Timing chain ?

[530-521]

Got my new valve cover gasket, but before I do that, I wanted to show you guys some pics of this timing chain, and see if you would run it, or if I should do anything with it....

 

 

 

Edited May 17, 2019 by 530-521

[mainer311]

Hard to tell from pics, but it looks fine to me. The sprocket on the crank wears out far before the one on the cam because it's much smaller. Typically the teeth will start to look like shark teeth instead of being symmetrical. Chain stretch is what needs to be checked, and you have to do that by lining up the timing marks and checking the pin hole on the cam. 

 

Typically everything is sold as a set and should be replaced together anyway.

 

Here's an example of one that has a stretched chain and a lot of wear. You can see that the idler looks decent, but the teeth on the drive sprocket are sharp at the top. 

 

Edited May 17, 2019 by mainer311

[banzai510(hainz)]

Double ck with others on here but the right side  guide  might be pushing in a bit. turn the crank to the right and it chain should be a flush type transition from sprocket going down  to the guide to the crank sprocket.

 

Sometimes people put a longer bolt in the stat housing and it pushes on the tight side chain guide thus grinding the chain.  How a longer bolt gets in there is rare as most people never NEED remove the lower stat housing

 

 

hard to tell you might be fine but that's what I notice from my chain here.

PS your top sprocket looks new.

Edited May 17, 2019 by banzai510(hainz)

[Crashtd420]

49 minutes ago, banzai510(hainz) said:

Sometimes people put a longer bolt in the stat housing and it pushes on the tight side chain guide thus grinding the chain.  How a longer bolt gets in there is rare as most people never NEED remove the lower stat housing

 

 

I thought this too.... might be an optical allusion but definitely worth taking a quick look to make sure your good....

[530-521]

Ok. The chain looks like it’s not coming off the sprocket at a 90° angle.

 

The bolt is not pushing on the guide though- it’s got like 1/16” to 1/8” clearance

[wayno]

OK, this is my thought, the chain guide is damaged on that right side in the photo, look down its length into the block, is it perfectly straight, if it is not straight but bent towards the chain then I would say someone put to long a bolt into the thermostat and bent the chain guide in, your photo in the last post tells me it is damaged because it is supposed to almost be touching the head casing in that spot, that you can even see the end of that bolt sticking out makes it too long.

I know it is hard to see in this photo below, but that guide is almost touching the side.

[wayno]

OK, I got a better photo I think.

 

You can see how the chain is not rubbing against the chain guide where it enters and the guide back is only a 1/16th of an inch away from the case, I would say yours is bent and needs replaced or at the very least straightened out, I have no idea if it can be straightened without removing the front cover, but first you need a shorter bolt for the thermostat housing.

Edited May 17, 2019 by wayno

[datzenmike]

 

wayno, my thought exactly!!! Probably made noise so they put a shorter one in. It's still too long. Probably a shorter bolt needed, then a chunk of steel and hammer it back straight.

 

Someone has already changed the timing chain, sprockets and guides, and forgot to put the two 10mm bolts in the front of the head. The tension guide is put in improperly. The tension guide should just touch the chain along it's length. That bolt is still too long.

 

 

 

 

To check timing chain for wear, set to TDC on compression stroke on #1 cylinder. There should be a timing pointer and a bunch of notches on the L16 crank pulley. Turn the engine only clockwise up to the pointer. If you overshoot back well up and try as many times as necessary to get it right. If you back up to the pointer you will introduce slack into the tension side and waste your time. Clockwise only up to TDC.

 

Now look either through the top hole in the sprocket or down behind it woiith a flashlight. You should see a V ot U shaped notch in the sprocket and a small horizontal etch mark in the cam thrust plate behind it. Like this...

 

 

The V or U should be just below or slightly to the right of the line above it. This cam is perfectly timed and the chain new. If you find the V notch to the left, secure the timing chain tensioner so it can't fall out with a store bought tool specifically for this. Take the cam sprocket off the cam dowel pin and move to the next number. L16/18 are set on the #1 at the factory so move to number 2 and check your V to etch alignment. If for some reason you are on #3 there is too much wear and slack and the chain needs replacing. 

[530-521]

Well- shit. Now looking closer, I see a broken bolt in front of the head. And it looks a bolt was definitely in contact with that tension guide... can you get just a tension guide??? Or should I just buy everything again and start over? Aaarrgh....

 

should I pull the whole motor??? Will it be easier to work on it?

