Is my Engine Wearing Out

[pnstalum]

Not sure if I should give up on this engine or not, I have not been able to keep it running lately. It will start fine, but only run for a few seconds then shut down abruptly. Once in awhile i can keep it going a bit longer, but it will shut down as soon as i rev it. It's been cool out (mid to upper 50's) but I have used a hair dryer to warm it up. Based upon the tuning chart, if I cannot keep the engine at idle and it shuts down without reving first I should be leaning out the hsn ... but that does not seem to be having any impact. Carb is set to about 1.5mm, linkage has been adjusted, engine has been sealed...not sure what to do next. Is it time to replace the motor. Still has resistance when spinning the flywheel and the glow plug burns well.

What should I be trouble shooting next? Any thoughts would be great.

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[moe7404]

fuel tank may have a crack in it, letting the pressure out. when fixing trouble on engines, my dad told me check the cheapest and/or easiest things first.

 

[2revo1maxx]

Check your clutch. If that's ok then it may be worn out or have bad bearings etc. How much fuel has been run through it? Got a good plug in it? Air filter plugged?
Leaning the hsn will not affect the idle, it's the lsn that you may want to lean a little. Idle gap should be 1mm.

 

[Phins Fan]

Whats the rough outside temp where your at? You may just need to burn a hotter glowplug. When it gets colder outside there are some motors that need a hotter plug to properly burn the fuel. Same can be said for super hot, run a cooler plug. Just my .02

 

[BamaFan]

Actually the hot plugs are for hot days and the cold plugs are for cold days thats why I just run a med plug and don't switch between plugs.

 

[Macguyver]

Actually the hot plugs are for hot days and the cold plugs are for cold days thats why I just run a med plug and don't switch between plugs.

wrong ...plug temp has nothing to do with the temp outside ...different plug temps changes the time the explosion takes place in the engine ...a hotter plug will ignite sooner than a cold plug

 

[BamaFan]

Maybe but if you run a hot plug on a cold day your car will run like crap and thats a fact!

 

[pnstalum]

Didn't think about checking for leaks in the fuel line / fuel tank. Temps have been in the upper 50s to lower 60s and I've been using a hair dryer to warm the engine before starting. I'm running a Dynomite Mach. 26 with Dynonite mc8 plugs. I can pick up a couple new plugs... but what would be best for this time of year.hopefully I can get another month of running in before hangingbher up until March.

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[MotoGod]

Maybe but if you run a hot plug on a cold day your car will run like crap and thats a fact!

I run Super hot plugs year round. Your tune makes it run like crap...not the heat range of your plug. A hotter plug gives you a broader tuning window than a colder plug. Also, the more RPMs you are turning the more benefit you will have from a colder plug (ie modded engines or onroad engines).

When it's cold, you need to richen your mixture since the air is denser and there is less oxygen in it. When it's hotter...you need to lean your mixture since the air is less dense and there is more O2 in it. It seems backwards, but I assure you it's correct

 

[2revo1maxx]

A more dense mixture has a tendency to pre-ignite with a hot plug. If your engine already has aggressive timing and a hot plug it will matter on a cold day. There are plenty of variables. These engines also rely on compression to some extent.

 

[pnstalum]

Here is a quick update...

Had a chance to work on it a bit yesterday, it was a nice day... sunny and about 60 degrees. I checked for leaks in the fuel system by blowing on the pressure line, fuel ran through the system fine, I plugged it up and could not detect any leaks.

I got it running a bit this time... but it sounded very rough, not smooth at all. Kinda like rrrrrratttt tttt, rrrrrrattttt tttt. Don't know if that describes it well. I could only drive it around very slow, as soon as I revved it would die... but I could drive it slow for several minutes. I checked my latest needle settings, the lsn is set about 1 turn out from closed and the hsn is set about 1.25 turns out from closed.

I know every engine is different, plus weather conditions factor into this... but any thoughts on ball park setting just to get this at least running. I'm good at tear down and repairs, but obviously have a lot to learn about tuning. Any help would be great.

 

[Phins Fan]

While every engine is different your settings suggest (to me) you are way too lean and need to richen both your lsn and hsn. Dont think anyone ever asked.... What engine/vehicle are we talking about?

