Technical Help With Transmission Leak

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Technical Help With Transmission Leak

RobertM

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Joined
Mar 23, 2024
Messages
44
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Location
Salt Lake City, Utah
Hi everyone it's been a while, a while back I was the guy who tried to drive across the country in a new (to me) Fiat 500L. I managed to make it from Pennsylvania to Florida to Illinois, a total of 2,600 miles, before the exhaust studs pulled themselves out of the head and I called it quits. Not without many other issues along the way which involved replacing the cap/rotor, plugs a few times, a hand full of condensers, plug wires twice, the entire fuel system from front to back, a front wheel bearing, and tons and tons of transmission fluid from a pretty massive leak.

Fast forward to today and I've had the engine and transmission out, I've removed and replaced the entire suspension, steering box, steering arms, carpet, exhaust, lights, tires, and a bunch of other odds and ends through the car tallying up to over $5,000 and leading to effectively a mechanical restoration, the only thing left on my todo list was to switch to an electronic ignition kit that I have sitting in the box still until today. I drove the car for the first time since tearing everything down and putting it back together to get it to a friend who does alignments at his house to get everything sorted and found out that I should have replaced my idler arm because it appears to be bent at an awkward angle compared to the steering box arm causing tons of bump steer, but in addition to that, upon arriving home I found the issue that is the subject of this thread.

When I pulled the transmission out I removed and replaced all the seals including removing the bellhousing, as that's where I suspected the leak to be originating from. I had a new gasket kit to reseal everything except for the bellhousing, after searching for a while I couldn't find anything for that specific part, I don't know if there is a gasket produced for that part? So I used black RTV, as I've used it for oil pans, and valve covers, etc. in the past with great success. I applied a small bead of it around the perimeter of the bellhousing but unfortunately I still have a leak. The leak is nowhere near as bad, prior to this I was loosing 1qt every 500 or so miles, so topping up the transmission was a normal gas station stop. Now I seem to be loosing about a drop every 5 minutes, to a point where it's livable, but I'd rather not have leaks.

My current course of action is going to be to remove the flywheel cover and see if I can tighten the bottom 3 bolts a little more to see if that's my issue, and before anyone asks I'm sure it's gear oil and not the rear main seal as there was no oil inside of the bellhousing or anywhere near the clutch when I removed the engine and transmission.

If any one has any additional suggestions or can point me to a gasket for that bellhousing I can pop the engine back out and take care of it the correct way!

One final note: I think, unfortunately, my Fiat will be going up for sale soon so if anyone around the western United States is looking for what will hopefully be a very well sorted out 650cc Fiat 500L let me know! I'll likely end up selling it for a bargain comparted to the amount of effort that went into making it what it currently is.
 
Model
500L
Year
1971
Hi everyone it's been a while, a while back I was the guy who tried to drive across the country in a new (to me) Fiat 500L. I managed to make it from Pennsylvania to Florida to Illinois, a total of 2,600 miles, before the exhaust studs pulled themselves out of the head and I called it quits. Not without many other issues along the way which involved replacing the cap/rotor, plugs a few times, a hand full of condensers, plug wires twice, the entire fuel system from front to back, a front wheel bearing, and tons and tons of transmission fluid from a pretty massive leak.

Fast forward to today and I've had the engine and transmission out, I've removed and replaced the entire suspension, steering box, steering arms, carpet, exhaust, lights, tires, and a bunch of other odds and ends through the car tallying up to over $5,000 and leading to effectively a mechanical restoration, the only thing left on my todo list was to switch to an electronic ignition kit that I have sitting in the box still until today. I drove the car for the first time since tearing everything down and putting it back together to get it to a friend who does alignments at his house to get everything sorted and found out that I should have replaced my idler arm because it appears to be bent at an awkward angle compared to the steering box arm causing tons of bump steer, but in addition to that, upon arriving home I found the issue that is the subject of this thread.

When I pulled the transmission out I removed and replaced all the seals including removing the bellhousing, as that's where I suspected the leak to be originating from. I had a new gasket kit to reseal everything except for the bellhousing, after searching for a while I couldn't find anything for that specific part, I don't know if there is a gasket produced for that part? So I used black RTV, as I've used it for oil pans, and valve covers, etc. in the past with great success. I applied a small bead of it around the perimeter of the bellhousing but unfortunately I still have a leak. The leak is nowhere near as bad, prior to this I was loosing 1qt every 500 or so miles, so topping up the transmission was a normal gas station stop. Now I seem to be loosing about a drop every 5 minutes, to a point where it's livable, but I'd rather not have leaks.

