Rebuilding a nitro RC engine seems intimidating, but it’s really not. The only special tool you need is a heat gun and that is only if you are removing the bearings or if the sleeve is seized.
I’ve always found thebug 404 on YouTube to be the best when it comes to learning how to rebuild a nitro RC engine. Below is is video on rebuilding a Traxxas 3.3 engine. Pretty much any nitro RC engine is the same process with minor variations.
Have a different engine?
Here’s thebug 404 rebuilding other engines:
Even if your nitro RC engine isn’t listed above, if you watch a few of the videos above you’ll get the idea of how it’s done. You can also search YouTube for your specific model and likely find someone who has taken it apart.
Don’t forget to check your manual! Most nitro RC manuals include a section rebuilding the engine.
Nitro RC Engine Rebuilding Tips
Work on a well lit and clean surface. You need to see what you’re doing and you don’t want to introduce dirt into any of the internal engine components before putting them back into the engine.
A common failure for Traxxas engines is the connecting rod. Traxxas recommends replacing the connecting rod every 3 gallons of fuel, but some owners are more cautious and replace it every 1-2 gallons. The fear is that the rod will break and cause damage to other engine components. If you are replacing the connecting rod, also replace the wrist pin.
A common failure for Traxxas engines are the bearings. The stock Traxxas engine bearings are not known for quality. Increased engine vibration, noise, and decreased performance are signs that the bearings need replaced. General advice is to replace them after every gallon of fuel. Ceramic engine bearings are the gold standard, but I’ve seen trusted nitro enthusiasts recommend only getting ceramic for the rear engine bearing and that a cheaper steel bearing will work just fine for the front bearing.
Two commonly recommended brands of engine bearings are Avid RC and Acer Racing:
- Traxxas Front Engine Bearing (7x17x5mm)
- Traxxas Rear Engine Bearing (12x21x5mm)
If you have another brand of engine, check your manual and exploded parts views for bearing sizes. Or you can use a set of calipers to measure the various dimensions of your bearings after you’ve removed them.
If you are replacing the piston and sleeve, also replace the connecting rod and wrist pin. You’ll need to fully break-in the engine after replacing the piston and sleeve. You don’t want to perform a break-in on an old connecting rod.
If your engine doesn’t want to turn over when you crank it with the starter, there is probably an issue with the one-way bearing. The one-way bearing (aka roller clutch) sits on the starter shaft that exits the back of the engine. The bearing can get dirty with oil which can cause it to slip on the starter shaft, making it difficult to start your engine. The one-way bearing can be removed by simply taking off the starter backplate. Try cleaning the bearing and crank/starter shaft with denatured or rubbing alcohol first. If you’re still having issues, get a new one-way bearing.
Study the exploded view of your engine. Nitro RC engines just aren’t that complicated. With a little study of the exploded view of your engine, you’ll understand how it goes together which will make the rebuild process easier.
Use denatured alcohol or 99% rubbing alcohol to clean the engine. You can clean it with water, but then you risk trapping water in the engine which can lead to rust.
The hardest part is removing the sleeve and the bearings. Those are the two components that will likely be “stuck”. A little heat applied to the crank case should free up the sleeve and same with the bearings. The videos above show you how to remove both components with a blow torch, but I recommend a heat gun.
Lightly apply 5w-30 full synthetic motor oil to the internal components as you put the engine back together. You don’t want any components to be dry and you don’t want to flood the engine with oil either.
Don’t be afraid to take apart your engine! If you’re having issues with performance or tuning, it’s time to inspect the engine. Once you do it a few times, it’s pretty easy.