lowkey235

I am concerned about blow by I get a lot of white smoke from my valve cover breather, hardly any from exhaust, I havent done a compression test yet. my fear is piston rings, do these symptoms seem right? I will do the compression test when I get the tools this week, dry and wet. off hand anyone know what cylider pressures i should be looking for, its a high mileage engine and I know it needs freshend but was hoping not to jump in all at once.

Erinyes

Main thing to look for (as I'm sure you know) is consistency between cylinders, within say 5%. That being said, as long as you're getting maybe 120 psi or more I'd be satisfied. For diagnostics, it will help quite a bit to know the details of the engine and the results of the wet/dry tests.

oldcutlass

Also make sure your pcv is functioning properly.

Old Olds Fan

either take off the breather cap and look for moisture or better yet the value cover (actual water droplets and white emulsified oil) if so you've blown a head gskt., or broken the block or heads, possibly a water leak from the intake crossover but it would have to be getting through the valley pan, you're looking for how water got in you crank case. Frequently you can drain the oil and not see anything (very small leak) Though there will be mud in the pan, stuck to the bottom.

BILL DEMMER

iirc, the factory says a max. of 10% variation is allowable.


bill

lowkey235

Thanks for the information, I hope to do the compression test this weekend, about the wet test...just a couple of ounces of motor oil in the sparkplug hole how long does it take to get rid of oil in the cylinders?

Erinyes

I could be wrong, but I always thought just two or three squirts of oil. A couple ounces per cylinder seems excessive.

BILL DEMMER

wasn't the amount of oil to use like a teaspoon? you only want enough to coat the ring to wall surface-you don't want to hydro-lock your motor.


bill

MDchanic

A couple of ounces will bend a rod.

- Eric

lowkey235

compression test is done, i used a capfull of oil for the wet test. this was done with a harbor freight gauge so take with a grain of salt I guess. cylinder#, dry/wet
1,30/40 2,90/150 3,120/120 4,70/135 5,88/120 6,120/145 7,30/40 8,120/150 I wasnt sure how long to crank the engine so I dont know if these are accurate IMAG0301.jpg

oldcutlass

You have issues with #1 and 7. I crank the engine until the gauge won't go any higher.

From your pic, you have some issues beyond a normal old age engine.

lowkey235

oops i did it on a cold engine, I might retest saturday after I warm it up, looks like I have a rebuild coming in the near future, now the debate is rebuild the 425 or look for a 455 core. ballpark how much to re ring the pistons? I can pull the heads and such but have no facilities to pull the engine.

BILL DEMMER

jmo, you need a complete rebuild. it looks like your valves are pretty weak. i'd rebuild the 425 and skip a 455.


bill

oldcutlass

x2 on rebuilding the 425.

lowkey235

I am new to this, is $3000 a good ballpark to rebuild the engine. parts and labor, I know there is no telling how much machine work until its apart, but I think a rebuild is above my skill level so I will have to get it done at a shop.

oldcutlass

$3-5000 with a shop. It all depends on how much machine work and are needed.

442rocketdave

You may pull it apart and find your ringlands broken, it happens to the pistons after years of use and with the blow by and problems in #1 and #7 that could be the culprit.