Technical Reviving 500L

[criceo]

Hello all,

It's been a year and a few cars since my '72 500L quit on my suddenly, and it's been languishing in my mechanic's lot, waiting for resurrection. Now that I'm narrowing my fleet, I have time and resources to focus on this car.

A recap of events: the car quit during the return of its first road trip on the exit ramp from the gas station. I managed to get it home, but it would die without full throttle and made a horrible rattling noise. What had happened was the rod connecting the thermostat to the fan shroud flap had come loose, causing the engine to overheat and the head to crack. After replacing the head, reboring the cylinders, fitting new pistons, replacing the carb, and installing an electronic ignition system, the car ran .... for less than a day. On its first drive on parkways it couldn't react the 55+ mph it could before. Then, suddenly, it lost power and wouldn't do more than ~35 mph. Then 30 mph, then 25mph, and eventually just wouldn't start at all. It would try to catch when cranking at full throttle and choke, but it would never start. My mechanic, in between working on my other cars, has tried checking compression and cleaning the carb. Seems like we have good fuel flow and compression. Unfortunately, nothing has seemed to fix the situation. And so it has sat.

But this car's time has come, and I have a list of options to go through before choosing the "nuclear option" of buying a fully outfitted 650cc engine. First is to check that my coil is getting a full 12 volts. Next is to remove the electronic ignition and reinstall the old points and condensor. Third is to get a new carb from a reputable source. Putting the old carb on has allowed the car to run, though from what I gather inconsistently and with an idle that won't stay proper. If anyone has a source for good carbs, aka not knock offs made in God-knows-where Eastern Europe, I would appreciate the help. I will try other fixes if I can find some that are worthwhile and promising, which I hope some people here can think of. The final step is to just stop throwing time and money at this lump and spring for a fully equipped 650cc engine. If I do so, I may sell my current engine, accoutrement and all. I may also mount it and display it in my home.

So, suggestions for possible fixes would be appreciated. Info on any difficulties you've encountered when swapping for one of those bigger engines would also be appreciated. I've heard that the transmission bell housing requires modifications to accomidate a different starter placement on the 126 engines, but don't know what modifications specifically or if there are ready-modified bell housings for sale. Would you believe this car has proved more obstinate to being repaired than the old Jags and Bentleys/RRs that I usually drive/deal with.

Merry Christmas to all

 

[dweebit]

Hello all,

It's been a year and a few cars since my '72 500L quit on my suddenly, and it's been languishing in my mechanic's lot, waiting for resurrection. Now that I'm narrowing my fleet, I have time and resources to focus on this car.

A recap of events: the car quit during the return of its first road trip on the exit ramp from the gas station. I managed to get it home, but it would die without full throttle and made a horrible rattling noise. What had happened was the rod connecting the thermostat to the fan shroud flap had come loose, causing the engine to overheat and the head to crack. After replacing the head, reboring the cylinders, fitting new pistons, replacing the carb, and installing an electronic ignition system, the car ran .... for less than a day. On its first drive on parkways it couldn't react the 55+ mph it could before. Then, suddenly, it lost power and wouldn't do more than ~35 mph. Then 30 mph, then 25mph, and eventually just wouldn't start at all. It would try to catch when cranking at full throttle and choke, but it would never start. My mechanic, in between working on my other cars, has tried checking compression and cleaning the carb. Seems like we have good fuel flow and compression. Unfortunately, nothing has seemed to fix the situation. And so it has sat.

But this car's time has come, and I have a list of options to go through before choosing the "nuclear option" of buying a fully outfitted 650cc engine. First is to check that my coil is getting a full 12 volts. Next is to remove the electronic ignition and reinstall the old points and condensor. Third is to get a new carb from a reputable source. Putting the old carb on has allowed the car to run, though from what I gather inconsistently and with an idle that won't stay proper. If anyone has a source for good carbs, aka not knock offs made in God-knows-where Eastern Europe, I would appreciate the help. I will try other fixes if I can find some that are worthwhile and promising, which I hope some people here can think of. The final step is to just stop throwing time and money at this lump and spring for a fully equipped 650cc engine. If I do so, I may sell my current engine, accoutrement and all. I may also mount it and display it in my home.

So, suggestions for possible fixes would be appreciated. Info on any difficulties you've encountered when swapping for one of those bigger engines would also be appreciated. I've heard that the transmission bell housing requires modifications to accomidate a different starter placement on the 126 engines, but don't know what modifications specifically or if there are ready-modified bell housings for sale. Would you believe this car has proved more obstinate to being repaired than the old Jags and Bentleys/RRs that I usually drive/deal with.

Merry Christmas to all

In your situation, I might consider swapping out the engine for an electric conversion!

 

[the hobbler]

In your situation, I might consider swapping out the engine for an electric conversion!

