Engine Issues

[bigben5054]

The pushrod is bent too.  Slightly, but obviously bent.  And it looks like the rocker arm was cutting into the side of the rocker stud on one side.

[bd]

That's a bummer!  A few possibilities that could cause a valve to hang open are a bent valve, a lubricant starved (dry) valve stem*, insufficient valve guide/stem clearance*, a dislodged press-in valve seat, a dislodged press-in valve guide, or something trapped between the valve face and its seat.  Removing the exhaust manifold to peer inside the exhaust port is a sound next step.  Peering through the spark plug hole may be telling but the view is limited.  In both cases, a small head borescope might benefit.  Look at the top of the piston too if you can. 

*The valve stem may have seized in the guide.

How high did you rev the engine during break-in?

[bigben5054]

Thanks Rich.  I'll see what I find when I pull the header.  For breaking in the cam, I had the idle set to 2,000.  Every once in a while I would slowly rev it up to 2,500 or so.  I don't think it ever went over 3,000. 

[bigben5054]

just pulled the header and didnt see anything obvious - although I couldnt get a real good look in there.  I dont have a borescope, so I'll have to see if I can find one.  Thing is, with the valve stuck open that far, it had to have been smacking on the piston, right?  I cant imagine a scenario where I dont have to pull the head.  Just hate dealing with the antifreeze.  Where is the best place to drain it from so I dont have that extra mess? 

[bd]

I agree, a borescope is optional and won't provide escape from the inevitable.  Nonetheless, Harbor Freight markets a couple of compact head models (8.5 mm) that may serve your purpose, 61839 and 61838.

Regarding cylinder head removal: first, drain the radiator into a clean pan.  Second, there are 1/4" NPT plugs threaded into the water jacket on the left and right center flanks of the engine block, a few inches above the oil pan gasket rail.  Typically, the plugs are threaded VERY TIGHT into the block.  If you are patient and diligent, you may be able to loosen and remove the plug to drain the water jacket on the offending side so the head can be pulled w/o coolant flooding the cylinders and floor.  If residual sediment is caking the base of the water jacket, you may need to probe the hole with stiff wire for coolant to drain effectively.  Replace the plug with a brass draincock for future service needs.

[JohnnyPopper]

bd's analysis is good but makes me wonder...

Do you think anything would bend the push rod except an obstruction?

I guess at the moment the rocker went sideways it could have bent. 

[Stewart G Griffin]

Just an outside thought here:   Did you use sealant on the head  bolts when you installed  the heads?

[Stewart G Griffin]

Ok something weird is going on here:   i go to Utube and this just happens to pop up on my feed:

https://endosnake.com/products/endosnake-viper-3-9mm?gclid=CjwKCAjwqdn1BRBREiwAEbZcRxpnxL9cvW7WVEVvDhtvflkwr32bxZiaFZqDhTAz_C4tG-k-E9tedhoCENsQAvD_BwE

Can google "read" what you are reading and analyze it?

[bigben5054]

Yes, I sealed the head bolt threads.  And yes, I think anything you do online is tracked these days.  My guess is it didn’t necessarily pick up on the plain text, but the Harbor Freight links that bd posted.

I haven’t gotten any further.  Just sitting here thinking through what could have happened and what the damage could be.  When I put the heads together I lubed the stems with motor oil.  Not sure what I could have done wrong there.  In order for a valve to hit a piston, I think you have to over rev and get into valve float.  I don’t think I did that either.  The mystery persists for now...

[bd]

Did the heads come bare?  Did you assemble the valves and springs onto the heads?

[bigben5054]

I bought the heads slightly used and they were assembled.  Just for good measure, I took them apart to wire wheel the valves and put new valve seals on them.

[bd]

Well, reaffirming what you already know, the next steps are removal, disassembly and thorough inspection.

[bigben5054]

Bent valve.  From the naked eye, it looks to me like the valve and piston just gently kissed once.  I pulled the lifter out and it came out no problem and looks fine.  I took the valve spring off and the inner and outer spring both look fine.  I tried to pull the valve out by hand and it wouldn't budge.  I used a wood block and rubber mallet to gently tap the stem and it would move maybe 1/4 inch is all.  So its not seized completely in the guide.  So...what happened?  My list of possibilities is:

1) wiped cam lope, caused slack in valve train and allowed rocker to slide off to side and pushed the valve at an angle
2) rocker just worked loose and slid off to side, pushed valve at an angle (not likely - rocker arm nut was still installed about same as all others)
3) I got bad info re valve springs good for .500 lift cam, and the valve springs can't handle this cam and allowed valve float (I'm not sure how this works exactly)
4)

Attached pics of the piston and valve.  Also attached pics of #8 showing some oil on the intake valve.  There was also a little oil in #8 cylinder.  #8 compression test was 150, others were 155-170.  Think there is an issue on #8, or just needs a little more run time to break in the (moly) rings?

[bigben5054]

Correction:  That is #2 with the wet oil and #2 was at 170 lbs.  So all good there as far as I am concerned.  Going to take the head to a machine shop today and see if they can fix and and give me some ideas on what might have happened.  I'll have them test the valve springs too so I know if these are truly appropriate springs for this cam.  I was thinking, perhaps I should not be so fast to rule out seizing.  I suppose it could have seized when hot, caused the valve to stick, piston hits it and does the damage, then after it cools down it frees up again.  Does that happen?  Or once they seize does the valve and guide basically weld together? 

[bigben5054]

Dropped off the head today.  Chatted with the guy at the machine shop for a minute before I left.  He quickly dismissed the idea of the valve springs not being sufficient.  I guess a .444/.466 lift cam isn't impressing anyone!  He seemed most concerned about a wiped cam lobe.  I haven't checked that yet, but should be pretty simple with the intake off.