Anyone attempted changing valve stem seals without taking the head off the block?

how would that even be possible?

Originally posted by SILVERNT
how would that even be possible?

Anything is possible when you have no idea what you're doing.

In a short answer: NO.

Long answer: No, you can't do that. For one, you'd have no way of getting a valve spring compressor on the spring to remove it, and for another, if you did manage to remove the keeper from the valve and remove the retainer and spring, the valve would likely fall into the combustion chamber and you'd be taking the head off anyway. Sounds like a pretty stupid idea, no?

I'm pretty shure its possible. I am going to try this method http://honda-tech.com/zerothread?id=1604753 (its a Honda but same concept) I just wanted to see if anyone had tried anything similar. If it turns out to be a huge PITA I'll just take the head off.

The valve spring compressor is a bitch even with the head off. You'd be using the hammer and plier method if you went with the compressed air method, and I guarantee you will break, damage, or lose something in the process.

Just drill a hole in the inside fenderwell to make it easier to remove that stupid motor mount bolt.

Originally posted by DarkOne

Originally posted by SILVERNT how would that even be possible?

Anything is possible when you have no idea what you're doing. In a short answer: NO. Long answer: No, you can't do that. For one, you'd have no way of getting a valve spring compressor on the spring to remove it, and for another, if you did manage to remove the keeper from the valve and remove the retainer and spring, the valve would likely fall into the combustion chamber and you'd be taking the head off anyway. Sounds like a pretty stupid idea, no?

Hey Dino, is that you? I'm confused.

You put # one cylinder at top dead center with the lobes facing up. Then pull out the cams and rockers (yes, you will have to redo your timing and technically you should put the rockers back to the valve they came from) Then put compressed air in the cylinder via the spark plug hole (I would use a constant flow at say 30-40lbs, just to be safe). At that point you can remove the rockers, springs and keepers. The valves should stay up. There is a "special" tool they make for compressing the spring but I generally make my own tools. IDK the part number but I'm sure you could search it out. Then you have access to the seal and you can pull of the old and put in the new. Put the springs and keepers back on then go to the next cylinder and repeat process. After they are all done, go back to number one top dead center and put your cams and rockers back in with the cams set at their #1 timing mark.

I'm going to see if I can find a write up on this but I just wanted to shoot out a quick reply so you wouldn't say it can't be done. Hell, I bet it's even in the Haynes/Chilton's book.

MB

Edit: yeah, I just checked in my haynes and they show that method. They even show the special tool. It grabs at the bottom of the spring and compresses the on top of the retainer. They don't show any # on it.

The point is, you're re-doing the timing belt anyways, it's stupid not to remove the head. You'd be better off wearing mittens if you just want to make the job more difficult.

Besides, most 420a headgaskets are probably on their last leg anyways, and any chance to replace it and use some ARP studs is a good one.

Originally posted by bullettdsm
Hell, I bet it's even in the Haynes/Chilton's book.

yeah, because they're full of "the right way" to do things. Bad example.

If you go through the trouble of removing the cams and cam gears, then the only thing stopping you from removing the head is ten head bolts, a couple of plugs, an intake pipe, and a downpipe.

I'm all about finding easier ways to go about doing maintenance (like popping off four suspension bolts to pull an axle from a trans and leaving the mess hanging vs. removing them) but I can't help but disagree that this is easier or better than just removing the head.

The reason I asked is because I wanted to save a couple bucks and not replace the headgasket that I just replaced a couple months ago.

Well, if these guys say it's possible, i guess I'm wrong. if you do it, take pictures and do a writeup for the Wiki.

Originally posted by DarkOne
I can't help but disagree that this is easier or better than just removing the head.

Oh, no argument there. As you say, you're just about there anyway. Also, the chances are pretty good (like dawg said) the HG is due.

I was just keying on the OP's question of can it be done and the first two posts ruled it out categorically, which I found kind of strange.

Would I do it? Nah, I'd just pull the head :thumbsup

MB

Originally posted by bullettdsm

Originally posted by DarkOne I can't help but disagree that this is easier or better than just removing the head.

Would I do it? Nah, I'd just pull the head :thumbsup MB

As would I. It's just easier. I know you said you just replaced the HG, but I would sacrifice the cost to make it easier on me.

