Can't turn over the Engine more than 270 degrees

[JoeMechanic]

3100 chevy motor I have the front bank head off..all I found was 1 broken valve spring and pushrod.I have a 15 mm socket and 3/4 drive ratchet and extension on damper pulley.I can turn her over but only 270 degrees than it locks up.There isn't any damage noticed in the cyliders the engine seems fine except for thse 2 broken parts.I am going to investigate more tomorrow and am leaning towards a broken camshaft..anyone else ever have a similar problem?..thanks for any advice.

[SappySE107]

Yeah, the engine I got dirt cheap had a broken camshaft and a nice gouge in one of the cylinder walls. I didn't have that much movement though:P Broken camshaft should let you spin 360 since you won't be turning every lifter or even the oil pump. Might have something in the rear bank.

[JoeMechanic]

ugg...I'm already into this thing for 9 hours

or so.Well at least its easy to take the rear head off now.The most problem area I had was to take the top engine aluminum mounting bracket off.I tried to wedge it out and couldn't..so I unbolted the lower dog bone mount and raised the engine as much as possible and then it came out except I chipped the power steering pulley(made of plastic).I should have unbolted the power steering pump through the 3 pulley holes and removed that first..I live and learn everyday.It really doesn't seem like anything in the rear head is the problem but I haven't really looked yet(valve cover still on).I will look today and try to find out the problem(top half of engine just about completely off).If its the cam or cylinder,piston or anything else I am going to put in a reman short block if I can find one or Wrecking yard low mileage engine.Should I go with the same or swap it for a 3.5L?..would the 3.5 bolt up to the 4T60e transaxle?,Joe.

[PCGUY112887]

The 3500 will bolt to the 4T60E just fine, however there are many other aspects of the 3500 that are different.

See my swap here

http://www.60degreev6.com/showthread.php?t=36647

[JoeMechanic]

Broken camshaft,1 broken exhaust valve #6 cylinder,One broken pushrod #3 cylinder one broken spring #3 cylinder..is the damage done!.I have the engine just about completely disassembled now I find the camshaft broken.I have to remove the engine short block to remove the camshaft(in 2 pieces)..I might as well replace this tired 160,000 mile motor.The question is what would be the best most reliable engine choice between another 3100,3400,3500 or 3900?.The system is OBD1.5 right now and i really would like to upgrade to a 3500 or 3900 engine.Would I have to replace the engine harness and the ALDL connector and under dash harnesses?.I want to do the least amount possible but upgrade from the 3100..any help would be greatly appreciated,Joe.

[PCGUY112887]

Jeez what happened to that motor?

[JoeMechanic]

From what I can tell the camshaft broke

thus causing the pushrod to break on #3 cylinder exhaust or intake valve that caused the spring to break which caused the #6 cylinder to break the exhaust valve and the broken piece of valve lodged in the spark plug hole jamming itself right next to the spark plug.Whats amazing to me is that no damage was done to the cylinder or piston just minimal damage to the head around the spark plug hole.He told me he was driving around 20 mph when it just quit..thats probably why minimal damage was done..if he was driving 60 on the highway he might have locked it up and pieces may have went through the oil pan?.All of this because of a broken camshaft..just broke between #1 and #3 Cylinders.