Can't adjust valves L18 engine and rocker rolled keeper

[racerx]

I have an L-18 and tried to adjust valves but could not finished. Other valves were easily adjusted but could not adjust Intake one in the back.  Went up and down with adjustment nut still could not open.  What do you think happened? I even went down to .06 and still feeler would not fit in. So I asked my neighbor, used to to be a mechanic, and he said that the spring may be stuck so I used a rubber mallet to try to losen the spring and noticed that the rocker got rolled out of the valve keeper.

 

1). How come the adjustment nut could not open the valve?

 

 

2). How do I put the rocker back to the keeper?

 

 

Thanks...

[ggzilla]

If the spring is stuck, the gap will be too big, not too small.

 

Possibly the adjustment nut is cross-threaded, or maybe the engine was not at TDC when attempting to adjust it.

[DanielC]

if you can remove the rocker arm, do that first, like this.  Pull off the "mousetrap" spring,   pull out the rocker arm, and watch for the pad that sits on top of the valve, inside the spring retainer, the top hat.

 

With the rocker arm out of the way, you should be able to get to the 17 MM lock nut, and the 14 MM nut on the rocker arm pivot, and remove then completely out of the steel part they thread into.   The nut should turn freely on the rocket pivot.  The rocker arm pivot should go easily into the insert in the head, after you clean out oil, and other debris at the bottom of the hole it threads into.  Get these parts screwing together, and then put the nut as high in the rocker pivot as you can then screw the pivot and nut assembly as far down as you can.  

Turn the engine clockwise until that cam lobe is straight up, the corresponding lobe on number one should be straight down, make sure you are using the same valve for reference., if you are working in an intake valve on #4, #1 intake is down.

 

Put the lash pad on the valve keeper.  Slide the rocker arm under the camshaft, into the lash pad.  Pry the spring down by using a big screwdriver to push on the valve retainer, and slip the rocker arm on the pivot.  

 

With the rocker arm in place, you should have lots of clearance between the rocker arm pad, and the camshaft.  If there is not,  the valve has a sunken seat, and the valve is too high on the spring end, and a valve job is probably needed, with the valve seats replaced. 

 

Many older L-engines has soft intake valve seat, and they worked good when we had leaded gasoline, the lead compounds lubricated the valve seat, but when lead was removed from gasoline, the seat wore out more.

[Silky_Johnson]

^^^^ Is this just a case of a worn valve and no more adjustment left? It seems like he's saying he can turn the adjustment and lock nut, but can't get any more than .006" clearance.

[darrel]

With the rocker arm in place, you should have lots of clearance between the rocker arm pad, and the camshaft.  If there is not,  the calve has a sunken seat, and the valve is too high on the spring end, and a valve job is probably needed, with the valve seats replaced. 

 

Many older L-engines has soft intake valve seat, and they worked good when we had leaded gasoline, the lead compounds lubricated the valve seat, but when lead was removed from gasoline, the seat wore out more.

This. More than likely the problem.

[racerx]

okay thanks for the response, that makes sense, but if I do what Daniel C says, won't the valve drop. BTW do you know of any excellent Datsun mechanics around San Jose, CA

[banzai510(hainz)]

most times its the exhaust valve that sinks as it gets Hotter.

 

Why woud the valve drop? Unless the keepers or what ever you call them 2 halve things the spring was pushed down soem how and those fell out then the valve would drop I guess but never seen this happen just because of a valve adjustment

[DanielC]

It is possible that pushing down on the retainers can cause it to move, and the valve to move, releasing the retainer locks, the half round things.   But it the engine has been ran any length of time they are stuck together, pushing the retainer down moves the valve too

[racerx]

Will L16 rockers and keeper fit an L18?  I might have to take parts from an L16, that's lyin around, and put it on my L18 - Like the rockers, springs and mouse trap looking springs and keeper.

[DanielC]

Yes, L-16 rockers will fit a L-18 engine.  However, the cam and rocker contact surface wear in together, and it is good to keep the parts with each other, and in the same location.

 

I have heard of some success with sanding down the wear pattern on the contact pad of the rocker arm with very fine sandpaper, but I have not actually done this myself, so I cannot vouch for the long term success of doing this.

[racerx]

okay thanks for the response Daniel C. but it will be okay if I take the rocker assembly from L16 and put it in my current L18?

[DanielC]

What do you mean by "rocker assembly"

[ggzilla]

It's not OK to mix and match them, as they are worn to the cam. Instead buy a new one and use cam lube on it. Some say you can use extra-fine sandpaper (non-iron oxide type) to "reface" the rocker and it will be OK.

 

The assembly includes a Valve Rocker, Spring, and Guide. The guide fits over the valve Collet (keeper). You might also consider the Pivot, Nut and Retainer (adjuster) as part of the assembly.

 

If it's only the adjuster that is not working, you can replace that separately.

[racerx]

I meant rocker arm.

[racerx]

Do you guys know what valve compressor is good for compressing valve.  I went on line and noticed that there are many types. I'm certain that there are some that would fit our Datsun L series engine better.

[Silky_Johnson]

Something like this if the head is on the engine: http://www.ktcautotools.com/mercedes-valve-spring-compressor-cylinder-engines-repair-tools-a1267-p-88.html

 

Something like this if the head is off: http://www.amazon.com/OTC-4572-Large-Spring-Compressor/dp/B000F5ECUY/ref=sr_1_1?ie=UTF8&qid=1356550261&sr=8-1&keywords=valve+spring+compressor

[datzenmike]

Do you guys know what valve compressor is good for compressing valve.  I went on line and noticed that there are many types. I'm certain that there are some that would fit our Datsun L series engine better.

 

From the text I assume you want to swap some rocker arms and lash pads??? If so the spring can be compressed with a simple pry bar (or big screwdriver) under the cam and lift upwards to pry down on the valve spring retainer and the rocker slipped off the adjustment pivot. Just be sure the valve is full closed

[Sealik]

 

 

[datzenmike]

Slick! How do you do cylinder #2 and #3? :P

[racerx]

Any neat tricks to keep the valve from slipping or falling off?

[datzenmike]

Not sure what you're asking. What exactly are you trying to do.

[racerx]

That there's a possibility that the valve will fall in if I mess with the spring or try to pry the rocker arm in place as indicated earlier.

[racerx]

Also I might end disassembling the rocker arm assembly and retainer.

[ggzilla]

If you remove the keeper, to keep the valve from falling down do what you do for any engine: Feed clean 1/4" rope or vinyl tubing down the spark plug hole, then rotate the crank (by hand) to compress the rope/tubing against the valve head.

[racerx]

Okay will try the rope/tubing. Also heard try compressed air.