Freezetron

Damnit!!! Allright, either im one of the worst Nitro tuners to enter this hobby, or i've just had crappy luck. As many of you know, I replaced my POS TRX 3.3 with a O.S .18TM last month and then the following happened. Read this thread to know the background history of the engine, it may be the reason why its having issues now....

http://www.rcuniverse.com/forum/m_56..._1/key_/tm.htm


Flash forward to today. I got my Spektrum DX3 installed the previous night, I have switched to Trinity Monster Horsepower 20% for better lubrication and I made sure my EPA were correct and not straining the sevos. Today I take it out finally to give it a trial run. It was around 80 degress today with about 10 mph wind, not a cloud in the sky. The engine fired right up and I began to make some high speed passes without the body to tune the engine and get used to the Spektrum. The engine is running good though it jumps up to around 260 degress so I richen it some more. I do a few more rounds, put the body on and began to go WOT across flat grassy soccer fields. The engine sounds great, its making a nice clean note with no hesitation or stuttering but I notice the temps continue to slowly rise up. Hmmm...must be the hot weather so I richen it a bit more and continue. Again, my temps slowly began to creep into the 270 range and beyond. Damnit...what the hell? Fearing hurting something, I pack up and head to my LHS to get some advice.

After explaining whats going on my LHS guy says its possible that the THS pipe is causing the engine to overheat due to lack of backpressure as he had trouble with this on his T-Maxx. The odd thing is, I had no tempature issues when I ran my truck at the bash pit as shown in this video a week ago. The only difference is that I was running White Lightning 20% fuel and stock radio.

http://s100.photobucket.com/albums/m...Spipetests.flv

He suggested to first fill up to a full tank, go run some laps at the track and monitor the temps after a few laps as the tank empties. If it continues to get hotter, swap to the stock Traxxas Blue pipe and retune. If that does not work, im looking at loss of compression after the engine heats up and a rebuild. I ask him if my break in failure with the motor above may have caused the motor to wear out prematurely and he said possibly. I also noticed AGAIN that my carb boot was leaking fuel again and again he stated thats usually pretty normal unless your having tuning issue.

So I packed up and went to the track, filled up with gas and fired it up and again, it ran just fine and sounded fine with no weird sounds. However, once again, the temps began to rise 260....267....270....273..278...300 and I finally shut the engine off. I drove back, threw the original Traxxas pipe back on, drove back and retuned. I noticed both today and when I first got the THS pipe, it requires a more rich setting when running the THS pipe vs stock. Otherwise it ran to hot, but before this, it was running fine at the bash pit with the only changes being the fuel and Radio since then

The temps seemed to hold for a bit longer but eventually, the temps began to get into the 290 range. I noticed that the more I attempted to richen to counter the higher temps, the crappier my truck performance was getting, same with the THS.

Fustrated, I packed up, headed home and took the entire engine apart and noticed alot of fuel deposits from around only 5 tanks of gas. Again my LHS states that if the pipe switch didnt' help, i've either got an air leak, or the compression is bad to where after the engine warms up, it begans to overheat.

Great...just farking great. 2 weeks away from a big race and now my beloved O.S is taking a dump. I would really appreciate help, idea's, suggestions on what to do here, cause im starting to loose my patience with this hobby. Keep in mind, the engine was PERFECTLY clean on the outside before running today.

Nathan9492

Try seal her up, and see how she goes

REVO_RACER

OMG you have the worst luck out of everyone on the forums Started with the diff then engine then this engine wow.

well you have yours self a lead there.

the leak could explane ALL your problems the high temps everything

Kawasakirider

Front bearing, look at the bottom of the crank case.

trx2.5maxx

Id seal the carb slide first... if ur front leaks its worst then what u have my os leaked at the carb slide.. sealed it no probs now

Kawasakirider

It's obvious his FB is leaking, look at the bottom of the crank. I didn't even notice the carb slide, my picco does that a little, it's not a problem but you can seal it with some RTV.

IOWAREVO

IMHO:

FB for sure, and maybe the flywheel was throwing it up on the slide boot but you would expect a grease trail to it.
Is that a crack on the carb throat too.

geez...I feel for you. definately BUM luck. I know you can replace the FB but never done it myself. The carb might work if you run a bead of sealer around the throat before you seat it in the block.

good luck

R/C Madman

My Feedback: (1)

It looks to me like the carb is leaking not the bearing. The fuel is dripping down the the side of the carb to the bottom of the crank case. Seal up the carb and give it a go. Your high temps are a result of a lean engine. You can get the same high temps from a leaking bearing but, it's been my experience that you will also see some power loss as well.

