: valve seals



Crown Vic Owner
12-05-07, 11:58 PM
Ok, its not because of my car, its because im curious about the northstar


HOW rare is it for valve seals to become leaky in these cars?

Is there any way to prevent it?

Submariner409
12-06-07, 09:18 AM
Valve stem seals are generally good for the life of a given stock engine. Some engines and rebuilds using aggressive cams and rocker arm (not cam follower) ratios will tend to distort the seal due to the valve stem wiggling in the guide.

That said, the N* is not any better or worse than other engines when it comes to valve stem seal life, and there is or are no magic potions to extend their life.

Considering the nearly total lack of lubrication (by engineering design) in the valve stem area, its a wonder the seals work at all. BUT if they didn't, an engine would begin burning oil at an astonishing rate as the intake valves sucked the oil out of the valve covers: don't forget that the entire intake side past the TB butterfly operates at 16"-22" of vacuum nearly 98% of your driving time, so the intake ports and valves operate in that vacuum.

Crown Vic Owner
12-06-07, 11:46 AM
so, in a nutcase, thinner oil would be better for the valve seals as more oil would go into the valvetrain?
Its just one thing i have never understood in OHC engines with the seals,

devilleconcours100
12-06-07, 12:39 PM
Crown Vic Owner, I have a 94 Lincoln Town Car, with the 4.6 OHC motor. It needs a new set of valve stem seals, and burns a quart every 750 miles (4qt of 5W30, and 1qt of Lucas Oil Stabilizer) or so. I've got 152k on her, and other than blue smoke on acceleration, I see no difference in performance than before, although, I change plugs now every 15k miles (Autolite coppers). On the 94 Concours N*, I believe I have a oil burning issue, due to the small amounts of blue smoke on accel that I've seen for a while, but its always leaked, so I'm not worrying about it.

Dave

Crown Vic Owner
12-06-07, 12:47 PM
lol, ford 4.6s are KNOWN for doing this


i am tearing apart mine soon to fix this myself

AJxtcman
12-06-07, 02:58 PM
I have never seen 1 bad seal. I have seen several bad guides, but not a wear problem or a guide to stem clearance problem. I have seen a few guides that have been gouged on the out side when installed.

devilleconcours100
12-06-07, 03:25 PM
So, a northstar that burns significant amounts of oil (i.e. blue smoke comes out of the pipes on accel), would be caused by what? Bad valve guides? Piston ring issues?

Dave

Crown Vic Owner
12-06-07, 03:39 PM
piston ring issues i assume.

Also, how often are the guides known for wearing out

Ranger
12-06-07, 09:31 PM
So, a northstar that burns significant amounts of oil (i.e. blue smoke comes out of the pipes on accel), would be caused by what? Bad valve guides? Piston ring issues?

Dave

Stuck piston rings. It needs to be taken out and flogged.

devilleconcours100
12-06-07, 11:07 PM
By saying "flogged" I presume you mean extended periods of WOT. ;)

Dave

Crown Vic Owner
12-06-07, 11:19 PM
Stuck piston rings. It needs to be taken out and flogged.
how much abuse the the 480s take?


I always get worried about overheating and ballooning the T/C and trans. If i could access trans temp and all that good stuff, i think i would be a bit calmer.

Ill admit it, i am freaking hard on cars, but the issue comes into play that i dont drive my damn car, maybe 500 miles in the last few months.

Submariner409
12-06-07, 11:24 PM
As regards post #3, the valve operating mechanism, OHV, SOHC, DOHC, F-head, has nothing to do with whether or not the engine uses valve stem seals. There is a definite metered amount of oil which reaches the rocker/valve stem tip area, and changing viscosity has absolutely no bearing on how much oil gets there. The valve seal is engineered to allow a molecular film of oil down the stem for lubrication. Many engines use iron valve guides and somewhat "looser" seals, and those tend to have a bit more oil consumption than those which use bronze guides, which tend to be more self-lubricating, and therefore can tolerate a tighter stem seal. You would be flat amazed at just how little oil is allowed to reach the rocker/valve areas in a NASCAR engine, and the magic tricks involved in getting that little bit of oil OUT of the valve cover area. Don't forget that most of that pricey oil is used for cooling all that rotating machinery, not greasing it.

Crown Vic Owner
12-06-07, 11:56 PM
Sub, i have never seen pushrod engines eat through valve seals as bad as OHC engines.

Maybe its because i dont know that much about the pushrod engines, but every time you hear about valve seals going, its usaully a pre modern OHC engine doing it.


Maybe its becuase all of the engines are getting older now, or they used shitty seal material at the time.

Again, i am throwing this idea out, not stating it as a fact or anything.

Submariner409
12-07-07, 12:08 AM
Yo !!! Not a problem. To make matters worse, the various seals made by several manufacturers all have different wear and sealing qualities, so it's a real crapshoot what to put in what, when, and on whose valves........... Seriously !!!!

I haven't seen the application lately, but there used to be a valve stem "seal" that compressed under the keeper locks, like an O-ring, not the slip-on top hat type. They were leaky bastards.........

Crown Vic Owner
12-07-07, 12:17 AM
Yo !!! Not a problem. To make matters worse, the various seals made by several manufacturers all have different wear and sealing qualities, so it's a real crapshoot what to put in what, when, and on whose valves........... Seriously !!!!

I haven't seen the application lately, but there used to be a valve stem "seal" that compressed under the keeper locks, like an O-ring, not the slip-on top hat type. They were leaky bastards.........
i agree


I am having the same issue with the ford mod motor now, and im starting to think just let the SOB run to death and die of detonation because of the oil.


I am looking at seals, and i know there not easy to replace, so i figure i may as well do cams when im in there, than, i ts like, should i do this, that, this, replace HGs and go to PI heads, go with a PI intake, bla bla bla.

The cadillac northstar seems like a well built motor, i just am worried at times the things going to poop out on me or start the common ford issues, although i have been reassured on some things 100000 times.

Ranger
12-07-07, 01:20 AM
By saying "flogged" I presume you mean extended periods of WOT.
Not "extended" periods. Just a quick WOT burst to 70 MPH or so in 2nd gear and then let it back down to 50 or so.


how much abuse the the 480s take?
Quite a bit from what our old Guru said. That is evidenced by the small amount of trans problems we see here.

Crown Vic Owner
12-07-07, 03:06 AM
Not "extended" periods. Just a quick WOT burst to 70 MPH or so in 2nd gear and then let it back down to 50 or so.


Quite a bit from what our old Guru said. That is evidenced by the small amount of trans problems we see here.

it seems like fluid changes are essential to these transmissions, am i not right?

Submariner409
12-07-07, 10:43 AM
You can probably do the valve stem seals right in the Ford. A bit of juggling, but there are adaptors made to pressurize a cylinder with shop air, which holds the valves shut (at TDC) which allows you to compress the spring, pull the retainer, locks, and seal, and replace whatever you want. IF it's an OHC, you can change the cam, too.....if it's OHV, tough call, probably have to drop the oil pan and pull the timing cover off the front of the engine in order to remove the cam.

Crown Vic Owner
12-07-07, 11:53 AM
its a modular


its OHC

I have access to the shop, but the issue is, i may go with preformance improved heads or even 4 valve heads as its not that bad of a swap.


Ugh, decisions.

Ranger
12-07-07, 07:01 PM
it seems like fluid changes are essential to these transmissions, am i not right?
Actually, the owners manual says the fluid is good for life under "normal" driving conditions. I change it at 100K regardless.

Crown Vic Owner
12-07-07, 09:40 PM
hah, i change mine yearly or every 6 months, along with coolant and whatever else needs to be changed