[AllanC]

. . . . i have an issue with a durango 3.6 v6, every time i install the new timing chain kit, the dimple mark in the crankshaft gets misaligned after two rotations to check if timing was well done. Im gonna post some pictures, so it's easier to understand: . . . .

. . . . Then i release all tensioners, and all good until here, but then, after i rotate the crankshaft to check if every mark fall where it is supposed to be, this happens: . . . .

I think you are experiencing slack in the chain when you release tensioners. Do not release tensioners Set all timing marks as you have noted. Install 2 chain guide tensioners. Watch the RH guide tensioner for lateral movement / compression as you rotate the crankshaft 2 full turns. Does the tensioner compress and allow the RH guide to move away from the chain? If YES then you are getting slack in the chain and this is causing timing marks to be off a slight amount.

When the engine is running oil pressure keeps the RH tensioner firmly against the chain to remove slack. Without engine running and no oil pressure there is only spring tension which might be insufficient.

 

[AllanC]

In keeping with my thought process on tensioner guide chain slack (post #17) I am thinking there could be even more slack in the drive chain between the crankshaft and intermediate shaft sprockets. This engine is different in that the crankshaft sprocket does NOT drive the camshaft sprockets directly. There is an intermediate sprocket assembly which drives the camshaft chains directly. If there is excess slack in the crankshaft to intermediate sprocket assembly chain, you would get a slight variation in timing mark alignment at the crankshaft. See attached image.

 

[AllanC]

. . . .So now my theory is, that cylinder head in particular (or maybe both) was excessively resurfaced. I already find info about it, camshafts retard a bit when you take off material from the cylinder head, so you gotta look for the minimum permissible cylinder head height to keep everything running well, and again, thanks to ImperialCrown, i know it is 0" for this engine. . . . .

I find it difficult to believe that removing a few thousands of an inch would move the heads closer to the intermediate sprockets, cause more chain slack and allow the crankshaft timing mark to advance a few degrees as you note. Look at the attached diagram and it will help to determine where the chain slack is occuring and skewing timing mark alignment.

Crankshaft to intermediate shaft sprocket chain has a colored link which should be oriented to top or 12 o'clock position. Crankshaft sprocket aligns such that dimple mark at block parting line. Camshaft sprockets aligned appropriately. Rotate crankshaft 2 full turns and stop. Plated link on intermediate chain drive should be in exact same position at 12 o'clock position? If NO and slightly off then issue is chain slack between camshafts and intermediate sprocket. If YES then the issue has to be slack in the crankshaft to intermediate sprocket drive chain.

 

[AllanC]

. . . .i think plated links don't come to the same position after you rotate the sprockets. Anyways, yes, plated link in the idler sprocket is at 12 o'clock position at the beginning, also, there is a plated link and an arrow in the crank sprocket that need to match (along side with the dimple mark in the crankshaft and the block junction). That is also set up properly before start rotating. The only slack i see is in the left cam chain. . . . .

I believe you have the 2 tensioners installed correctly on the crankshaft to intermediate sprocket assembly drive chain?

My error on thinking that the plated links would return to initial timimng position in 2 crankshaft rotations. I am still thinking of a direct drive from crankshaft to camshaft. In that arrangement the camshaft sprocket is twice the diameter of the crankshaft sprocket. That gives a 2 : 1 where crankshaft makes 2 revolutions to 1 revolution of the camshaft.

Howver this Pentastar V6 has an intermediate drive sprocket and that complicates things. I do not know the drive ratio between crankshaft and intermediate sprocket; I will call it ratio A. There is another drive ratio between the intermediate sprocket assembly and the camshafts; call it ratio B. You multiply the 2 ratio fractions together and you get a ratio between the crankshaft and camshafts of 2 : 1.

I believe if you continued to turn the crankshaft additional turns that plated link on the crankshaft to intermediate sprocket assembly would eventually appear in the 12 o'clock position. and the dimple on the crankshaft would be at or close to the block parting line. The plated links on the camshaft chain will be in their original timing position.

. . . .How do i fix this slack anyways, is there some kind of method to do this? All tensioners are new. . . . .

So you have convinced me that head shaving does cause excess chain slack and this causes a slight misalignment of the timing marks as you have noted. If you could find 2 camshaft to intermediate sprocket drive chains that are a few thousands of an inch shorter in length that would correct the problem. But I highly doubt such a modified chain is available.

You could try and move the fixed guides on the camshaft drive chains. Do not know if there is room to move the fixed guides to remove slack. See attached image.

I wonder if thicker head gaskets are available for the 3.6 liter V6 engine? A thicker head gasket would remove some if not all of the chain slack and remedy the situation. In a sense a thicker head gasket has the same effect of increasing the deck height. Do not know if thicker head gaskets would create sealing issues?