How do I change the valve rockers? M20

[Mr. Horsepower]

Broke the rocker in cyl 1 intake on my M20B20 1990 mod EURO engine :(
(If rocker is the correct word?)

How do I change it?

Have red that the whole head has to come of because the shaft that holds all 6 rockers need to be pulled rear, and it then stops in the fire wall.

Thanks for help.

[91greg325i]

Broke the rocker in cyl 1 intake on my M20B20 1990 mod EURO engine :(
(If rocker is the correct word?)

How do I change it?

Have red that the whole head has to come of because the shaft that holds all 6 rockers need to be pulled rear, and it then stops in the fire wall.

Thanks for help.

When mine broke, I had to pull the head (m20b25, not sure of the differences between your engine and mine). It honestly wasn't THAT bad... but if you have to have the car up and running soon, it may be a bit tricky if you have other things going on. I've heard of people drilling through the firewall to move the rocker shafts (not sure of the correct term) out of the way. But if you have anything but a track/crappy car, I probably wouldn't do it... Good luck, broken rockers are never fun.

[Adrian_Visser]

A search would yield plenty of info about this. Pretty sure you can just remove the rad and jack up the engine a bit though to get the clearance necessary to slide the rocker shaft out.

[Omaliyo]

^^^ that

I read you can take the Rad out and jack up the car and the rockers will come out...

[ZombiE30]

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)

[!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

[Adrian_Visser]

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

[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.

[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]

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.

[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.

[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.

[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.

[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.

[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.