L20 not cranking

[720 Freak]

Ok so I'm new to the forum and thx for adding me. I've just finished replacing the head gasket on the L20 got everything back together and now it won't crank, I think I have the plug wires right according to what I've found on the net but the best way to describe what it sounds like when I try to crank it is the way a motor sounds when it had no plugs in. I'm pretty sure I've got spark but it's so bright outside here today it's kinda hard to tell so I'm gonna look at it again tonight. Any advice that you guys might have is def welcome

[datzenmike]

The term 'not cranking' to me sounds like the starter is not cranking the engine over. Cranking means turning. Your other statements suggest that it is turning but failing to start. I'll assume that it is indeed turning over with the starter....

 

 

Set the engine to TDC compression stroke on #1 using the notch on the crank pulley and the timing scale. (both #1 valves will be closed if you look under the valve cover)

 

Take the cap off the distributor and see what terminal and wire is above the rotor end. This becomes the #1 plug wire. Going counter clockwise around the cap the remaining wires are 3, 4, 2.

 

 

 

Maybe a good time to say what was removed or touched while changing the head gasket. Was anything done to the head? nothing removed? The distributor was not removed? The timing chain was properly blocked so the timing chain tensioner would not fall out? Timing chain was not removed?

[HRH]

Timing is off.  Either cam is 180 out, or distributor is 180 out.  Re-check and adjust accordingly.

[720 Freak]

So if the tensioner has fallen out do I need to remove the front engine cover to replace? I don't remember reading anything about a tensioner when I researched the job but simply could've forgotten it (old age) lol I did mt best to make sure to keep everything is the same position when I removed it but I didn't " block" the timing chain

[oldschool_510s]

if you didn't block the chain then you might have lost the tensioner

[HRH]

Uh-oh!  Time for Wapner!  Yeah, if you did the head gasket and didn't block the chain, your chain went slack and definitely is out of place on the bottom sprocket and/or your tensioner is wanging around in your timing case.  You might have gotten lucky and it didn't spit out, but guaranteed your timing is off.  If tensioner is still in, rotate keyway on crank to straight up and down (by hand with ratchet).  See where cam position is.  If out, BLOCK CHAIN, then remove camshaft pulley bolt and walk the gear around the chain to put in proper position so top and bottom end is in the correct orientation once more.

 

Make sure you're on top dead center, not bottom dead center.  Keyway will be up when this is the case.  Coordinate that with 11:45 distributor gear position.

[datzenmike]

To keep the timing chain snug a spring loaded and hydraulically actuated tensioner is used on the L series engines. The tension on the chain between the two sprockets keeps it in place but if the cam sprocket is removed it pops out of it's holder like this...

 

 

 

 

It can't be got at to put back without removing the timing cover I'm afraid. Do not crank the engine further it may still be replaced if the spring isn't crushed like this one. If the front is coming off maybe a good time to replace the guides/tensioner and chain?

[720 Freak]

So this sounds like what my problem is, can this be done with the motor still in the truck or do I have to pull it? After all this I'm gonna basically have a rebuilt engine!!! I feel like a big ol D.A. for not doin the chain blocking! Hey anybody wanna come help me do it! I'm in NE Ga and I'll feed ya and buy the beer!!!!

[HRH]

MM?  That's you, isn't it? ;)  How's that bus!

[datzenmike]

Set engine to RDC.

Drain and remove rad.

Remove dizzy, oil pump, water pump, alternator.

Remove the metal water by pass line from thermostat housing down to the lower rad hose inlet on the timing cover. You may be able to disconnect the ends and remove it with the timing cover.

Put a bar through the cam sprocket to lock it and loosen the cam sprocket and the crank pulley nuts. Set/check motor to TDC now and remove pulley. Watch for the woodruff keys on the crank/pulley. From this point on the crank must not be turned.

Remove the oil pan bolts across the front and about half way back behind the timing cover on both sides. This will allow it to droop slightly and the timing cover to slide forwards and out.

Remove the small bolts on the front bottom of the head so the timing cover can slip out from under it.

 

The timing cover should now be able to be unbolted and removed. Watch for the oil slinger just in front of the crank sprocket... looks like a washer.

Replace the timing cover oil seal. Grease the new one so it does not start up dry.

The timing cover will with difficulty separate from the oil pan and head gasket and slide forward. Slip a knife between it and the gasket to loosen. 

 

Remove all traces of the timing gasket on the block. Install new gasket dry, no sealer needed.

 

The crank sprocket will have a DOT on one of the teeth at approximately 3:00 o'clock and the cam sprocket should be on the #2 hole for the camshaft dowel. You may have to turn the cam slightly but don't turn the crank. This will place a DOT on that sprocket at about 2:00 o'clock. The chain will have two bright links and when installed, they will be on these two DOTS.

 

Re-install tensioner or replace it and the guides if possible. Driver's side guide is mounted close against the side of chain. On the tensioner side, push the tensioner all the way in and push the guide above it as far to your right as you can and tighten in place, release tensioner.

 

Oil pan and underside of head gasket may be sealed with RTV.

[oldschool_510s]

man mike that brings back old memories for me its been 20 yrs and now im back into Datsun s again

[dr.feltersnatch]

[720 Freak]

thanks a lot for the help, as soon as the new parts I ordered get here I'm gonna jump in.