What started off as a broken heater hose quick disconnect that dumped all the coolant and tripped the cylinder head iverheat protection ended up with me removing all hoses, upper intake/plenum, both valve covers and the lower intake manifold while re-lacing spark plugs, coil packs, a fuel injector and all injector o-rings, EGR valve, EGR tube to manifold connector, DPFE sensor, fuel injector connector shells, thermostat and gaskets.
So, as I went to install the lower manifold with injectors and fuel manifold attached, the 3rd mounting bolt from the front on the LH side was the only one that didn’t want to thread in by hand until the attached washer was snug against the manifold mating surface. The overall length of all of those bolts from bottom of the bolt head to the tip is 1.5”. The washer is 1/16” thick and the length of th piece that broke off is 5/16” total. There is about 1/2” of bolt still sticking out above the cylinder head intake mounting surface. The last 1/4” of the bolt is tapered and not threaded. Thus, that leaves about 11/16” of the bolt in the cylinder head with about the upper 7/16 of that actually threaded. That means that excluding the unthreaded tip, the length of bolt threaded into the head is about 1/16” shorter than what is protruding from it.
I tried taking the bolt in and out multiple times before it broke, swapped it with another bolt that behaved the same way, and eventually used a torque wrench to torque it to 6 lb-ft (torque spec calls for first torque pass to 89 lb-in/7.42 lb/ft and then an additional 90 degree turn). When the bolt reached the 6 lb-ft torque, about 1/4” of the bolt below the washer was still extended above the intake manifold mounting surface.
I backed it out slightly and then tried tightening with a 1/4” drive ratchet and the after a few turns the bolt snapped. I don’t recall having any issues getting any of the bolts out and I cleaned up all of the bolts and applied copper anti-sieze before attempting to install them. I really don’t see how I could have cross-threaded this bolt, but it sure seems like either I did or it was done previously.
At this point I have tried using a thread chaser on the visible portion of the broken bolt and then double-nutting with stainless steel nuts. The nuts continue to thread off of the bolt as an assembly no matter how tight I attempt to tighten them. I have sprayed PB Blaster on the bolt entrance into the head as well.
I don’t have a torch, other than a handheld propane torch and don’t have a welder. I don’t want to risk warping the cylinder head to intake mounting surface, but I have to get this broken bolt out.
I am going to try to find some other nuts that have a rougher surface than the stainless steel ones and possibly with a built in washer/lip to give more gripping surface between the nuts. I could also try to fit a lock washer in between the, but I’ve seen differing opinions as to whether that would be of benefit.
I’ve tried to find a mobile mechanic that has a welder, but as yet have not found anyone in my area. I could buy a low-end welder at Harbor Freight, but I’d prefer not to as I would rarely use it.
I greatly appreciate any assistance. I’ve had this vehicle apart for 6 weeks now between waiting on parts, weather and issues like this coming up.
Many Thanks,
Ted
