Running Very H.O.T.

[Savage SSX]

Hey all I think I have a stumper, My K4.6 HO on my savage is running exceptionally hot.

The first time I tuned it "for the best throttle response" It ranged from 350 - 370 degrees.

I figured that was a little hot as the fuel going into the engine was actually boiling. So I took the motor completely apart and cleaned it out and put it back together and the temps stayed the same.

So I retuned it and richened it up and got between 310 and 330 degrees. The manual says 250 degrees is tops so I reset the motor to factory specs and even richened it out a little more until it started to spit fuel out of the tail pipe and I got the temperature down to 285ish. Keep in mind the motor ran like crap on this tune, it was getting way to much fuel.

I put two different pipes on it and replaced the seals thinking perhaps an exhaust leak was the problem but I noticed almost no difference in temps. I cleaned the air filter with no such luck. Then I thought perhaps there was a drag on the car like the brakes were sticking or something so I loosened up the brakes a little and oiled what I could but still the temps are nowhere near the "high mark of" 250.

Anyone have any ideas? I am running blue thunder 20% nitro.

 

[SchrodeMode]

How were the bearings in the engine? I was working on a guy's Slayer because it was doing the same thing, had it so rich that it would stall but it was still hot. I pulled the engine and the inner bearing was shot.

 

[Rolex]

I'd be willing to bet that your LSN is WAAAaaaaaaay too lean.

 

[2revo1maxx]

Make sure the lsn and idle are at their proper setting or close to it.
Overheating and raw fuel spitting are strong signs of a bad air leak. Check for cracks in the carb or engine, if that stuff checks out ok then you may want to rebuild the carb entirely.....I think it's sucking air through the carb. If the engine is leaking air, it will also be leaking fuel.
What plug and fuel are you running?
What are the temps outside?
What does H.O.T. stand for?

 

[lesclaypool]

Are you certain your temp gun is accurate?? Try another one, because that just sounds out to lunch. And where are you measuring?

 

[ozziii]

I think H.O.T just means hot, might have been just trying to make it stand out a bit.

 

[knall]

Are you certain your temp gun is accurate?? Try another one, because that just sounds out to lunch. And where are you measuring?

I was thinking the same thing. My temp gun sucks too. if its running good, and smoking blue, do the spit test.

But then again he did mention fuel boiling.....never heard of that happening..... maybee air bubbles entering through a fuel line leak?

 

[Savage SSX]

When I took it apart the bearings looked ok but there cheap enough I can just replace them anyways if it might help, after a few hours of run time a couple times a week there was no fuel leaking down the side of the block so it would seem that at least fuel is not leaking out. Yes H.O.T. does just mean hot..... I have never seen temps this high on any of my motors and yes I use the same temp gun for them all so the gun itself is not out of the ball park.

As I said in my original comments the current tune is factory stock on all needles "the LSN included" and I am running 20% Blue Thunder fuel.

As for an air leak at the carb that is entirely possible is there any particular way to test for air leakage "the block, carb, and surrounding areas are dry when I don't have it running so rich it barely runs".

As for the fuel boiling, that is possible or air could just be getting in. I am not sure but within about 45 seconds or so there is little or no fuel in the line from the tank to the motor.

 

[ksrichard]

If you got that hot. Id rebuild the carb and change fuel lines. Use zip ties at the connections. Also get enough line so you can loop the pressure line a few inches before exhaust inlet.

 

[ksrichard]

As far as leaks or cracks. Remove engine and spray it with soapy water. Blow into fuel line while
covering intake and exhaust. If you see bubbles you found your problem.

 

[2revo1maxx]

That's a good way to test for leaks, but don't get all freaked out when you see bubbles coming out of your new bearings.
Did you mean there's little fuel in the line after 45 seconds while it's running?....Or when you shut it off?

 

[ChasCS]

Hi,
I don't mean to be mean...
Throw another shrimp on the RC...Smile
When my car reaches temps near/above 250*F it gets shut down!
I regularly check my engine temp both with a temp guage and telemetry on my Spectrum DX3s.
But I also have the alarm set on my Tx for around 230*F.

I hope that this high temp issue of yours, can be figured out and corrected for you.

