Transmission rattle? 87' GL manual dual range 4x4

[Brianmitchtay]

Hi all, I've been trying to figure out the source of a new rattle coming from my Ol' wagon and I'm stumped, hoping maybe someone here might be more experienced and have a better idea. My guess is the transmission but I'm not sure how or what about it.

 

I get a sort of rotary metallic rattling that happens mostly in the first three gears, barely audible in 4th and fifth. It almost sounds like an exhaust shield vibrating but it stops immediately if I pull it out of gear or even just push in the clutch. (So I'm pretty sure it's the transmission) It's at its very loudest when the car is cold, going up a hill in second gear, downhill it reduces to a gentle whine, it also gets less noticeable after the car has been running a while.

 

It sounds like it's coming almost directly from below the shifter, and my first thought was "Gee, I must be low on transmission oil" but taking a look it shows to be ever so slightly over full. 

I'm trying to think of anything it could possibly be that isn't the transmission (Mostly because if it's the transmission I won't even know where to start fixing it) and the only thing I can come up with is maybe the cv axle?

 

When I bought the car the guy selling it offered me a spare transmission and I didn't take it because I don't have a garage and didn't want to be running around with a spare tranny in the back all the time!! Ooof, feeling pretty stupid about that now. 

Any thoughts are appreciated, I'm hoping to be able to get some free days here to tear it apart sometime in the next few weeks, here's hoping it's not such a serious issue that my subie blows up on me before then. Doesn't seem to be, as it doesn't effect performance at all.

 

Cheers, 

Brian

[el_freddo]

Gday Brian,

 

Firstly, what model Subaru are we talking about? The four and five speed are quite different.

 

It sounds like an odd issue, I’m looking forward to working out what it is

 

Cheers

 

Bennie

[Brianmitchtay]

Hi there Bennie, this is a 5 Spd manual dual range 4x4 1987 GL Wagon with the 1.8L SPFI EA82 engine. I appreciate you having fun with the diagnosis guessing game! I'll for sure post back here with pictures and updates as it comes along and I figure things out. So far I know one of my front wheel bearings is going so I'll have to tear the out soon and I'll take a better look at it all then.

 

I took it to a mechanic today to get some thoughts on what it might be and his best guess was it might be the rear U joint on my driveline coming out the back of the tranny, which sounds about right for the intermittent rotary ticking, (which I failed to mention at all in my OP, ha)  I'm not really familiar with the ins and outs of those joints, so I'm looking forward to a weekend when I can get down to my storage unit to pull out the factory service manuals and have a look to see if that makes sense. 

 

Cheers from Utah

[el_freddo]

If it’s a uni joint you’ll also get an oscillating vibration at a set speed. Uni joints are easy to check: hold the two parts of the uni joint that connect to the yoke (the centre piece that looks like a cross - best description I can give), try twisting each hand in the opposite direction. Do this in both directions and look for movement at the bearing caps getting closer or further from the two parts, or feel for movement and possibly clicking.

 

Once you’ve experienced a dead uni joint you’ll know what you’re looking for. Youtube may have a video of this check to help guide you.

 

L series uni joints are not replaceable without some machine work. Over here it’s common to change the uni joints to accept a Mitsubishi or old Holden unit if going down this route.

 

If you get a ticking sound that is speed dependent in a particular gear you have a chipped gear tooth. I’ve not heard of multiple gears having a chipped tooth at the same time. I also can’t explain how you chip a tooth but have seen it once on first gear on a Gen2 ej22 liberty (legacy).

 

Cheers

 

Bennie

[Brianmitchtay]

Ok so I finally got the opportunity to really take a good look at things down under and I believe what I have going on is a combination of some exhaust shield rattle(is that common on these?) And a uni joint that's right on the edge of going out, it has the tiniest bit of play in it, is pretty rusted all around, and has been replaced before, as evidenced by the grease port and the snap rings.

 

First I'm going to try just greasing it to see how that serves, and if things don't get significantly better I'll just pull the prop shaft and replace the joint since I found one on Rockauto for $4 anyway; should be easier to do since the original stakes have already been milled out!

[DaveT]

Exhaust shields rattle.

The grease may quiet the bad u joint, but it won't save it, it's dead. Get a new one on the way, but don't panic.