Chain tensioner popped out during head gasket replacement

[fatdogsdaddy]

I blew the head gasket on my 85 Nissan 720. I placed the head back on but I couldn't get the cam sprocket back on the cam. I grabbed a flashlight and saw what I didn't want to see, the spring of the tensioner and the chain touching itself so I have decided my wood block failed and I have to pull the timing chain cover and put everything back in place. My main concern is how do I break the crank pulley bolt loose without disturbing the timing since the chain is already off the cam?

[datzenmike]

Place in 5th gear clutch engaged, set the parking brake, have someone hold the brakes on.... this should immobilize the crank. Set the 2mm socket on the crank bolt and have a breaker bar or short pipe on the ratchet handle hanging down. Climb under the truck front end and position yourself so you can kick backwards with right foot against the ratchet handle, kicking it to the driver's side or counter clockwise to snap it loose. Take a few practice motions so your foot comes down like stepping on a ladder rung and be sure everything is clear.  The trick is to do this once and as hard as you can. The bolt will make a snap sound and about a half turn and it can easily be spun off by hand.

 

Now check that you are still at TDC, probably are, then tap the back side of the pulley with the heavy socket. I did this just yesterday and have done this at least a dozen times on L and Z engines and never needed a puller. Keep tapping, probably 30-40 times, you do not want or need to hit harder, just keep tapping it and it will slowly move forward and off. The pulley sits on a woodruf key so watch for it if loose, usually they stay on the crank.

 

One of the water pump bolts goes through the timing cover and holds it on so remove it and you don't have to take the water pump off. Also the oil pump and the distributor and drive spindle must come out. There is a 10mm bolt behind the oil pump. Don't forget the 4 bolts coming down from the head into the top of the timing cover and the 6? oil pan bolts up from underneath.

 

Now is an excellent time to replace the crank oil seal while the timing cover is off. Just pry out with a screwdriver and tap the new one in.

[fatdogsdaddy]

Thanks so much datzenmike. I had forgotten to add anything else I should take care of while I've got it ripped apart to my original post and you covered that too. If you ever make it out to Vegas I'll buy you a beer.

[weldingrod]

The fun part comes when reinstalling water pump and distributor while maintaining your timing.

[datzenmike]

 

Not at all. The engine was set to TDC so install the oil pump/distributor drive spindle into the oil pump as shown on the left. When installed, the top of the spindle should look like the picture on the right. If not, re-position the spindle until itlooks like a clock at about 11:28. Note that the smaller of the two half moons is to the left side or front of the engine. The distributor can only fit into it in one position so your timing is unaffected.

[fatdogsdaddy]

Well my never ending project keeps on giving, I attempted Datzenmike's technique and the crank turned on me. I backed it up to the original position and gave it a kick (tried twice) and it keeps moving. Any other ideas before I go borrow an impact wrench? Also once I finally do break it loose can I just back it around to the starting position and go from there? if it does turn is the Z24 a non-interference motor? Do I have to worry about pistons and valves bashing each other if it does turn?

[datzenmike]

In 5th gear, clutch engaged, (pedal up) parking brake on and brakes held? no way unless your clutch is toast. This bolt is tightened to 100 to 120ft lbs. I've snapped them loose with the engine laying on the ground with nothing to keep the crank from turning. The trick is a sudden impact, HARD!!

 

Yes any TDC will work as you have to set the timing chain and the distributor anyway... but you still have the chain on the crank sprocket. Turning it might snarl up the chain. I would stay as close to the present TDC as you can and back it up if it moves off.