Should I rebuild this head??

[Dave M]

Helo again everyone,

I'm considering some comments made in my last post.

To reiterate, I'm swapping out the bottom end for a rebuilt one and found the head as seen below. Its not a great pic, but what we're looing at is #5 which had big time blow-by (super low compression, normal during wet test). The remainder of the valves have a thin brown coating which can almost be picked off with a fingernail (see the intake on #6). Other than #5 being a pig, there is no indication that the head should require a complete rebuild.

Its also important to note that this head was rebuilt < 50,000km ago, but obviously has a coating due to the high mileage (1/2 mill kms) and the bum rings in #5. What are my options here? Is there a way to clean this up without doing an entire rebuild. If I bring it somewhere can they tell me if the guides and seals are OK without breaking the bank? Can they/me clean this up safely/economically.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Engine/Block_Swap/Engine_1011.jpg


Not trying to be cheap, just trying to be cheap :)

Thanks again,

Dave M

[JonE]

Yah, any automotive machine shop can diagnose the head components and then let you decide what to do. Not very miles on that rebuilt head bodes well for less work necessary. Sometimes, if the guides/seals are ok, then maybe just retouching the faces and seats will make it good again. If they retouch the faces/seats then new seals will be necessary. Probably worth having it looked at as long as you have it off. Depending on your intentions, how long you'll keep it, etc.

[Bellicose Right Winger]

35k miles isn't a lot for a valve job and blow-by in #5 shouldn't have hurt the valves. You can check relative condition of guides by rotating cam to open valves and check movement at valve head when you push valve head. You can check valve seat for leakage by rotating cam so valves are closed and filling combustion chamber with very thin oil. like WD40 and check for leakage at intake & exhaust ports.

How bad was oil consumption with old engine?

Paul Shovestul



Helo again everyone,

I'm considering some comments made in my last post.

To reiterate, I'm swapping out the bottom end for a rebuilt one and found the head as seen below. Its not a great pic, but what we're looing at is #5 which had big time blow-by (super low compression, normal during wet test). The remainder of the valves have a thin brown coating which can almost be picked off with a fingernail (see the intake on #6). Other than #5 being a pig, there is no indication that the head should require a complete rebuild.

Its also important to note that this head was rebuilt < 50,000km ago, but obviously has a coating due to the high mileage (1/2 mill kms) and the bum rings in #5. What are my options here? Is there a way to clean this up without doing an entire rebuild. If I bring it somewhere can they tell me if the guides and seals are OK without breaking the bank? Can they/me clean this up safely/economically.

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Engine/Block_Swap/Engine_1011.jpg


Not trying to be cheap, just trying to be cheap :)

Thanks again,

Dave M

[Dave M]

You can check relative condition of guides by rotating cam to open valves and check movement at valve head when you push valve head. You can check valve seat for leakage by rotating cam so valves are closed and filling combustion chamber with very thin oil. like WD40 and check for leakage at intake & exhaust ports.

How bad was oil consumption with old engine?

Paul Shovestul

Thanks for both your input.

I was hoping there were ways to diagnose without too much trouble, and, now that you've said it, I do recall the valve seat leakage test. However, bentleys does state that camshafts should be removed, maybe so all the valves can be seated via gravity simultaneously.

As for testing the health of the guides, I found the following in benltleys.
http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Engine/Block_Swap/Valveguidespecs.jpg
But...... since i don't have one of these (below), and it requires that the stems be extended flush wit the end of the guide, is there any way to tell without dis-assembly?

http://img.photobucket.com/albums/v11/dave_macisaac/Bimmer/Engine/Block_Swap/Valveguidecheck.jpg

I have spoken with a local 'head shop' and he's willing to look at mine tomorrow. I will come prepared with bentley and any other wisdom you guys can afford.

Thanks again,

Dave M

[632 Regal]

Dave, your there, have it checked. Without you taking the springs off you cant specifically tell the side play. I would just take it in to a "trusted" shop for diagnosis.

[Dave M]

Dave, your there, have it checked. Without you taking the springs off you cant specifically tell the side play. I would just take it in to a "trusted" shop for diagnosis.

Its going in tomorrow, whether its trusted or not is beyond me. Supposedly the only place a reputable import shop sends its heads.

I'll report back,

Thanks jeff

Dave

[632 Regal]

hopefully the seals are shot and that puts an end to it... Ill wait for a report.

[Dave M]

hopefully the seals are shot and that puts an end to it... Ill wait for a report.

Hopefully shes smokin hot and neked.....and the seals are shot.

[Rigmaster]

Dave,

IMHO, valve stem seals are cheap- as is a basic "valve job"- just reseating the valves to the seats and making sure everything else looks OK.

If you spend a little extra $$$ now while it's all apart- you'll likely add many many more miles (or KM's) to the life of the engine.

Look at it this way- a valve job and new stem seals should cost alot less than 1 new car payment.

Bret.