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Captain Obvious

Complete Misfire on Three Cylinders

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I realized the inner spring was free of the outer ones. Got them all the same just eyeballing. So far so good.

I think that's the cause of lash pads jumping out too.

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Measure each end and you'll also get an idea of the tolerances for an individual head.  If they're not tight within a head, they won't be tight across many heads.

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2 hours ago, Captain Obvious said:

So I'm taking the valves out, and here's the springs from a couple of the valves. I never even knew the springs had a variable pitch and a "proper direction" to them, and apparently neither did my PO. The retainer caps are at the top for both of these, but the pitch direction is different between the two:
P1150231.JPG

I'm not sure how much difference it makes in the grand scheme of things, but just another detail that was missed.

 

The narrow pitch side of the spring goes down against the head. Wide pitch side is up connecting to the retainer.

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So, I measured two heads, both of which I am pretty confident  that they haven't been milled. Can't be 100% certain since I didn't buy either as the first owner.

I will reference cam tower numbers and cam tower number 1 is closest to the sprocket.

First, my new old stock in box E88. Nothing to clean here. 

1=4.2474, 2=4.2471, 3=4.2475, 4=4.2478, 5=4.2479

 

Second, my N42 head from the 75 280z with 55k miles I am refreshing. N42 heads were generally used on 75 and 76 280z models and are the same as N47 except for shape of exhaust ports and liners in N47. I want to also mention that I only took two measurements because getting a stamp sized spot to be as clean as my new E88 head took a decent amount of time and effort. 

2=4 2479, 4=4.2478

Bottom line, I think these two heads and CO's N47 head are uncut / unmilled.

Hope this is helpful. It was an interesting exercise for me.

 

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Well this is great news that you have no piston / valve damage and are getting your car back on the road.

We are all at the mercy of the POs’ shortcomings / shortcuts! Mine had done some pretty scary things too - especially on electrics - things like adding a 50A fuse for the washer pump ‘cause the 5A kept blowing (he didn’t bother trouble shoot/cover his hacked about naked wiring that was intermittently shorting out)!!!

Keep at it fella - looking forward to hearing about her growling again!

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Thanks all for the encouraging words, and thanks also for the additional investigative work on the head thickness. I guess the bottom line is that I've got a reasonably high degree of confidence that my head was never planed. Surprising to me that the PO would get as deep into the head and NOT have it cut, but thankful for small miracles. Just one less thing to get screwed up under his ownership.  LOL

15 hours ago, jonathanrussell said:

The narrow pitch side of the spring goes down against the head. Wide pitch side is up connecting to the retainer.

Right. I saw that in the manual. The point of the pic is that so far I've taken out one of each direction so far. My PO apparently didn't know they were unidirectional and just tossed tehm in random. I will put them all in the right way when I put this thing back together.

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17 hours ago, Zed Head said:

What's the backstory on the car?  I wonder how deep the PO got in to the engine.

Back story? Typical. I bought it a number of years ago with very little detailed info about it's history. I got a couple pictures from the PO taken during some of the work he did to the car, and a couple of the pics show the head off the engine, so I know he did that much.

I also have a stack of receipts that include ONE piston and rings for said piston. So I don't know what goes wrong with an engine that requires the replacement of just one piston, but the implication is..... My PO has been into the bottom end as well.   :facepalm:  Kinda makes me wonder what kind of trouble lurks down there.

All that said... I didn't buy the car for the condition of the engine. I bought it for the condition of the underside. It's pretty much rust free. To me, everything else is easy.

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So anyone got a recommendation on valve seals?

Nissan genuine?
Doesn't matter, all the aftermarkets are fine?
Low profile Ford (I think?)?

Viton? Anything?

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In the head I built last summer I used Sealed Power ST-2034 seals. Too recent to say how they will do long term but so far so good. I chose them because they are a viton seal.

The seals I had sitting around that came in a few gasket kits just seemed kind of hard as a rock.

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22 hours ago, jonathanrussell said:

In the head I built last summer I used Sealed Power ST-2034 seals. Too recent to say how they will do long term but so far so good. I chose them because they are a viton seal.

+1 on the Sealed Power seals.  I installed them 4 years ago, no issues thus far....

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Thanks guys. I (think I) just nabbed the last 24 off rockauto. I need 12 for this engine, and 12 for my P79 when I get back onto that.

So, now that it may be too late.... Same part number for both intake and exhaust?

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And, since no car good project goes along without complication, I've found another PO caused issue with my N47 head.

I had known for some time that a couple of my valve cover bolt holes were stripped out. Not the end of the world. And I also already knew that on one of them, my PO had tried to drill out the old bolt and missed. Hole was off center, half the steel bolt still stuck in there, crappy threads... The usual. Well, I decided that since I had the head on the workbench, I was going to do something about it.

Mistake.

I'm looking at the whole situation, and noticed that there is a chunk of brass way down in the bottom of the off center chewed up hole. I have no idea what that's all about, but I don't want it in there. So I start drilling it out.

Figured out what was going on there... When he drilled (half) the old bolt out, he drilled too deep, and actually punctured through into the water jacket below. AAARRRRRRGH!!!!! That chunk of brass was some sort of plug he stuffed down into there to seal the bottom of the hole back up.

