#137864, "Head bolt issue explored." Apr-25-13 08:05 PM by 0Boost
I recently rebuilt my engine due to the head gasket leaking oil everywhere. while I had it apart, I decided to explore the whole head bolts bottoming out thing. so I decided to snap a few pics of what I found if anybody is interested.
Here is what I noticed when I pulled the corner bolts out. the tip of both bolts on drivers side of head had a shine to them while the other two looked normal.
After seeing the head bolts, I decided to pull out the bore scope and take a peak inside. Both bolt holes on driver side looked like this. you could see a ring at the bottom where the tip of the bolt dug into when the motor was first put together.
I used felpro bolts and compared them to the originals and they were the same length. I did not want to risk putting them in and end up in the same situation later. so I cut about 3 threads off all 4 corner bolts. then I used a bench grinder to bevel the tips a little bit. after that I ran a thread chaser over just the tips (not the entire bolt) just so they would thread in properly without any issues. they threaded in perfect and I torqued them down to the correct spec with an mls gasket. at this time I have about 3k miles on the build and no problems.
not sure why I put time into an old issue, might have something to do with boredom. but I figured others might be a little bit interested in it and maybe even help someone out in the future.
#137865, "RE: Head bolt issue explored." In response to Reply # 0
The photos are neat. I heard about this issue a long time ago and used an old welding rod and tape measure to check the difference in depth on that side. Interesting to know that you can see the marks in the block.
#137871, "RE: Head bolt issue explored." In response to Reply # 1
Best thread I have seen in a long time! This topic is so interesting because there's very little reliable information online about the head gasket problem on the 420a. I researched for hours before doing my head gasket change and could not cross-reference good information for the life of me. Some say the bolt lengths were corrected, others say the holes were drilled deeper, some say to cut threads and some say not to, some say the problem was fixed in '97, others say '99...
Most sources I read said the problem was definitely fixed by '99. I own a '99 and the head gasket didn't go out until 176k (I read the problem would occur at around 100k if the motor had the head gasket problem. Therefore, I used a MLS gasket and the Felpro head bolts without any modification. We'll see how it goes. I figure if it lasts another 176k I should be fine since by then I'll be ready for a rebuild I suppose.
I called Mitsu. and got the head bolt measurements and they had the same lengths in their database as the Felpro head bolts in case anyone was wondering.
#137873, "RE: Head bolt issue explored." In response to Reply # 2
Thanks!
I went through the same as you. I searched and searched till finally I just tore it down and did some investigating. at that point I decided to take some pics and document my findings and the method I used to correct it.
#137874, "RE: Head bolt issue explored." In response to Reply # 3
I for one I appreciate your effort.
My biggest question now is if/when they fixed the problem. If they did fix the problem, it would be nice to know exactly when so we could all check our engine numbers and see if we're safe.
#137875, "RE: Head bolt issue explored." In response to Reply # 4
on the eclipse, im not sure. I don't think they really fixed till 2000 which by then the 2g eclipse was no more. but those engine were still going in neon and other platforms and I don't recall hearing or seeing an issue then. I read on allpar they didn't come out with the revised headgasket and torque procedure until 98 also. my mother owned a 99 Plymouth breeze, and her head gasket failed at around 70k.
so my guess is the motors used up till 99 didn't get fixed on the assembly line. they must have fixed the issue when they revamped the new models for 2000 and up.
