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Threads - crossthreading?

('03-'05) 
731 views 7 replies 4 participants last post by  subzoom 
#1 ·
I'm doing some timing work (180k miles) due to a thermostat seal leak that allowed oil and coolant to mix together for a short time. All oil and coolant have been drained, and I even went so far as to flood the engine with oil for a few days and then drained it out just to wick away any possible moisture that I could (thanks to physics, it all just utilizes gravity to get to the bottom of the oil pan). I'll be doing oil changes every 1.5 months to ensure that all of the gunk gets flushed out of the system.

With all of that said, I now have some experience with using heli-coils to fix over-torqued bolt holes in the engine block. But what about possible crossthreading? When I went to put a timing gear (the one under the tensioner pulley, next to the water pump) on, I had a lot of trouble getting it on since the timing belt itself was not being very flexible. In the process, I managed to get the bolt in at a slight angle. I tried backing it out, but realized that it was going to be stuck in there and that I'd have to re-thread. I don't have time right now for that, so I just screwed it in. My torque wrench gave me the "you messed the threads up, somehow" message by not torquing. It certainly won't come out by hand, so I put everything back together.

I'm going to give it a start tomorrow, but I wanted some advice from people that actually work on the same kind of engine if any of you have ever encountered this kind of problem and how did you solve it?

My current solution is to order a new bolt, take it to the auto store to find out its dimensions, then obtain a respectable heli-coil. In about 20k-30k miles, my plan is to take it all apart and install new timing parts (since it's due for a timing overhaul at 210k miles). I want to believe that nothing should happen to that bolt while it's in its cross-threaded place during whatever amount of time it takes to put that many miles on her, but I have heard that a bad threading job can jostle a bolt loose and even snap the head off of a bolt while flying down the road.

So what should I do? Continue with my plan, alter my plan, or just get the stuff together and do a complete timing overhaul in less than 10k miles?
 
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#3 ·
I had to run it for a few hundred miles. Haven't ran it for over a week now, been gathering parts. Just got it pulled apart today finally. Timing was off a little bit on the passenger cylinder - center and drivers side at 12 o'clock, while the passenger was at about 2 o'clock. Not happy about this. I've never had this problem before, so I'm not sure just how bent the valves may be.

I was able to pull the bolt and sure enough, it's all shredded up in there. Blew it all out. Thankfully, it's on the water pump and not the engine block itself. However, that 2 o'clock cylinder has me worried.

I suppose my next question would be, if a cylinder got turned manually (ie. by hand) rather than from compression, would that be enough to bend a valve stem? I'm looking at replacing the timing cover on the drivers side and something looks to be a bit amiss there as well. I'm wondering if I should even bother at this point. Backup plan is to get a second vehicle, then take the time to pull the engine and do 'er over real good this summer.

On the bright side, I managed to get the engine clear of coolant on the first try. Not seeing any white residue show up in the oil cap region.
 
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