Air bubbles building up in fuel feed line.

[Fish]

We have been running at 160 to 180...time to lean them babies then! thanks!!

 

[2revo1maxx]

Svecobrar, is that a plastic pipe? I'll bet it's melted inside.

---------- Post added at 7:30 PM ---------- Previous post was at 7:28 PM ----------

LOL fish don't burn up your engine. Tune for performance, not temps....and don't let it hit over 260-270.

 

[svecobrar]

Yes its a plastic pipe. But what does it being melted internally have to do with the bubbles?

 

[2revo1maxx]

If the baffle is melted inside you won't have enough fuel pressure.

 

[svecobrar]

I solved the air bubbles problem. I turned the fuel feed needles direction so the fuel line doesn't have to pass by the exhaust to get to the carb. I also installed a GH cooling head. My problem is that the thing still over heats. I run it without a body and i've tried 20% odonell, traxxas top fuel and cool power 25% and it still over heats. I rebuilt the carb, sealed the carb and the backplate and it still over heats and runs slow as hell.

I regularly see over 280 with poor performance. I've searched google for overheating answers but there all the responses are the same and i've tried them all. The only other thing i can think of is to replace the engine bearings, as the flywheel side seems sensitive to brake cleaner (checking for leaks), but only sometimes. Sometimes it kills the motor, and other times it does nothing, holding the engine at roughly the same rpm.

Any help is appreciated.

 

[Nitro4910]

If it's still overheating then it's time to retune it.

 

[Metalhead Matt]

If you can't get er tuned, it may need rebuilt.

 

[svecobrar]

I have to pretty much retune the engine every time i drive it. I just had the piston and sleeve repinched through rcrenew.com and the compression is great on it. I'm thinking about replacing the bearing of the engine but i don't think this little 2.5 is even worth it anymore. Another $40 on bearing and misc. and i would have been able to just trade it in towards a 3.3.

I have gone back to factory settings and tried retuning it from there a bunch of times already. My buddy and i spent almost 3 hours on Saturday trying to figure it out, but no matter what it would over heat. We could get it to run at 240-250 but it would be stupid slow, two hours lean and the temperature would jump up to 290.

 

[Metalhead Matt]

I must have missed the repinch. That sounds like bearings and/or an airleak.

 

[svecobrar]

How could the bearings cause this problem. I don't mind replacing them but i don't like throwing parts at something without understanding as to why the object might need it.

 

[Metalhead Matt]

Worn bearings can lead to tune chasing, glow plug failure and other erratic behavior. They're so cheap there isn't much reason not to replace them when the engine is a part. This sounds more like an air leak though.

 

[svecobrar]

I've already sealed up the carb and back plate, i guess i could do the pinch bolt also but i can't see there being that bad of a leak there. And there isn't a way to seal up the bearings without replacing them, is there?

 

[nikko508]

Your air leak is most likely at your carb, and very possible that your front bearing is worn/leaking if you over heated a few times, replace the bearing and seal the carb. The 2.5 eng likes to run hot so temps in the 250+ is somewhat normal.

 

[2revo1maxx]

Don't replace the front bearing without doing the rear bearing too.

 

[svecobrar]

Is this the bearings i would need, I mean this is what it shows in the manual for part numbers but i'm assuming these would be pretty hard to replace. http://www.amainhobbies.com/product_info.php/cPath/1_68_1721_238/products_id/7039/n/Traxxas-Front-and-Rear-Engine-Ball-Bearings-TRX-25-25R-and-33

Also considering the fact that this is gonna be another $30 should i just consider a trade in for the 3.3. I haven't had this thing running full strength in so long that i don't even remember if this engine is worth running. Is the 3.3 considerably faster than the 2.5?

 

[svecobrar]

How hard is it to replace the bearings without the proper tools, i found this how to: link but it seems pretty involved http://www.beatyourtruck.com/forum/showthread.php?59431-Replace-Engine-Bearings.

 

[2revo1maxx]

Just put the block in the oven at 250°, they'll fall right out.

 

[rgreen]

putting the alum pipe from the jato 3.3 vs the stock plastic pipe that came with my jato 2.5 sure helped bring temps down and made it tune easier. that 2.5 is a good little eng when tuned right! Good luck.

 

[redcat fan 124]

redcat rampage xt air locking it causes it to shut off