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1969 Opel Gt 1.9 Automatic
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Discussion Starter · #1 ·
Hi guys so my automatic trans on my 1969 Opel gt is leaking. My grandpa and I can't find where the leak is. We think it could be the kick down cable. The trans is leaking on the exhaust pipe. So it smokes a little when you drive it.

Does anyone know where this leak could be?

Thanks Sam
 

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Detritus Maximus
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If the trans cooler lines are on that side, check the fittings and the lines themselves for cracks or pinhole leaks. Especially at brackets or clips, anywhere the line touches anything or is rusty.
 
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Über Genius
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O-ring on the dipstick tube.
 
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Just Some Dude in Jersey
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The kickdown cables usually don't leak, but anything is possible. The speedo cables ARE known for leaking. The housing cracks and the seals in the speedo gear could be old and let fluid through.

The fill tube o-ring might be leaking or the fill tube isn't inserted all the way. It MUST be inserted until the bulge in the tube is tight against the tranny. It could be the cooling lines.

To know for sure, you'll have to spray that whole tranny area with engine cleaner and go for a drive to see if you can spot fresh tranny fluid leaking.

Generally, you have to replace the F+R main seals and install the "deluxe" style of pan gasket. I replace the coolant lines with AN fittings and braided flexible rubber hose. Replace the speedo and kickdown cables and the seals inside the speedo gear.

It's a 50 year old tranny that's been sitting for a long time. Stuff like seals need replacing after all that time. The good news is that the auto trannies are indestructible. Fix the leaks and it will last forever.
 

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The vacuum modulator will go bad over time. It is connected to the vacuum "tree" on the manifold below the carburetor. When the modulator goes bad, fluid is sucked up into the manifold, causing smoke out the exhaust. However, if the vacuum line has deteriorated, not unusual for fifty-year-old neoprene, it could be leaking here as well.
 

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I did remove the automatic transmission in my 70’ GT parts car a long time ago. I probably had the exhaust and intake manifold out but the good news is that somehow the bolts were easier to access than they are on the 4-speed manual transmission bell housing, that is if you were having to remove it. Somebody correct me if I’m wrong, that seems to be the way I remember it but it was a long, long time ago. I’m just trying to be encouraging here.
The best thing to do would be to remove and service it as Gordon suggested.

If it’s not severe enough for that, at least service everything external that you can. I just replaced the speedometer seals on a 50 year old manual transmission and the rubber was so hard I had to break it apart to remove it. The new inexpensive rubber seals from OGTS were so pliable they fit right in place.
It’s always a good idea to clean around the transmission as best you can, drive it around, park it overnight, I always slip a piece of cardboard underneath it and see where it drips when I’m tracing any leak, look straight up and you’ll be in the ballpark to where the leak is.
 

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Detroit,where my home was
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My Ascona with auto-trans used to smoke white shortly on starting and driving away for a few hundred meters and then stopped. After inspection I saw that it was leaking from the fill tube.
After a maintenance when I pulled out the engine and trans I saw that the fill tube was correctly connected but it sat lose in the hole. The culprit was the "O" ring, it was worn out and hard. After replacing it with a new one the smoking was gone.
 

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1969 Opel Gt 1.9 Automatic
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Discussion Starter · #8 ·
Thanks for all the help. Also I forgot to say that the oil is dripping on the outside of the exhaust so it smokes from the passenger side. When we start working on the rockers and seats we might take the trans out. Is it hard to take it out with the engine still in the car? We really don't want to take the engine out because it runs so good and it needs nothing.

Thanks Sam
 

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Just Some Dude in Jersey
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It's a VERY good thing to remove your engine and tranny on an unrestored GT. Drop them both at the same time. You will then be able to do a proper cleaning of the engine and engine compartment and do a proper full regasketing of the engine and tranny. Along the way you will learn valuable things about your car.
 

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Über Genius
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An experienced Opeler can have transmission and engine out in less than 2 hours with the proper tools and an engine lift.
The whole unit comes out the bottom as a full unit.
You won't have to mess with anything that will make it run different when you put it back in, if you choose not to. The only exception might be sealing the intake gaskets..
 
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An inexperienced guy like myself with a helper it took a day carefully putting each fastener etc in a separate categorized numbered plastic bin storage drawer. On a separate piece of paper written down the drawer location of each fastener. Don’t rush it when you’re ready. I also don’t have the lifts, proper hoists etc I just rented an engine hoist and had some clearance/alignment trouble. The key word in First Opels post is “experienced”. My experience was one day out, one day in with a helper.

Eventually you’ll want to pull the engine and transmission as the other guys suggested. Your old gaskets and rubber seals will frustrate you to the point that it’s inevitable. If I were in your shoes I’d stay close to the house and keep driving it around for as long as the fun lasts. No one can blame you, you’re learning how to do the repairs along the way, hopefully you’ll find an external leak somewhere on the transmission.
 

