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Old 01-04-2010, 06:30 AM   #1
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Default Help with Front Bearing Issue

Guys,

I have a Losi 350 Engine in my 2.0, I began to notice that the idle was inconsistent and that my tune was as well. Shortly after that I noticed the front bearing was leaking and had some front to rear play in the crank. I went to remove the front bearing last night in preparation for replacement and the bearing basically just slid/almost fell right out. From inspecting the head and plug the engine has been running overly rich, so I assume that may have caused the front bearing to start leaking.

This didn't seem right to me so I wanted to ask you guys if you think the case could have stretched or if the bearing may have spun in the seat and "milled" it out a little? I have not been able to find any cracks around the seat area by the way.

Also, would a new bearing possibly fit tighter?

Thanks
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Old 01-04-2010, 06:39 AM   #2
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It could have a fracture thats not really visible. Have you taken the bearing out before? What tools did you use to get the bearing out?

How much runtime is on the engine? You may talk to Horizon and see what they say. Also check out my thread, "The Speed Shop" we do work of all kinds related to bashing/racing and can get you taken care of for cheap.

my email is alanburton20@gmail.com
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Old 01-04-2010, 06:40 AM   #3
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I would start out by putting in a new bearing. Make sure you heat the block up in an oven and freeze the new bearing before insertion.
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Old 01-04-2010, 07:01 AM   #4
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The engine has approximately 2.5 to 3 gallons on it.

I use a hex driver to push the bearing out the front, and it took NO FORCE to do it! It just slid right out.
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Old 01-04-2010, 07:02 AM   #5
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Also, while I have you guys on the line.....

I noticed when I had the back plate off the engine that the rod to crank connection has a tiny bit of play in it, that is only noticable at TDC when the piston hits the pinch area. Is this acceptable or is the rod bushing spent?

Thanks.
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Old 01-04-2010, 07:13 AM   #6
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Quote:
Originally Posted by portyansky View Post
I would start out by putting in a new bearing. Make sure you heat the block up in an oven and freeze the new bearing before insertion.
Heat the block up for sure but i would put the bearing in the freezer it builds up Condensation in the bearing and causes it to rust and thats not something that you want. Just heat the block and put the new bearing back in.
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Old 01-04-2010, 08:41 AM   #7
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Matt,
End play in crank is a big deal, especially if due excessive bearing wear. You first must see if laderial movement in front + rear bearing. If noticeable cold you can be certain that the bearings are not performing properly at operating temp. The front bearing is under a great deal of load and often engine case will show signs fatigue(stretch slightly)and loose bearing press fit. 2, 3,or 4 tenths of one thousandth an inch and you will see difference from needing heat and preasure to remove, or an easy tap to remove. Take caution here the condition of your engine case. Change the front bearing if not both. Bearings are very important with how they will effect your engines performance. It is vital these miniature high speed bearings perform well at operating temps, with minimal vibration, as to keep engine operation steady and smoothe. Both engine case bearing surfaces are line bored and essential they remain concentric, and be with a bearing assembly press fit.The front can still perform ok with a tight slip fit but again Beware of your engines potential if remains loose after bearring replacement. Theres a reason we do not put roller skate bearings in these engines. The engine bearings are your closest tolerance engine parts. Good, bad, or indefferant how well your engine bearings perform effects the other moving parts in your engine. For example, Since you had brought up crank pin conrod bushing looseness, bad bearing/inpropor bearing fit will excelerate the wear factor. Little - less than 0.003" high to low measurement max. RayAracing will be offering customers crank pin wear inspection free service to piston+sleeve set reconditioning-resizing customers in 2010. If I could get JR to work again on our order form Hope this helps. Good luck!

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Old 01-04-2010, 09:30 AM   #8
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Excellent and very informative reply Ray, Thanks, I appreciate that info.

It sounds to me like my little Losi350 has probably given all it is capable of. Probably a lot less trouble just to go ahead and replace it. No sense fussing with a $100 motor.
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Old 01-04-2010, 10:19 AM   #9
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That's a shame too, cause that is the little engine that could!
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Old 01-04-2010, 10:26 AM   #10
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From you guys who have helped me out in this thread. Let me ask you your opinion:

If you were going to replace this engine and wanted to get an engine that had a lot of low end torque, so that the feel of the buggy was almost electric powered, what engine would you get?
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Old 01-04-2010, 10:39 AM   #11
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Old 01-04-2010, 12:18 PM   #12
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Quote:
Originally Posted by Matt Chester View Post
Excellent and very informative reply Ray, Thanks, I appreciate that info.

It sounds to me like my little Losi350 has probably given all it is capable of. Probably a lot less trouble just to go ahead and replace it. No sense fussing with a $100 motor.


Your welcome Matt!

Not to Say the Losi 350 is a bad $150 engine model. Put it someones hand that exercises good preventative maintenance ( example: preheats before starting , meticulously changes/replaces air filters and keeps entire engine clean ) and not to say you wont get 5 or 6 gallons out of engine. The nature of the beast is stress finds its weak point and this engine was manufactured assembled with low end bearing quality. Furthermore, Take that engine NIB and replace both bearings with top grade European manufactured bearings, and you got a different animal. In addition, Stress relieve the engine case along with internal engine parts completely and engine longevity would be up there with the best of them Add atleast $50 to cost HaHa

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