Scott-
It is unlikely that the valves will be causing your problem, the valve
guides are the likely wear item that would cause high oil consumption. If
you are burning a lot of oil it's more likely than not the rings and/or
cylinder bore.
A quick check is as follows: Obtain a compression gage from your local
auto parts emporium. Remove the coil wire to prevent the engine from
starting. Start with any cylinder. Remove the plug, and insert the gauge.
Have a helper turn the engine over using the starter. Compare the
compression reading with book spec (on you engine I think you will be
looking for around 165PSI). Going on the assumption that the reading is
low, add a teaspoon of engine oil into the cylinder through the spark plug
hole and repeat. If the compression value rises appreciably, you can be
pretty damn sure that it's the rings/bore. If not, likely the valve guides.
I have seen people have good success in just replacing rings. You will
need to check the bore for ovalness, and a possible "step" in the upper
portion of the bore where the piston rings aren't wearing. Assuming things
aren't too bad, rings (and rod bearings while you're at it will probably
solve the problem.
If it's the head, plan on a complete head overhaul, with new guides,
hardened seats, and, possibly new vavles, although they might not be
absolutely required.
Regards,
Chris
At 06:35 PM 11/9/97 -0600, Der schwarze Buccaneer wrote:
> I've got a '72 MGB that uses oil as if it were gas. I tried
>manipulating the smog control devices on my own, to no avail, hoping it
>would be a quick temporary fix. Now I'm left with two possibilities -
>the rings or valves (or both). I've got a Haynes manual, but it doesn't
>really explain how to tell which is the likely problem, or how to test
>them. I am thinking about pulling the head off and just seeing what it
>looks like in there, but I figured I'd see if anyone has anything helpful
>to say before I do. What do I look for with worn rings or valves?
> I'm thinking about trying to replace the valves, springs, etc.,
>with new parts, grind the valve seats with paste, and replace just the
>rings on the pistons. I've never tinkered with pistons before, so I know
>nothing. How do I determine if oversized rings are needed? Can I expect
>some improvement by changing just the rings without a full rebuild (and
>w/o new pistons), granted, I don't know what the pistons look like, but
>assuming they are not ruined? I'm not looking for 'like new,' at the
>moment, I just want it to get better _oil_ mileage until I can afford to
>fully rebuild the engine (or replace it with a cheaper to maintain American
>one).
>
>
>
>
> -Scott Allen
> js-allen@students.uiuc.edu
>
> "At dawn we will face the greatest test of our resolve. But I
>say this: though starving, hunger will not weaken us; though diseased,
>illness will not cripple us, and though weary, exhaustion will not claim
>us. We can fight knowing that all true Reiklanders will forevermore
>honour our valiant gesture of defiance, even though our bodies be left to
>feed the beasts of carrion.
>
> Mind you...we could always surrender." -Rick Priestly's Siege
>
>
>
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