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Any way to replace valve stem seals without removing spark plugs?
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Any way to replace valve stem seals without removing spark plugs?
I just did my plugs twice in four months and I am really not excited to do it again but I can't find any technique to get the valve springs and seals off without removing the plugs and either running air or a small length of rope into the cylinder to keep the valves up while the work is done.
Am I doomed to another round of labor for the plugs?
Re: Any way to replace valve stem seals without removing spark plugs?
I'm sure it's "possible" to leave the plugs in. That doesn't mean "practical", let alone "A Good Idea".
You will do about 15 times as much work trying to get out of that trivial little bit of nothing, as the work you're trying to get out of.
The rope method is by for better than compressed air. Best way to do it is, remove all the plugs; turning the motor by hand (a good reason all on its own to remove them), bring a cyl up to TDC, doesn't matter whether it's the firing instance of TDC, or the other one, especially with the stock cam; stuff the cyl full of rope, 3/8" nylon works pretty good; put a socket on top of the retainer that's large enough for the keepers to fit easily inside it, 5/8" is about right, and bonk it real good with a hammer; the keepers and retainer will fly off, make sure they don't land inside the engine; take off all the old stuff; put the new "positive" seal onto the guide all the way; compress the new spring after measuring the installed height with your valve spring mic and selecting the appropriate new shim stack to bring the height to the correct value; put it on the head compressed, install the new retainer and new keepers; remove compressor. Repeat 8 times, in the firing order.
Re: Any way to replace valve stem seals without removing spark plugs?
If you remove the heads, the spark plugs can be left in place. So... technically yes it is possible.
If you do the air method, the primary issue is it wants to turn the engine over unless you are dead nuts on TDC.
Now, I haven't tried this personally, but last time I did the job I pondered regulating the pressure down till it would not be so apt to turn the engine over and adding a valve to
turn the pressure on slowly. Might help.
Ultimately though, I just left most of them at BDC. Still worked just fine.
GD
Last edited by GeneralDisorder; 08-15-2017 at 11:49 AM.
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by Tootie Pang
Thanks. I will look into that tool and I will lock the crank by clamping the serpentine belt to a fixed object.
I would DEF do the rope method. I think it's more reliable than the compressed air...just my opinion.
I did this myself using the rope method. In addition, some complained about my "unconventional" way about putting rockers back on. But let me tell you--there is a difference between a flat-rate tech and a "purist." One is quicker.
Also, at a 3.75" bore, piston surface area is (3.75/2)^2 * 3.14 = 11 sq in. With 100 PSI of air, that's 1,100 pounds of downforce on that piston. Maybe that piston should be BDC. Yeah. I don't think a serpentine belt or even a crank pulley bolt would do well with that.
Last edited by Tootie Pang; 08-15-2017 at 02:13 PM.
Re: Any way to replace valve stem seals without removing spark plugs?
I second the rope method. You don't need expensive tools to do a relatively simple job. And for the most part, the rope squished to the top the head I feel is more reliable than air.
Yes, you can use air. But rope is more readily available, cheaper, and fail safe in comparison when loosing air.
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by sofakingdom
If the piston is at BDC and the valva falls into the cyl, what then?
Use rope. It works. Air doesn't.
With 150 psi of shop air that valve aint going anywhere. Now if you don't have access to a reliable air supply or think you might lose pressure somehow in the process then definitely don't do it that way. Air did the job for me and wasn't particularly difficult..... I do have a 5 HP Quincy QR-325 air compressor though so not worried about losing pressure in my shop. If you have a little weakling compressor for brad nailers it might be a poor idea.
Rope works too - I've used that on other engines to loosen or tighten the crank pulley bolt to spec. I think it would probably take slightly longer, but requires no air supply and there's basically no way for the valve to slip into the cylinder.
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by RocketyMan
I would DEF do the rope method. I think it's more reliable than the compressed air...just my opinion.
I did this myself using the rope method. In addition, some complained about my "unconventional" way about putting rockers back on. But let me tell you--there is a difference between a flat-rate tech and a "purist." One is quicker.
I would have to agree that Rope is probably the safest method. Reason being its not going to want to push the cylinder back down, and the rope can't bleed down or fall out. So the valves will stay where they should.
For a DIY at home, probably 10x more reliable than a cheap air compressor.
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by Thirdgen89GTA
I would have to agree that Rope is probably the safest method. Reason being its not going to want to push the cylinder back down, and the rope can't bleed down or fall out. So the valves will stay where they should.
For a DIY at home, probably 10x more reliable than a cheap air compressor.
Also place some strong magnets in the area to hopefully grab the keepers that are surely to fly into never-never land.
Re: Any way to replace valve stem seals without removing spark plugs?
Yeah..that's also something I forgot as well. I used one of those 5 lb magnet strength on a extendable pole. Essential for getting those keepers and making sure they dont fall down the oil return holes in the head!
Re: Any way to replace valve stem seals without removing spark plugs?
Air works fine. Don't drag *** and after the rocker is off, you'll
Tap the valve to loosen the retainer from the keepers, compress the spring, have the keepers jump to your magnet, release the spring , replace the seal, and reinstall stuff in very little time.
If your compressor makes you afraid it can't hold a valve up for a few minutes, you probably need to buy a new one, or to get some good anti-anxiety meds.
Do 4 in an evening if you do drag ***.
If you keep track of the threads each nut is fastened by, you don't have to worry about lash.
Daunting, but easy work.
Re: Any way to replace valve stem seals without removing spark plugs?
