How do I change the valve rockers? M20

[Mr. Horsepower]

Have you posted a pic?


Now I have got one rocker out of the part engine, and it seems to me that I have to pull the head of on the other engine :( The rocker shaft, should it not be pulled out easily?
If I was going to get this one anywhere I had to hammer it!

[Syncro325is]

[Mr. Horsepower]

Looks like I just have to fit my S14 into it :P

Problem is that I have to use the car every day to work...!

If I just could push the shaft far enough against the firewall to get the rocker out. What is the key you are talking about?

[Syncro325is]

no, they are held in with a key at the front of the head. they are not an interference fit.

You're right, I forgot about the key...
But just because the shafts do not come out easy does not mean that they are bent. Its a tight fit.

[nando]

Don't think I'm getting this right. Is the shaft going to be pushed towards the radiator or the firewall?

I'm only going to chance cyl nr 1 rocker.

it really should be pulled forward towards the radiator.. you could do it the other way but I don't know if there is enough room.

btw it is easier off the car of course. for fun I took apart my old head to see how fast I could do it, took about 10 minutes with a 10mm wrench (to remove the eccentrics for clearance) and a flathead screwdriver. no hammer at all.

[Mr. Horsepower]

Don't think I'm getting this right. Is the shaft going to be pushed towards the radiator or the firewall?

I'm only going to chance cyl nr 1 rocker.

[nando]

My shafts did not come out easily on my head, which was not warped, nor was it easy to get the shafts out of ricksloans m30 head(s) all of which were pretty stuck in there. If It weren't a tight fit then why wouldn't the shafts slide out and eventually push the rubber stoppers on each end out?

no, they are held in with a key at the front of the head. they are not an interference fit.

[nando]

if it's a rear rocker you only have to pull it far enough to get the broken rocker out. but you do have to release the tension on all 6 for the shaft to slide out easily. you don't need much clearance to the firewall since you really shouldn't have to push very hard on them, unless everything is covered in a heavy sludge. lifting the engine gives you room to completely remove the shaft if you wanted to pull all 6 rockers.

[Syncro325is]

sorry, ninja edited. How would you suggest getting the shaft out of the head still connected to the motor? Pulling the rad out may give you enough clearance to get the shaft out, IF it releases easily. Chances are though that it will not.

Ok...guess I have bit of a clue here now. I have done a search though.

I don't have to pull the shaft more then about 10cm maybe or do the whole shaft need to come out to pull just one rocker?

Cant believe they made it so tricky. Even Opel is easier to change rockers on then!

I have a 1984 part engine that I will take my rockers from, so I will get some "practice" on that one first.

I also thought that jacking the engine must give more clearance to the firewall.

I might consider replacing the rockers with new ones... unless your part motor has real low miles or "fresh" rocker arms. Do the job once.

[Mr. Horsepower]

Ok...guess I have bit of a clue here now. I have done a search though.

I don't have to pull the shaft more then about 10cm maybe or do the whole shaft need to come out to pull just one rocker?

Cant believe they made it so tricky. Even Opel is easier to change rockers on then!

I have a 1984 part engine that I will take my rockers from, so I will get some "practice" on that one first.

I also thought that jacking the engine must give more clearance to the firewall.

[nando]

when you do have the head off, (because you will have to take it off to change the rocker arms) you can lathe down an m20 rocker shaft(a smidgin) to use as a "push rod" to get the stock shaft out. It works very well without damaging the shaft! and you now have a new tool!

again, wrong and unnecessary unless something is really screwed up.

[Syncro325is]

wrong

if you have to hammer the shaft out, it's bent, or your head is warped, or things are so full of gunk your engine is fucked anyway.

the proper way to remove the rockershafts is to release the tension on all the rockers by sliding them off the cam lobes. Once the tension is off the rockers, the shaft should slide out easily and cleanly without hammering on anything.

you can do this on the car as well, although it's much harder because you have to be able to rotate the cam. you can get the shaft started by using the slot where the "key" goes to pull on it.

Using a BFH to force the shaft out is just going to damage the shaft/plug and is completely unnecessary.

My shafts did not come out easily on my head, which was not warped, nor was it easy to get the shafts out of ricksloans m30 head(s) all of which were pretty stuck in there. If It weren't a tight fit then why wouldn't the shafts slide out and eventually push the rubber stoppers on each end out?

This is what I learned from the master tech at Zygmounts BMW.
When you do have the head off, (because you will have to take it off to change the rocker arms) you can lathe down an m20 rocker shaft(a smidgin) to use as a "push rod" to get the stock shaft out. It works very well without damaging the shaft! and you now have a new tool!

[nando]

FYI: the rocker shaft will not just "come out" or "slide out".
It's a pretty snug fit, and I had to use a drift and a BFH to get mine out. (With the head out of the car, on my kitchen table).
You may want to keep that in mind if you're trying to do it in the car. (ie much smaller clearances)

wrong

if you have to hammer the shaft out, it's bent, or your head is warped, or things are so full of gunk your engine is fucked anyway.

the proper way to remove the rockershafts is to release the tension on all the rockers by sliding them off the cam lobes. Once the tension is off the rockers, the shaft should slide out easily and cleanly without hammering on anything.

you can do this on the car as well, although it's much harder because you have to be able to rotate the cam. you can get the shaft started by using the slot where the "key" goes to pull on it.

Using a BFH to force the shaft out is just going to damage the shaft/plug and is completely unnecessary.

[Adrian_Visser]

Listen to those who have done it not those who have read about doing it (i.e. me).

[!kid]

FYI: the rocker shaft will not just "come out" or "slide out".
It's a pretty snug fit, and I had to use a drift and a BFH to get mine out. (With the head out of the car, on my kitchen table).
You may want to keep that in mind if you're trying to do it in the car. (ie much smaller clearances)

...what he said