lost HG #4 why?

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killed300ex

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Truck has been thru 4 HG in the past year or so. First two where done by mass diesel both blew out under #5 exhaust manifold then the next ones I did it blew out the same place it doesnt blow into the cylinders only loose coolent out the side of the motor. I checked the block and head with a machinists straight edge and they both came in at under .003 for flattness. Truck only has maybe 8k with 4 head gaskets. Head has orings and arp studs. Studs torqued to 130. Could the threads be pulling on that side of the block letting the head lift? Not sure what to do to make this thing stay together? thinking about switching to firering and either arp 625 or maybe bigger studs?
 
My suggestion is to have both the head and block decked and check the protrusion on the o-rings. Follow the proper torque sequence when reinstalling and periodically come back and retorque the studs.
 
Something likely isn't flat. It may not be present at the angle you checked.

What are your boost and drive pressures? With o rings, it almost shouldn't matter I guess.

625's could help, but it would likely just band aid a surface issue. $.02

Are you running a coolant bypass? If not, make or buy one.

Also, are you waiting till she's up to operating temp before railing on it?
 
yes it has always been up to opperating temps. been driving the truck for almost 30 minutes befor it went yesterday and it wasnt even a full throttle blast just 3/4 or so to pass a car. NO coolent by pass guess ill look into one. Dont know my drive pressure but im pushing around 60lbs of boost. Is there anyway to deck the block in the truck?? Just had the motor out 6 months ago really dont feel like taking it out again.

Also line torqued the two outside rows of studs and its stoped leaking
 
It would have to be flatness, I ran regular studs for years at 70 psi! The drive pressure on your twins will not be high, likely 1 to 1 at 60-65, firerings are not a cure all and can be a PITA, much more than O-Rings, additionally $1000 set of studs wouldn't fix it.....way overrated!

Jim
 
double and triple check o-ring protrusion, if one side of a cylinder measures 3-4 thousands different, your going to blow Head Gaskets all day. I always put new rings in when my head comes off, even if nothing is wrong, just to maintain maximum protrusion.

Lavon
 
recheck the flatness of the head and the block. also check or even just go ahead and replace the O-rings. check the O-ring grooves aswell to be sure they were cut out correctly and not one side deeper than the other.
 
I retorqued mine for 3 heat cycles. I think it is especially important when using o-rings. It seems like the o-rings settle into the headgasket as it is ran. at the first two retorques some studs were no longer torqued to spec and had to be tightened. I back the nuts off one at a time and relube them before I torque them everytime. You should get a real smooth pull when torqueing, if it chatters add lube to the nut and washer and then torque them. OK I'm done rambling.

Derek
 
Evan i think its time for the new motor. you should bring that thing down here next week and we will take a look at it and see what needs to be done, ill tow it if you need a tow. give me a call if you want me to take a look at it
 
01CumminsSport said:
Evan i think its time for the new motor. you should bring that thing down here next week and we will take a look at it and see what needs to be done, ill tow it if you need a tow. give me a call if you want me to take a look at it
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Thanks for the offer I am plannin on pulling it apart as soon as I find something else to drive for while. unfortunitly I dont have the money to pay a shop to pull it apart right now. think ill pull it apart then just take it to a machine shop to let them go over it. If i need some help ill let ya know.
 
evan if you need help ill help you at no charge, i still havent seen what this truck can do you can use the shop if you want, just let me know
 
killed300ex said:
I checked the block and head with a machinists straight edge and they both came in at under .003 for flattness.
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How long was the straight edge? IIRC, spec is .003" over a foot, .006" over the whole length. Even if the 1' straight edge says its ok, it could still be out over all.
 
X2 on the Oring protrusion & timing. While you have the head off, dial indicate True TDC & mark it on the balancer. Then re-verafy your pump timing. You might also check the pop pressure on the injector closest to where the gasket went... Lower pop pressure=higher effective timing.
 
The reason I am asking.... When I put the R700 kit on my12v I blew a HG in less than 3 miles after 3rd re-TRQ..... turns out that they had my waste gate at 60 psi..... my drive pressures were off the chart..... took it to 34 psi start and wide open at 40 psi and all is right with the world .......
 
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