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Author Topic:   Motor got hot 300*My son
Dirt Maniac

Total posts: 103
posted July 17, 2004 04:46 PM  
My son got his motor hot and it blew the bottom water hose off. He ran 2 laps like this before he had enough sense to come in. My question is the motor really smells burnt inside but the pistons look good. It did take the bearings out. 20 cleaned the crank up. But my main question is the heads. One head looks good. But the other head is real black on the outside just like it has been in a fire. Would you be afraid of running this head or not. I have never gotten a motor this hot before, so I don't know what to expect. Thanx

Dirt Freak

Total posts: 206
posted July 17, 2004 07:21 PM  
If their not cracked now, it won't be long before they are.I would replace both heads.

Dirt Full Roller

Total posts: 49
posted July 17, 2004 07:29 PM  
you could take the heads and have em magnafluxed to check for cracks, i'd be a little worried they might have got warped also.

Dirt Freak

Total posts: 370
posted July 17, 2004 10:25 PM  
Have a machine shop check them for flatness and hidden cracks. Sounds like he did a number if you had to clean the crank too. I would take it somewhere and really check it out the human eye is only so good and thats not very.

Dirt Forum Champ
Total posts: 635
posted July 19, 2004 10:45 AM  
Are they stock castings or aftermarket? Stock castings won't take heat very well. An aftermarket casting will fair much better.

At the least have them crack checked. Preferably mag'd, pressure tested, decks checked/milled and touch up the valvejob & guides.

Dirt Maniac

Total posts: 148
posted July 19, 2004 02:45 PM  
I built my own pressure tester. If you are interested, reply and i'll post directions and a picture if i can. It's cheap to build. I use it every time i get a set of heads ready to go to the machinist. That way i don't pay to machine a junk head.
How many of us have trashed a $2000 engine trying to win a $200 race. Ok, everybody hands down. Your son can log that lesson in the books now too.

Dirt Forum Champ
Total posts: 569
posted July 19, 2004 03:43 PM  
Sounds like after you spend the $1500 on getting the motor back together, you should get a $25 idiot light.

Dirt Maniac

Total posts: 136
posted July 19, 2004 08:16 PM  
The heads will surely need a valve job if nothing else but to loosen the guides back up.

Dirt Full Roller

Total posts: 40
posted July 20, 2004 07:49 AM  
Originally posted by WesternAuto17:
Sounds like after you spend the $1500 on getting the motor back together, you should get a $25 idiot light.

The idiot lights are good but if he blew the lower hose off, there is no water flowing by the sensor so the light would not come on because it would not know it was overheating.

Dirt Forum Champ
Total posts: 569
posted July 20, 2004 08:08 AM  
Well, the hose probably blew off because the engine was being cooked. Even if the hose blew off on its own and that caused the overheating, the guage would either work (water or not, its still hot in there) or it would bottom out to nothing.

Either way, unless you have an unlimited motor budget, you gotta keep an eye on those guages and lights.


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