Cam movement - reassembly

[Borjawil]

09 3.5l 

Following a head gasket swap I have installed and torqued the heads, and I am installing the cam pulleys. While they came off by hand, it seems they don't want to slide fully on more than catching the key on the cam slot. Having it lined up like this, I tighten the bolts to about 50-60ft lbs (manual says 70 and then 90 degrees). I can still move the cam side to side about 1/4". This is with the 3 bolt backing plate off. Is this normal? 

[John/Horace]

Each cam pulley should go back on the cam it came off of. Could be slight tolerance difference between the pulleys. There could be a burr on one of surfaces, use scotch bright etc to polish up surfaces. Sometimes sliding pulley on first and then putting in key works better with some assembly’s.

 

Got a picture of what has 1/4” movement. Cams are fixed in place from what I have seen.

[Borjawil]

Took the pulleys off an reinstalled, went back on easily this time. 

 

As for cam movement - facing the enging, left side is timing gear pulleys, right side is cam thrust plates. Cam and pulleys installed. No rocker assemblies. Thrust plates not on. I can push and pull on the timing gear pulleys (passenger side to driver side or left to right) and get movement. So the end of the cam on the thrust plate side is flush to the head or sticks out of the head. Just learned that its called a thrust plate, and assuming with this name that is holds the cam laterally in place. I also see its coated with...idk the name for it but the black coating for wear that some lifters are coated with to slow/prevent wear on cam lobes. 

[John/Horace]

The deposition of black DLC coatings is a precarious process that can only be executed by a DLC coatings expert, such as Bekaert. DLC (short for Diamond-Like Carbon) coatings are the protective layer one can find on coated engine components. These have a typically black color, which makes the coated components easily recognizable. 

[Borjawil]

Good info. So I'm assuming play without the plate on is ok. Which leads me to my next question. My gasket kit didn't come with the thrust plate gaskets. I have cork and the blue paper gasket rolls to make gaskets. Preference or advice on using either? I figure the blue is denser and likely more suitable to the high heat location. And I'm assuming thickness plays a role so the plate is effectively doing its job. 

 

And a question the DLC coating. Since the cam rests against the raised portion of the plate, how crucial is the DLC coating? Some around the edges was removed when I was removing the old gasket. 

 

also ran into a weird situation with the head bolts. New head bolts with my kit, torque in stages to 65?ft/lbs then another 90 degrees. I'm aware of what it feels like to have a bolt tightened snug and like it won't turn more without the use of a longer handle/bar to get a bit more. Tightened all the bolts in sequence to 65. Then rechecked the 65. Then another 90 degrees. Manual states after the 90 degrees the ft pounds should be 90?ft/lbs plus or to replace the bolt. I had 2 or 3 bolts that I could keep turning with what felt like the resistance of 65 ft lbs and never really got that bottomed out resistance feeling. Did the 90 degrees on them and then another 1/4 or so to make sure. Didn't want to push it in case of stripping one out.  Not sure if my head just wasn't seated fully, shitty bolts, or what. 

[Borjawil]

Also received loctite and grey hi temp gasket sealer in the kit, but as far as I can see no gaskets previously had sealer on them. If there are any that require it let me know! 

[John/Horace]

I haven’t changed a head gasket in years. Timing belts and chains etc I have done recently.

 

The 90 degree twist after torque is the loading to yield of bolt I guess, I sent a link about TTY head bolts, should be buried in the pages of info on that site. Could have bad new bolts or threads in block, not sure. Under heat load these fastners do get tighter I believe. Magnums and 300’s used the 3.5 engine, try checking on their site, you still see lots on the road, mainly hemi models probably.

 

Usually the ears of valve covers  take a bit of rtv even though there is a gasket on cover, seems to be a common leak spot.

Loctite is used on bolts without spring washers that are critical and non accessible afterwards. Cam pulley bolts and other high speed spinning parts. Even high torque large fastners like crank pulley bolts often have a clear loctite product that is hard to see. Fastners that can be major issue if they back off will often have loctite.  Blue semi permanent is great, be careful of red permanent stuff, very difficult to remove fastner later.

[John/Horace]

Cut and pasted. Thread locker is for reusing cam sprocket TTY bolts.

 

If you have to replace a camshaft, the labor on this job is nine hours for just one side! The cams themselves are hardened nodular iron. Left and right cams are different (the left one is longer) so they can't be interchanged, and the cams are installed into the heads from the rear so they can't be changed without removing the engine from the car. Journal bearing diameters are 42.939 mm to 42.960 mm. The cams are held in place by thrust plates at the back of each head. 

 

The cam bolts that hold the drive sprockets are unusually long, threading into deep holes in the front of each cam. Chrysler says this compresses the end of the cam when the bolts are tightened to improve strength. This is probably necessary because the left cam sprocket sticks out quite a distance from the head. The cam bolts are the torque-to-yield variety (40 ft.-lbs., plus a 90 degree twist), but Chrysler says they can be reused provided locking compound is applied to the threads.

 

The belt-driven cam sprockets have D flats for rough alignment but no keyways - which means a special alignment procedure is required when the cams are installed or the timing belt is replaced to achieve correct valve timing. The procedure involves removing the cam covers on the back of the heads and fitting a special tool on the head that holds the cam in the proper position. The cam bolt that holds the sprocket is then tightened to lock the sprocket in the proper position. Chrysler says this technique assures better cam timing because it eliminates the problem of tolerances stacking up.

Edited May 6, 2020 by John/Horace