[Crashtd420]

Depends on if you have a stand and a way to pull it and your comfort level..

 

Everything can be done with the engine in place, radiator definately needs to come out either way you do it.....

[Draker]

1 hour ago, 530-521 said:

Well- shit. Now looking closer, I see a broken bolt in front of the head. And it looks a bolt was definitely in contact with that tension guide... can you get just a tension guide??? Or should I just buy everything again and start over? Aaarrgh....

 

should I pull the whole motor??? Will it be easier to work on it?

 

If it were me, I'd pull the motor if the front cover has to come off. It's by no means necessary though.. you can do the job with it in the truck. It's easier on a stand though,

 

 

[Draker]

I would probably attempt to bent that guide back first though.  What bolt broke?

[530-521]

2 minutes ago, Draker said:

I would probably attempt to bent that guide back first though.  What bolt broke?

 

 

At at the bottom of the pic- sorry it’s blurry

 

 

[530-521]

I’m thinking I’m going to need a manual. Is the Chiltons good enough?

[Draker]

I'd pull the motor. That broken bolt is going to make it hard to get the front cover off. You could drop the oil pan a bit.. but that shit isn't going to seal up again and you'll likely have leaks.

 

If you have a picker and an engine stand, it's about a 2-3 hour job to get it on a stand. I've done it in 90 minutes without a lift.

 

 

The first option is still there.. just try to bend it back and deal with it another day.

[530-521]

1 minute ago, Draker said:

I'd pull the motor. That broken bolt is going to make it hard to get the front cover off. You could drop the oil pan a bit.. but that shit isn't going to seal up again and you'll likely have leaks.

 

If you have a picker and an engine stand, it's about a 2-3 hour job to get it on a stand. I've done it in 90 minutes without a lift.

 

 

The first option is still there.. just try to bend it back and deal with it another day.

 

I think I'm gonna pull it. I want It to be right, and this is going to be a learning experience for me... I’ll get a stand and picker

 

I need a manual- what do you guys recommend?

[Draker]

http://www.nicoclub.com/FSM/520_521/Datsun-521-Service-Manual.pdf

[Draker]

more manuals found here: https://nicoclub.com/datsun-service-manuals

[wayno]

If it were me I would remove the bolt in the thermostat housing that is sticking out the side of the inside of the case, find one the right length that does not stick out, then I would use a stick of wood(1"X1"?) and try to bend that chain guide back to where it is supposed to be, you really don't need to get it slammed against the inside case as it is worn at the top already so there is a little more room, that is not a critical area in my opinion, but I don't know that for sure.

I do not think pulling the engine is needed yet unless it is leaking in the front where the broken bolt is that I cannot see, that I expect might require removing the head, and I still would not remove the engine to pull the head, removing that front cover is a major job which will require removing the head or dropping the front of the oil pan, not something I would do if I could help it, there is a lot involved either way.

[530-521]

Ya Wayno- it’s leaking. There’s also a broken bolt for the water pump... I’m thinking to wrench it all while it’s in the truck... I dunno...

[datzenmike]

Totally agree with wayno. That broken bolt does not do much. The gasket around the timing chain only seals in fumes and oil spray. Not worth the risk, time and trouble to fix.

 

I would use a steel bar and hammer that guide over after replacing that long bolt with a shorter one. The correct thermostat housing bolt is flush with the inside of the head surface. Use washers on the bolt if you have to.

[530-521]

1 minute ago, datzenmike said:

Totally agree with wayno. That broken bolt does not do much. The gasket around the timing chain only seals in fumes and oil spray. Not worth the risk, time and trouble to fix.

 

I would use a steel bar and hammer that guide over after replacing that long bolt with a shorter one. The correct thermostat housing bolt is flush with the inside of the head surface. Use washers on the bolt if you have to.

 

Ok- you’re making me feel better about it... I’ll just try to bend that guide back some and run it for now- I think what I was seeing leaking was still the valve cover gasket...

 

how about the broken water pump bolt? Can I get to that easy enough to repair by pulling the water pump?

[wayno]

Is the broken water pump bolt leaking?

 

[datzenmike]

 

If water... look at the weep hole on the underside.

[530-521]

Guys- there is a coolant leak- but it’s hard to tell exactly where it was coming from exactly, because of the ridiculous valve cover gasket leak... should I put the valve cover gasket back on first? Then asses further? 

 

Sorry I’m such a pain in the ass- I appreciate the help.

 

John