Front Seal Unazzed
 

Anybody ever seen a front seal push out of the timing chain cover for no apparent reason? The whole seal, metal and all.

A little too much blowby?

They're brand new motors, 540's. About 75 hours, breathers in both valve cover. However, on a couple of occasions each of them have pushed the dipsticks out about a half inch.

Doesn't use any oil or drip from the breather.

i agree with mild,to much crankcase pressure can cause that.

Long story short. Rebuilt one motor put new valve cover breathers on both, two per motor. After long hard runs old motor lost oil out of rear main seal. Pulled old motor replaced seal, oil leak not so bad now and both dipsticks are up two inches. WTF!! Took the foam out of the new breathers and that fixed my problem.Good luck and be safe.

Are these motors boosted or naturally aspirated?

There is hardly any blow by at the valve covers. Are you talking pressure just from the displacement of the pistons? Why the hell would it push out a driven in seal before it could pop a valve cover breather out of its grommet, which on my motors just happen to fit loosely?

NA Matt.

Since you mentioned this the dipsticks have only been pushed out when the breathers have a few hours on them since being rinsed with Avgas.

Thinking about it now, the only way the crankcase pressure gets to the rocker area is the pushrod holes which isn't very much after they're filled with pushrods so yea, I can see that now. Same with the dipstick, not a very large area. Take into consideration the area of the front seal and I guess it becomes the easiest relief valve.

What about a non filtered vent line from the valve covers to the flame arrestors? Hmmm, I'm pretty sure that's the way they were from the factory. Probably created my problem with the K&N valve cover vents.

Thats why it needs, IMO.

Something to help suck out the crankcase pressure.

Hell, stock carbed HP500's have a vent line from each valve cover going up to the flame arrestor from the factory.

I don't think it'll do much sucking but it'll be a free flowing vent unable to become restricted by an oil soaked breather.

Those k/n breathers suck . It could very well be you need more crankcase venting.

Oh it will suck some of the pressure out for sure.

Go out for a cruise, pop the hatch enough to get your hands on the flame arrestors and see how much it sucks your hands at 3500 RPM's.

Also dont do anything to try to keep the dip stick from blowing out. If that gets stuck in, the pressure will blow out somewhere else, like that gasket again.

That's how my blower motors are set up, two 3/4" hoses per motor from non filtered vent to flame arrestor.

I'm pretty sure getting rid of them will fix my problem because the only time my dipsticks were pushed out is when I had a few hours since I'd rinsed the oil out of them. I just never put two and two together without some additional input. When you put all the pieces together, Oil soaked breathers, (which is basically a clogged vent given the volume of air the pistons are displacing), dipsticks pushed out, The front seal would logically be the weakest relief valve. And one more thing I just thought of, last weekend one of my breathers was in the bilge when I put the boat on the trailer, but it wasn't the motor that pushed the front seal out. I'll update after I run with some open tubing from the valve covers the the flame arrestors but I believe that will fix all issues. QUESTION: What effect if any would elevated crankcase pressure have on oil presssure?

Agreed sir.

Wrong seal?

Nah, it was the right seal.

The pressure in the valve cover and the pan will be equal. Also we used to hook springs over the dipsticks to keep them from walking themselves out. I don't think crankcase pressure is the problem.

Used to see this all the time. I assume they are stamped timing covers? Not genuine GM? Or maybe even genuine. Take a look and I bet you will see the bore in the cover has a little taper to it.

Solved it by wire brushing a new seal to remove whatever coating was on it, then install using Loctite Retaining Compound. Use an arbor press and support the cover properly so it goes in straight.

If you do the math on the actual surface area of the seal exposed to pressure it's not very much. You have to subtract the area occupied by the crank. And yes I think you would pop a breather out before anything else. It's been a while but I think 2-3 CFM is a about what the blow by should be. And you cannot even feel that coming out the breathers.

Yea, stock GM valve covers. And that's what is coming out the valve covers, basically nothing, at idle that is. I'll clean all the coating off and use the green retaining Loctite but probably plan on destroying the TC cover if I ever have to replace the seal, that stuff is bad news. If it's not pressure then why are my dipsticks being pushed out only when my VC breathers are saturated?

It's like they are vibrating out because there's no oil residue anywhere near the tube.

Yep, they are vibrating out. You could always try a run without one and run a hose from the dipstick tube up to a pressure gauge at the dash just to take a look and see what's really there for pressure.

If you ever have to remove the seal use a heat gun - softens the LT real nice :)

I may be wrong but I don't think you'd get an accurate reading of crankcase pressure at the dipstick tube because its submerged in oil. And you'd have to have a high dollar gauge to read pressure that low I'd think, but again I may be full of sh!t. I have been before, on more than one occasion actually.
Dude, I used that LT to take up slack in a worn pillar block bearing some years ago. Last I knew it was still in service.

I use a small punch and put a few punch marks around the front seal in the cover to help tighten it up a bit. If I get a front seal that has the sealant around it I wipe it with lacquer thinner to activate the sealant and they seam to hold better. Never silicone a seal in that has the sealant on the seal. Been there done that they don't work together. I have the cheap K&N breathers on my 632 and at 6000 rpm not a drop of oil out of the motor. Breathers are out of the box with nothing stuffed inside. Now my aluminum power steering reservoir that's another story. Once it gets warm my bildge looks like murder.

Yep, the LT is amazing. Better living through chemistry :)

As far as the pressure, yes you are correct it should be almost un-measurable as long as there are breathers. The gauge will read whatever pressure there is no problem. The effect of the oil in the dipstick is 0 for all practical purposes as the pressure is the same at all points as long as there is no flow.

So - the pressure in the crankcase is most likely not the problem for either the seal or the dipstick. Checking it with a gauge would prove that if there is any doubt.

assuming this is a gen VI BB the front seal/cover has no inner stop(pain in the ass) I would try a GM seal and use some RTV around the outer edge...it's also very hard to try to put the seal in without the tool..good luck, Rob

It's a Gen IV, should have mentioned that up front.

I had the same exact problem. Got a national seal from Teague. Scuffed it up and put loctite around the seal and installed it. No problems.

Hopefully this and changing my venting will prevent this from happening again. ^