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Engine woes- read on if you dare


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Leon just relayed a conversation he had with Isky about rocker arms.  He said that new or mildly worn used was the way to go.  Now you report that new Nissan rocker arms were "bad rockers".  Any chance that they weren't actually new Nissan?  What will you be checking on the rocker arms?  Looks like a quagmire.  

 

Post #232 - http://forums.hybridz.org/topic/111062-leons-other-260z/page-12?do=findComment&comment=1122005

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Schneider says there is no such thing as new "nissan" rockers anymore-only after market. The kit I purchased was back in 2006, so they said more likely they were Nissans. No way to know for sure, unless someone can tell me.

As far as checking rockers, I will be checking rockers for consistancy between the two surfaces to make sure they are truly parallel and flat . 

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I'm pretty sure that these are original 1976 rocker arms, pictures.  From my old cylinder head, off an engine which appeared to all original.  Either 150k or 250k miles.

 

And here's a link with a few pictures of the ITM rocker arms.  The used ones are different and the ones he replaced have a Z, instead of an X.  No idea if that's relevant.

 

http://forums.hybridz.org/topic/106910-loud-tickingknocking-noise/

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post-8864-0-42553800-1411948888_thumb.jpg

post-8864-0-52035400-1411948897_thumb.jpg

Edited by NewZed
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I'll add that I also spoke with Ron about new aftermarket rocker arms. The new ones I bought earlier this year (Sealed Power brand) look essentially identical to Nissan rockers, at least from the manufacturing standpoint (2-piece with hardened inserts). He agreed that they'd work just fine, FWIW.

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  • 2 weeks later...

So I have been doing some searching - could this be from dirt? I've never run this engine without a filter, but maybe I got careless and had dirt in my CAI? It's the only explanation I can think of that would score the bores ALL the way to the top of the bore. It would have to be wedged between the piston and bore.

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I will add that I looked at some old pics I had of the block fresh after hone I guess. I must have went to the shop right after they finished honed the block and before installing the pistons. Magnifying the pic as much as I could I swear I could see a faint hint of these marks under the cross hatching-weird. 

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I loved my little 2.4-maybe she will live again!

I take the motor by to the builder tomorrow for his analysis on this -it ought to be interesting. I get the feeling he thinks I beat on that motor, but I really didn't. I drove it hard at times, but not abusive. 

Edited by madkaw
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I can't tell you present ring gaps because all parts are at the machinist. The machinist said I was concerned over nothing after a cursory look. With the block and pistons in hand he will mic everything out. He thought a hone and new rings would make things all better. I argued the markings traveled the length of the bore as if done by a machine, not rings. Maybe I didn't or couldn't see these marks with a cross hatch hone over top of them before?

The shop did all the assembly work last time, but this time I will be doing the assembly. These were probably ITM pistons and rings, but can't swear to that either.

We did go with SI valves and guides for the head. Still no word from Schneider on the cam. It gets a little old dealing with the lack of customer service anymore.

I'll see how this motor goes second time around , I might be shipping to Rebello for the 2.8!    

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  • 8 months later...

Almost a year later: where should I start.

 

Block- as suspected, was overbored and wasn't properly honed . Aftermarket piston size was right at .030 over, so clearance spec put rings at large gap. After second hone piston to bore was .0045- too much.

 

Head: uneven rocker wear causing uneven cam wear and side loading of valve guides. Since new guides were installed on the original build I would say the guides were not in perfect. Guides were off just enough for uneven wear. Intake valves showed extensive wear for 12000 miles. Exhaust valves didn't show same wear. All valves ( SI , I believe),we're installed on original rebuild.

I also believe valve stem seals were not installed correctly leading to build up on back of valves.

 

MACHINIST ADMITTED HE DID NOT DO A SWIPE ON THE LASH PADS.This would have all been prevented if he knew what he was doing.

 

Another words - shitty rebuild.

 

This time around I pulled the original block out and had it properly bored and honed.

Replaced rockers,cam , intake valves with stock Nissan.

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