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Tue Sep 05, 2006
20:20
The motor in my 1991 Golf started burning a little oil about 6 months after I bought it, and it has become worse over the past couple of years. I knew it was caused by leaking valve stem seals, because it was only on startup as well as acceleration immediately after deceleration that I would get blue smoke from the exhaust (blue smoke means burning oil). If the piston rings had been the problem, then the oil burning would have been a constant.

This past weekend, I finally got around to replacing the valve stem seals. Even though I'll be doing an engine swap (at some point), I don't want to be burning oil for many reasons. Oil in the exhaust can eventually clog the catalytic converter... and plus, it just sucks to be "that guy". You know, the guy that drives an older car that kicks out plumes of choking, blue smoke every time it's started. It got to the point where I felt bad about parking near other cars at work because I didn't want to envelop other people's cars in my oily clouds.

You may have heard of the "rope trick" (or "indian rope trick" or "redneck rope trick") sometimes used when replacing valve stem seals. In order to replace the valve stem seals, the valve springs, upper valve spring seat, and valve keepers need to be removed. When those items are removed, there is nothing to stop the valve from dropping down into the cylinder bore, on top of the piston. For this reason, in order to replace the valve stem seals without removing the cylinder head you must have a way to prevent the valves from falling. A common method is to adapt a compressed air line to the spark plug holes and use compressed air to keep the valves pressed up against the cylinder head. A less common method, however, is to take a length of good, flexible rope and stuff it in through the spark plug holes. With the rope packed tightly, it will keep the valve up in place while the springs are being compressed, allowing for removal of the keepers. I had heard about this method, but had never tried it. This seemed like the perfect opportunity to test the effectiveness of the "rope trick", since my air compressor is not at our new house yet.

This first picture shows the bridge of my home made valve spring compressor bolted into place on the cylinder head. Note that the airbox, valve cover, camshaft, and cam followers (lifters) have all been removed. I also had to disconnect the intake air boot and throttle body enough to move them up out of the way. Note that before starting disassembly, you may want to line up all your timing marks since the camshaft does have to be removed. Also note that removing the camshaft bearing caps requires them to be removed in a particular order. Refer to your Bentley manual for specifics... do not attempt a job like this without a good shop manual. (click picture for larger view)


This picture illustrates how the spring compressor works - just a lever that hooks under the bridge and pushes down on a cylinder. The cylinder has a window cut out of it to provide access to the valve keepers while the springs are being compressed. Notice the rope stuffed into the spark plug hole. Here I have pistons 1 and four at top dead center and pistons 2 and 3 at bottom dead center. Obviously, much more rope was required for 2 and 3. In fact, it took about 12 feet for each of those. If you try this method, make sure your rope is going to be long enough. (click picture for larger view)


Here is a closeup of the compressor in action - you can see the cylinder pressing down upon upper spring retainer. You can also see the valve keepers forming a collar around the end of the valve stem. (click picture for larger view)


Once the springs are compressed, the valve keepers can be removed. A pair of needle nosed pliers works well, but a telescoping magnet works even better. Here is one of the keepers on the end of the magnet I used: (click picture for larger view)


When the keepers are removed, the upper spring retainer, inner spring, and outer spring can be removed. Here is a picture of those parts removed (2 keepers, retainer, and both springs): (click picture for larger view)


Now the valve stem seal can be removed, which can be tricky. Here is a picture looking down into the lifter bore after the springs etc have been removed. You can see the stem seal at the bottom. (click picture for larger view)


Here is a pair of needle nosed pliers that I modified to function as stem seal pullers: (click picture for larger view)


The seal needs to be gripped down low, where there is a small metal lip that protrudes. The tricky part is that it's easy to mistake the upper portion of the lower spring seat for the bottom of the stem seal. Grab low on the seal, but don't grab the lower spring seat lip. Be careful not to scratch the valve stem during this process - that's difficult because you normally have to pull pretty hard to pop the seal loose. You have to be ready to relax immediately once the seal comes loose or once the pliers start to slip - otherwise you'll get sudden, wild movement which could do some damage. Here is one of my old seals, removed. Six of mine came out in one piece, and two of them tore up a little bit during the removal process. If they tear into pieces, make sure all of the pieces are accounted for before installing the new seal. You don't want pieces of the old seal circulating in your oil or stuck in place of where the new seal needs to press into. (click picture for larger view)


