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Author Topic:  This was not my day. Tried new oil a month ago...  (Read 1212 times)

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Offline SergTTopic starter

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This was not my day. Tried new oil a month ago...
« on: September 25, 2015, 06:51:38 AM »
UPD: I correctly breaked it in and after that was using this engine for a month. This engine has an annoying overheating problem.
I tried every possible thing: checked it for air leaks, carb settings, different carbs, engine cover modifications - all is useless.
Engine quickly heats up to 150C if bashing - then it boils up fuel in carb and stops working.
So I decided to try a new oil...

That's what happened to my OBR 9.4Hp after few minutes of engine running ( (with new oil)
I mixed it 40ml per Litre, started engine and let it work at idle for 5 minutes. Than after 2 minutes of bashing - engine loses power and stops. Piston got stuck in cylinder.

And the "Repairing"
I removed that piece of metal (inside cylinder) with knife, than polished affected region with polishing tape. Then I decided that polishing is not a good idea and made a few strokes with a coarse sandpaper over damaged region.
The idea was - that micro scratches will hold some gas-oil mix inside - I hope this can improve lubrication of the damaged area.
Then I did the same operation with piston, replaced piston ring and assembled everything back.
Engine works as usual, but I know that I have to replace cylinder and a piston.
...or get a Skopod or RCMax engine )
« Last Edit: September 25, 2015, 02:46:19 PM by SergT »

Offline Rooster Tail Engines

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Re: This was not my day. Tried new oil a month ago...
« Reply #1 on: September 25, 2015, 07:57:53 AM »
What a bummer! bang head

Did you run it in?  It sounds like you ran it at idle for 2 minutes then went bashing. 

These cylinders can nip up quick if your not careful. Tney can get hot on that side without a proper break in.

The repair you did should work no worries so i wouldn't stress. thumbsup
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Offline Crazy_stu

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Re: This was not my day. Tried new oil a month ago...
« Reply #2 on: September 25, 2015, 12:54:41 PM »
Yet another horror story about OBR's engines.

I feel sorry for everyone that buys one, they are just so hit and miss
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Re: This was not my day. Tried new oil a month ago...
« Reply #3 on: September 25, 2015, 02:12:29 PM »
I don't quite follow did you break it in as per instructions by OBR or was what you said your break in
Or it's been running but you just changed oil and that happened
Can you verify which of these two it is


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Offline SergTTopic starter

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Re: This was not my day. Tried new oil a month ago...
« Reply #4 on: September 25, 2015, 02:50:47 PM »
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Can you verify which of these two it is
I correctly breaked it in and after that was using this engine for a month. This engine has an annoying overheating problem.
I tried every possible thing: checked it for air leaks, carb settings, different carbs, engine cover modifications - all is useless.
Engine quickly heats up to 150C when bashing - then it boils up fuel in carb and it stops working.
So I decided to try a new oil...

I updated the top post.

Offline corty351w

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Re: This was not my day. Tried new oil a month ago...
« Reply #5 on: September 25, 2015, 03:28:54 PM »
My OBR reed engine had the same problems, always ran hot, carb bulb ran dry and would never hold tune. I think most of the problem with those engines is heat soak into the carb, I made up an isolator for the carb and it cured the problem with mine. Was a different engine all together.

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Re: This was not my day. Tried new oil a month ago...
« Reply #6 on: September 25, 2015, 03:54:42 PM »
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Yet another horror story about OBR's engines.

I feel sorry for everyone that buys one, they are just so hit and miss


you should add the 71 cc to that  as well stu 

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Re: This was not my day. Tried new oil a month ago...
« Reply #7 on: September 25, 2015, 04:35:48 PM »
Don't forget the ALX 78.
Wat oil did you change to as some break down from heat,I found Castrol xr77 to be good but its been discontinued.
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Offline SergTTopic starter

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Re: This was not my day. Tried new oil a month ago...
« Reply #8 on: September 25, 2015, 05:28:47 PM »
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I made up an isolator for the carb and it cured the problem with mine.

I thought to make an isolator, but this is not the cure for engine overheating problem. It still runs at extreme temps. Maximum measured was 210C (used FLUKE pyrometer).



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Re: This was not my day. Tried new oil a month ago...
« Reply #9 on: September 25, 2015, 06:13:21 PM »
It will cure your carbie problem bringing in cool fuel to the motor. Will run better. Maybe send it back to OBR get them to check it.
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Offline corty351w

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Re: This was not my day. Tried new oil a month ago...
« Reply #10 on: September 25, 2015, 07:32:14 PM »
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I made up an isolator for the carb and it cured the problem with mine.

I thought to make an isolator, but this is not the cure for engine overheating problem. It still runs at extreme temps. Maximum measured was 210C (used FLUKE pyrometer). 





The isolator might help the running hot issue, as the carb won't get as hot causing it to lean out. It surprises me that obr don't include some type of carb isolator as most other rc reed engines have them fitted standard, TS, SF, BZM etc
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Offline SergTTopic starter

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Re: This was not my day. Tried new oil a month ago...
« Reply #11 on: September 26, 2015, 07:06:53 AM »
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I made up an isolator for the carb and it cured the problem with mine.

What material was used for a isolator?

Offline Jester Racing

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Re: This was not my day. Tried new oil a month ago...
« Reply #12 on: September 26, 2015, 08:12:29 AM »
It looks like a type of tufnol (fabric reinforced resin)
But there are many plastics that could be used as most have insulating properties. As long as it can handle the heat.
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Re: This was not my day. Tried new oil a month ago...
« Reply #13 on: September 26, 2015, 09:57:42 AM »
Hey serge I have a product instock called the Minifold. It comes with gaskets and mounting bolts. Works a treat and adds more torque to help with clutch heat that ends up as case heat. thumbsup

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Re: This was not my day. Tried new oil a month ago...
« Reply #14 on: September 27, 2015, 12:21:25 AM »
My OBR after about 2.5hrs.....and of those 2.5 hours it ran well for about 15mins...then...

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....only thing that survived were the cases blob ....they use shit to build there stuff

Do your self a favour Serg and throw everything but the cases in the bin,then send those to an engine builder to build you a new motor......be cheaper in the long run and no doubt faster thumbsup
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Offline SergTTopic starter

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Re: This was not my day. Tried new oil a month ago...
« Reply #15 on: September 27, 2015, 03:32:21 AM »
A friend of mine said, they have to use molybdenum piston coating to avoid this.
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It is easy to apply this at home - apply with brush, dry in oven at 150C for 3 hours..
Two layers are enough.
« Last Edit: September 27, 2015, 05:36:22 AM by SergT »