So now I'm going to spend the next bunch of hours working on trying to fix that crap.    :facepalm:  

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I was playing with seals last night, after removing the valve (practicing using my valve spring depressor) I put some heat shrink on the end to cover the retaining slot, heated it up to form a nice seal installation tool to prevent nicking the seal when replacing. They sometimes come with those little candy stripe straws, I think the heat shrink works better, thinner, tighter fit and the shoulder created by the shrinking worked well.

Some interesting reading on the subject of seals, somewhere I read to NOT use assy lube just coat the valve stems with the oil you normally use. something about the assy lube gumming up. Seems unlikely it could be an issue but, for what its worth I read it.

compared the old seal to new Nissan OE, the old one had a noticeable larger hole that the stem fits into . It was somewhat stiffer than the OE seal as well, but still not what I would call too stiff. I was surprised to find is still pliable at all considering 43 years old.

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3 minutes ago, Captain Obvious said:

And, since no car good project goes along without complication, I've found another PO caused issue with my N47 head.

I had known for some time that a couple of my valve cover bolt holes were stripped out. Not the end of the world. And I also already knew that on one of them, my PO had tried to drill out the old bolt and missed. Hole was off center, half the steel bolt still stuck in there, crappy threads... The usual. Well, I decided that since I had the head on the workbench, I was going to do something about it.

Mistake.

I'm looking at the whole situation, and noticed that there is a chunk of brass way down in the bottom of the off center chewed up hole. I have no idea what that's all about, but I don't want it in there. So I start drilling it out.

Figured out what was going on there... When he drilled (half) the old bolt out, he drilled too deep, and actually punctured through into the water jacket below. AAARRRRRRGH!!!!! That chunk of brass was some sort of plug he stuffed down into there to seal the bottom of the hole back up.

So now I'm going to spend the next bunch of hours working on trying to fix that crap.    :facepalm:  

yikes... geez Louise, does it ever end :(

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What a bummer regarding the valve cover bolt hole.

How do you think you are going to fix? Could have the hole welded up slowly so you don't warp the head, then drill, tap. I wonder if you re-tap and then seal the valve cover bolt threads does it matter....at least for a quick fix?

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I have an N47 bare head. It's an early one with the spray bar and oiler cam BUT I've robbed that stuff for my E31. Cam, towers and valves.

If you are interested I'll get it down and send you some pictures.

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Thanks guys. I (think I) just nabbed the last 24 off rockauto. I need 12 for this engine, and 12 for my P79 when I get back onto that.
So, now that it may be too late.... Same part number for both intake and exhaust?
I ordered the sealed power seals as well, and as far as I can tell, it's the same part number for both intake and exhaust.

I have a set of ITM engine componets seals that came with an entire gasket set at home, and all 12 valve stem seals look to have the same dimensions.

Sent from my Coolpad 3310A using Tapatalk

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And, since no car good project goes along without complication, I've found another PO caused issue with my N47 head.
I had known for some time that a couple of my valve cover bolt holes were stripped out. Not the end of the world. And I also already knew that on one of them, my PO had tried to drill out the old bolt and missed. Hole was off center, half the steel bolt still stuck in there, crappy threads... The usual. Well, I decided that since I had the head on the workbench, I was going to do something about it.
Mistake.
I'm looking at the whole situation, and noticed that there is a chunk of brass way down in the bottom of the off center chewed up hole. I have no idea what that's all about, but I don't want it in there. So I start drilling it out.
Figured out what was going on there... When he drilled (half) the old bolt out, he drilled too deep, and actually punctured through into the water jacket below. AAARRRRRRGH!!!!! That chunk of brass was some sort of plug he stuffed down into there to seal the bottom of the hole back up.
So now I'm going to spend the next bunch of hours working on trying to fix that crap.    :facepalm:  

Oh boy, you are finding all sorts of Easter Eggs in this engine. What’s next...this saga isn’t over I expect. Know when to hold them and when to fold them buddy! Hint hint!


Sent from my iPhone using Tapatalk

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I would tap it, and use a something like a set screw with some red Loctite.

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Another thought....

Does anyone make a thread repair insert (like time-sert) that is closed on the bottom of the inside?

Another thought....

You could change this one fastener to a stud and thread lock it in then tighten that one with a nut. That way the water passage is sealed and you are not ever removing it.

Edited by jonathanrussell
second idea

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4 hours ago, Captain Obvious said:

That chunk of brass was some sort of plug he stuffed down into there to seal the bottom of the hole back up.

So now I'm going to spend the next bunch of hours working on trying to fix that crap.    :facepalm:  

Don't confuse from with function.  If it doesn't leak then, technically, it's fixed.  If you can get the hole properly aligned and threaded so a valve cover bolt works correctly, then, technically, the problems are solved.  You could be heading down a worm hole trying to fix something that is only aesthetic.

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 I'd be tempted to try one of the liquid or putty epoxy thread repair kits on a low torque bolt (or stud) like the valve cover bolts. Loctite, Permatex, JB Weld all have something to offer. 

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1 hour ago, Zed Head said:

Don't confuse from with function.  If it doesn't leak then, technically, it's fixed.  If you can get the hole properly aligned and threaded so a valve cover bolt works correctly, then, technically, the problems are solved.  You could be heading down a worm hole trying to fix something that is only aesthetic.

You're forgetting...CO has a touch of OCD. :love:

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You're forgetting...CO has a touch of OCD. :love:

Just a tiny tiny bit, but so do I.


Sent from my iPhone using Tapatalk
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