My current course of action is going to be to remove the flywheel cover and see if I can tighten the bottom 3 bolts a little more to see if that's my issue, and before anyone asks I'm sure it's gear oil and not the rear main seal as there was no oil inside of the bellhousing or anywhere near the clutch when I removed the engine and transmission.

If any one has any additional suggestions or can point me to a gasket for that bellhousing I can pop the engine back out and take care of it the correct way!

One final note: I think, unfortunately, my Fiat will be going up for sale soon so if anyone around the western United States is looking for what will hopefully be a very well sorted out 650cc Fiat 500L let me know! I'll likely end up selling it for a bargain comparted to the amount of effort that went into making it what it currently is.
Hi everyone it's been a while, a while back I was the guy who tried to drive across the country in a new (to me) Fiat 500L. I managed to make it from Pennsylvania to Florida to Illinois, a total of 2,600 miles, before the exhaust studs pulled themselves out of the head and I called it quits. Not without many other issues along the way which involved replacing the cap/rotor, plugs a few times, a hand full of condensers, plug wires twice, the entire fuel system from front to back, a front wheel bearing, and tons and tons of transmission fluid from a pretty massive leak.

Fast forward to today and I've had the engine and transmission out, I've removed and replaced the entire suspension, steering box, steering arms, carpet, exhaust, lights, tires, and a bunch of other odds and ends through the car tallying up to over $5,000 and leading to effectively a mechanical restoration, the only thing left on my todo list was to switch to an electronic ignition kit that I have sitting in the box still until today. I drove the car for the first time since tearing everything down and putting it back together to get it to a friend who does alignments at his house to get everything sorted and found out that I should have replaced my idler arm because it appears to be bent at an awkward angle compared to the steering box arm causing tons of bump steer, but in addition to that, upon arriving home I found the issue that is the subject of this thread.

When I pulled the transmission out I removed and replaced all the seals including removing the bellhousing, as that's where I suspected the leak to be originating from. I had a new gasket kit to reseal everything except for the bellhousing, after searching for a while I couldn't find anything for that specific part, I don't know if there is a gasket produced for that part? So I used black RTV, as I've used it for oil pans, and valve covers, etc. in the past with great success. I applied a small bead of it around the perimeter of the bellhousing but unfortunately I still have a leak. The leak is nowhere near as bad, prior to this I was loosing 1qt every 500 or so miles, so topping up the transmission was a normal gas station stop. Now I seem to be loosing about a drop every 5 minutes, to a point where it's livable, but I'd rather not have leaks.

My current course of action is going to be to remove the flywheel cover and see if I can tighten the bottom 3 bolts a little more to see if that's my issue, and before anyone asks I'm sure it's gear oil and not the rear main seal as there was no oil inside of the bellhousing or anywhere near the clutch when I removed the engine and transmission.

If any one has any additional suggestions or can point me to a gasket for that bellhousing I can pop the engine back out and take care of it the correct way!

One final note: I think, unfortunately, my Fiat will be going up for sale soon so if anyone around the western United States is looking for what will hopefully be a very well sorted out 650cc Fiat 500L let me know! I'll likely end up selling it for a bargain comparted to the amount of effort that went into making it what it currently is.
there is NO gasket between the actual gearbox body and the bell-housing----this is a "metal-to-metal" joint. A small bead of gasket 'goo' is normally sufficient to prevent any oil-leak. Fiat used to give the instruction that the gearbox casing and the bell-housing should always be changed together if one or the other parts needed renewal---but nobody ever did! Check the drive-shaft boots and their retainers----a known source of gearbox leaks. Just as a matter of interest, why, after all the trouble you had collecting the car, and all that you have since spent on it. are you selling the car?
 
there is NO gasket between the actual gearbox body and the bell-housing----this is a "metal-to-metal" joint. A small bead of gasket 'goo' is normally sufficient to prevent any oil-leak. Fiat used to give the instruction that the gearbox casing and the bell-housing should always be changed together if one or the other parts needed renewal---but nobody ever did! Check the drive-shaft boots and their retainers----a known source of gearbox leaks. Just as a matter of interest, why, after all the trouble you had collecting the car, and all that you have since spent on it. are you selling the car?
I actually replaced the boots and retainers in the process of resealing everything. I think applying a bit more torque to the bolts might be a good idea as well. I need to dig up if there's an official torque spec for it.

