Complete Misfire on Three Cylinders

[Av8ferg]

I’m gonna guess that there is likely some valve damage considering you drove it for awhile to get home but maybe I’m wrong. I think it’s a head removal anyways s time will tell. I fully expect a detailed report post removal.

I know you got car issues besides the Z, hope you get some free time to hash them all out.


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[Zed Head]

I think it depends on how fast the broken piece stopped spinning and how extended the open valves are.  Inspection will tell.

The back cam tower could be removed and the broken half lifted out, I think.  That might be fun.

[siteunseen]

On 5/15/2019 at 9:54 PM, S30Driver said:

Wow. must have been weakened from those 10,000 rpm shift points of your spirited driving .

Only thing I can think of is a bearing froze after the break or a flaw in the metal that decided that was the time to let go.

 

 

Atlanta in Zup's car?

[madkaw]

Maybe the cam had been dropped at one time and was cracked - and it finally gave out. 

[Captain Obvious]

18 hours ago, siteunseen said:

Atlanta in Zup's car?

Shhhhhhh.....    

Zed Head, I could take the back half of the cam out easy. Maybe I'll do that (if I can sneak some time in the garage when I "should be working on other things")

[Captain Obvious]

Update on my dead engine project...

I made a rocker removal tool. After multiple failures and spending waaaaaay too much time on it, I finally hit on a geometry that worked:

I took the rockers out so I could turn the cam without having to worry about valve positions, etc. I put the engine on #1 TDC before taking stuff apart so I knew where everything was. Way easier to spin the engine over with the plugs out and all the rockers removed.

Then I made a cam chain wedge tool. My tool is about an inch longer than average because that's just how I roll. I wanted to get the tool down as deep as possible to assure it was holding the tensioner shoe back. I also came up with a (yet to be fully tested and therefore potentially stupid) removal plan. That's the screw on the front and the metal removal handle:

Since the tool is longer than most, I had to remove the cam gear bolt to get the tool into place. Being careful not to knock the gear off the end of the cam (not really a difficult task), I took out the bolt, slipped the tool into place, and then put the bolt back in until I was sure the tool was fully seated in place and holding the chain:

Here's some pics of that whole process Bolt out just long enough to get the tool to clear the bolt head:

Then get the bolt back in place for now:

And here's the tool fully installed wedged into place:

And here's how the removal tool is supposed to work:

Hook the screw head with the hole in the metal handle:

And pull the wedge back out:

Worked in test. We'll find out later if it works as well in real practice.

[AK260]

Sorry to hear that CO! I’ll be the first to admit I didn’t for a moment imagine camshaft failure was the root cause! (And I didn’t watch the vid)

My initial thought after cam shaft discovery was that I hope you didn’t bend valves!! [emoji33]

I know some engines have a non-interference set up with dished pistons etc. Do you have access to a borescope to be able to look through the plug holes and check for marks on rear 3 pistons? Would hate to see you install new cam and have a bent valve to a “paper clip being bent back and forth a thousand times” trick and kill the head.

Good luck!!

Ps. Loving the home made tool! [emoji106][emoji106]

[Captain Obvious]

Thanks for the compassion. The general consensus is that the design IS an interference engine. So if that's true, depending on where the cam stopped, there may be some significant carnage. I should know for sure very soon.

I don't have a borescope, but I did pull the plugs and have a peek in the holes. I see some stuff in there that doesn't look right. Can't tell if it's evidence of a collision or what, but something in there is weird.

[240260280]

The machine shop broke the cam on this car when replacing it. I did not see the cam but I suspect removing cam towers with the rockers not removed is one way to do it.

 

 

[Dave WM]

how do folks store complete heads? I have my spare N42 complete (valves/cam) with the valve cover on and a 2X6 on the bottom tied together with some strapping. I positioned the camshaft to a point where only 2 valves were opened. On those two I removed the rocker/lash pad, tagged and bagged them, left them inside under the valve cover, then return the camshaft to the point where no valves were opened before strapping the 2X6 to the bottom.

Edited July 8, 2019 by Dave WM

[Mark Maras]

I pulled and labeled the rockers, lash pads, springs, and valves. Left the cam in. The head now rests on a flat piece of wood awaiting the resurrection.

[siteunseen]

3 hours ago, Dave WM said:

how do folks store complete heads? I have my spare N42 complete (valves/cam) with the valve cover on and a 2X6 on the bottom tied together with some strapping. I positioned the camshaft to a point where only 2 valves were opened. On those two I removed the rocker/lash pad, tagged and bagged them, left them inside under the valve cover, then return the camshaft to the point where no valves were opened before strapping the 2X6 to the bottom.

I bought my N42 from a local machine shop that had it after the owner never came back to get it.  They'd had it for 10 years inside a plastic bag with about an inch of styrofoam on the bottom protecting those 2 valves.  I've got 3 or 4 heads stored on top of a piece of foil faced insulation with valve covers on each.