After a search, we located a seal to replace the internal one in the 700 cylinder head mounted distributor. We buy them from the local Honda bike and lawnmower dealer, and I'm not sure what the original application is, but the size is perfect.
To do this job, you need the seal, #91205-KF0-003 Honda. Most likely, this is a good time to change the wire connector for the hall effect switch, Volvo # 1346793, and the holddown for the wires to keep them fron hitting the rotating parts,Volvo # 1346794.
In case you are not aware of it, the hall effect switch is available separatly from the housing for a bunch less money than a whole distributor, too. Volvo #1346792. A few blacksmithing skills are needed for that part of the job, but it is not too tough. I have found the only way to check the hall switch is with a lab scope, but also find that a car with 250,000 km or more almost always runs better with a new one. I guess after it has turned on and off a couple of billion times, the magnet or transistor or whatever starts to get weak, and won't give a clean voltage change.
Here are the basic instructions- ignore the bits about the parts you are not changing.
Remove the distributor cap, rotor, and plastic sheild, and remove the distributor from the head.
Mark the slot drive in relation to the rotor notch- it can be installed 180 degrees out.
Punch the retainer pin out- use a good punch and a solid surface to support the drive. The pins can be quite tight.
Remove the drive, collect and count the thrust washers, remove the shaft from the housing and collect those washers too.
The black wire retainer is usually broken away from the housing. I have found the best way to get the wires out is to VERY carefully grind the plastic away, finishing with the wire wheel, until the tab holding the individual wire in is free. Don't mix the wires up- the new housing is marked + and -.
The white wire holddown will come off with a little screwdriver work.
There is a serrated steel washer peened into the aluminum housing- pry it out, trying not too bend it too badly- It can be straightened with a hammer if need be.
Pop the seal out, clean the housing, push the new one in, carefully tap the steel washer in ( don't worry about peening it in- it can't go anywhere anyway. Assembly is reverse of removal.
If you wish to change the hall switch, there are two tricks- use a dremel or die grinder to grind off the two rivets or you will punch out the thin aluminum of the housing, and will be buying a new distributor. I know this, because I have a test unit at the shop with the switch epoxied in! The other trick is to take a 5/16 bolt about 5 inches long and drill a depression in the end of it to just fit over the end of the rivet in the new switch. You also must grind the end down in diameter so it is only supporting the rivet, and not touching the plastic. Grab the bolt in a vise, get a friend to hold the distributor in place, and carefully peen the rivets. I have a very small chisel that works well, or a centerpunch will do the job. Don't overtighten the rivets- all that is needed is to keep the switch solid. For this part of the job, somebody who has riveted things in the old days with a hammer can be a useful ally.
I hve done lots of these seals, and have found it to be a very good fix. --
jim- Streetwise Service, Saskatoon