Ok this is the 2nd time my head gasket fails after the rebuild. I am only 7 months into it with a 3yr warranty. So the shop will fix it , BUT what the he'll is happening to it?
Is it the high RPMs cuz it's only a 3 speed and going 70 mph it's at 3200 RPMs?
Is the shops fault not machining the heads properly?
I don't understand , I haven't even taking it offroad yet in fear that I might kill my engine
My guess is head is warped or deck is warped, cheap low quality gasket, poor finish on the surface, improper torque and or torque sequence ,Try new head bolts. My experience is head gasket rework is usually the installers fault. Also high RPM wont cause the problem. Lugging it is harder on it.
Have the shop pull the head and put a straight edge on the block and then the head. Why was it rebuilt before, did you overheat it and warp the head. And when it was put back together was new head bolts used.some places don't know how to mill the head and deck the block.
By a new engine, do you mean it was a crate motor from large rebuilder, or overhauled by a local shop? If engine came in a crate from large rebuilder, then odds are very, very high the heads and block were resurfaced if required.
However, it is possible that when the last two head gaskets failed, it overheated and now may be warped......So fersure check both for straightness.
Even new head bolts won't correct if the following condition exists when someone installs the head:
They must FIRST clean out the bolts holes in the block making sure they are absolutely dry-no water, oil or antifreeze however slight the amount, can be left laying in the bottom of the bolt hole. Dirt either. When they lube the head bolt threads just prior to insertion, use only enough lube to lube the threads, not dripping with oil.
What often happens is even when a new bolt inserted in a dirty and or wetted hole it will not screw all the way in, and even tho you are at torque, the bolt is not strechted nor is it clamping enough........Gasket will eventually leak everytime.
Check block and head for straightness, buy absoute best head gasket, check head bolts are proper length, clean the crap out of the bolt holes, and then tighten bolts in proper sequence...that should be the end of it.
Have the shop pull the head and put a straight edge on the block and then the head. Why was it rebuilt before, did you overheat it and warp the head. And when it was put back together was new head bolts used.some places don't know how to mill the head and deck the block.
By a new engine, do you mean it was a crate motor from large rebuilder, or overhauled by a local shop? If engine came in a crate from large rebuilder, then odds are very, very high the heads and block were resurfaced if required.
However, it is possible that when the last two head gaskets failed, it overheated and now may be warped......So fersure check both for straightness.
Even new head bolts won't correct if the following condition exists when someone installs the head:
They must FIRST clean out the bolts holes in the block making sure they are absolutely dry-no water, oil or antifreeze however slight the amount, can be left laying in the bottom of the bolt hole. Dirt either. When they lube the head bolt threads just prior to insertion, use only enough lube to lube the threads, not dripping with oil.
What often happens is even when a new bolt inserted in a dirty and or wetted hole it will not screw all the way in, and even tho you are at torque, the bolt is not strechted nor is it clamping enough........Gasket will eventually leak everytime.
Check block and head for straightness, buy absoute best head gasket, check head bolts are proper length, clean the crap out of the bolt holes, and then tighten bolts in proper sequence...that should be the end of it.
It was overhauled at a reputable shop.
The rebuild was done because a piston rod shot through the oil pan.
I will call and make sure to tell them to clean out the bolt holes
the reason i ask about head bolts is because on some larger diesel engines that i rebuilt the head bolts will stretch and will not torque down giving false torque on head gasket. i put new heads on a 4.0 ford v-6 that came with new bolts in the gasket kit,i guess that ford doesnt want used bolts due to stetching.
The reason you are often required to replace head bolts is because they do stretch when taken to torque. Now don't misunderstand-the bolts are designed to stretch a certain amount when tightened to proper torque, all is good when they do stretch. However, after countless heatcyles, the bolts loose their ability to stretch again if reused.
Believe it or not, a torque spec is just and indirect way to measure desired bolt stretch. Yes, by using a torque spec, we insure the bolt is stretched the proper amount. Seeing as there is no way to measure bolt stretch directly, we use torque tables that were developed in the lab to get us as close to possible.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Ask a question
Ask a question
Jeep Wrangler Forum
9M posts
468K members
Since 2005
A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance, for all JL, JT, JK, TJ, YJ, and CJ models!