Rocker Shaft

Hello,

I've just fitted a new head gasket and got the head back on my 2.5 N/A but I can't get the rocker shaft to seat properly. When I did my rebuild it was as easy as lifting it off and then just placing it back down when it came to re-fitting it.

Number 4 Pushrod seems to be sticking up a little, as does number 7, and the shaft seems to balance on these two push rods, number 4 a little more than number 7, the rest of them are all loose.

The rod is sat in its little feeler properly (as far as I can tell from the feeling), so I don't know what I've done wrong or how to fix it!

Any suggestions?
-Pos

Possibly this valve is open at the point the engine is stopeed at, so the cam is pushing the pushrod up, which is then in the way of the rocker? Try winding the valve clearances right back, then fitting it. You should re set these anyway with a new head gasket.

That would make sense actually, because when I lifted the rocker off, the spring would have elongated slightly allowing the valve to close?

Aye. I would expect some of the valves to be open, the engine won't stop with them all shut unless you have a problem! Check all your pushrods to make sure none of them are bent, I have some spares if you need them. I also have a spare rocker shaft if yours is damaged :-D. Make sure that you torque up your head bolts lots, i forgot to once and then had a perpetual oil leak. Also, make sure you do a good job of setting the valve clearances, or you will burn you valves, loose power and make too much noise, etc. The new head gasket will mean that they are all thrown out. DId you get to the root of you blow-past problem?

Thanks for the advice! Well it looks like it might have been head gasket failure after all, hence the reason why I have deiced to change it. There was a hell load of oily mess when I took the gasket off and a couple of chunks missing too. Plus, the fact that I used a bit of hylomar heat resistant silicone gasket underneath the previous head gasket causing high spots

The morning will tell!
-Pos

It does sound like it then! That much blow-past is often something like that. As i think was said before, whoever told you to put hylomar on the head should have their automotive rights removed! Ah well. When i didn' torque up my head bolts it let a layer of oil sit between the gasket and the block, which leaked when it got hot. I guess, in an extreme case this could ignite with combustion and so destroy the gasket.

pos said:

Thanks for the advice! Well it looks like it might have been head gasket failure after all, hence the reason why I have deiced to change it. There was a hell load of oily mess when I took the gasket off and a couple of chunks missing too. Plus, the fact that I used a bit of hylomar heat resistant silicone gasket underneath the previous head gasket causing high spots

The morning will tell!
-Pos

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Sorry to butt in but from your exchanges I can tell you are having probs.

It sounds as if the flame ring blew out, so did you run a straight edge across the head to make sure it's ok, cos it's gonna blow again if it aint flat.

Aint the head bolts angle torqued after you pre-torque them.

And in reference to the rockers just tighten them down evenly and the valves will be ok, no need to slacken them off, once you have run it reset them since **** and such tends to throw them off, and also they need to settle in, so don't even put the cover back on run for a minute or so and recheck them and then a week later once it's had a good run.

Also with the cover off you are looking to make sure the rockers are getting oil, just in case you blocked it up.

I think everything is alright with it, it runs absolutely sweet as a nut all abide some stupid mistakes I made when re-building! They're fixed now so all should be ok! I will take ur advice with the rocker assembly!

Cheers
-pos

david451 said:

Sorry to butt in but from your exchanges I can tell you are having probs.

It sounds as if the flame ring blew out, so did you run a straight edge across the head to make sure it's ok, cos it's gonna blow again if it aint flat.

Aint the head bolts angle torqued after you pre-torque them.

And in reference to the rockers just tighten them down evenly and the valves will be ok, no need to slacken them off, once you have run it reset them since **** and such tends to throw them off, and also they need to settle in, so don't even put the cover back on run for a minute or so and recheck them and then a week later once it's had a good run.

Also with the cover off you are looking to make sure the rockers are getting oil, just in case you blocked it up.

Click to expand...

On the TDi the bolts are angle torqued, but not the N/A. And I have heard of engines being run with the rocker cover off, and i saw my dad once after he tried it - oil everywhere so i would pick somewhere very empty...
5 of the rocker shaft bolts on this engine are also head bolts, and so need to be torqued up. The others are not head bolts, and do not need as much torque, or they will shear.
WRT '**** and stuff', yes they will be thrown out after a rebuild, but running them for even a small distance (100 or so miles) with them set too close can damage the valve seats, so I was thinking as a) POS has rebuild his head twice already he would like to check this and b) it only takes 5 minutes. But i agree, definitely check them again a week later, and then a bit later again.
I also hadn't really thought about the flame ring, this is a good point, but again I think POS may already have put the head back on. Hmm...