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Discussion Starter · #12 ·
When we start on the body work we might take the trans out maybe even the engine. I won't be able to drive it when doing the body work so I could take the engine and trans out. My grandpa has a pittsburg engine lift.

Also that is my kohler k241 that I restored.

Thanks Sam
436650
436651

Also yes that is a massive back fire. This engine is just so much fun it backfires and is crazy loud.
436653
 

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I just had the same problem on my 73 GT. The shift lever that changes gears on the side of the trans has a seal that will allow fluid to blow onto the exhaust and smoke. It is hard to see the lever as it is just above the pan and the exhaust is very close so it is a narrow gap. I couldn't find it either and had to pay a transmission guy to fix it.
 

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1969 Opel Gt 1.9 Automatic
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Discussion Starter · #14 ·
How much did it cost? And do you think you have to take it to a transmission guy?

Sam
 

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Just Some Dude in Jersey
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It's a simple seal that's pressed in, you pry it out with a screwdriver and press in the new one, just as you would the F+R main seals on your engine or the tranny. It's pretty small, so it might take some difficulty getting it out. I think there are 2, one on each side of the tranny. Mantas have the gear selector lever on the left side of the tranny and the gear selector shaft passes through the tranny from right to left to allow both GT and Manta configurations to be accomplished. In my experience, those gear selector seals never leak or need replacing, so I have never replaced them in 40 years and multiple GT's with autos.
 

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You can replace the seal but as said it is small and will be harder to get out than a main seal. My car had been sitting for15+ years and had gobs of silicone around the trans oil pan so I had an "independent" trans guy change the oil, clean the filter and put a proper gasket on the pan as well as changing the seal. If you can move the exhaust away, it will be much easier to see and do in place.
 

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Just Some Dude in Jersey
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A tip: NO GASKET SEALER ON THE GASKET. The cork or deluxe rubber type gaskets expand with oil absorption to make the seal. The pan bolts are intentionally torqued looser than you think they should be so that the oil can soak into the gasket. Same goes for the engine oil pan bolts. If you are afraid that the bolts will unscrew, put some red Loktite on the bolts before torquing them. The torque is literally just a fraction more than hand tight. Try to make sure that your pan(engine oil pan, too) is flat at the bolt holes where they meet the tranny/engine. Put a straight edge along them to see if they are bent inwards or the pan is bent. Shine a flashlight behind the straight edge to look for light gaps. The pans are remarkably malleable, if you see that the bolt holes are dented inwards, a light tap with a hammer will dent them flat or outwards.

Over the 50 years of these cars, previous owners will often have over tightened the pan bolts and caused the bolt holes to be dented inwards. I myself am guilty of this and didn't learn the proper way until 10 years ago. Auto tranny pans, especially if the trannies have been removed at some point and banged and and bumped around on a garage floor, will often have dented/warped pans. Sometimes people will use the pan as a convenient jack point and warp it with the jack.
 

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A tool is available for this repair :
PMD Products GM Transmission Shifter Seal Remover Installer Turbo 300 350 400 700-R4 4L60 Includes Seal
I have used one of these for years and it's great and fast. HTH
 

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1969 Opel Gt 1.9 Automatic
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Discussion Starter · #19 ·
A tip: NO GASKET SEALER ON THE GASKET. The cork or deluxe rubber type gaskets expand with oil absorption to make the seal. The pan bolts are intentionally torqued looser than you think they should be so that the oil can soak into the gasket. Same goes for the engine oil pan bolts. If you are afraid that the bolts will unscrew, put some red Loktite on the bolts before torquing them. The torque is literally just a fraction more than hand tight. Try to make sure that your pan(engine oil pan, too) is flat at the bolt holes where they meet the tranny/engine. Put a straight edge along them to see if they are bent inwards or the pan is bent. Shine a flashlight behind the straight edge to look for light gaps. The pans are remarkably malleable, if you see that the bolt holes are dented inwards, a light tap with a hammer will dent them flat or outwards.

Over the 50 years of these cars, previous owners will often have over tightened the pan bolts and caused the bolt holes to be dented inwards. I myself am guilty of this and didn't learn the proper way until 10 years ago. Auto tranny pans, especially if the trannies have been removed at some point and banged and and bumped around on a garage floor, will often have dented/warped pans. Sometimes people will use the pan as a convenient jack point and warp it with the jack.
Wait so no gasket sealer on the gasket for the pan?

My car has gasket sealer right there. Does that mean I might need a new pan?

Sam
 

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Can Opeler
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Wait so no gasket sealer on the gasket for the pan?

My car has gasket sealer right there. Does that mean I might need a new pan?

Sam
No, but you do always have to clean off ALL old gasket material anytime you put any gasketed car parts together.

I’ve used gasket sealer on cork gaskets with really good luck. Oil still enters and expands the gaskets from the side. The gasket sealer fills any voids and helps with assembly.
 
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