manual transmission fluid change

[SharkB8]

This question is surely too stupid to be on any FAQ (I did look though..)..

As I understand it my 1993 Protege's manual transmission oil is drained through some "big bolt" on the bottom of the transmission, and the gear oil is added through the speedo cable hole...? I'm sure I'll be able to find the Big Bolt.

Could someone try to explain where the speedo cable connects to the transmission? Which side, how far from top (or bottom), etc.

Until this past week I had never turned a wrench before, but somehow I managed to change my own oil AND replace a tail light bulb all in one day, so I have been walking around all day with my chest way out, a ratchet in my back pocket and a pack of smokes up my t-shift's sleeve. I thought that since I'm on a roll I should tackle the transmission fluid since the original owner doesn't recall ever having it changed.

Also is there any sort of trick to getting the speedo cable back in?

[therieldeal]

on the protege, the speedo cable screws onto the vehicle speed sensor. this is located on the back of the tranny on the top, near the firewall.

unscrew the cable, unbolt the 10mm bolt, and then twist/wiggle the speed sensor out.

[SharkB8]

Is this it?

When it is loosened off the threads, is it supposed to turn the whole cable around with it or should it spin independently of the cable.

The entire cable is turning also, which seems to be preventing it from coming all the way off.

It looks like there is some type of junction in the cable, half way up. Does that come apart? If it comes apart there, maybe the the bottom half of the cable could then turn.

[ftjandra]

Yes, that is it. The junction should come apart, but for the life of me I could never do it...push-pull-turn I tried everything, lol. The big thing on the bottom should turn independently...once unscrewed, it should be able to just slide up the cable and the cable should be able to be disconnected from the actual speedo sensor.

If for some reason, that's not happening, then just remove the speedo sensor with the cable still attached by removing that one 10mm bolt on the base (visible in that pic on the bottom right). That flange right under the bolt head is part of the actual speedo sensor. The sensor is round so turn it back and forth to loosen it and should just pull out. You can pry between the flange and the transmission case, but be careful not to break off the flange, happened to me...

It also acts as the dip stick...this should help:


-F if you have the SOHC motor (one long axle on passenger side)
-G if you have the DOHC motor (intermediate/half shaft bolted to block, then a shorter axle to passenger side)

--Ferdi

[SharkB8]

Great, thanks for the info. I am running out of daylight here but I will pull my car back up onto the ramps and give 'er another quick try.. thanks..

[SharkB8]

I actually got the sensor pulled out, put back in and the speedo still works. Its almost dark so I will wait and do the fluid change another day. Plus I guess I'm going to need a really long funnel.

I am amazed how clean the gear oil is. Its like it was just put in there yesterday, not 100k miles ago. Why does it stay so clean but motor oil is dirty within a couple thousand miles?

[tehstocker99]

once you put the pretty oil in, nothing from the outside gets in it to contaminate, so it just chills in the gear box slushing b/w gears, where as the engine oil does all the nasty work and cycles through the entire engine to lubricate all the parts that get super dirty due to the explosions in the cylinders...if that makes sense.

[SharkB8]

Ah.. motor oil is closer to the combustion.

[therieldeal]

yep, the gear oil is completely sealed inside the gearbox. isolated from combustion and other contaminants.

[SharkB8]

For some reason I thought I needed 8 quarts of fluid, and I only needed about 3.

Rather than taking it back for a refund (I could but the bottles are sort of scuffed up and dirty now), could I use this gear 75w90 gear oil as motor oil in a lawn motor, wood splitter or even my car?

[jay]

Save it for next gearlube change. You should be on about a 30k interval to make the trans live longer.

[therieldeal]

do not use gear oil as engine oil

how did you come up with 8 quarts?

[SharkB8]

A guy at work told me I would need to pick up 8 quarts.

Of course this guy also told me that hydraulic fluid is just as good, and a lot cheaper, so I should have known something was wrong. I'm no mechanic but I thought that for gears, maybe gear oil would be best.

[SharkB8]

BTW, what would happen if I overfill the gear oil area?

Since the oil fill hole is in such a convenient location, I basically just filled it to overflowing, and then siphoned a bunch out with some plastic fuel line until the level was (i think) somewhere close to the top of the plastic mini-gear shown in ftjandra's picture above. I couldn't really tell though - by that point everything within sight was covered in oil. If anything there might be just a bit too much. What would happen if there were a lot too much?

[therieldeal]

with way too much you could have seal leakage problems. if it doesnt start leaking, i wouldnt worry about it.