Thanks, I've got a great vintage Sears 20 gallon, 240V compressor. Very trusty. I am thinking of buying three more of those spark plug air adapters and making a hookup manifold. This way I can pressurize an entire side at the same time and there will be no movement. Might be worth the extra $50.
Re: Any way to replace valve stem seals without removing spark plugs?
You could only do the cylinders with closed valves. Otherwise the 20 gallon compressor will not keep up with the air consumption. It may even have a tough time doing 4 cylinders that have closed valves due to blow by. Watch your system pressure with the motor kicks on and make sure it's not losing it's battle. Air will escape through the rings at some fairly constant rate and the compressor will have to cycle. That little machine is in the 8-12 CFM neighborhood and it doesn't take much of a hole at 100 psi to overpower the pump's output. 1/4" diameter orifice would easily do it with flow to spare.
GD
Last edited by GeneralDisorder; 08-17-2017 at 02:31 PM.
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by Tootie Pang
Yep. I'll remove all the rockers so that all the valves are closed. ( I think I can do that IIRC). It's been a while since I did any rocker arms.
Yes, that can work. But you only need to pressurize the cylinders opposed to each other in the firing order - 1 & 6, 8 & 5, 4 & 7, 3 & 2. The pressurized cylinder that is at BDC will keep the crankshaft from rotating with both valves closed.
Re: Any way to replace valve stem seals without removing spark plugs?
150 psi!!! wow... No wonder the engine wants to turn over.. I put a regulator inline and set it to 60. Never had a valve drop. (rockers backed off) Tho the rope idea works great too..
Re: Any way to replace valve stem seals without removing spark plugs?
If your patient and do it right you don't even need to pull the plugs and play with rope. Rotate the motor till number one cylinder is on tdc compression. There'll be play on both rockers. Compress the springs to remove the keepers and you're set. With the piston at tdc it's impossible for the valves to drop out of the guides to the point you can't grab them(yes, I tested that theory, lol). You can do the companion cylinder method and do 2 pistons at once so you only have to rotate the motor once or do one cylinder at a time in firing order. I did one at a time so I wouldn't lose track. And btw, anybody try to use that bar style spring compressor on a tpi motor?? Not enough room to compress the springs far enough. I bought the other style tool to do mine...
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by sofakingdom
I'm sure it's "possible" to leave the plugs in. That doesn't mean "practical", let alone "A Good Idea".
You will do about 15 times as much work trying to get out of that trivial little bit of nothing, as the work you're trying to get out of.
The rope method is by for better than compressed air. Best way to do it is, remove all the plugs; turning the motor by hand (a good reason all on its own to remove them), bring a cyl up to TDC, doesn't matter whether it's the firing instance of TDC, or the other one, especially with the stock cam; stuff the cyl full of rope, 3/8" nylon works pretty good; put a socket on top of the retainer that's large enough for the keepers to fit easily inside it, 5/8" is about right, and bonk it real good with a hammer; the keepers and retainer will fly off, make sure they don't land inside the engine; take off all the old stuff; put the new "positive" seal onto the guide all the way; compress the new spring after measuring the installed height with your valve spring mic and selecting the appropriate new shim stack to bring the height to the correct value; put it on the head compressed, install the new retainer and new keepers; remove compressor. Repeat 8 times, in the firing order.
Re: Any way to replace valve stem seals without removing spark plugs?
Put the piston @ TDC before stuffing the rope in. Then the valve can only fall a bit more than a half-inch or so, even without the rope. Which of course you can grab it and pull it back up easily enough when reassembly time comes, even if you let it drop.
As stated above, about 3/8" nylon (the real soft flexible kind of stuff) works best.
This method is SO MUCH quicker and easier than air. It takes less time to stuff the rope in than it does to screw in the adapter, let alone try to get clearance for hooking up the air line (good luck with that if you have headers) or deal with the air pressure turning the motor from TDC to BDC and THEN dropping a valve into a cyl. And still, air, even with 120 psi, won't hold the valves closed against the force of using a spring compressor to dislodge retainers from keepers. I will NEVER use air again.
I can't believe people would actually argue about this... try it once, you won't go back to air, either.
Re: Any way to replace valve stem seals without removing spark plugs?
I just use a socket and a hammer to dislodge the retainers prior to using the compressor. Whack em a few times and they come loose no problem. The valve goes from pretty stiff to bouncy when the retainers unsticks.
Re: Any way to replace valve stem seals without removing spark plugs?
Alright. I'll go rope method. Terrified of that valve dropping in. Can't beat TDC with a shim in there. A few things:
1. What size/type of rope?
2. I can take out all the plugs first?
3. I can use the distributor for TDC per cylinder? And, I'm being lazy, anyone have a pic of the 89 TPI distributor cap with the cylinder numbers?
Re: Any way to replace valve stem seals without removing spark plugs?
Originally Posted by Tootie Pang
Alright. I'll go rope method. Terrified of that valve dropping in. Can't beat TDC with a shim in there. A few things:
1. What size/type of rope?
2. I can take out all the plugs first?
3. I can use the distributor for TDC per cylinder? And, I'm being lazy, anyone have a pic of the 89 TPI distributor cap with the cylinder numbers?
Take out all spark plugs--makes turning the engine over by hand easy.
It's unnecessary to look at the cap/rotor--just look at your timing mark on the front balancer for cylinder #1. I personally just followed the firing order. Every 90* you move on to the next one. Just put your hands on the front crank pulley and move it. Stuff rope in...then ram it shut with the accessory pulley so you know its RIGHT on it. You can also tell when you release the keepers the valve only moves a SLIGHT amount...then it'll click and the keepers will come off.
08-14-2017, 11:38 PM
