Timing Cover and Timing Chain

[geldartb]

wow seriously.

i think i used something around the range of a short depth 24mm socket with a long enough bolt to accommodate the socket.

forget what bolt it was or the length but its a GM bolt.

you better hope you didn't screw the bearings up by all this hammering your doing to the crank.

[PCGUY112887]

You would need a much larger socket than that... you would need something about ~36mm to get it to fit over the end of the crank, since such a huge socket is uncommon I haven't been able to do it!

The pounding with the pipe idea came from SappySE107 so I figured it would be safe. I got a new crank bolt today and a shorter crank bolt and some washers to try to suck this gear on.

[1988GTU]

Careful to not pull the threads through. Murrays Auto usually carries all those big ass sockets that you only use once and pay 20.00 for....

[PCGUY112887]

Are we sure the 3500 crank bolt is M12x 1.5? The external TCE trigger bolt was fairly messed up... As if it was the wrong pitch bolt. I cleaned out the crank threads and they appear perfect, but when I thread in a new m12x1.5 bolt from napa, it gets chewed the same way. I am using oil on the threads as well.

[CNCguy]

All 3100, 3400, 3500 & 3900 use an M12 x 1.5 bolt to attach the crank pulley.

I always use a long bolt and a bunch of washers/spacers to pull dampers on. I start by running the bolt into the bottom to see how many washers are needed. Then I remove the bolt and add enough washers so the bolt is about 1/4" from the bottom. Crank the bolt in almost to the bottom then add another 1/4" of washers. By doing this you are using the majority of the threads to pull with. If you start with little thread engagement it is easy to pull the threads loose. Luckily, your crank had stronger threads than the bolt and most of the damage is done to the bolt threads.

I also use high pressure grease on the threads.

[PCGUY112887]

The problem is the threads aren't getting torn up due to using the bolt to pull, just me threading it into the crank pulling nothing, just using the wrench to tighten the bolt, the crank eats the bolt. It doesn't distort the thread pattern, but rounds down the threads quite a bit. The already ate up TCE bolt goes in the easiest while the new bolts take a bit of extra turning due to the grinding going on to the threads. I really wanted to put in my new bolt but it scares me when it gets eaten that much and it leaves lots of metal flakes in the crank threads.

[CNCguy]

If the new bolt doesn't go in easily the threads in the crank are already damaged. The threads probably have some galling and deformation. Just run a tap into the threads to clean them up. Be sure to get the tap lined up properly so it doesn't destroy the rest of the threads. After you get them cleaned up use the aforementioned procedure to reinstall the damper.

[1988GTU]

Goto the junk yard and pull another bolt. See if it threads in. If it doesn't, then you need to address your crank with a tap like /\ is saying.

[3400-95-Modified]

I cleaned out the crank threads and they appear perfect

How did you go about cleaning the threads up? Were you simply referring to maybe blowing them out or using air to clean out the crap?? because if thats it you need to do more.

As others have suggested... Run a M12x1.5 tap in your crank to fix the damage you have done... before its too late.

[PCGUY112887]

Thanks guys, I shall do that. I may have my mechanic run a tap through it, I've done it before with other things but I would hate to screw up my crank! I need him to hack off my trailing arms anyways so I can put my GMPP ones on finally. The metal sleeve came loose in the bushings so they are nice and stuck on.

Anyways I put it back together on Sunday using the already marred up bolt since it threads in correctly and got the motor started and drove around. It seems to be running nice with my new chain, my valvetrain and entire motor is definitely more quiet than it was before. I went and bought a nice 1/2" Digitorq torque wrench to put everything to spec as well.

I was quite surprised to find absolutely no stretching with my stock 3500 chain, it was almost a shame to pull it off! I would have to go pull out my title to know how many miles are on it with my cam, but it's been my DD for over 2 years now.

I was also surprised at the difference between the 99 chain and my stock chain. I took a number of pictures to show how much beefier it looks and a video.

http://www.youtube.com/watch?v=FI2iJyd088k

[3400-95-Modified]

DAMN, thats alot of room on the side... your a lucky bastard...

How did you determin that your original chain was not stretched? Did you check the play with the center guide removed? And you also bought a new pre 2000 center chain dampener correct?

[PCGUY112887]

The video shows me tugging on it with the center guide still installed, but even when removed the chain was just about as tight. And yes I bought the 99 chain dampener as well from the part numbers you gave me along with both sprockets and the chain.

[3400-95-Modified]

Um, wow I didn't watch the vid till now... No timing chain is that tight when installed... That doesnt seem right at all.

My stock 3500 one, and 3400 one had more play than that off of a 4k mile stock 3500 and 3400 engine.

Did you have a 3500 dampener in the middle before? Or did you install a 3400 one when you put your cam in?

Was your sprocket possibly pulled partially off on the first set? I wonder if your pulley wasnt on far enough and allowed the lower sprocket to walk in and out, generating noise, and also metal flakes. Either way that chain seems too tight.

[PCGUY112887]

The 3500 dampener was installed before, all stock stuff that came with the 10k mile motor. When I had the motor apart for the first time the chain was the same way. The all new 99 stuff is the same way as well.

I thought maybe the old sprocket was coming loose at first, but if anything it was too TIGHT. It was fairly tough to get off there, and putting it at 103 ft lbs this time didn't seem super tight at all.

FYI the new chain wasn't that tight until I turned the motor some by hand to check alignment of the sprockets. But it was still fairly tight on both sides before hand.

[IsaacHayes]

Strange, mine was never that tight either even with new chain.. that does seem "off"...