Is machining really necessary?

[86bmw325e]

Hey guys,



So I have the typical cylinder 3-4 head gasket oil leak and it is PISSING. Unfortunately, my landlord is going to start asking questions about the spots in their parking lot, so I need to fix it. I'm looking to tackle this job in 1 week at my parents during April vacation. I'm an ASE master tech and I'm not worried about tackling the job and I know the importance of machining; however, I also know there are times when it is acceptable to forgo machining. In my case, I am time limited and don't have the time for a machine shop to go through the entire head and do what they have to do, plus re install it in the same week. Not to mention, if I sent it out for machining, the cam would have to be removed and I would have to replace the cam bearings. This car is a little more than a winter beater. I mean, I'm trying to make it nice, but as of now, i can't sink an assload of money into it. On the same note, I don't want to go through all this work and have it piss oil two days later. I purchased an oem BMW head gasket kit. What are your expert opinions?

[digger]

if the surface is already flat machining it wont make it any flatter, also the surface needs to have good finish and be meticulously clean.

ive been told 0.003 is maximum flatness spec for the M50 head so you could use the same guideline (at your own risk) but personally i dont see how it is a difficult or time consuming job to machine. there are no cam bearings to replace and it takes all of 10 minutes to dissemble a head. might as well to a vJ and new stem seals if the head hasn't been refreshed anytime recently

what gasket was on there?

[Cabriolet]

I'm an ASE master tech... I know the importance of machining...

OP you answered your own question
The minimum that MUST be done is head decked and valve seals replaced.

if I sent it out for machining, the cam would have to be removed and I would have to replace the cam bearings. I don't want to go through all this work and have it piss oil two days later. I purchased an oem BMW head gasket kit. What are your expert opinions?

1. there are no cam bearings.
2. you answered your own question, not machining the head means it wont seal.
3. the bolts are TTY, replace them when doing the headgasket. use only BMW bolts. you did not mention them, though im guessing you got them with the "kit"
4. if you dont have time, buy another head, have that machined and dropped on after you pull your head, then sell your head to recoup the cost.

[86bmw325e]

I'm not sure of the current head gasket, I'm assuming its the one from the factory as there is a TSB on all data about them leaking and an upgraded head gasket having silicone around the oil galleries.



I guess I was fooling myself when I posted this. I was hoping for the impossible "you'll be fine man, just do it", but I guess machine shop it is.



I just ordered new head bolts and washers, they did not come with the gasket kit. All parts are oem BMW because I really don't want to do this again. If you couldn't tell, I'm new to euro cars, especially BMW's as all I've ever done is a clutch job in an 08 328xi.



Thanks for the much needed reality check, hopefully I can take some pictures and do up a detailed guide, we'll see. If my boss lets me do it in the schools auto shop, I may have more time.



On longshot know of a good machine shop in Massachusetts with European experience?

[Bearmw]

Eastwood machine in Somers CT can do most anything. Paul's machine in West Springfield is good for basic stuff but you can't be in a hurry.

[redlightpete]

I installed a used head without machining and have had no problems. If it's flat, it's flat. I did use a BMW headgasket.

[TobyB]

If it's flat, it's flat.

Ayup. If it's straight, it's straight.
But a non- leaking head may or may not be straight when it comes off the block.

If time is critical, I think I'd get another head ready. Then you're running again the same day.
Pretty much guaranteed, low stress.

t