. It does need a new ring though, it also needs a sleeve as you can feel the wear. If the bearing is indeed bad then replace it.Otherwise the new one isn't likelly to be any better.The old ring will break in a lot faster than the new one and it won't cost ten or fifeteen bucks.Andmay lasttwentyyears depending on how well you take care of it.

airraptor

My Feedback: (66)

Sport i have some old engines also. I never use after run or even run my engines out.
The one thing that has changed is the bearings are different than they were a long time ago.

some engines injest more than others and some dont. To many variables to say how long bearing will last. If you look at the head in this post you will see tiny tick marks something has caused those. till he gives us a better picture or he comes on here we will never know. I would still replace the bearings and not because of the way they look.

Basil Yousif

My Feedback: (3)

What is the perpose of using RTV if you want a metal to metal contact! Here's some more pictures - a better one of the head. Come to think of it the plug was going in like the threads were stripped on the head on the last few flights. I think this is all because the engine was running very lean and hot. The carb needle was out to 4 turns and the engine was running very lean. Any more out and it wouldn't run. It took me 5 hours to set the low end needle and I wans't going to play anymore with that one. Has anyone had this model engine running with no service forover 5 years.

airraptor

My Feedback: (66)

It still looks like you have injested something or something is coming apart. Look at the head with tiny nicks in the chamber area and then look at the case where the rod looks to be rubbing or the bits of metal are causing it to rub.

also when your going to post pics of the inside of your engine can you clean out all the oil. This will allow us to see the engine better. thanks

Take a picture of the top of the piston. it does look like you have been running it hard. some where on the piston skirt just below the pin and some blowby past the ring.


I just saw that your in roseville lol close to me. I should be going to RC country next week maybe i could meet you there and look it over for you.

Basil Yousif

My Feedback: (3)

Yah I am the trasurer for the AMOS club - Associated Modelers Of Sacramento our field is located in Lincoln near the casino. see www.amosrc.com - maybee you can come over and fly at our field I can get you in as a guest and youcan check this engine out.
We have a giant scale event on the 29,30th of this month if you want to come over then.

airraptor

My Feedback: (66)

ok i will see if i can make it. I am the president of VVRC here in fairfield/vacaville. I trying to close on a house and might be moving that weekend but maybe i could make it out.