Timing chain guide

[Captain Obvious]

2 hours ago, Dave WM said:

they recommend some gasket sealant around the water holes on the block to cover,  I was going to do that around the oil holes to and from the pump as well.

Good progress. I'm with you... I'd put a little sealant around the oil holes and the water holes. The rest of that gasket's sealing work is oil, but it's not under pressure.

[Dave WM]

Rad is done, picking that up today, Now I just have to wait for the parts to come in. I think I will go out on a limb and suggest to everyone, REPLACE the timing chain guide if you don't know the history. This assumes the chain is ok, replace the guide anyway. One more thing CLEAN the tensioner. Its the only active part of the whole system, seems like a good thing to make sure its not hung up. I am adding this to the list of all things to do on a Z. 1st water pump now chain guide. It seems the L28 is pretty bullet proof, but don't want to skimp on those two things.

[Dave WM]

picked up the rad today, looked nice, removed the tape from the neck (protect it from the fresh paint) looked inside, looked exactly the same, build up about 20%, I wonder if they just painted it. Anyway complained, they were very understanding and will take it apart and examine again. I hope they don't just clean up the few ones I can see and call it done. Been to them over the past 30 years at least. Never had a problem. At best now I will prob make this a spare rad and pop for a new one, have to take my chances on made in China stuff, which is exactly what I was trying to avoid.

Edited September 30, 2019 by Dave WM

[Dave WM]

So I got the tight side guide today (ordered it orig before the osk order) turns out it is make in japan as well (beck arney) I went ahead and installed it just to see how it goes on, While messing with it I removed the tensioner from the loose side. It was pretty smooth but did have some kind of burr in the cylinder that I could feel. I seriously doubt it could get hung up on that between the spring and the oil pressure, but clearly it will be replaced as well. I did notice there is a gasket behind it. the gasket was not in the felpro gasket kit I ordered, I don't know if it will be in the OSK kit, seem like it should, but if not the gasket that is there seems very intact so will leave it be for now. I also ordered a spare TC cover just cause it was cheap from japan. IDK why I do stuff like that, but figured just in case I managed to break one removing it I would have a spare. Sick.

Oh and the tensioner had 3 distinct gouges where the chain rides, I don't know if they are there when ne and just deepen or if the shoe is supposed to be smooth, off to google images...

ok no grooves is the way it should be new.

 

Edited September 30, 2019 by Dave WM

[Dave WM]

On ‎9‎/‎29‎/‎2019 at 9:09 AM, Av8ferg said:

Found this in my Nissan L Series Engine Rebuild book. Might be what happened to you.




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my guide has the same wear area on the upper corner as shown in the pick above, that and its kinda ripped there, SO I think that is the smoking gun, somehow it must have worn just enough to expose the metal and then the sharp edge of the metal catches a chain link, and bingo, disaster. So I maybe would have caught it if I had been more diligent about inspection of that area, look for thinning plastic on the narrow side top edge. The "badly worn" part is confusing since from all the checks the chain has very little wear, IF stretching is a indicator of wear.

Edited September 30, 2019 by Dave WM

[Av8ferg]

This is the problem in having a car that has had untold owners and maintenance. You just don’t know what’s been done when. One of the reasons I broke my engine all the way down and plant on replacing all consumables/wear items.
I don’t think you failed in inspecting this, but that chain might be the original one and sometimes is easy to have the “not fix it if it ain’t broken” mentality.


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[siteunseen]

I bought a $250 Bosch OE fuel pump before ever putting a gauge on the existing one. This forum, couldn't live without it. 

 

 

[Ninjaneer11]

Hey Guys, long time lurker, first time posting. I am going through a rebuild on the L20B out of my 620 and had a similar problem. I've been scratching my head as to how the guide would break like it did and this had shed some light on it. A few dings in the oil pan, scratches on the front cover, and almost worn through oil jet were the result. I'm surprised it didn't do more damage. I appreciate the knowledge that gets shared here.

[Captain Obvious]

16 hours ago, Dave WM said:

I removed the tensioner from the loose side. I did notice there is a gasket behind it. the gasket was not in the felpro gasket kit I ordered, I don't know if it will be in the OSK kit, seem like it should, but if not the gasket that is there seems very intact so will leave it be for now.

I'm no expert on the finer points, but I do not think there was a gasket behind the tensioner when that motor left the factory. I believe the gasket behind the tensioner is an indication that  someone had replaced all that stuff in the past.

Do you see any manufacturer marks on any of the parts? I'll look the factory stuff over from my F54 tensioner. If anything, I would expect to see either a Nissan mark, or a Hitachi mark on my original stuff. I'll check.

[Dave WM]

1 hour ago, Captain Obvious said:

I'm no expert on the finer points, but I do not think there was a gasket behind the tensioner when that motor left the factory. I believe the gasket behind the tensioner is an indication that  someone had replaced all that stuff in the past.

Do you see any manufacturer marks on any of the parts? I'll look the factory stuff over from my F54 tensioner. If anything, I would expect to see either a Nissan mark, or a Hitachi mark on my original stuff. I'll check.

I did some searching and found some comments either here or a zcar.com, there was talk about at one time Nissan used a gasket but was later deleted..

When the new parts arrive I plan to take some pics to compare the old to the new, will also show the wear marks on the shoe. there was also some talk about a small hole on the top of the tensioner looks like drilled thru a plug. My guess is it was for oil to squirt out of. Seem some tensioners have it some don't. I cant imagine a lack of oil in and around the chain parts with all that oil from the valve train spilling over from the top of the head. I picked up the rad, looks better still has some deposits in it but at this point I don't want them to mess with it anymore. The new OSK parts are supposed to be here tomorrow.

Edited October 1, 2019 by Dave WM

[Dave WM]

2 hours ago, Ninjaneer11 said:

Hey Guys, long time lurker, first time posting. I am going through a rebuild on the L20B out of my 620 and had a similar problem. I've been scratching my head as to how the guide would break like it did and this had shed some light on it. A few dings in the oil pan, scratches on the front cover, and almost worn through oil jet were the result. I'm surprised it didn't do more damage. I appreciate the knowledge that gets shared here.

so yours broke ahead of the mount bolt and dropped the top half. Mine broke the mounts themselves and dropped the whole assy pretty much intact. Interesting. Did you have the correct bolt length for the T stat housing? that is the 1st suspect for why it would fail. Other than that its assumed a worn chain and or worn guide.

[Dave WM]

Ok maybe a minor detail but should the chain be in actual contact with the guide (tangent the Datsun book says) or just a tiny bit of clearance on the exit (loose side) and entrance (tight side). there is enough adjustment to set it up for contact or just a bit of space (like 1mm) seems to me a tiny bit of space is better to avoid excessive wear of the plastic, but maybe that allows whipping which is bad. I am going to go back over the FSM and see what it says.