Advice on Replacing Valve Seals

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shorty73
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Advice on Replacing Valve Seals

Post by shorty73 »

Hi everyone. I need some advice on an oil burning problem. I just got a '68 F250 with a 360 automatic (been wanting an old truck to work on for ahwile now). It was a flip that had been sitting for a long time. It was running but not derivable and I had it towed home. After dealing with some stuck valves and bent pushrods from old gas, I’m getting a lot (I mean lot) of smoke when it warms up. I had disassembled and cleaned up the driver side rocker assembly when I had things apart and now the flow of oil is huge (wish I’d left them alone at this point but it was pretty nasty under the valve cover). I’m thinking the valve seals are bad and plan to replace them. My question is, if the guides are also worn, will replacing the seals stop the oil burning? I have read there are different types of seals, which style should I use?

I’ve never done much with engine internals so this is new territory for me. I plan to replace seals with the heads on the truck. Any suggestions would be appreciated, but I mainly want to find out if new seals will fix the smoking even if the guides are worn. Odometer reads 94k , so probably 194K. Compression on the three cylinders showing oil fouling on the plugs (6, 7, and eight) is around 140 (other cylinders ranged from 118 to 148). And can I use an air compressor to keep the valves in place or will I be using the rope method due to miles?

Thanks in advance.
1968 F250 2wd 360/c6 PS PB (disc) Camper Special
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shorty73
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Re: Advice on Replacing Valve Seals

Post by shorty73 »

Added a quart of Rislone and that seemed to take care of it. As long as I don't have to stop for oil and add a quart of gas I'm good with it.
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sargentrs
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Re: Advice on Replacing Valve Seals

Post by sargentrs »

Personally I prefer the rope method. Nothing worse than the air pressure bleeding off while you go to the bathroom. :doh:
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Re: Advice on Replacing Valve Seals

Post by Jacksdad »

If it was sitting for a while, you may be having issues with the rings sticking too. Get it hot, pull the plugs and pour a little Marvel Mystery oil into each cylinder. Pop the plugs back in and leave it for a day or two. It'll smoke like crazy when you start it up (your neighbors downwind will probably never speak to you again) but it'll clear pretty quick.
1971 DRW F350 cab and chassis with an Open Road motorhome conversion, Dana 70, 352 (originally 390)/C6, PS, power front discs, and 159" w/b.
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shorty73
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Re: Advice on Replacing Valve Seals

Post by shorty73 »

I was wondering if it might be stuck rings and had planned on doing some MMO in through the plug holes. I might bump that up on the list of things to do. Since the Rislone cleared the smoking, I won't know if the MMO worked until next oil change. The trucks not going to get many miles, so that might be awhile!
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Re: Advice on Replacing Valve Seals

Post by Jacksdad »

You can do it between oil changes - you can run MMO in your engine oil, so the small amount you use in the cylinders won't harm anything. After it's soaked for a day or two, take out the plugs and crank it over with some rags or paper towels over the plug holes to catch the excess - it can get messy.
1971 DRW F350 cab and chassis with an Open Road motorhome conversion, Dana 70, 352 (originally 390)/C6, PS, power front discs, and 159" w/b.
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shorty73
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Re: Advice on Replacing Valve Seals

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Ok, I plan to spend as much of the weekend working on her as I can. I've only had it up and down the street once about 2 months ago (and it died on me :o ) There's a few more must do items before I dare take it out again. Since it's my birthday tomorrow, I already told the wife, this weekend is mine, especially since the last two weeks were spent cranking away on a big house maintenance project.
1968 F250 2wd 360/c6 PS PB (disc) Camper Special
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