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Tach jumpy all of a sudden...
Posted 20 January 2004 - 01:56 PM
I was going down to the store last night, 25 degrees outside. The car was fine when I went down there. But, as I drove back, the tach started jumping around from 2000 all the way up to 4000 RPM, sometimes stopping at 4000, then going back down and jittering. I pushed in the clutch and revved it up a couple of times, the tach settled back down, smooth as its always been. Then, a little while later, it started doing it again!
what is the problem, I have read on the repair manual section, that this is caused by a bad distributor, I don't believe it would just start doing it out of the blue. This is the first time it has happened. Could there be something else wrong? anyone else have expereince with this? I don't have the money to get a new or used distributor right now, and things keep going wrong with this thing. It is also my vehicle for going back and fourth to work in. What can I do?
Posted 20 January 2004 - 03:16 PM
Posted 20 January 2004 - 03:30 PM
Done it for quite sometime.....
Never fixed it......
Mudrat picked up a spare Junkyard disty here for $12.
I figure when mine becomes a problem, I'll do the same.
82 Hatch, frozen in the garage....
01 Forester, bent but not broken.
Posted 20 January 2004 - 03:39 PM
Posted 11 February 2004 - 03:13 AM
What's happening (I'm betting) is that the lower spinning bits in the distributor are occasionally hitting the sides of the distributor body. How does this happen? Glad you asked!
The distributor shaft has some flutes machined into it that draw a small amount of oil up to where the distributor shaft rests the distributor body. Unfortunately the shaft does not ride on bearings, but just sits on thin washers. Anyway, the flutes can get clogged, eliminating any lubrication of the washers, and the distributor shaft assembly eventually wears it's way lower and lower in the housing, eventually hitting the sides of the housing (why this makes the tach jump, I don't know, but it does).
You can get a set of "distributor thrust washers" from a Subaru dealership for a few bucks and add them to the stack to raise the shaft assembly (add some grease while you're there). You'll have to tweak the timing a bit too. If not fixed it will get worse, but at a very slow rate. I drove mine for six or seven years with a jumping tach.
If you get a distributor assembly from a wrecker, you'd be wise to take the lower gear off, remove the shaft, and make sure the lubrication flutes are clean.
Posted 11 February 2004 - 03:47 AM
Posted 11 February 2004 - 03:51 AM
Thet did an awesome job for me - 24 hour turn around.
Just pop the cap off your disty, and try to move the shaft - if you notice ANY (and I do mean ANY) play on a ND, then it's shot. I was very sceptical when I first took my disty apart to look, as the play was hardly noticeable, but it was there. When I got it back from the shop, it was solid as a rock - no play AT ALL.
Almost 100% positive this is your problem - the disty is the only thing on your car that can cause this. A bad coil won't do this - as the tach signal (and what fires the coil), has to come from the disty.
The cheapest I found rebuilt distys, was from roobuilders in Denver - $145 for a complete Hitachi setup.... not cheap. Especially when I just needed a $35 rebush.
Posted 11 February 2004 - 04:08 AM
I should add to my earlier comments that adding more thrust washers won't help with the side to side play, but like GD says you can get away with a lot of slop on a Hitachi distributor. When you have it out just spin it by hand and make sure nothing hits (I forget the proper terms, but the star shaped piece just under the rotor will often collide with the, uh, 'prongs' that it spins between. You can bend the prongs out a bit so they clear. Not a perfect solution, but it'll probably get you around.)
Posted 11 February 2004 - 04:11 AM
Posted 11 February 2004 - 11:58 AM
The air gap is critical to performance. Fix the one you have or get a suitable used one.
Posted 11 February 2004 - 03:15 PM
I was hesitant to mess with the air gap, but considering the shaft was already flopping around so much I figured I might as well. It performed adaquately that way for awhile until I was able to find a replacement.
Like Qman says, get a replacement. My car was a beater, so "performance" just meant "running."
Posted 11 February 2004 - 03:45 PM
Posted 12 February 2004 - 11:32 AM
You guys saved me from having to search for the old post! Cool!
The disty on the new hatch is TOAST.
Posted 26 February 2014 - 05:34 PM
I know this is kind of an old one, but I came across this last night. I've got a Hitachi distributor and have about 1/8inch or slightly more vertical play in the shaft, but no side to side movement that I notice. The stator has slightly more gap on one side of the reluctor than on the other. I tore down the whole thing to regrease it all as well as replace the vacuum controller. It looked like it had chewed through something and had a thin strip of round metal lodged in the bottom of the distributor kind of near the pick-up coil plate. Almost like it had chewed through a bit of one of these washers. When one of you says thrust washer and the other says bushing are you guys talking about the same thing? Or is there a sleeved bushing that would fit over the shaft and slide down into the housing to hold the shaft in place? Either way I think I need to add a couple more thrust washers/bushings to eliminate the up/down play.
Posted 26 February 2014 - 06:23 PM
The thrust washer set is Subaru P/N: 491867401. Was hoping maybe the local dealership still had access to them, but of course they are discontinued. I hit up Regis Philbin there in Portland and they have do have them. I can't imagine it'll be more than a few bucks.
Posted 13 March 2014 - 11:08 AM
Ok so I found the bushing you guys were talking about. Mine was definitely worn. I had a spare one so I popped it out and put it in along with a new washer set. Here's a few pics of the pieces for anyone that might run into this in the future.
Bushings. Mine was so worn when I looked at the housing I couldn't tell there was anything on top. After looking at another one though it stood up quite a bit further from the housing.
The new bushing definitely fit a lot tighter than the old one.
And the thrust washer set that the diagram depicts.
Unfortunately though none of this solved my jumpy tach, but it does seem to have helped with the intermittent miss that I was having.
Posted 16 March 2014 - 04:30 AM
Probably the lube in the tach itself is getting old and thick that is why it more than likely plays up when it gets colder, more common issue than people realise I have a mate that is a trained Scientific Instrument maker who has been an Auto, Marine and specialist Instrument repairer for thirty years including Artillery laying instruments and he says that scenario is quite common on older instruments.
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