Here is a new stem seal, for comparison: (click picture for larger view)


Before installing the new seal, do two things. First, apply a thin coat of clean oil to the surfaces of the seal. Second, cap the end of the valve stem with something plastic or rubber to protect the seal from the sharp edges of the grooves which mate with the valve keepers. I used a rubber end cap like they use for those coated metal wire racks. It wasn't quite long enough to cover the keeper ridges, but there was no problem with the seals catching as long as they were pushed swiftly over the cap. Here is the cap I used - you can tell it's stretched quite a bit: (click picture for larger view)


This is the perfect time to replace your hydraulic valve lifters if necessary. When I removed my lifters, I left them set upright overnight to see if the pistons would bleed down like they're supposed to. They didn't, so I suspected they were gummed up and not able to self adjust properly. I had a set of new lifters hanging around anyway, so I decided to use them and then work on reviving my old ones if possible. Here are the new ones, fresh out of the box: (click picture for larger view)


After all eight seals were replaced, here are the new lifters installed and the camshaft set into place. (click picture for larger view)


Refer to your shop manual for further reassembly instructions. Camshaft bearing caps must be installed in a particular way, and torqued correctly. Also make sure to use a new valve cover gasket. Be aware that if you install new lifters, you should give them plenty of time to bleed down after the camshaft is installed. They come fully pressurized, which means the valves will lift down further than normal which can cause piston and valve damage. My Bentley book says to wait 30 minutes, so that's what I did. Upon starting the car after this procedure, I noticed a lot of lifter noise (loud tapping/ticking), but it went away after a couple of minutes. I took it for a spin around the neighborhood and by the time I got back to my garage, it was nice and quiet.

In closing, the rope trick works quite well. Just be prepared to spend plenty of time feeding the rope through the spark plug hole, and packing it in with a long, thin screwdriver (be careful not to damage the spark plug threads).

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Date: 09/09/06, 08:23:11 PDT
From: seamus casey
Comments: brilliant trick...let me know if you need help moving your compressor to the new house, lol.

Date: 09/09/06, 17:06:42 PDT
From: max
Comments: Haha, thanks! I'll take you up on that at some point. I still need to add a couple circuit breakers and buy lag bolts / lead anchors in order to install the thing over here.

Date: 09/15/06, 07:24:43 PDT
From: k. dawson
Comments: I did this on a 302 V8... you only need 3 feet of rope tops. Find the compression stroke/exhaust stroke, then insert the rope and crank the piston against the head gingerly to 'tamp' the rope. That's the 'other' part of the rope trick. If you used not enough rope, you'd be pulling the head to dig your valves out if you don't use the piston to secure the rope. Other than that, good diy tips.

Date: 09/15/06, 12:52:40 PDT
From: Max
Comments: Yes, good point - thanks for mentioning that. In my case, I didn't want to rotate the crankshaft at all because I was doing this the lazy way, without removing the lower timing belt cover and v-belt pulleys, which is why you can see the timing belt vise-gripped in place in some of those pictures. It was easier for me to use lots of rope than worry about my timing belt jumping off the crank pulley. I would highly recommend that anyone else doing this take the time to remove the timing belt completely... it's the old "do as I say, not as I do" thing. :-)

Date: 09/20/06, 19:10:55 PDT
From:
Comments: Would probably be a good idea to use a new, lint-free rope, if there is such a thing.

Date: 09/21/06, 11:34:26 PDT
From: max
Comments: A good quality, flexible nylon rope is about as lint free as you can get. You certainly wouldn't want to use a rope made of that stiff nylon that splinters, though. Also, you obviously wouldn't want to use a rope that was saturated with debris... you want something fairly clean. Combustible debris (such as dust, or tiny specks of grease) isn't a big deal because it will just burn. Chunks of stuff, anything that won't burn (like grains of sand), or synthetic debris that would melt and clog the catalytic converter are not things you want in the combustion chambers. Just use common sense and keep it all as clean as you possibly can - it can never be too clean, when it comes to engine internals.
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