how to change valve stem seals without taking head off?

[posix]

Hello!

had a leakdown and compression test done on the engine a while ago and the numbers were good. Want to change the valve stem seals because there’s some signs they might need to be replaced.

I don’t want to take the head off but want to replace the valve stem seals. Partially because the numbers from the tests are good, partially because I don’t know where to get an m90 head gasket, but mostly because if I take the head off I’m going to want to take the block apart....

any tips on how to change the valve stem seals without taking the head off?

 

[OCCoupe]

Shortcuts are exactly that, shortcuts. For want of a dollar it’s not worth taking a shortcut. I’m sure you’re tired of hearing me negate your approach but I’m speaking from experience. Do it right the first time. Remove the head, send it out to be inspected and rebuilt. It’s not a lot of money in the grand scheme of things. Rebuild the head, install a new headgasket, new head bolts (yes new head bolts. The cheap bastards will disagree but they aren’t going to start a go fund me page for you when they realize they gave you bad advice). You’ll be happy, your engine will be happy. Your wife will be happy and your dog will be happy. Plus I will be happy knowing that you listened. And there you have it! That’s how you replace valve stem seals without taking the head off.

 

[Markos]

No reason to take the block apart just because a head job. That’s like saying if you need to replace your transmission, you might as well flush your cooling system “while you are in there”. Pulling the engine is significantly more scope, and you do stat to talk about “while you are in there stuff”. Like if you pull the motor then replace the clutch. While the trans is off get it resealed.

The m30 head is IMO easy to remove. You are swimming with space in the engine compartment. You have large nothing-special head bolts that hand tools will remove. An exhaust manifold that is easy to access. I say go for it.

 

[posix]

Engine is coming out either way.

 

[posix]

Ok ok. Decided to take head off and taking mikes advice to change the head bolts as well.

thank you both for the fast and good advice

 

[jman]

OCCoupe has valid points but to answer your original question - you make an adapter for your air hose that screws into the spark plug hole, the air pressure will keep the valve from falling into the cyl. while the spring is compressed and removed. I have done this on a couple cars that were very low mileage, under 75K but seals where 40 years old.

 

[m5bb]

OCCoupe has valid points but to answer your original question - you make an adapter for your air hose that screws into the spark plug hole, the air pressure will keep the valve from falling into the cyl. while the spring is compressed and removed. I have done this on a couple cars that were very low mileage, under 75K but seals where 40 years old.

Just for talking sake, there is another way that racing guys use.
You get nylon rope about 1/4".
You stuff the rope in one cylinder with the piston down. You slowly bring the piston up and the the rope holds the valves in place. You can change springs and seals.
Repeat for each cylinder, and don't forget to leave a tail of rope hanging out so you can retrieve it.
Getting ready to do this on an M88 to add the double valve springs that were an upgrade.
Gary

 

[Eric V]

Hello!

had a leakdown and compression test done on the engine a while ago and the numbers were good. Want to change the valve stem seals because there’s some signs they might need to be replaced.

I don’t want to take the head off but want to replace the valve stem seals. Partially because the numbers from the tests are good, partially because I don’t know where to get an m90 head gasket, but mostly because if I take the head off I’m going to want to take the block apart....

any tips on how to change the valve stem seals without taking the head off?

What symptoms might indicate bad valve stem seals in an engine with good compression and leakdown testing?

 

[sfdon]

Hello!


I don’t want to take the head off but want to replace the valve stem seals. Partially because the numbers from the tests are good, partially because I don’t know where to get an m90 head gasket, but mostly because if I take the head off I’m going to want to take the block apart....

I would never use anything but a real bmw headgasket on a m90 engine.
from the dealer
Carl Nelson will tell you the same thing.
4 times as expensive and worth it
i have a small stack of worthless failed gaskets from others.

certainly heat cycle and retorque without the expansion tank cap on.
that gasket has 7 thousandths difference between fire ring and gasket material-

 

[m5bb]

I would never use anything but a real bmw headgasket on a m90 engine.
from the dealer
Carl Nelson will tell you the same thing.
4 times as expensive and worth it
i have a small stack of worthless failed gaskets from others.

certainly heat cycle and retorque without the expansion tank cap on.
that gasket has 7 thousandths difference between fire ring and gasket material-

Don knows.
Cometic gaskets are great but expensive. All metal gasket that the turbo guys use. Will hold combustion pressures. I use on my almost race M30 motor.

 

[posix]

i checked REALOEM and there's two

What symptoms might indicate bad valve stem seals in an engine with good compression and leakdown testing?

there some blueish smoke coming out every now and then. especially when i do the engine braking test and sometimes on a cold start as well. oil consumption is not very high but there is definitely some.

 

[posix]

I would never use anything but a real bmw headgasket on a m90 engine.
from the dealer
Carl Nelson will tell you the same thing.
4 times as expensive and worth it
i have a small stack of worthless failed gaskets from others.

certainly heat cycle and retorque without the expansion tank cap on.
that gasket has 7 thousandths difference between fire ring and gasket material-

i went on REALOEM and saw there were three versions, im guessing different thicknesses?

1,72MM - 11121730951
2,07MM - 11121730224
2,20MM - 11129065668

Would this be dependent on the thickness of the head after resurfacing?

definitely buying genuine bmw head gasket.

 

[Dick Steinkamp]

i checked REALOEM and there's two

there some blueish smoke coming out every now and then. especially when i do the engine braking test and sometimes on a cold start as well. oil consumption is not very high but there is definitely some.

Smoke on engine braking...especially in a lower gear with a trailing throttle on a long downhill...and smoke at startup are generally signs of worn valve seals. If the motor is making good compression, good power, no funny noises, etc, I would not remove the head for machine shop work. I can't think of a good reason to fix things that are not broken on ANY car.

I have done both tricks (compressed air and rope) to replace valve stem seals on several cars. Quick and easy. If there are no "gotchas" doing the same to your E3 it is what I would do. You'll have an investment in a valve cover gasket and valve stem seals and a couple of hours labor.

 

[tochi]

i checked REALOEM and there's two

there some blueish smoke coming out every now and then. especially when i do the engine braking test and sometimes on a cold start as well. oil consumption is not very high but there is definitely some.

Valve stem seals that are old, worn and/or brittle may certainly be a cause of oil being sucked into the combustion chambers. However, valve seals may only be part of the problem. Other considerations include worn valve guides and even worn valve stems. Naturally, the seals are the easiest to replace.