Rebuild Altima Hitachi Distributor

[artdg]

Rebuild Altima Hitachi Distributor
Disclaimer: Whoever decides to do this project is fully responsible for him/herself. The author is not responsible for any bodily or property damages.

There are a lot of talks about the oil leak problem of Altima distributor. To limit the length, this post concentrates on the rebuild project. The reader can find informations such as how to take out the distributor, etc., from other sources.

This project covers the 1993 -1995 Altima Hitachi Distributors. Products from other vendors may have different design. But I think they have similar structures.

It is a misunderstanding that the outside O-ring causes internal oil leak. In fact if it leaks, oil will seep through the gap between the engine body and the distributor base. The real issue is the internal oil seal.
Recently I bought online three internal oil seals for my 1994 Altima Hitachi Distributor. I disassembled the distributor, replaced the oil seal and reassembled it. The distributor works fine after installation.

The link to buy the internal oil seal is http://www.bestpartsonline.com/servl...-Nissan/Detail
Check the part description, make sure you buy the right part --- Oil Seal, Hitachi Ignition Distributor for Nissan (High Temp) Counter Clock-wise Ref# B2131-01M00
On the web page, you can click detail description and specification to see more. The maker is KOK. They may be the supplier of the original oil seal. The material looks high quality.

The following is what I did in the project. I provide some photos in the link for your reference https://picasaweb.google.com/1146600...chiDistributor#
Take the cover off, you see a black sleeve (pardon me if I use the wrong word) where you screw the rotor, a thin shining slotted metal plate and the optical sensing block. The sleeve is tight fitted to the shaft. The sleeve presses the plate down to a washer behind the plate. Before doing anything, it is MOST IMPORTANT to mark the relative position of the plate and the sleeve. The correct ignition timing depends on this position. Use a permanent marker draw a line connecting the square hole of the plate and the base of the sleeve, make sure a visible mark is on the sleeve. Later when pressing the sleeve back, you must match the marks.

It is very difficult to separate the sleeve from the shaft. Some sleeve has parallel surfaces made on it. This will save a lot of trouble. My one does not have. It is a round cylinder. So I made a pair of parallel flat surfaces on the sleeve with a table grinding wheel. Remember the distributor base can rotate around the shaft. When grinding the surface, if some parts get in the way, just rotate it away. Any work involved with a grinding wheel is a RISKY operation, so be really careful. Hope someone will come up with a better idea. The two flat surfaces I made fit into a 19 mm flat wrench (it can be a different size). The other end of the shaft is a ring with keys, which fit into the end of the camshaft.

1. Use a piece of cardboard to wrap and protect the ring, put it between jaws of a vice. Position the distributor vertically. Tighten the vice slightly; the keys will prevent the shaft from rotating. Don't use excessive force when tightening, the key ring may break. Inject a bit WD40 into the small well at the top of the sleeve. Rotate the wrench slowly in alternative direction. After the sleeve clears the slot plate (the plate won't move when the sleeve moves), rotate the wrench counterclockwise, don't change direction. If other parts get in the way, rotate the base. Rotate the sleeve several rounds, it will separate from the shaft. After several rounds, if the sleeve can rotate easily but refuse to come off, you can consider punching the shaft out. Clamp the flat surfaces on the sleeve with a vice, nearly horizontally, punch the shaft through the hole of the sleeve top. Make sure someone holds the distributor, or provide it with a very soft landing. You don't want to damage the slot plate. The outside surface of the shaft is quite rough after the twisting. Don't try to file or sand it smooth. If you get too much metal off, it won't provide a tight fit later.

2. After separating the sleeve, carefully take the slot plate out. There is a washer under the plate. The washer is NOT flat. Pay attention which side is convex. I did not pay attention when I took the washer out. When put things back, I use the convex side facing the slot plate. But I am not sure if it is the original position. The other parts are easy to separate. Please see the photos.

3. Finally you see the bearing. You need to drive the shaft out. Adjust the vice jaws to loosely hold the key ring. The end of the distributor base sits on the jaws' upper surface. Punch the top of the shaft (protected with a wood board) with a hammer. The shaft is easy to come out.

4. Take the bearing out, and then you see the Holy Grail, the internal oil seal. If it is too difficult to take it out as one piece, you can cut it and pull it out. Be careful not to damage the soft aluminum base.

5. Clean the electronic part. You can use electronic cleaner spray or some good stuff. Or just cut some paper towel, and then wet them with gasoline. Then slide the paper in the sensor gap. When you clean the slot plate, DON'T erase the marker.

6. The outside diameter of the oil seal is larger than the well where it sits. You need to push hard to get the new oil seal in place. Apply a thin film of grease on the thickest part of the shaft. Penetrate the shaft through the oil seal.

7. Before you install the bearing, tape an nut (smaller than the diameter of the shaft end) or temporarily glue it. The nut will provide a strong and direct axial reaction. The key ring is irregular and movable. We don't want to damage it either. Get a 1/2" short copper pipe. Sit the end nut on a hard surface; punch the copper pipe to drive the bearing in. The bearing should be in its well in the base. It also must flush at the shaft shoulder; otherwise the slot plate would not be in correct place. The distance from the bearing to the top of the shaft should be about 32 mm. You can get this value by measuring the distance of the shoulder and the thickness of the bearing, when they are separate. If smaller than that, the bearing should be further driven downward. When the bearing is at the right position, the gap between the key ring and the end of the base is very small, about 2 mm.

8. After installing the bearing, install the bearing cover, electronic assembly and cover. Put the collar in and then the washer. Put the washer the same direction as you saw in step 2.

9. Put the slot plate into the sensor gap, with marker upside. You notice a small flat surface on the shaft where it meets the slot plate. This surface matches the shape of the slot plate's center hole. This shape prevents the plate from rotating around the shaft, thus provides accurate ignition timing.

10. The critical step is to press the sleeve in. You need a large vice. If you can arrange the vice vertically, things would be much easier. (I used a vice sitting horizontally, it still worked). Apply a thin film of grease to the shaft. Match the marks of the slot plate and the sleeve. Put them together between the vice jaws. Tighten the vice, the sleeve moves towards the slot plate. Pay attention to the position of the plate to shaft, and the position of the marker on the plate and sleeve. If you see the marks do not match very well, do adjustment by rotating the sleeve as in step 1. Use force but not excessive force to press the whole thing together. I might have used too much force when I was doing this. The slot plate is bit warped. But the plate does not touch anything when it rotates, so the distributor still works. If the plate touches something when it rotates, you must rework. I don't know how to, because it did not happen to me. I guess you can loose the sleeve a bit as in step 1 and then re-press it using a proper force. The end nut plays a critical role here. Without the nut, the sleeve and the shaft will skew when being pressed, because the keys at shaft end are irregular. That was when I got the idea of putting a nut there.

11. If you finish step 10 successfully, remove the end nut, put the cover back and try your luck on your old Altima.

Before you use liquid gasket to seal the gap between the engine body and the distributor base, you may want to test and adjust it for a few days. During this time, oil will seep out and make a mess. I made a small metal pan to catch the oil. It is 60 mm long and 50 mm wide (in distributor shaft direction), 8 mm deep. It is fastened to the cap using the lower screw. See photos. You may want to keep the pan there, even after you use liquid gasket, because you may still have oil leak problem. When there is oil in the pan, use napkin or paper towel to clean it. Don't need to take the pan out.