3 Spd Troubles

[grslightng02]

Today while driving my GT home from work my transmission seemed to just die out on me. I learned the other day while having the oil changed that the transmission gasket was leaking fluid, but not intensely. One more thing for my fix it list.

So today when my transmission started to slip out of gear (all gears) I tried to manually upshift and downshift. Once in a while the trans would shift back into gear, but only briefly and then would slip out again. I added some transmission fluid and it didn't make much difference.

The one thing I found peculiar was if I put the car in park, and turned the motor off, restarted the car and shifted it into drive, it popped into gear. If I tried to put it back into gear after slipping out, without turning the motor off, it wouldn't do it.

I know someone who has an extra 3spd Auto to replace mine at a reasonable price ($250 I think he said). I would of course have to pay someone to install it. I'm wondering if this isn't just a minor maintenance problem that could be fixed along with a new bell housing gasket. Or should I buy the newer used 3 Spd Auto and swap, or price wise, should I just go for a 4spd or 5spd Stick?

[oldopelguy]

It's almost impossible for the bell-housing gasket on an auto trans to fail, it's an o-ring style and without movement between the two parts it shouldn't happen. What are you using to determine that it has a problem? Or do you mean the oil pan gasket is leaking, because that is a possibility? The new pan gasket will come with a new transmission filter, so it would pay to just get the filter kit and swap it out as well while you're in there.

How are you checking the fluid level in the transmission? You are doing it with a warmed-up transmission, the engine running, with the transmission in park or neutral? And according to the dip-stick it's full?

There really isn't any "newer" auto trans available for your car, all the GT automatics were the same. Just make sure if you're going to replace it that you actually get one out of a GT, the shifter is on the passenger's side unlike on the rest of the Opels here in the US. Swapping it out is actually not that bad a job, hardly worth paying someone to do it unless you simply don't have the tools or space to do it yourself.

Swapping in a 4-speed is just a matter of getting all the parts and turning some wrenches, but sometimes it's difficult to round-up everything. For a 5-speed you would also have to have your current driveshaft made longer which would require a trip to a driveshaft shop. Either way getting your hands on everything you need: pedals, center console, clutch cable, transmission, crossmember, driveshaft, and so on does tend to add up in both time and $.

[namba209]

I'll go along with Stephen on this. Double check you fluid level with the engine up to temp, start the engine then go from park, down through all the gears then back to park, again through all the gears,mand with the engine runnjing check the fluid level. One thing, if you had your tranny serviced, whatever that means. They could have drained the torque convertor too. It takes a while for the fluid to go back in and fill it up, so, even though you had it "serviced" you could still be low on fluid. The other possibility, that could be expensive, is the front pump gears are worn, or the pressure relief valve is stuck open. Both require a teardown to repair.

[grslightng02]

As far as the "newer" 3 Speed, I was referring to a running 3 Speed Auto pulled from another GT. I haven't had the transmission serviced, I just added fluid to it and checked the fluid level while the motor was warm. I'll order an oil pan gasket and transmission filter and try that.

I thought dropping the oil pan was a difficult process though unless you're pulling the motor? That's what I've been told. Is that wrong? Shouldn't you just be able to drain the oil pan, loosen the bolts to the oil pan, remove and clean it, put the new gasket on, new transmission filter in, and reinstall the oil pan?

[BMWonly]

Originally Posted by grslightng02 I thought dropping the oil pan was a difficult process though unless you're pulling the motor? That's what I've been told. Is that wrong? Shouldn't you just be able to drain the oil pan, loosen the bolts to the oil pan, remove and clean it, put the new gasket on, new transmission filter in, and reinstall the oil pan?

Removing the transmission oil pan can be done in minutes, with everything installed. Replacing the engine oil pan gasket requires to unbolt and lower the engine crossmember to get the necessary clearance. I had to do that (after reassembling and installing the engine) when I forgot to install the oil pick-up tube gasket.

[oldopelguy]

Originally Posted by grslightng02 I just added fluid to it and checked the fluid level while the motor was warm.

And with the engine running, right?

It's a big deal; many people try and check their transmission fluid with the engine off. With as many pressure passages and hydraulic servos and such as the auto trans has it's impossible to know how many of them have drained back to the pan at any given time. This means that the only way to ensure you are getting a consistant reading is to make sure every passage and hydraulic component is filled up and check the leftover oil in the pan, ie by having the engine running. Opel knew this, as did every other auto manufacturer, and the marked the dip sticks to corrispond to proper level only in the remainder.

And since all those passages are draining back to the pan, if you do check the fluid level and fill the transmission without the engine running you will always be low on fluid by some ammount once it all pumps up into the transmission. Or, put the other way, a properly filled auto transmission will look significantly overfilled with the engine off.

Without a doubt this is the root cause of nearly every failed Opel auto trans I have ever run across; low oil level because someone checked the level with the engine off. The only other thing I have ever seen kill an Opel auto transmission is towing the car with the driveshaft in.

And removing the transmission oil pan is no big deal, like BMWonly indicated, it's something that can be done in minutes. Hardest part is trying not to spill oil everywhere when you do it.

[Killer Texas GT]

one Item over looked is the vacum lines, verify that the vacum lines are not cracked or split going to the modulater valve, this can cause shifting problems, also.

[RallyBob]

Originally Posted by oldopelguy And with the engine running, right?

And fully warmed up as well...

Don't forget, overfilling is just as bad as underfilling. These TH180's are super-sensitive to oil level, better be within 1/2 pint of the correct level!

[grslightng02]

The car was warm when I checked the fluid level, but the car was not on. I just was not able to have the car on at the time I checked the transmission.

I'll check the fluid level today while warm AND running. I'm also going to order the transmission oil pan and filter kit from Kragen.

[grslightng02]

Today I drained the oil pan for the transmission. I removed the pan, washed it thoroughly and put the new gasket on. To my surprise the transmission insides looked very clean! I replaced the filter and reinstalled the pan. I put a bottle and a half of fluid in and started the engine, shifted throught the gears a few times and let the engine warm up. Checked the fluid and added until it said full.

To my delight the transmission shifted well and ran smooth! Thanks for the advice guys!