Uhgg

iTrader: (11)

I think I might have burnt up my 8.0 on my MGT. The last time I ran it it got way hot, been having problems keepin the temps down, even when it is cold outside. The temp at the glow plug was about 425, that was after it died while I was waiting for my buddy to get my temp gun out of my tool box, it was smokin below the cooling head and I thought it was just some stuff I picked up while running around in the leaves and stuff so I didn't pay too much attention to it. Yesterday I tried startin it and it just sputters and tries to start but won't run, I got to lookin and there was exhaust comin out between the cooling head at the top of the cylinder. I am pretty sure that it is either warped or cracked, I haven't started tearin it down yet cuz I'm not real sure as to what I need to look for while tearin it down to tell what's wrong with it.

Are there any tell-tale signs that I should look for while tearin it down to definitively tell what exactly is wrong with it other than an obvious crack?

Thanks, Uhgg

MTclassPro

iTrader: (33)

My idea is I think that you had it too lean, making the temps exceed the maximum safe limit and the heat started to deform the case and over time it made it so bad it couldnt even keep a decent tune.

snowboard094

iTrader: (5)

The maximum safe limit he had it at 425 degrees!!!! WOW, that is really hot. You might have fried your rod bearing. Spin the motor by the flywheel and see if it turns over without binding. If it binds you will need to tear it down and replace parts of just buy an new motor.

Duster_360

iTrader: (21)

Man , you cooked it - 425F...ouch!!! Way too lean!

If you have exhaust coming out between cyl head and block, you've either blown the head gasket/shim or warped it badly. My guess also is the piston/cyl are shot - see how far into cyl you can push piston (easily, not forced). If you get top of the piston to go past top of cly, its way past done, even near the top of the cyl, its done..

The Pope NJ

iTrader: (1)

Okay I will be the optomist here. Assuming that you have a decent tune. The head screws could just be a little loose causing an air leak around the head leaning the motor out and alowing exsust gases to come out from under the head. If this is the case you may not have destroyed the motor. You would have still had good lub in the motor and as long as you set it to BDC when it was cooling you may just have to tighten up the head.

Good luck I hope it is okay. If not you have an excuse to get a killer new motor.

boomgagem

iTrader: (45)

I'll go with The Pope here, don't assume anything. Tear it down, post some pictures. I will ask this though, how long did you run it that hot?

Uhgg

iTrader: (11)

I have been havin trouble off and on holding a tune and with temps. I would set it to factory settings and then it would be too hot and I would richen it, then the next time I would go to run it it would't start until I lean it out. I didn't run it very long at 425, the last few times I ran it it would get up to like 375 and I would shut it down and richen it some. I would always have smoke comin out of the exhaust so I thought I was fine until I would check the temps. I will tear it down and get some pics posted.

Thanks for all the feedback so far, what motors are comparable to the 8.0?

LiqrSicc

iTrader: (10)

Nothing touches the torque of this motor. And you're not going to be satisfied if you go with something smaller to replace it. I had the 8.0 and although the motor was powerful, I had a hell of a time trying to keep it tuned. If you reached 425 I guarantee your main bearing seal is shot and you have an air leak. Are you past your warranty already? Associated will swap your engine for I think around 150 but then again you can get a whole new engine and keep your old one for spare parts for the probably less on eBay. I ended up replacing mine with an LRP z.28r and was disappointed. Went back to an 8.0 after that.

There's not much support here for the MGT but you might want to check AEForums. Theres a group of members dedicated to that engine that might be able to help you out.

The Pope NJ

iTrader: (1)

Picco .28 is a great motor for MT's lots of power and very fast. for a little less money there is the lrp. 28 not quite the power of the picco but still a very stong motor. They both throw a savage around very well and I have a hard time believing they wouldn't do the same in a MGT.

Uhgg

iTrader: (11)

I started to tear it down and found that 4 of the 6 bolts on the head were loose. I pulled it off and checked the piston and if feels tight and still pops, it is smooth and doesn't feel like it is binding when I run it around by hand. I am not real familiar with the inner workings of these motors, where is the main bearing and how can I check it? I gotta get some new plugs for this and my Savage X and then I am going to test it. The last time I was running it it sounded funny while idling, kind of like it was pinging, I opened the high speed then, should I have opened the low speed instead? As far as the warranty on it I am not the original owner of it and have no idea when it was originally purchased. Thanks for all of the feedback, I really appreciate the help.

The Pope NJ

iTrader: (1)

Sounds like my best hopes where right. Your main bearing should be fine as you would have still had plenty of lub in the botom end of your motor even though the top end was leaned out by an air leak (Provided your tune to start with wasn't to far off)

Stubbs

iTrader: (58)

Just to share a funny story, one of the racers in my club got his SC8 so hot earlier this season that it actually caught on fire around the motor! Not sure exactly what was the cause of his lean mixture, but the motor was toast (no pun intended) after his little "thermal event".

savage.25

i've had my stock s-25 engine up to 400F before. i shut it down right away. mine ran fine after that but it wouldnt hold a tune to save its life.. and plus it was too slow so i bought an STS .28, now the stock clutch cant handle the power... geez if its not one thing its another!!

glad to hear that its not cooked..

LiqrSicc

iTrader: (10)

If you havent actually owned an 8.0 and tried it you wouldnt know. For racing a .28 is probably perfect. But having the amount of torque and hitting 54mph on the 8.0, then dropping down to a .28 it's a considerable difference. Especially if you're used to the bigger engine. The LRP z.28r spec3 powered my savage x well, but the MGT is overweight by a few more pounds.

Uhgg, hopefuly it's just a leak from the loose head. The 8.0 engine is notorious for the leaky main bearing seals which are only rated at 250f. This was probably one of the more difficult engines to tune as they have 4 needles instead of the usual 3 I'm usually used to. It's tough to keep a tune but when it's running it's a great engine. Good luck!

Uhgg

iTrader: (11)

Ok I took it out today and ran it and it started right up (with new plug). Ran it around for a bit and checked the temp, it was almost 300 so I opened the low speed almost a full turn, repeated the process until I got the temp down below 250 after runnin back and forth about 50 yards 1 way. It sounds kind of like it is four stroking when under low throttle or when I let off the throttle and it is decelerating. I think I have the low speed throttle open far enough now and it is smokin pretty good when under throttle. Any ideas that might be causing this? I can make a sound clip of it if needed.

Thanx for all the help.