Chas

 

[EXTREME1]

venom makes a good on-board temp gauge it's programable,has fail safe.$40

 

[lesclaypool]

Hi,
I don't mean to be mean...
Throw another shrimp on the RC...Smile
When my car reaches temps near/above 250*F it gets shut down!
I regularly check my engine temp both with a temp guage and telemetry on my Spectrum DX3s.
But I also have the alarm set on my Tx for around 230*F.

I hope that this high temp issue of yours, can be figured out and corrected for you.

Chas

I say this with the utmost of respect, but don't worry about temps so much. Setting a high temp alarm of 230, and shutting it off at 250 IMHO is just waaaay over thinking temps. On a very hot humid day an engine running pig rich can hit 230 at barely more than an idle. Generally speaking(unless you have mechanical issues) if you are seeing smoke throughout the RPMs, your idle isn't 'hanging' and is coming right down after WOT blasts, and your idle temps drop a degree or so every 5-6 seconds, you are good to go. If that happens to be at or around 230, awesome. If that happens to be at or around 270, awesome. I would set your high temp alarm for something more like 280-290, which may start to be cause for concern(like the OP in this thread).

I just know for myself that I would hate to be bound by seeing certain temperatures with my tuning. Not only that, but you're going through more fuel, and you're selling the engine short of some serious performance at times. And by tuning to 'max' temps like that its not really 'preserving' engine life, its just unnecessary.


But I digress, this wasn't intended for the OP, as I realize there's something weird mechanically going on there.

 

[EXTREME1]

yeah i've got my venom temp,fail safe set at 300 degs.seems like my revo runs best on performace tune @ bout 270-280 but i let mine cool too bout 200 degs. in between tanks.

 

[2revo1maxx]

On a well tuned engine with no mechanical issues a change in fuel oil content can mean a difference of 20 or 30 degrees, oily fuel tends to run hotter.
There are many variables, but the best way is to let the engine tell you how it's doing. My temp gun is mainly for checking to make sure the engine is warm enough.

 

[Rolex]

The temp is just the final check after it's running really good. There are many engines and just as many fuel variations out there that no one number on a thermometer will tell you you've got it.
Some engines aren't happy till they are at 285 and run like pigs at 250.
Another quick check for a LSN lean condition is to pinch the fuel line close to the carb after the engine has run for a while. About 3 seconds to speed up and then quit is what you're looking for. Any less than that and you're too lean.

 

[ChasCS]

Hi,
I was only thinking that following what my Savage X 4.6 Manual "suggested" for proper operating temperature, it states to run the car, & adjust the carb, when properly tuned, it should be running below 250*F. Using recommended 20% to 25% Nitro content.
So who do I listen to ?
I don't doubt your combined wisdom or previous experience, but I don't want to damage or cause trauma to my 4.6 engine either. (?)

Chas

 

[Savage SSX]

Thanks for all your input. I will give the soapy water a shot and see how it works as well as zip tie the hoses. I will test it out tomorrow and post the results. Hopefully we can be one step closer to finding the problem.

 

[lesclaypool]

Hi,
I was only thinking that following what my Savage X 4.6 Manual "suggested" for proper operating temperature, it states to run the car, & adjust the carb, when properly tuned, it should be running below 250*F. Using recommended 20% to 25% Nitro content.
So who do I listen to ?
I don't doubt your combined wisdom or previous experience, but I don't want to damage or cause trauma to my 4.6 engine either. (?)

Chas

Fair enough, I totally understand that angle. But the proof is in the pudding. Eg: A guy who buys that kit and lives in Arizona and wants to run in the middle of July, is going to have a kit that runs like garbage and is a dog because it's so pig rich just to keep the temps 'in the correct range'(whatever that is..). So if he leans it out until it's performing well, idling nicely, and seeing smoke all the way through, and the temps are at 270, there's cause for concern and he needs to shut it down? What if that is the sweet spot 'tune' for that day?? Yet if he richens up a bit - to keep it under a certain temp - it'll run like poo??

I guess my point is, manufacturers need to cover their butts. These are cheap RTR engines that lots of newbs are going to buy and have no idea what they're doing, so they follow what the manufacturers recommend.