J_Bone

My Feedback: (1)

The front bearing leaks out, that can be cause from running too rich and real close to hydro locking and something has to give. Some times it's the front bearing. It's not that catastrophic though. Just been running it rich. I mentioned not to use the THS pipe in a previous thread....

The piston looks fine, but is that burnt fuel on the edge of the engine block? Was the head on tight? That could be a problem area.
Remember, heat doesn't ruin a Nitro engine. It's the lean condition which with the lack of lubrication.

Freezetron

Yeah, look at my link to my first problem with the O.S the damn cooling head was loose and leaked fuel hence the burnt stuff

Freezetron

And whats the deal with this carb boot thing? Is there supposed to be fuel in their to lubricate it, but not leak out or what? I dont' see how you can seal a moving part.

Freezetron

Allright, got the damn bearing to come out. I stuck my 17mm socket wrench in their and gave it some good wacks and it popped out.....doesn't look like its bad either. When I put the crankshaft on, I can play with it a bit side to side, dunno if thats normal.

ThunderbirdJunkie

My Feedback: (3)

I'm assuming you retuned for the new fuel. The Trinity stuff, though, has more oil, which means less methanol content, which means the engine will run hotter. how hot is it running? I'd try running the White Lightning again and see if it makes a difference. If so, use the Trinity to start a bonfire

OK, I reread your post. 290, but it got hotter when you richened it, yes? 260, and after you richened it, it got hotter, yes?

Go back to default settings...tune for performance. run a half tank, check temp. as long as there's smoke and no stutter and it's not doin anything but haul ass, you should be good. Other than that, only thing I can suggest is to borrow some White Lightning from a buddy and see if that helps. 260, btw, is an acceptable temp. just keep it under 300 and you'll have one happy 18TM

ThunderbirdJunkie

My Feedback: (3)

side to side play is not good. how much fuel you have through the engine?

Freezetron

1 gallon.

ttoks

buy a quart of the lightning fuel and see if it overheats with that, if it doesn't overheat it's the new fuel, seems to me to be the most likely culprit, should seal your engine up anyway weather your having troubles or not.

you'll need new bearings as well, should call up O.S and see what they can do for you.

Kawasakirider

Was the bearing cooled down when you put the crankshaft in it to see side to side play? It may have been expanded a little bit. As T bird says, side to side play isn't good, replace the bearing.

Dil

seal up the entire thing... from your crank bearings to the carb,,, seal it up tatolly and it should be fine,,

Freezetron

So how exactly do I seal up an engine. And I have a hard time believing the fuel is the culprit...

IOWAREVO

Here ya go! Engine sealing 101. It's a different engine, but it will get you going.

http://www.savage-central.com/module...wtopic&t=54465

ThunderbirdJunkie

My Feedback: (3)

Ice, that's the only thing I can think of besides what's already mentioned.

get some Permatex RTV, I use the copper stuff that's o2 sensor safe. get it at any auto parts store. Just pull the carb and the backplate out (you've already done that, judging by your pics) so spread a thin layer around the top of the neck of the carb where it mates to the crankcase, and a thin layer around the backplate where it bolts to the crankcase too.

I also just looked at your pics-


Don't know if anybody else noticed, but it looks like the sleeve around your carb's neck has got a good size crack in it. Does OS sell that seperately? That could cause an air leak, too.

ttoks

i suggested seeing if it overheats the whatever fuel you were useing before because it all started when you swaped fuels, and if it isent the problem it eliminates it as the problem.

IOWAREVO, you just beat me with that link lol, i love that link.

-edit- jeez the forums are busy tonight.

IOWAREVO

I probably got the link from you ttoks, lol.

I agree with tunderbird on the carb thou if you can get a seal up around the "o" ring it should work. All the mixing happens above the ring. Might as well inspect the the ring too. The crack kind of looks like it's where the pinch screw passed behind it on the block.
I'd seal the pinch screw too.

tommythecat

My Feedback: (2)

They do sell the sleeve seperately, but honestly, that crack shouldn't hurt. That happens when you tighten the nut on the retainer pin too much. I ran mine with a very similar crack for 8 gallons with no issues at all. That sleeve is only there to insulate the carb from the engine heat, the o-ring at the top is the seal, and as long as it is good the sleeve can be cracked or pitted to hell without creating a leak.

I do agree with most of what has been posted here. It really sounds like an airleak, although seeing as how the only thing you changed before the problem started was the fuel, I would eliminate that as a possibility first. Try some known good fuel and see if the problem goes away. Any time you change anything and start having a problem, the change you made should always be your first suspect as to the cause of the problem.

LSTVega28

I have no advice but....hope you get it running ice!