Losi 3.4 engine rebuild help

[codfish]

I've been in a fist fight with the 3.4 engine for a few weeks and I finally tore the engine down and I found that the internal bearing is bad. Any idea how to remove and reinstall this bearing without buying the tool?


Also the head button and piston are pitted around the edge. What would cause that? I’m not sure if this engine is a toast or should I rebuild it.


Any suggestions on a mid-block engine with a SG crank?


Thanks,

Codfish

 

[ninnon]

If you can find a sleeve, piston and head button for a decent price I'd just do that. It looks like dirt has got into the engine. Have you been running an air filter? As for replacing the bearings, heat in the oven and they should fall out with little force.

 

[codfish]

If you can find a sleeve, piston and head button for a decent price I'd just do that. It looks like dirt has got into the engine. Have you been running an air filter? As for replacing the bearings, heat in the oven and they should fall out with little force.

I always run an air filter but I think I'm the third owner. Have no idea what someone else may have done.

 

[ninnon]

I always run an air filter but I think I'm the third owner. Have no idea what someone else may have done.

Ok. It's probably best to get a new engine... Chances are it wasn't broken in.

 

[codfish]

Thanks. That is what I figured...just wanted another opinion.

 

[olds97_lss]

For future bearing removal reference:

 

[codfish]

That's pretty easy....might try it for fun.

 

[GAJ]

I tried it a couple of weeks ago - the removal part anyway. Heated the block up to 225 on a hot plate, tapped the block on a piece of wood, crank bearing dropped out. Used a dowel from the inside and pushed out the front bearing.
I was having a problem getting the block up to 225, so I covered the block with a metal can, this brought the temp up quickly.

 

[Nitro Fanatic 2016]

I've been in a fist fight with the 3.4 engine for a few weeks and I finally tore the engine down and I found that the internal bearing is bad. Any idea how to remove and reinstall this bearing without buying the tool?


Also the head button and piston are pitted around the edge. What would cause that? I’m not sure if this engine is a toast or should I rebuild it.


Any suggestions on a mid-block engine with a SG crank?


Thanks,

Codfish

It's def. been ran lean! I'd rebuild it.

 

[codfish]

Ordered a new 3.4 yesterday. Too many things needed it was better to buy the entire thing. Hurry up Fed Ex. I want to drive.

 

[ninnon]

Ordered a new 3.4 yesterday. Too many things needed it was better to buy the entire thing. Hurry up Fed Ex. I want to drive.

Remember to break it in Then you can have some fun. Keep us posted

 

[codfish]

Always break in first. Hard to believe someone wouldn't.

 

[ninnon]

Always break in first. Hard to believe someone wouldn't.

Remember to get some videos of it up and running in the media section, we want to see this thing

 

[codfish]

New engine is here! Now if it didn't snow for the last day. Hoping the snow melts by this weekend and I can get this thing started.

The manual is pretty vague on break in. Any thougths?

 

[ninnon]

New engine is here! Now if it didn't snow for the last day. Hoping the snow melts by this weekend and I can get this thing started.

The manual is pretty vague on break in. Any thougths?

There are many break in's available. How vague were the ones that came with the engine?

 

[codfish]

This is from the manual. I guess I was expecting more from it. I have broken in three traxxas engines and their break in procedure is more extensive.

" When the engine starts, the exhaust should emit lots
of blue/white smoke, indicating that the engine is excessively rich (a good thing during break in). During
the first tank of fuel, you may wish to set a higher than normal idle speed and/or leave the glow plug igniter attached in order to keep the engine from stalling.
Drive your vehicle around while “blipping” the throttle and avoid operating the engine at full throttle for more than 2–3 seconds at a time. Consume the entire
first two tanks of fuel in this manner. After the first two tanks of fuel, begin leaning out the high-speed needle valve 1/8 turn at a time. It generally takes about 5
or 6 tanks of fuel before you’d want to start tuning for “maximum” power."

 

[olds97_lss]

Check out the first post in this thread:
https://www.rcnitrotalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/

Typical method: https://www.rcnitrotalk.com/how-to-break-in-a-rc-nitro-engine/
Heat cycle (closer variation of what I've done with 10 years worth of engines): https://www.rcnitrotalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/#post-600523

 

[codfish]

Heat cycle (closer variation of what I've done with 10 years worth of engines): https://www.rcnitrotalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/#post-600523

I was thinking about using the Heat Cycle break in. one question...I am guessing the 2-3 minute time frame is driving the car and a slow to medium pace...not hammering the throttle?

Thanks for your help. Hoping the snow melts tomorrow and I can do this on Saturday.

 

[olds97_lss]

Yes, the 2-3 minute is slowly increasing the throttle, letting off to coast, slowly increase, let off to coast. Avoid hitting high RPM's. By slowly, I mean from idle to 1/2 throttle within 3 seconds or so.

If it's that cold (below 60F), you really need to wrap the head with something or it will not get up to proper temps. Personally, I won't break an engine in if it's less than 50F outside.

Also avoid hitting water or driving in damp areas, water on the head will cool it off way too fast. All break-in running should be done on relatively flat pavement. Make sure on the cool downs, you put the piston at BDC. To make it easier, take out the glow plug and rotate the flywheel until you see the piston at the bottom of the stroke, then mark the flywheel and something else on the truck that is stationary so you can just rotate the flywheel quickly to the right place every time.

 

[codfish]

This is what I thought. I have already marked the flywheel so I am good to go there. It is supposed to be 50 tomorrow but the street is still snow packed so I think it might be sitting a while. We will see.

Thanks,
Codfish