As for why I'm selling it, I'm planning on moving into a new house soon-ish, and I'm planning on using the money from the Fiat to prepare my current house for sale and to put toward the down payment on the new house. The car was initially a bit of an impulse buy and a little more forethought would have had me waiting until after I moved. We currently have 4 cars crammed into a 2 car garage with another 2 parked outside, and out of the Corvette, Miata, Mini, and Fiat the Fiat has proved to be the last one I want to hop into to go for a spirited canyon drive.

I'm not in a super big rush to sell it, I plan on listing it for sale for what I've spent on the car + repairs in hopes to not take too big of a loss, and I'm going to continue driving it around as much as possible before it goes, but eventually the need for the money will increase and the price will drop.

I'm sure it won't be too long after it's departure that I delve back into an interesting old Italian car, though I'm thinking it might be a Fulvia next time!
 
there is NO gasket between the actual gearbox body and the bell-housing----this is a "metal-to-metal" joint. A small bead of gasket 'goo' is normally sufficient to prevent any oil-leak. Fiat used to give the instruction that the gearbox casing and the bell-housing should always be changed together if one or the other parts needed renewal---but nobody ever did! Check the drive-shaft boots and their retainers----a known source of gearbox leaks. Just as a matter of interest, why, after all the trouble you had collecting the car, and all that you have since spent on it. are you selling the car?

I actually replaced the boots and retainers in the process of resealing everything. I think applying a bit more torque to the bolts might be a good idea as well. I need to dig up if there's an official torque spec for it.

As for why I'm selling it, I'm planning on moving into a new house soon-ish, and I'm planning on using the money from the Fiat to prepare my current house for sale and to put toward the down payment on the new house. The car was initially a bit of an impulse buy and a little more forethought would have had me waiting until after I moved. We currently have 4 cars crammed into a 2 car garage with another 2 parked outside, and out of the Corvette, Miata, Mini, and Fiat the Fiat has proved to be the last one I want to hop into to go for a spirited canyon drive.

I'm not in a super big rush to sell it, I plan on listing it for sale for what I've spent on the car + repairs in hopes to not take too big of a loss, and I'm going to continue driving it around as much as possible before it goes, but eventually the need for the money will increase and the price will drop.

I'm sure it won't be too long after it's departure that I delve back into an interesting old Italian car, though I'm thinking it might be a Fulvia next time!
The torque setting for the gear-case to bell-housing nuts/bolts is 25 ft-lb (35 Nm). I understand your reasons for selling the car----sadly, only hindsight is 20/20 vision. Lancia 'Fulvia'---brilliant little car, wouldn't mind one myself!
 
No avoiding splitting the bell housing then 😂 I did it recently and it was a job I quite enjoyed, put it together with black heat proof type sealant which I’d very carefully applied but didn’t tighten down fully until some hours had passed, just a gentle nip to begin with.
 
No avoiding splitting the bell housing then 😂 I did it recently and it was a job I quite enjoyed, put it together with black heat proof type sealant which I’d very carefully applied but didn’t tighten down fully until some hours had passed, just a gentle nip to begin with.
You were wise to replace the spigot-shaft seal/bearing housing as a complete unit. The shaft-seal-in these housings can often be real "pain-in-the-bum" to remove, and on a couple of occasions I have not been able to remove the old seal and in the end had to resort to buying a complete housing.
 
No avoiding splitting the bell housing then 😂 I did it recently and it was a job I quite enjoyed, put it together with black heat proof type sealant which I’d very carefully applied but didn’t tighten down fully until some hours had passed, just a gentle nip to begin with.
I think my leak was originally coming from the split anyway though the entire transmission was black and covered in so much junk it was hard to tell. The leak is much slower now than it was as well. It left maybe 5 drops on the ground after it's parked rather than the half pint that it used to.

I haven't gotten a chance to look any further into it, I was going to wait for my new steering idler to come in to really get back into 'Fiat mode'.
 
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