Help , Why this happen
- Thread starter Rolos10
- Start date
Jimbo
You can fool some of the people some of the time
Your head bolts look damaged.
It looks like you over tightened them (a lot) and also damaged the head.
The max torque spec for the head bolts is 220 inch pounds.
Are you sure you didn't tighten them to 220 foot pounds?
You also might want to check the calibration of you torque wrench.
It looks like you over tightened them (a lot) and also damaged the head.
The max torque spec for the head bolts is 220 inch pounds.
Are you sure you didn't tighten them to 220 foot pounds?
You also might want to check the calibration of you torque wrench.
Jimbo
You can fool some of the people some of the time
I see this happen to the head bolt pad next to the exhaust but not the other three.
The reason it happens to the one next to the exhaust is because it can get very hot in that location.
The heat can get excessive in that location if you race in a part of the country where the temperature gets hotter that this Yankee can take for very long. Places like Arizona, Southern Ca. New Mexico, Texas and Mexico etc etc.
Other things that can make the engine run very hot are taping off the blower housing, too much header wrap, very sticky tires, and high kart and driver weight and improper ignition timing.
It normally does not affect the other 3 head bolts.
I have seen the flange on the head bolts bend or cup somewhat over time (normally the one next to the exhaust) but i have NEVER seen a head bolt that appears to be cracked or damaged like the ones in you picture. I would like to see a better / closer picture of the flange on those head bolts.
I'm still suspicious of the torque that was applied to those head bolts.
If you bought the engine used the previous owner may have over torqued them. If you are the original owner then i'd still say you better check your torque wrenches.
The reason it happens to the one next to the exhaust is because it can get very hot in that location.
The heat can get excessive in that location if you race in a part of the country where the temperature gets hotter that this Yankee can take for very long. Places like Arizona, Southern Ca. New Mexico, Texas and Mexico etc etc.
Other things that can make the engine run very hot are taping off the blower housing, too much header wrap, very sticky tires, and high kart and driver weight and improper ignition timing.
It normally does not affect the other 3 head bolts.
I have seen the flange on the head bolts bend or cup somewhat over time (normally the one next to the exhaust) but i have NEVER seen a head bolt that appears to be cracked or damaged like the ones in you picture. I would like to see a better / closer picture of the flange on those head bolts.
I'm still suspicious of the torque that was applied to those head bolts.
If you bought the engine used the previous owner may have over torqued them. If you are the original owner then i'd still say you better check your torque wrenches.
CarlsonMotorsports
Site Supporter
I'll agree with the others -- just looking at the bolt hole bosses on the head don't look flat (ie way over torqued, or possibly someone chamfered them = bad idea). Even the backside of the head of the bolt (thrust surface) looks distorted, likely from one of the previous two reasons given.
It's not uncommon at all to burn a head gasket near the head bolt closest to the exhaust. Where yours burnt through though looks like it was not torqued enough, or it was previously over-torqued, causing the corners of the head to pull down. Where I normally see a head gasket failure is between the top two head bolts since the spread is so wide on the bolt pattern and one bolt carries a LOT more heat than the other.
Don't re-use head gaskets (especially the soft graphite ones we have to use on the LO206 rules.)
-----
?Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
It's not uncommon at all to burn a head gasket near the head bolt closest to the exhaust. Where yours burnt through though looks like it was not torqued enough, or it was previously over-torqued, causing the corners of the head to pull down. Where I normally see a head gasket failure is between the top two head bolts since the spread is so wide on the bolt pattern and one bolt carries a LOT more heat than the other.
Don't re-use head gaskets (especially the soft graphite ones we have to use on the LO206 rules.)
-----
?Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com