wuld bad valve seals cause oil to burn- 1qt every 150mi? im heading towards the plenum, u?

 

A stuck PCV valve will do that, as will severely thrashed valve guide boots/seals.

 

is there anyway to diagnose bad valve seals?

 

If it blows smoke at startup, chances are good valve seals are bad.

 

no smoke on startup. it mainly smokes when you start gettn into the gas a bit. its not noticeable in the rearview mirror but if i rev it in place ill get a cloud of smoke behind me

 

a guy at a machine shop quotes 3-400 for valve seals but said even if the compression is good the rings could still be bad, is that true? he said with 170k its time for a rebuild...is he just tryn to line his pockets or what? i could attempt the valve seals but idk if i want to or not...

 

Valve seals really aren't that bad to do, IF you have the neat little tool to compress the springs ON the engine. (the other one requires removing the heads.... don't wanna go there.) Having compressed air available helps a lot too, but, isn't an absolute requirement. Can just stuff rope into the spark plug hole to keep the valve from dropping into the cylinder. (something you do NOT want to happen.......) Basically, pull all the rocker arms/sparkplugs, run a bunch of rope into a cylinder, turn the crank till the rope is compressed against the valves (combustion chamber...) use the nifty little tool to compress the springs, pull the keepers and retainer, pull the spring off, change the seals, and then reverse the process to put the spring/retainer/keepers back on. Do both valves on one cylinder, move on to the next.

However, given that you see more smoke when 'getting on it'.... that doesn't sound like valve seals is the major issue....... they may be contributing though....

You are pushing awful close to 'bad ring' territory though...... the pressure jump from wet to dry shouldn't be much over 20%.... some of your results exceed that. (and some by a good stretch....) so that becomes questionable..... for a high mileage engine though.... not that bad. Not bad enough to condemn it at least.

And then of course.... compression test tells us nothing about the condition of the oil control rings. Only real way to check those, is to tear the engine down, and have a look. If you are going to go that far just to check though, might just as well hone the cylinders out, and put in NEW rings......

The volume of oil you are burning though, really suggests blown plenum. (I am in the same boat...... as soon as I have a second vehicle up and running, that is going to become the task of the day.) My plenum is most certainly blown, and I run through a quart every 100 miles or so. Still no smoke out the pipe unless I step hard on the go pedal....... I have not done the vacuum test on mine. The story was readily apparent just looking down the throttle bore, and seeing pooled oil. Ooops.

 

#8 is way low.you need to do a leak down on 8 and 7.thats the only way to know were your loss is coming from and go from there.those results dry/wet id say rings are shot and a leak down is in order.for the plenum you need to really look at the back of the manifold for oil pooling.removing tb and shinning a light works good or mechanics mirror/light.the vac test only finds large leaks.

 

im not too hesistant to do valve seals by myself, however i thot id get some prices and oppinions from a few local machine shops to see if it was worth the hassle of doing it myself. however the opinions were likely formulated in their favor...duh!

someone on this forum said u can just positition each cylinder to tdc b4 you do the valves for that cylinder and that will limit the valve to drop only about an inch, is that true?

haynes manual says if the pressure increases after adding oil to the cylinder "the rings are definitely worn, if the pressure does not increse significantly the leakage is occuring at the valves or head gasket". so like your saying the wet test points to rings... however the directions on the compression tester say only to do a wet test if the readings are low, according to the haynes manual "no less than 100 psi and 40 psi dif amng cylinders" id say my readings fall into that category i guess. i may have put too much oil in the cylinders...not sure? also take into account that it took several strokes for the compression to reach its peak, the build was very gradual for 1 or 2 cylinders.

as far as plenum goes, im confused! i passed the test in the tsb as you are aware of. however i have wild vents and can not find any vac leaks. i burn 1qt/ 100mi like you do...ughh!

so your saying rings or valve seals wouldnt burn that much oil? just my luck it would be a combo of all 3! haha but beleive me id love to throw an airgap on it and have it run like a champ, but with 176k on it maybe its time for some new blood, idk

 

according to the haynes manual no less than 100 psi so it actually seems to me to be on point, why do you say that? i burn 1qt per 100 mi, does that imply that its a large leak or no?