Just as the title says i recently bought a K5.9 motor from a LHS and i did my best at breaking it in right. My problem is that the motor STAYS around 250 degrees.. no matter how much richer i run it, I cant get it to drop down more than around 5 degrees. I thought since the motor only cost $200 i figured it would be ok to just let it run that hot and try not to run it for long periods of time. Needless to say, Today during a normal run (Jumps, a few straight stretches, and some grass dougnuts) the glow plug literally shot out of the top like it was a gun. It only went about 2 feet above the motor but it still blew out! When it landed i tried to pick it up and it was suuuper hot so i took my thermometer and stuck it against the plug and it read over 280 before i took the thermo off. That must have meant that inside the motor was about the same temp. I have no idea what im doing wrong but i cant tune the motor because of how hot it is. I HAVE to keep it running waaay rich just to keep the temp at 250. If anybody knows of anything im doing wrong then please let me know. lol Cuz i cant figure it out for anything and im about to contact HPI and get a new motor thinkin this one is faulty. Thanks for any help!

Motor:
http://www3.omnimodels.com/cgi-bin/w...IG5250&P=0

(BTW I have an OFNA hyper 7 that i mounted this motor to. Also im using 20% nitro and 12% oil premixed fuel.)

EDIT: I forgot to mention that when i first tried to tune it, Before i figured out that it was running really hot,I tried to lean out the motor and it wouldalways die. I dont think it has anything to do with it not getting enough fuel because the motor will stay running while its rich. And yes i know that trying to lean it out cuts some fuel out but just a 2 hour turn from factory makes it die. It will still start and it will still move but it seems that it bogs the motor down and makes it die incredibly easy. Please dont assume that im an idiot because of how i explained it and try to tell me how leaning it gives it less fuel, I know this. Im well aware of that, But it REALLY should not die with the very small adjustments i do to it. I have the LSN set at 1mm like the book told me and everything so im lost. lol

I think i might have a small leak. The bottom of the HSN where the nipple for the fuel line is. When i first got the motor i loosened the HSN to move the nipple so the fuel line would fit comfortably and now i guess it un-sealed it. It only has a really small leak and i dont know if thats enough to create the kinda heat im getting but yeah, Im gonna try to seal it all tonight and see what happens.

good luck, are you going to seal the while carb, or just the hsn

Well i sealed everything that leads into the motor but i dunno if it worked cuz i guess i put to much WD-40 in the motor and now it wont run right period. lol Its all good tho, Im gonna tear it apart again tonight and try again with alot less WD-40. If that dont work then ima have to pay someone to do it for me. lol

Well it still does not want to let me lean it out. Today when i ran it, I didnt run it that hard aside from full throttle a few times and some laps around my front yard but i leaned it out and noticed that it was giving more power like its supose to, It was still up around 280 tho. When i turn it down and make it more rich it makes the motor almost worthless as far as power is concerned and it it still runs right around 250. Does anybody have any idea what im doing wrong or know why its doing this?

Do some searching in the HPI Monster Truck section and you will quickly find that the K5.9 isn't that great of a motor. BUT, 280 degrees isn't all that hot, especially if you are doing a lot of high speed runs, putting some strain on the motor, and if the weather is hot/humid. As long as there is a healthy looking stream of smoke coming out of the exhaust and there is no erratic engine performance, then you should be good.

try to ritchen the low end needle could be to lean on the bottom

Well the smoke doesnt look bad. Even when i lean it out really good, It still has a good steady stream of white smoke. It doesnt fade until i come to a dead stop. As far as the 280 is concerned tho, My glow plug shot out of the top of the motor when it was that hot so i dont know. Another thing that i dont know if anyone pays any attention to is that my exhaust pipe is around 350ish when the motor is at 250+ I dont know if thats normal either but i do know that exhaust DO get really hot. When the motor gets up above 250 it acts like it doesnt have power and it usually dies pretty easily too. Im just gonna take it to my LHS and run it around their parking lot then show them what its doing. They might know a little more than me lol

EDIT: The low needle is still set at factory and i thought they always set those to a bit rich, Ill have to check that out tho.

if the glowplug popped out it is because it was not tightened correctly...which caused and airleak, which caused the high temps........the loose glowplug is not the result of being too hot, but rather the cause of being too hot...

I was actually considering getting a Savage XL but I heard that the K5.9 engine is a POS that is really hard to tune and always overheats and doesn't have that long of a life. But hey, I don't have one, but I really wanted it until I figured out that the engine sucks.

I know there's guys that have their issues with the K5.9 but I love mine and I'll surely get another or just have the sleeve pinched when it's time.
I'm on gallon #11 and it's still running strong.
I also know several guys that have the K5.9 and they all love the engine.
When properly sealed it's a great engine for an RTR IMO.

from my understanding the 5.9 has air leak issues from the factory.
seal it or use green slime where all seals are.
i'm not quite sure why anyone would use WD-40 in their nitro engine.
WD-40 really has no lubricating qualities to speak of, it is a super thin penetrating fluid for dispersing water and eating rusty nuts and bolts.
keep it out of your nitro engine.
if you're using it for an after run, it's a giant mistake, use an after run oil that is meant for after run use.
also WD-40 has the tendency to gum up ,much like castor oil.
it also dries out leaving you with a dry start on your next run.
if you don't want to spend the 4.00$ on the tiny bottle of after run oil, seek out a hardware store and locate some marvel mystery oil as it is the same as after run oil.
about 4-6 drops down the carb opening and turn it over for a count of 4 seconds(if using roto start) or about 4-6 pulls(if using a pull start)
repeat this step twice.

What fuel are you running as this could be one of the issues

that is a great question

IMO byron 20% is one of the best.
o'donnells 20% is good as well.

I know alot of people like to tune their motors based on temperature, but I have personally never used a temperature gun and have always been able to get a very good tune on my cars. I'm not saying that using a temperature gun is wrong, I just don't see a reason to use one with such significant operating temperature differences from one engine to the next. If you graphedthe ideal operating temperature of all the engines out there, the distribution would be huge. Again, not dissing anybody who likes temperature guns,I just don't see the need for them. Tune it so it runs smooth and cleans out on the high end leaving a light stream of smoke, like a small smoke trail as you drive it by.

As for your other issues, keep your glow plug tight and check it every now and then. The fact it popped out doesn't mean much of anything, just that it wasn't tight enough to begin with. Someone mentioned sealing the engine and that is good advice. I would seal at the carbuerator and engine backplate, the plate behind the pullstart if you have one.Tuning an engine with air leaks is a nightmare. Not saying yours has any, but better safe than sorry.

Could also be a leak in the exhaust area, that will definitely make the engine run very hot.