305 burning oil

[solve4x]

My '87 305 is burning oil....a lot a startup, a little at idle, lots when engine is revved.
Compression is good 140-180 on all cylinders..  Cyls 6&8 had badly oil fouled plugs.
No signs of head gasket leak(no oil in coolant, coolant in oil, not using up coolant).

Sounds like a need valve seals???
Only 92K on the truck and motor.  Has had several stints of sitting behind the house...last registered in '09.  Thinking about using it as a weekly driver, not wanting to dump tons into it at the moment.  Maybe valve seals and brakes would get me going again.

If I drove it downtown right now, I might cause an environmentalist protest march against old oil burning trucks!

[bd]

40 PSI is quite a spread between cylinders - they should all be within ~10% of one another.  180 PSI, if on 6 & 8, could be from all the oil in those cylinders.  140 PSI is slightly low and may be from normally worn rings.  Perform a wet/dry compression test.

Puffing blue smoke at start-up is caused by worn or brittle valve guide seals.  Best to service them with Teflon positive press-on seals in conjunction with the factory o-ring seals that are caged by the spring retainers.

Number 6 & 8 cylinders fouled with oil is caused by a deteriorated intake gasket.  Do you have an EGR valve?

If the exhaust is smokin' like a coal burner, you might want to go ahead and do something about it before Congress passes another law.   

[solve4x]

Not sure if I have an egr or not..if it came with one, I'm sure it's still there....is there something to check there?  Never an engine light on.

Thanks for the teflon seal tip...is there a special source for those?

I'll redo the compression test...has some consistency issues with the first couple of cylinders I did.  Had less than 10psi improvement with wet tests.

Sounds like replacing valve seals should lead to some major improvement.

[bd]

An '87 305 should have an EGR valve.  The EGR tends to concentrate heat in the intake manifold along the right side gasket rail at the center of the head, resulting in baked intake manifold gaskets, which allows oil to pass from the valley directly into the #6 and #8 intake ports - the result is oil fouled spark plugs in those two cylinders.  Non-EGR engines have a similar problem, but not as bad.  The only solution is to remove the intake and replace the gaskets.

You can use Felpro Viton Positive-Stop valve stem seals, which are effective and 'do not require machining' of the valve guide boss, or you can use Teflon Positive-Stop valve stem seals that 'require machining' of the valve guide boss.  For an otherwise stock configuration, the Viton seals are preferred and cost less to install.

So, the bottom line is don't replace just the valve stem seals and expect your oil consumption problems to be solved.  You'll need to replace the intake gaskets, as well.

[solve4x]

Good advice!
Thanks bd

[zieg85]

Good advice!
Thanks bd

Awesome advice, these are the little nuggets of info I yearn to pick up.  I had a 305, that did just like you described.  It ran perfect, just drank a qt. of oil every 3-400 miles so I changed the engine.  I can't help but think this advice would have helped me back then...

[solve4x]

Zieg, you are so right!
I have asked dozens of people who have given me dozens of answers...mostly wrong guesses...no replacement for real experience from those willing to share.  This is a great forum.

[Irish_Alley]

you can learn a lot just by sitting back and reading what others are saying and their experience with certain problems. or you could just stalk bd and learn most of it lol

[PromiseKeeper]

Good advice!
Thanks bd

Awesome advice, these are the little nuggets of info I yearn to pick up.  I had a 305, that did just like you described.  It ran perfect, just drank a qt. of oil every 3-400 miles so I changed the engine.  I can't help but think this advice would have helped me back then...

me too! Currently buttoning up a 305 engine swap that sounded very similar. Bought a 305 that has 50,000 on it....hope it turns out to be a good one!

[solve4x]

UPDATE--
The old grey mare is back on the road today!
All new brakes and new intake manifold gasket....plus lots of little stuff
The intake gasket seems to have fixed the burning oil while idling problem.  I do still get a puff of beautiful blue smoke at start up and a blue streak when I accelerate.  The valve seals might be next on the list.

 
This was a big project for someone who has never attempted any engine mechanics.
Thanks again for the great advice.   

[bd]

Thanks for the update and congrats on the repairs!!!  Now she goes!  ...and stops, to boot!  What a Great combination!   

[frotosride]

UPDATE--
This was a big project for someone who has never attempted any engine mechanics.
Thanks again for the great advice.   

Stick around here long enough and you will be surprised what you will have the confidence to tear into and fix instead of just buying a a new one...and the pride and self worth of knowing you did it is priceless...

[solve4x]

Well, valve seal week has arrived.  Got the tools and parts lined up and did the first cylinder.
Here's my question.  I bought the seals listed above from Summit.  They look different  from those I see on videos.

When I got into the job ,I found that the exhaust seal is bigger than the intake seal...my new seal fits into the exhaust seal I took off.  After 30 minutes on the phone with Summit, I'm still not sure I've got the right seals.  The new ones are all the same size.

Any thoughts...Remember it is a 87 R10 305, sometimes different from the C10's.

Knowledge from experience appreciated!
Scott

 

[solve4x]

A picture tells the story.
Left to right: old exhaust, old intake, new seal, new Felpro Viton seal

So I'm thinking of going with the new seals on all 16.
Any wisdom?
Scott

[bd]

IMHO, there are three checks for you to determine fitment.

1)  Does the Felpro SS72861 ("Viton") seal fit both the intake and exhaust valve stems?

2)  Does the "Viton" seal snugly fit both the intake and exhaust valve guide bosses?

3)  Is there adequate clearance between the valve spring retainers and the valve guide bosses with the valves fully open for the seals to fit without interference?  This is highly unlikely to be an issue, but worth inspecting on the first valve pair resealed.

If the answer is "Yes" to all three questions, use the "Viton" seals.  If "No" to either question 1) or 2), but "Yes" to 3), use Felpro SS72527 on the intake positions and Felpro SS72526 on the exhaust positions.  Alternatively, you should be able to use the Felpro SS72527, which I believe are also Viton rubber, in all intake and exhaust positions. 

In general, on a stock to mildly modified SBC engine, the exhaust won't draw nearly the amount of oil past the guides as the intake.  Hence, umbrella style seals are satisfactory in the exhaust positions if the valve guides are serviceable.  However, the positive oil seal offered by the SS72861 and SS72527 should provide improved advantage for new-to-mildly worn and performance engines.  On the other hand, if the valve guides are worn out, the excess wear will need to be corrected for a satisfactory outcome. 

Whichever stem seals you select, you should also replace the square-cut rubber o-rings that sandwich between the valve stems and the spring retainers (supplied with both the SS72526 and SS72527 seal kits).  Good luck on your project.