Valve stem seals info needed and is it worth while in my case?

[MikeB]

truck has had a long history of giving a puff of blue at start up.

Classic symptom of oil running down the valve stem past the valve guide. After engine shutoff and a few hours of sitting, oil pools on the back side of the valve or top of piston. It then burns off in the first few seconds after startup. Umbrella seals are cheap and work well to resolve this problem. However, if #7 cylinder is fouling plugs you may have a bigger problem.

 

[shiftpro]

All new valve seals on a set of 781s or 049s... hehe.

 

[Catbox]

I bought this Proform tool and set my 18 year old at the time on the task of changing all of the valve stem seals on our Suburban daily driver. It may have taken him 3 hours from start to finish.

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[SirRobyn0]

Classic symptom of oil running down the valve stem past the valve guide. After engine shutoff and a few hours of sitting, oil pools on the back side of the valve or top of piston. It then burns off in the first few seconds after startup. Umbrella seals are cheap and work well to resolve this problem. However, if #7 cylinder is fouling plugs you may have a bigger problem.

I agree. I remember seeing trucks w/350s that would foul a plug or two due to valve seals back in the day, but not in 100 miles, and the after hill misfire seems odd.

I think in the end there are a lot of could be's and what if's in regards to my issues, I'll start with #7 seals and see what happens. If I still have issues I will have to decide how much I feel is worthwhile both time and effort on the ol 305.

I bought this Proform tool and set my 18 year old at the time on the task of changing all of the valve stem seals on our Suburban daily driver. It may have taken him 3 hours from start to finish.

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Cool appreciate the tip on the tool and time frame info. As I said I'm not engine builder, but have been in repair since the 90's, IDK what I will do for a spring compressor, I may barrow one. I might look at Harbor Frieght, but one thing I won't do is buy one off a tool truck for how knows how much more, that will likely only see the light of day a few times.

 

[Catbox]

I was able to cheat a bit with my tool purchase, Max worked for an auto parts store that carried the brand tool.
So I used his store discount.

 

[MikeB]

Not as cool but works fine!

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[SirRobyn0]

Not as cool but works fine!

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$8.99 I'm ordering one. That I can get behind for limited use.

 

[SirRobyn0]

Ok, umbrella seals will be here on Wednesday, as will a tool like the one Mike has. The umbrella seals I've ordered are FEL-PRO SS PN# 10058 catalog indicates they are rubber and good for intake and exhaust. So next question and I fully expect that I will get different opinions on this, but still I'd like to hear them. What about the factory seals? Should I replace those as well? or simply remove whatever is left of them?

I think I'm good to go on what to do and how to do it. Thanks for the help ya'll.

 

[85 Squarebody76]

Not as cool but works fine!

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That tool works great... I used one for 25 years... Broke the ceramic off a plug and welded a male QD fitting on it to charge the cylinder and hold the valve closed to put the umbrella seal on...

 

[75gmck25]

Just a suggestion - the inexpensive tool should work fine for stock springs, but if you ever buy upgraded performance heads you want the better spring compressor that was first posted.

I bought new Blueprint heads with dual springs and during final setup I wanted to swap in light springs before degreeing the cam. I tried borrowing the cheap spring removal tool from Autozone, but there was no simple way to get it to compress both springs and get the retainer off.

I finally bought the better spring compressor and it was like night and day easy. You just screw it on the stud and push the lever down to compress the spring, and it overcenters and the lever stays down. Then you take all the time you need (with both hands free) to get the retainers off.

 

[Grit dog]

@SirRobyn0
Don’t recall if you posted this, but have you checked compression on #7?
If it’s fouling plugs due to low compression and oil getting by the rings, replacing valve seals seems an effort of diminishing returns.
If I’m thinking right, anyway.

 

[SirRobyn0]

@75gmck25 I read reviews on the cheaper tool last night and did see that they are not really all that great. I might see if any of the parts stores can loan me a better tool. Look I'm a tight *** and I don't wanna spend $60 on a tool to do two valves, but also since I'm a first timer I don't wanna waste a bunch of time mucking around with a tool that's being difficult, so we'll see what happens.

@Grit dog IDK in which thread I posted this but I have done a full comp test since this all started happening. Without checking my notes I don't recall the specific readings but they were all just fine. Of course a good compression test is a good sign, but it is possible to have a damaged oil control ring, but still have good compression ring, it's not normal but can happen. My bigger concern isn't the plug fouling and misfiring that occurs after it fouls, but the misfire that occurs after a hard pull up hill. What is that from, oil past the guide temporarily causing a mis? could be... A weak spring? maybe.... Seat? possible. IDK I've got to start somewhere, cause it doesn't show on a comp test, and it's not a tune up issue, so maybe it is all just oil control. We shall see.

 

[SirRobyn0]

@75gmck25 Nevermind on my last message, I just canceled my old order and ordered the proform. Looks like an easier tool for me to work with anyway.

 

[Grit dog]

Ok just a thought. I’m tracking now.

 

[SirRobyn0]

Ok, tools and parts are all here, so this is my plan and costs so far.
Fel-pro umbrella seals $19.99
Fel-pro valve stem seals (the oring like things) $14.99
Proform valve spring tool $50.00
16 Comp cams OE pressure spring (pretty close anyway) $40.00
Total: $124.00
Valve cover gaskets free out of my stash.

So I've read a lot about whether a guy should run, reuse, or get rid of the original oring style stem seal, and it seems there are a lot of opinions on that, but I figure at high mileage I don't think it could hurt to run both.

Someone I know in person has expressed that the idle mis after a hard run could be a weak spring. His reasoning is that it's doing it at high RPM to, but I'm not noticing it because the engine is whipping over quickly, and at idle, a 1/2 cylinder mis is noticeable until the head temps drop enough for the weak spring to seal. And if I install a full set of springs I've done every thing I can without pulling the heads, and I'll be out a couple hours of time and $124 to try this. I also understand the idea that it could be preignition, and that's a very valid idea as well I think.

But what am I actually going to do? Well that's going to depend on what happens when I open it up and how much time I have. I'm going to start with #7 and it will get at least the seals. If it looks like I'll only be doing #7 I'll probably skip the springs so I can send them back. If I've got time and it's going all right then I'll work down the line and do seals and springs all the way around.

So I'll be doing this on the farm, there is no where to work inside and the weather forecast is not promising, so I might have to pull it under a popup tent or something to at least keep the engine area dry. You seen the forecast @Grit dog doesn't it sound like a good weekend to work outside under the hood. Oh, and I'll need to put a starter in the Jeep before I get to do the square.