4AGE valve issue

[stahlz_ae86]

Ok guys, I've got myself a Gen II 4AGE (red & black top) which I bought with knowing it had a problem but it wasn't an issue because I'm be-building it anyway. When I got it and it was still together you could only turn the crankshaft around from the front of the motor about 180 degrees. Upon removing the camshafts, then taking the head off i found that cylinder 3, intake side, valve at flywheel end of motor was "open" while the other 15 were closed. The strange things about this is the bottom end can now be turned in full rotations now as the valve isn't restricting its movement any more, yet I was to the understanding the valves cannot come into contact with the pistons. Also, the valve can still spring back into place when it's lightly tapped, but with the camshaft on, every time i turn the cylinder 3 around the good one still springs back and the crap one stays open. The valve cap (not sure if this is correct terminology) is also broken.

What a "valve cap" looks like 'together'


And apart???


The valve springs both look back to normal when tapped in


I also still have to do RWD conversion etc...for the rebuild, and I have to buy new cams coz the ones in it are pitted(will go to highest possible on stock computer). The bottom end looks fine from first inspection but will pull apart and do rings and bearings etc anyway.

This is my first engine re-build so any input will be much appreciated.

[LeeRoy]

I'm not too sure what your asking but looks to me like its gotten a bit crusty in its old age.

2 things that spring into mind with what your saying.
- Spring is rooted, maybe due to heat or what not
- or Valve has some damage

I would pull the head apart and put in new stem seals and check the springs and valves as with a problem like that they may be in need of replacement especially since the motor isn't turning over.

- LeeRoy

[stahlz_ae86]

It turns freely with the head off.

I will be giving the head to an engine reconditioner to re-seat the valves (2 45 degree shims apparently on the head itself and the valves)

should i get them to replace all the valves? Seems odd that a spring would be stuffed (or the valve for that matter) if it still springs back into place when it's tapped.

[stahlz_ae86]

Might I add, lightly tapped. It's so odd that the spring wouldn't pull it back if only the lightest of hammer taps gets it. Could the valve have a slight bend?

[EVOSTi]

im a mechanic and i still dont service my own heads, they are a fine art and unless you are pretty confident and experienced its best leave it to the experts. could be the valve spring, general sludge in the head or quite possibly the valve guide.

take the head to an engine/head builder and just ask for a general service. they will check everything, adjust clearances, new valve stems seals, pressure test etc.

do the bottom end yourself, take the head to a builder.

[30psi 4agte]

I think what has happened in your case is:

The shim has prob poped out of the bucket( valve cap ) and got caught on the lip of the bucket causing the cam to depress the valve futher into the cylinder and hit the piston.
This is the reason for the damage to the bucket also.

4ages will not hit valves usually but in this case it is possible.

I would take the head to someone in the know and get it checked or if you are mechanicaly minded pull the valve out yourself


I would say the valve is damaged and prob the guide also

P.s the correct terminology for the " valve cap" is Cam bucket and that little steel piece is a Shim. - you can buy different size (thickness) ones and this is how you set your valve clearences up.

[stahlz_ae86]

just looking at a dismantled pic (from bill sherwoods page) and it appears the shims are seperate to buckets. So yeah quite possible. Never taken a valve out will get dad to show me when he gets home, coz i'm curious now...

http://www.billzilla.org/4aghead.jpg

[30psi 4agte]

Getting the valve out is easy.

Put a stuffed rag up under the combustion chamber ( where the valve faces are) to hold the valves in but not damage them.

Then get a spark plug socket and put it over the valve spring. then give the socket a good clout with a hammer and this will pop the collets (things that hold the valve and spring together) out.

[stahlz_ae86]

Goin outside, will do now and if there's something interesting to see will post up pics too. Thanks

[EVOSTi]

well the heads comming off anyway so why bother with that drama and risk losing the collets when you wack the valves? another way if you have the time is to make a simple tool to remove the collets, involves using come steel bar and an old socket to make a lever to depress the valve spring down, prob a little safer.
either way just give the head complete to a head place

[stahlz_ae86]

[stahlz_ae86]

It's out, everything intact, could it be the slightest of bends in the valve? I see why you said to use a spark plug socket now, so the collets get stopped by the rubber. Thanks.

[oldcorollas]

it only takes a veeeery slight bend to make a valve stick..

have a look ont he valve stem to see if there is some part that has been rubbing... probably on the top half of the stem..

then, thouroughly clean all the crud off (not the stuff at the bottom... just the upper3/4 of the stem.. away from the carbon on the lower 1/4) , and roll the valve along a flat plate of glass, with the valve head hanging off the end. if there is a bend in the valve stem, you should see it wobbling up and down.

if the valve head has been hit, it will also not be turning ina true circle.

inspect the piston for damge too, however, since there are valve reliefs, the piston would have contacted the valve squarely, and not left a mark on the piston.

edit: and yes, take to a REPUTABLE head shop that does good work. tell them exactly what was happening (ie valve sticking but would pop back) and get them to check the valves and the guides. get them to tell you prices if they will change the guides or valves.

if they recut the seats (either 45deg, or a 3 angle job) then they need to adjust the shims as the valves will sit closer to the cam. get them to do it professionally, especially as this is your first build.. BUT, ask them nicely to explain what they will do, and what they did (and if you ask very nicely, how they knew what had to be done)

[stahlz_ae86]

Thank you for your help

[EVOSTi]

there is a LOT of crud on the back of that valve, looks to have had a decent VSS leak.