Well I'm going to attempt it sometime this winter with the head on. Wish me luck :)

Ive done it many times, just just on a 420a...but many offshore powerboat motors at work. It's not that uncommon at all...:shrug

Like Bullet said, keep the valve closed with shop air, move the piston to TDC compression and keep the motor from spinning (from what ive seen, it WILL want to turn, HARD) An easy way to do it if youre doing all of them, is one piston fires every 90*, so start with 1...then go by the firing order. 18436572 for a 350 for example, start with 1...turn 90 and do 8...in our case, 1342. easier, faster, then most weird other methods like using an extension down the spark plug hole to attempt and semi locate the piston (although this down work...) use a leak down gauge setup, and keep the pressure high for peace of mind

if it makes more sense to get everything out and do it off the car, do it that way...if you dont have everything you need to do it right, rethink it

edit: SOMETIMES it DOESNT make more sense to pull the heads...like when you have a boat engine bay with 4 motors and two heads each! thats a LOT of shit in a tight space...you thought our engine bays were tight!

Originally posted by turbo8u
SOMETIMES it DOESNT make more sense to pull the heads...like when you have a boat engine bay with 4 motors and two heads each! thats a LOT of shit in a tight space...you thought our engine bays were tight!

Well of course. However, in this case and in my humble opinion, it does.... even if it means another $40 MLS gasket :shrug

Good luck to you :thumbsup . I haven't done this with the 420a's so I would be curious to get your opinion on how it works out. And yeah, in my quick post on how-to I did not put in what turbo8 points out. The crank will want to turn.

MB

This is an easy one; just use a long piece of rope. One that can be fitted thru the sparkplug hole. Fit enoungh of the rope inside the cylinder and turn the crank by hand until the the piston doesn't go any higher. A good idea is to make a knot at the end of the rope so it doeen't fall in completly into the cylinder. The rope will hold the valve in place. You can then use a homemade tool to push the spring and pull the retainer out.

I personally have replaced the seals on a 420A without removing the head while doing it exactly the way the Haynes manual happens to suggest it. I only did it out of a late night circumstance where a new HG (or new head bolts) were not available in the late night time frame. If you happen to own the proper valve spring compressor (like I thankfully have) and compressed air, it can be done.

I didn't have any issues with the setup myself and honestly, not having to pull off the wiring harness, heater hoses, vacuum lines and all the little things that goes along with the job sure made it a LOT faster. If you have the time, just replace the HG while you've got it ripped apart already.

Not for everyone or every circumstance.

When I took apart my old head I took out the valves, and I bought one of these kits off of ebay. I definately could have taken them out with the head on it. This was the only one I could find that would seat to the spring right. With this one you can take out all 16 valves in about 4-5 mins. Just make sure if you leave the head on you put air in the cylinders. I definately recommond this set.
http://cgi.ebay.com/ebaymotors/VALVE-TOOL-SPRING-COMPRESSOR-INSTALLER-REMOVER-TOOLS_W0QQitemZ170061903504QQihZ007QQcategoryZ35625QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

Originally posted by 98VengeI4
When I took apart my old head I took out the valves, and I bought one of these kits off of ebay. I definately could have taken them out with the head on it. This was the only one I could find that would seat to the spring right. With this one you can take out all 16 valves in about 4-5 mins. Just make sure if you leave the head on you put air in the cylinders. I definately recommond this set. http://cgi.ebay.com/ebaymotors/VALVE-TOOL-SPRING-COMPRESSOR-INSTALLER-REMOVER-TOOLS_W0QQitemZ170061903504QQihZ007QQcategoryZ35625QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

Thanks for the link, I'll probably end up making a tool similar to that.

Originally posted by customrsturbo
This is an easy one; just use a long piece of rope. One that can be fitted thru the sparkplug hole. Fit enoungh of the rope inside the cylinder and turn the crank by hand until the the piston doesn't go any higher. A good idea is to make a knot at the end of the rope so it doeen't fall in completly into the cylinder. The rope will hold the valve in place. You can then use a homemade tool to push the spring and pull the retainer out.

The string trick is certainly another strategy. But when I thought about it for our heads, I thought that there was quite a degree of difficulty in getting the string down there and having it lay out on the piston. With that "tunnel" to the spark plug, I would be concerned about the string "laying out".

MB

To insert the piece of rope thru the spark plug tunnel and into the cylinder, I use a long screw driver.