Sportster rear cylinder head bolts

I just had a head gasket leak, when i pulled the rocker box off i found that 1 of the 4 head bolts had completely come loose , could turn it very easily with my fingers , while the other 3 were still tight and still torqued to spec.Does anybody know why 1 fastener would have lost its clamping force while the other 3 remained tight . They have been fine for approx 20,00 miles.
Thanks Tim

When chasing the threads where the loose head bolt was, does everything feel good & threads on bolt look ok? Lots of reasons for bolt to be loose from: Improper torque or torque sequence (I doubt sequence though...), thread damage, to forgetting to use locktite on that bolt when it was installed.
The only thing I would say now is: Try to figure if the head is warped and that the thread on both the bolt & engine aren't damaged. If it were me I'd be tempted to install a new reputable gasket & if there is no thread damage, assemble it back together as per the manual & closely monitor for the next few rides for leaks.
My guess would be a previously crappy install....

Metal fatigue, Threads pulling out of the block, stud stretching or not torqued properly IE no mineral spirits on threads not pulled to 90 degrees after torqued. So many variables it is hard to pin point one. I will bet the head gasket is blown in that spot. IMHO while I had it apart I would replace all of the fasteners including the studs and have the Jug and head checked to make sure they are perfectly flat, if not corrected by a machinist. I would do this for both front and rear cylinders even though the front one is not leaking yet.

FXDC is right. It probably would be a good idea to go over the front as well. Your to that point anyway if the rear head is warped and if not, why not inspect & replace the front gasket instead of doing that job twice...

i decided to at the time i found it to just retorq the particular bolt per the manual and see what happened it resealed for about 50 miles and has started to leak again , i have not yet pulled the rocker box off to see if the headbolt held the torque,but the headgasket that is in there right now is a cometic and the head was toequed at that time per the HD manual
tim

Cometic gaskets must have a perfectly flat and clean surface to seal properly I tried them a couple of times on a mustang I had the gaskets would hold for a while then start to leak. I went with a set of felpro gaskets and are still sealed up tight five years later. On kart engines I stop using gaskets and only use Toyota FIPG. I do not recommend it for any engine you care about I have to use a rubber mallet to get the head off.

Well Here is what i found the inside stud pulled out of the engine case destroying the threads after 22,000 miles of service with no problems. Found a repair kit for it called timesert. They make an insert for this repair specifically for HD engine studs.
++ TIME-SERT MANUFACTURER KITS - Harley Davidson ++, Harley Davidson spark plug blow outs, blown out sparkplugs, Harley Davidson stripped spark plug, Harley Davidson sparkplug blow outs, Harley Davidson spark plug stripped, Harley Davidson spark plug
tim

Thanks everybody, for all the input, will let you know how it all turns out
tim

Thanks again for everybody's input, got the bike back together with the timesert installed, all seems well so far had about a ten mile ride to shake it down. Today i am going to put a few more miles on and see what happens.
Tim

I second replacing the head bolts. And do you have a manual.
In the touque specs does it say to torque them to like so many foot pounds and then say turn it from 6:00 to 9:00 for the second part of the torque procedeures.
That is another step in the torque that is pretty important.

And have you checked yer torque wrench to see how close it is.
I borrowed one and it was like over 10ft lbs off.
I went to Northern tools and got one. Got another one from Sears.

:roflmao::roflmao::roflmao:

Wait till you start workin with Computer controlled bikes more and git away from Carbs.

Start Now !
yA KNOW If it wasn't for technoliogy we might not be here on this forum

We'd have to be at a Meet and greet at the local tavern..........:cussing:

And yer cell phone, you could just throw it away too. :gah: