Valve Guide replacement....

So if it 'uses no oil' & 'runs very well' why do you feel the need for a rebuild ?

 

A better way to tell the root cause for the smoke is have someone watch you drive:

Upon deceleration, if there is smoke it is likely valve guides due to the vacuum pulling oil past the valve seals and guides.

Upon acceleration, if there is smoke it is likely piston rings.

Independent machine shop will run roughly $150/guide/valve (cost includes labor and materials).

 

Are you looking to needlessly throw away $10,000?

Tell you what, just mail it to me and save yourself further trouble.

 

How much oil are you going through ?
You may be looking for a problem that doesn't exist yet..

 

Understand that price quoted would be machine shop work only..
Heads would need to be removed etc..
Brian's figure would be a lot more realistic.

 

Correct, the $150/guide is after the heads are removed and dropped off at machine shop.

Removing heads in the car is not a fun process.

 

It is not that big an issue on the 12's. I have seen them go many times more miles than you have done and still not be symptomatic. Doing it now is like removing your appendix because it could in the future be a problem. Were you to bring it to me with the symptoms you have I'd turn you away. I have enough cars to fix that are really broken to take one apart that is perfectly fine. But then I know a lot of shops that do not let that bother them.

 

The above was very well explained.

 

You seem intent on changing your valve guides. I'm sure you'll find someone to do it...and take your money...

 

How about actually doing a leak-down test to see if you even have a problem? The bad "brass" valve guides were pretty rare on the 456M and "white smoke" is often water vapor. If you did have to replace the guides, using Ferrari sintered steel guides is a very expensive way to go. Good bronze guides are much less expensive and just as reliable and long-lived. Do the leak-down test first and come back to us for options on doing guides if they actually need doing. Likely better to send the heads to a really good machine shop than have your tech do them.

 

Speaking of Leak Down test, you generally want to see less than 10% variance between cylinders on one bank. If the smoke is from oil leaking past guides or piston rings, it should be a tint of blue and not purely white.

 

I would not worry about white smoke, I would worry only if the smoke is blue. Can you be sure that the smoke is blue?

 

White that dissipates is usually condensation. White that lingers and smells bad is antifreeze.

Many have trouble distinguishing between blue from oil and white from steam. I do not draw conclusions from descriptions, only personal observations.

 

If he is insistent on using the Ferrari sintered iron guides it will be more than that just for the guides.

 

Valid point about guide types. Once guides are replaced, the seats will need to be recut to match the new location of valve plus tip height. No guarantee replacing guides will not result in replacing other components too (such as valves). The snow ball can roll down hill fast once the engine is opened.

If you'd like more opinions, post a cold start video.

*I do recommend someone with expertise remove/install camshafts/heads/engine as you can easily bend a valve when re-installing camshafts if the engine is not clocked/positioned correctly.

 

Replacing 12k miles old valve guides... Just curious, how old are your tyres?

 

The guides on my 99 M GTA went bad at 17K miles.
Cost was around $10K.