As always though, I am always open to critisisms of what I think! I am keen to learn and painfully aware that I know only the beginnings about engines and land rovers... Most of what I have said is experience, as I have burnt my valve seats due to too tight clearance, 'cos i thought I had done it right in the past... We shall see.
Let us know how it goes POS

Without the rocker shaft, none of the valves can be open. They will all have been pulled shut.

The push rod pushes the rocker up the other side pushes the valve down, take this off, they ALL close.

The cam lobe will be raised on some, check your push rods are seated properly, they sometimes sit a little high if they have not seated properly - then you will need to screw your clearences all the way back or you will be trying to seat the shaft against the raised lobes.

I don't fully understand what you mean by adjusting the valves, and I have never adjusted anything, even after my engine re-build

Do you mean adjusting the tappets (rocker arms clearance)? What gauge feeler should I be using?

Also, when you talk about winding the valves back in, what do you mean by that?

Cheers

-Pos

boydy1989 said:

...whoever told you to put hylomar on the head should have their automotive rights removed!

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Indeed, however, I remember this: he came onto the forum and said he had used it, we said he shouldn't have.

discomania said:

Without the rocker shaft, none of the valves can be open. They will all have been pulled shut.

The push rod pushes the rocker up the other side pushes the valve down, take this off, they ALL close.

The cam lobe will be raised on some, check your push rods are seated properly, they sometimes sit a little high if they have not seated properly - then you will need to screw your clearences all the way back or you will be trying to seat the shaft against the raised lobes.

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There's always going to be a lobe up, and unless you romp down one end of the rocker shaft and snap it you should be able to tighten it down evenly, let's face it many are hydraulic and you can't wind them off.

That's the way I have always done it anyway, but I guess if you are unsure then it is a good idea to wind them off, and play safe.

The lad is having trouble seating the rocker shaft; if he increases the clearences on them all the he will have an easier time of it.

He is going to have to do them all anyway so its not going to add any significant amount of time onto the operation because its just means he is ready to do all the clearences when the shaft is torqued down.

pos said:

I don't fully understand what you mean by adjusting the valves...
...Do you mean adjusting the tappets...

Click to expand...

discomania said:

...you will need to screw your clearances all the way back

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Yes I was referring to the tappet clearances.

Don't bother with a feeler guage yet, just get the shaft torqued down, then use a 0.010 inch (.25mm) guage for your clearances.

pos said:

I don't fully understand what you mean by adjusting the valves, and I have never adjusted anything, even after my engine re-build

Do you mean adjusting the tappets (rocker arms clearance)? What gauge feeler should I be using?

Also, when you talk about winding the valves back in, what do you mean by that?

Cheers

-Pos

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Oh gees, you worry me.

The rocker shaft controls the valves, when you tighten it down just make sure you do it evenly and watch that the valves go down at the same time, if it goes solid make sure that you have not missplaced a push rod.

On one side of the rockers is an adjusting nut and screw you need to set the engine in the right sequence to adjust them, if you dont then you risk bending a push rod or burning a valve, or it rattles like fook and don't run properly.

Although it chucks a little oil out you need to run it with the cover off for a minute or two to settle the tappets, and check oil feed to the top end of the engine.

On an overhead cam engine you would get soaked if you run it like this so don't ever try it.

pos said:

Thanks for the advice! Well it looks like it might have been head gasket failure after all, hence the reason why I have deiced to change it. There was a hell load of oily mess when I took the gasket off and a couple of chunks missing too. Plus, the fact that I used a bit of hylomar heat resistant silicone gasket underneath the previous head gasket causing high spots

The morning will tell!
-Pos

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you did what!!

set ya tappets with a rule of nine

e.g.
1 fully open set 8
2 fully open set 7 etc


fookin hylomar.....

discomania said:

The lad is having trouble seating the rocker shaft; if he increases the clearences on them all the he will have an easier time of it.

He is going to have to do them all anyway so its not going to add any significant amount of time onto the operation because its just means he is ready to do all the clearences when the shaft is torqued down.

Click to expand...

It does actually because it's impossible to set them up with them all wound off, when you turn the engine you cant tell which valves are on the rock.

The guy seems lacking in even the basics and might snap the rocker shaft I guess and this might ensure he does not but I don't know where it's leading, coz he needs a manual or he's gona fook it up again.

true ... if not snap may bend it. hope he tightens everything down in the correct sequence as well