 

[pnstalum]

That's what I was also thinking Phins Fan... I have a Savage 25 with a Dynamite Mach .26. I bought the truck used so I have no idea how many tanks / gallons have been put through the motor but it seems to have good compression. I'm just not sure what is considered a "big" adjustment, a quarter turn / half / turn, etc. I was thinking of leaving the LSN alone and moving the HSN to two full turns from closed as a starting point and adjust from there. Any thoughts of what might be "in the ballpark" to get started?

 

[BamaFan]

I would put the lns flush and back the hns out a full turn and start there. It's easier to tune rich to lean vs lean to rich.

---------- Post added at 12:47 PM ---------- Previous post was at 12:45 PM ----------

Full turn from where it's at not closed. I would even put the hsn at 3 turns out its not going to hurt anything and you should be fairly rich at 3 full turns out. Tune your hsn first then dial in the Lsn.

 

[pnstalum]

Thanks to all the feedback here, I am starting to get this straightened out. Spent a little over an hour with it yesterday, sunny and in the mid 60's. Backed the hsn out two full turns from closed and she started running pretty good... appears it was set way too lean and was actually starving for fuel. Ran it around for a full tank and ended up backing richening another 1/4 turn. I was running in short grass and temps seemed to be in the 150oF - 160oF range. I know not to tune based on temps alone, but I think I'm still a bit lean... I'm trying to tune based on how the motor returns to idle after a high speed run and temp. Anyone have some thoughts on a good temp range for the dynomite engine?

Now that I have the hsn just about sorted out...I think I'm just about ready to move on to the lsn. Now I know the hsn controls the amount of fuel entering the Carb and in turn impacts the lsn ...but to what extent? If I adjust the hsn 1/8, should the lsn be adjusted 1/8 or 1/16, etc? What is the best way to dial in the lsn, basically just how it jumps off the line?

Although the last couple of weeks have been frustrating at times...I've learned a lot about how the engine performs and is tuned. Thanks again for your help.

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[2revo1maxx]

Google your engine settings! They may both need to be set at flush, or it could be any number of turns out from closed.

 

[Phins Fan]

Thanks to all the feedback here, I am starting to get this straightened out. Spent a little over an hour with it yesterday, sunny and in the mid 60's. Backed the hsn out two full turns from closed and she started running pretty good... appears it was set way too lean and was actually starving for fuel. Ran it around for a full tank and ended up backing richening another 1/4 turn. I was running in short grass and temps seemed to be in the 150oF - 160oF range. I know not to tune based on temps alone, but I think I'm still a bit lean... I'm trying to tune based on how the motor returns to idle after a high speed run and temp. Anyone have some thoughts on a good temp range for the dynomite engine?

Now that I have the hsn just about sorted out...I think I'm just about ready to move on to the lsn. Now I know the hsn controls the amount of fuel entering the Carb and in turn impacts the lsn ...but to what extent? If I adjust the hsn 1/8, should the lsn be adjusted 1/8 or 1/16, etc? What is the best way to dial in the lsn, basically just how it jumps off the line?

Although the last couple of weeks have been frustrating at times...I've learned a lot about how the engine performs and is tuned. Thanks again for your help.

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Actually your temps would suggest you are still rich as they are relatively still low for a nitro engine. I run my MGT .28 around 210 and she screams but still doesn't overheat. When I was tuning and around 170-180 it performed well. Once I got a little leaner its nearly impossible to keep the front tires on the ground!!!! Not that you want to squeeze every bit of power out of yours by running it too lean but I would still work on leaning it out some more and get the temps up a bit. Just my .02

 

[2revo1maxx]

It depends on how hot or cold it is outside, and make sure your temp gun is set to read anodized aluminum.

 

[pnstalum]

Just noticed a typo in my previous post regarding engine temps... should have read 250 oF to 260 oF, not 150. I have it running good now, I think I just need to tweek the tuning a bit. Might be still running a bit lean as it does not drop to idle quickly after a high speed run, it seems to "hang" of "stutter" a bit first.

I have learned a lot about tuning from this experience and this forum... now I can enjoy some bashing, at least until something breaks.

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