advice on changing vale stem seals

[int77345]

i have an original 345 in my scout II. it started smoking last year, but only out of the right exhaust pipe, and only at idle, and only when the engine is around normal operating temperature. any engine speed above idle and the smoke stops. on a hot summer days last year the smoke would get pretty bad.

im thinking the valve stem seals are causing the smoke, or at least playing a large role in it. iv traced the problem to #6 cylinder. it is the only cylinder with a black oil filled spark plug, all other cylinders on good. putting a bore scope down #6 spark plug hole, and the piston is covered in oil, and carbon looking burnt oil .

questions---
1. what kind of valve seal is better ? the umbrella ones or the O ring type ?
2. installing the umbrella type does it push all the way down the valve stem ?
3. when removing the rocker arm rail assembly, does the engine need to be at TDC ? or does that matter ?
4. what kind of sealing do the rocker arm rail assembly bolts need ? none or some ? lock tite ? permetex ?

ill post up pictures as i go, it will be interesting to see what such a high mileage and old engine will look like under the valve covers.

 

[FDChappie]

Valve stem seal problems are usually smoke on startup, what you describe sounds like rings. Sorry.

 

[int77345]

oh it defiantly could be rings, honestly the engine needs to be rebuilt/replaced.

valve stem seals, seems to be the easiest to try. that's were im starting first

 

[FDChappie]

Ok,
1. the "best" type of seal are the positive seals that fit over the top of the valve guide.
2. Yes
3. Doesn't matter. Remove bolts a little at a time and evenly.
4. Permatex #2 is good.
You might want to do a compression check first though, so you don't waste time.

 

[int77345]

parts ordered......

"You might want to do a compression check first though, so you don't waste time."---- yes that is true
the engine runs very smooth, and i can lug it down to 400 RPM no jerking around, if the compressions are low, they are all evenly low.

 

[Winchested]

I used the orange valve stem seals. Sealed power or enginetech I believe. worked well. Just a pain to swap with the heads on.

However it's usually only cyls 7 and 8 that have the issues. Due to the oil pooling in the back of heads.

Yup sounds like you've got 1 cyl with bad oil rings.

 

[int77345]

im really rooting for bad valve seals.

so bad rings/oil control ring. ----ever seen one that only lets oil past at idle ? any engine speed above idle, even WOT there is no smoke...

 

[int77345]

Ok,
1. the "best" type of seal are the positive seals that fit over the top of the valve guide.
2. Yes
3. Doesn't matter. Remove bolts a little at a time and evenly.
4. Permatex #2 is good.
You might want to do a compression check first though, so you don't waste time.

question........ do you seal every bolt ? looks like oil goes up one of the bolts and in to the rail. does the "oil" bolt get the permatex also ?

47 year old motor was very clean inside. first time it has ever been opened.

 

[FDChappie]

Just put sealant on the bolts that go into the intake runners. Looks like that engine has had regular oil changes.

 

[Robert Kenney]

A few comments,
1) While working on a particular cylinder's valves, place that piston at TDC, this makes sure the valve wont drop into the cylinder. The other trick is feeding 1/4" clean rope into each cylinder and manually moving the piston up to trap the rope against the valves at or close to TDC for each set of valves.
2) When you remove the valve spring retainers, look at the orings if installed and see if they are broken that's likely the oil burner.
3) Umbrella's are the easiest and most effective with out machining the guide tops. The positive or PC seals all require that you machine the guide ends to accept them.
4) Umbrellas will ride up and down with the valve and close to the underside of the retainer. Make sure there is enough space for them at full lift between the guide and retainer.

 

[Robert Kenney]

im really rooting for bad valve seals.

so bad rings/oil control ring. ----ever seen one that only lets oil past at idle ? any engine speed above idle, even WOT there is no smoke...

No on rings causing oil burning only at idle. Traditionally oil burning under load is rings.

 

[int77345]

this was the intake valve seal on #6 --- the spark plug with the most oil. --- this broken up old umbrella seal must be most of the problem with that cylinder -----the exhaust umbrella was still in tack

 

[FDChappie]

That's pretty crispy.

 

[Robert Kenney]

this was the intake valve seal on #6 --- the spark plug with the most oil. --- this broken up old umbrella seal must be most of the problem with that cylinder -----the exhaust umbrella was still in tack

View attachment 40219View attachment 40220View attachment 40221View attachment 40222

That’ll do it.

 

[int77345]

almost reassemble time, ---- the service manual states 14-16 foot pounds for all 5/16 inch bolts. am i reading that correctly ? docent seem tight enough for oil soaked moving parts.....

 

[jeff campbell]

almost reassemble time, ---- the service manual states 14-16 foot pounds for all 5/16 inch bolts. am i reading that correctly ? docent seem tight enough for oil soaked moving parts.....

That's correct

 

[Robert Kenney]

Those diecast stands are the limiting factor for torque.

 

[int77345]

im surprised it stays together ill bust out the hardly ever used Inch pound torque wrench

 

[Robert Kenney]

im surprised it stays together ill bust out the hardly ever used Inch pound torque wrench

It does, but with hundreds of billions of miles on the SV and half SV family of engines, it works well.

 

[jeff campbell]

They do quite well for how spindly they are,but it's all that's needed ! Them old fvkers new what was happening. They did well.