z24 head bolt ring - Head gasket replacement

[Lt_Dylson]

Hi

 

First of all I'd like to thank everyone (especially Datsun Mike) for the help this forum has provided in working on my recently purchased 85' 720 king cab 4x4, carbureted z24.

 

Here are some pics of that -

 

 

I bought this off craigslist about 6 weeks ago and 2 weeks ago the head gasket blew. It has 117k miles on it and otherwise the engine was running pretty A1. From what I have read this is about par for the course. Although I've never done anything beyond oil/tranmission fluid/oil filter change I read through all the words on this forum and decided to do it myself. It was my plan to learn about auto repair with this truck and I figured this was a good time to start and save myself about $1000 (not to mention there was no way I could afford to send it to a shop having just purchased the truck with cash a few weeks before). So far I've spent about $350 on tools, parts, and both the Factory Service manual and the Haynes as well as $40 on machine shop service (resurfacing and compression check on the head).

 

Anyway - I have 2 questions/issues

 

1. Last night I got the the head, cam sprockets and everything bolted up again. I pulled out the timing chain tensioner wedge and was thrilled that everything seemed to be holding together/tensioner did not pop out. So I'm feeling pretty good at this point and was getting ready to put the valve rocker cover back on when I noticed this small metal ring in a pool of oil on the shelf where I first put the cylinder head. 

 

 

It was one of the rings that slots into the head bolt hole in the block between cylinder 3 and 4. I did not know there were 2 - this one must have come off with the head and fallen out without me ever noticing it. The other one stayed in the block and was reinstalled when reassembling the engine. 

 

After I finished loosing my shit at the thought of having to redo everything and get a new wedge etc. I decided to stop and consult a higher power (...no god, im talking about Ratsun...)  about whether this was a big deal or not. On the one hand I don't want to do anything that would put me at risk of blowing another head gaskets. On the other hand this ring just loosely fits around 2 of the head bolts and its not involved with any fluid movement in the engine so maybe its just there as a way to easily align the cylinder head and the block?  I am worried that it does the important job of controlling/guiding the expansion and contraction of the aluminum cylinder head. (FYI, I used a Factory OEM head gasket) 

 

So that's my first question: Do I need to take everything apart again and reassemble with this ring?

 

 

2. My second question is - What is the thing between the starter motor and the oil filter (caked black with grime and an electrical plug going to it).
I cleaned it off and its a goldish metal cannister similar looking to a fuel filter.  What is it and could it be leaking oil?

 

 

I've scoured both the FSM and Haynes and there seems to be absolutely no mention of it and its left out of every engine diagram or drawing. My Guess is that is some kind of electronic feedback for oil lever, pressure, or temp. 

 

I'm pretty sure the oil pan gasket is leaking, but there must be something else leaking all over the intake side of the block just above the oil pan gasket... or maybe its old oil and dirt from previous leaks...

 

(also you can see where the head gasket was completely blown between cylinder 1 and 2 and coolant sitting on top cylinder 4..... also notice how beat up the blue wedge is... i broke it while wedging it in and the chain was taking chunks of plastic out of it as it went.)

 

 

Thanks everyone for your help!

 

(I also have a new 32/36 weber carb that I will be installing with this. Will probably post about that soon.) 

 

  

 

 

 

[]2eDeYe]

That is an alignment ring. There should be 2 of them, they go into the block at the 2 corners where the head bolt hole is counter-bored. It will be pretty obvious once you find the 2 holes. 

 

 

Edit: 

 

Now would be a good time to do the oil pan gasket and reseal the timing cover. 

[Lockleaf]

I'm afraid I can't answer your question about the alignment dowel. I'm a bit lazy and willing to gamble, so I would just run and ignore the risks. Sometimes I win, sometimes I lose :-).

 

The canister you describe is the oil pressure sending unit. It is the controller for the oil pressure gauge you have in the cab. Yes it could potentially leak oil.

[Lt_Dylson]

Thanks for the reply ]2eDeYe. The issue is that I have already reassembled the motor with the new gasket. The cam sprocket is bolted up again and I have removed the wedge (which broke during removal).

 

So do I need to take it all apart again just to put this second alignment ring? The alignment ring on the exhaust side is installed, so just one is missing.  

[bananahamuck]

I'm afraid I can't answer your question about the alignment dowel. I'm a bit lazy and willing to gamble, so I would just run and ignore the risks. Sometimes I win, sometimes I lose :-).

 

The canister you describe is the oil pressure sending unit. It is the controller for the oil pressure gauge you have in the cab. Yes it could potentially leak oil.

 

 

This ^^^ ,, but i don't think it's laziness just more like it should be in there but,,,, it will work without it.  Just keep-her in a spot where you can find it again,, but i don't think it will cause head gasket to fail.  and he's right about the canister also.

[bananahamuck]

Oh,, and nice looking truck man... B)

[Lt_Dylson]

thanks guys!

 

 

Another question: is possible to re-torque the head bolts with the cam sprocket still on?

[datzenmike]

The dowels align the combustion chambers over the cylinders. You can't be out too far as the head bolts themselves all have to fit through their respective holes in the head. It is possible the head is skewed to one side slightly, depending which dowel was missing. If the front is there the rear may be slightly off, rear is on the front is off.

 

Possibly the gasket is properly in place and the head skewed. This would be the least bothersome. The gasket could have the metal rim (fire ring) over the edge of the cylinder slightly. If so it won't last long from the heat. Slightly worrying is the oil feed hole between the block and the head. It's directly above the oil pressure sender mentioned above. The gasket has (usually) a larger oval opening to allow for slight mismatch so oil can flow up into the head.

 

If you haven't started it up yet, take a really good look at the head and see if you think it looks straight sitting on the block. Also look for the gasket hanging out over the block more on one side. Maybe post some pictures and I can look at my Z24 I have sitting outside.

 

If there is evidence it may be shifted, the head bolts can be loosened and the head shifted over. Re-torque the head in the proper sequence and stages again. Fire it up and check that oil is lubing the valve train. If you have any doubts replace.

 

If it's been run and there is suspicion the head or gasket is skewed I would re do it with a new one, and put that dowel in.

[Justin Berni]

Hell yeah the oil pressure sending unit can leak, my truck use to leak a quart between filling the gas tank(about every week), oil was pissing from there, replaced it and no more leak.

[datzenmike]

That sender you have... the one that has two wires... be sure to slide the proper size spanner down behind it against the block and loosen it. Resist the urge to just twist it off by grabbing it. That outer can will come loose from the sender. Done it and it ruined it.

 

Not that there is a reason for removal. Oil runs down hill and likely that's normal oil leaking from the valve cover above it..