Revo 3.3 running hot
05-12-2022, 09:54 AM
#1
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Revo 3.3 running hot
Hey guys, i recently finished the break-in on my new Revo (Traxxas method) and im on my 7th tank now. The truck is still tuned a bit rich, plenty of blue smoke and no symptoms of a lean mixture.
However the truck has been running hot, well over 300 degrees according to the Traxxas link app and reading 240-270 at the glow plug with a generic laser IR gun. If i run it hard it can get another 10-20 degrees hotter. 70-80 degrees outside.
I'm unsure if an air leak can cause this without showing any other symptoms. The idle is a bit rough and inconsistent but i haven't set my idle gap yet.
Another issue i ran into is that the glow plug wasn't sealing all the way and was impossible to start. Threw a new copper washer in there and it fired up. But if i turn the motor over by hand i can hear a tiny bubbly leak sound coming from the glow plug area. There is no visible fuel or anything coming out around the glow plug. Am i just hearing little fuel droplets getting pushed around in the cylinder?
I'm stumped on where i should go from here and hesitant to run it until i figure it out. Any help would be appreciated!
However the truck has been running hot, well over 300 degrees according to the Traxxas link app and reading 240-270 at the glow plug with a generic laser IR gun. If i run it hard it can get another 10-20 degrees hotter. 70-80 degrees outside.
I'm unsure if an air leak can cause this without showing any other symptoms. The idle is a bit rough and inconsistent but i haven't set my idle gap yet.
Another issue i ran into is that the glow plug wasn't sealing all the way and was impossible to start. Threw a new copper washer in there and it fired up. But if i turn the motor over by hand i can hear a tiny bubbly leak sound coming from the glow plug area. There is no visible fuel or anything coming out around the glow plug. Am i just hearing little fuel droplets getting pushed around in the cylinder?
I'm stumped on where i should go from here and hesitant to run it until i figure it out. Any help would be appreciated!
05-12-2022, 12:03 PM
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So it started fine yesterday, went to start it today and i think the one way bearing went out. Ratcheting sound when starting and i can rotate the flywheel backwards. Not having much luck with this thing
05-15-2022, 05:49 AM
#3
What fuel and glow plugs are you using? 99% of the time your fuel is the problem with slipping starters. Glow plugs don’t seal because they aren’t tight enough. If your idle gap isn’t set correctly, you can’t get the needles set correctly and often the low end ends up being too rich even though it may seem to run right. The overly rich bottom looks fuel in the crankcase which slathers the starting components with oil and causes slippage.
The recipe for success in most cases:
- Idle gap set to .0.4-0.8mm - larger gap for new engines and close it up as idle speed increases during break-in.
- Break in on oily fuel 13-15% oil for first couple quarts, then 12% oil MAX!!!
- Use a MEDIUM heat glow plug, NOT HOT OR ULTRA HOT.
- Set the High speed needle first - I find it best to set it to peak, then set the Idle/Midrange needle, then go back to the High speed to double check it and set it back a little rich.
With your IR thermometer, you should see the temp drop about 1° every 2-3 seconds if the low speed is set correctly. You want it to be a little bit loaded up after 10-15 seconds of idling. This ensures the idle is rich enough after a good WOT run that has the glow plug very hot. A really hot heat range plug will retain more heat than a medium plug resulting in the need for an overly rich low speed which is essentially drowning the plug to cool it off and this consequently makes it hard to restart without adding throttle. Expect to need to add a little throttle to restart sometimes, but it should not be difficult and require a lot of time to do.
The video below is one of my trucks; Note how it sounds. That was running on custom blended oily fuel - 15% oil and 10% nitro.
The recipe for success in most cases:
- Idle gap set to .0.4-0.8mm - larger gap for new engines and close it up as idle speed increases during break-in.
- Break in on oily fuel 13-15% oil for first couple quarts, then 12% oil MAX!!!
- Use a MEDIUM heat glow plug, NOT HOT OR ULTRA HOT.
- Set the High speed needle first - I find it best to set it to peak, then set the Idle/Midrange needle, then go back to the High speed to double check it and set it back a little rich.
With your IR thermometer, you should see the temp drop about 1° every 2-3 seconds if the low speed is set correctly. You want it to be a little bit loaded up after 10-15 seconds of idling. This ensures the idle is rich enough after a good WOT run that has the glow plug very hot. A really hot heat range plug will retain more heat than a medium plug resulting in the need for an overly rich low speed which is essentially drowning the plug to cool it off and this consequently makes it hard to restart without adding throttle. Expect to need to add a little throttle to restart sometimes, but it should not be difficult and require a lot of time to do.
The video below is one of my trucks; Note how it sounds. That was running on custom blended oily fuel - 15% oil and 10% nitro.