Part of the pleasure of a 500 is its quirks, and the pleasure driving it will give you. Going to car shows and putting among the Ferrari and Lamborghini cars is a guarenteed way of really jaring them off, and having a queue of people wanting to talk to you and relate their adventures and memories of these little beauties. The fitment of an electric conversion will remove a lot of those pleasures, as well as being very expensive, Due to its size (or rather, lack of) not many batteries can be fitted into the 500, which severly limits their range

 

[fiat500]

Part of the pleasure of a 500 is its quirks, and the pleasure driving it will give you. Going to car shows and putting among the Ferrari and Lamborghini cars is a guarenteed way of really jaring them off, and having a queue of people wanting to talk to you and relate their adventures and memories of these little beauties. The fitment of an electric conversion will remove a lot of those pleasures, as well as being very expensive, Due to its size (or rather, lack of) not many batteries can be fitted into the 500, which severly limits their range

I second all of that. The smells, sounds and feel of a petrol-engined Fiat 500 are unique and make it into a living creature. An electric motor makes it simply an oddball novelty for buzzing around short distances.

Watch this video to the end and you'll see the owner of a supercar collection given an expression of joy that I haven't seen in his responses in many other videos of extremely high-end cars:

 

[fiat500]

Part of the pleasure of a 500 is its quirks, and the pleasure driving it will give you. Going to car shows and putting among the Ferrari and Lamborghini cars is a guarenteed way of really jaring them off, and having a queue of people wanting to talk to you and relate their adventures and memories of these little beauties. The fitment of an electric conversion will remove a lot of those pleasures, as well as being very expensive, Due to its size (or rather, lack of) not many batteries can be fitted into the 500, which severly limits their range

I don't get it that Mark at Motobambino seems to be a great admirer of the electric conversion.

 

[Goldnrust]

Going back to the original post, to expect a 500 to do 55mph+ on its first run with a freshly rebuilt engine, might be pushing it... rebored cylinders with fresh cross hatching from the hone and new rings will run 'tight' and a bit hot for a couple of hundred miles till it all really settles in. In that time it's a good idea not to push the engine too hard for too long as you might overheat it. But that said, obviously it should still run and drive fine and certainly 45-50mph shouldn't be an issue!

It sounds like your mechanic has checked for fuel and compression but you didn't mention checking for a spark? Electronic ignition systems don't especially like being stuck on the side of a 500 engine, right in the path of the hot air coming out of the thermostat flap, on the best of days! Have you got the old points system you could try again as a diagnostic tool to check spark?

As it has decent compression then a valve related issue, or other mechanical problem, seems unlikely, but there's no harm in pulling the valve cover for a bit of a visual inspection to make sure things removing at the right times and that the valve clearances look good etc?

 

[the hobbler]

I don't get it that Mark at Motobambino seems to be a great admirer of the electric conversion.

I have had a ride in Marks 500EV----well engineered and resonably quick, but soulless! I think that Mark has done it to "keep up with the times" more than a love of EV's

 

[fiat500]

I have had a ride in Marks 500EV----well engineered and resonably quick, but soulless! I think that Mark has done it to "keep up with the times" more than a love of EV's

A good assessment.

 

[the hobbler]

A good assessment.

I know Harry (through work)---next time I see him I will have to tease him as which way round 500 ignition leads go!

 

[grubscrew]

From what you say that it got slower and slower, something is getting hot again. If it ain’t toast it could be many things…….fuel/ air ratio, valve gaps too tight, lack of cooling again such as slipping belt. Keep us posted.
As for 15 degrees outside, I could do with some of that!

 

[Bounding Bambino]

Part of the pleasure of a 500 is its quirks, and the pleasure driving it will give you. Going to car shows and putting among the Ferrari and Lamborghini cars is a guarenteed way of really jaring them off, and having a queue of people wanting to talk to you and relate their adventures and memories of these little beauties. The fitment of an electric conversion will remove a lot of those pleasures, as well as being very expensive, Due to its size (or rather, lack of) not many batteries can be fitted into the 500, which severly limits their range

Im going to 2nd Toms opinion on this. Again to start off i am in no way against electric conversions or electric drive, im actually quite the opposite as being a tech nut as i was growing up, i was modifying and having fun building some of the fastest electric golf carts at the time (late 90's early 2000's), and had an appreciation for the advancements in electric drive and new battery technologies (change from dc to ac 3 phase motor drives, beginning to see lithium in hobby applications). I daily drive a classic 80's Mercedes, and honestly I think of times i wish it was electric drive (classic benz styling and ride quality, but modern ac drive for performance and efficiency). Swapping out to a ac drive on my Benz would actually imo not be the most sacrilegious thing, some old benz nuts might get their nickers in a knot, but i have a 2nd benz for shows which is all period correct, and one for DD which would be nice to have as electric. Doing electric drive doesn't really subtract from the soul of the car as the power plant isn't the main heart of the car (style and comfort), and i have another original example to tout around. Benz, specifically in their S class cars really tried to make the engine as quite and smooth as possible, something electric drive improves upon so i see no harm done.

The fiat is however different. I feel that a large part of the 500 experience and soul lies in 2 things (styling, and experience). With the engine being a major aspect of the experience. The power or "lack of" along with its unique sound, really ties in the package of the entire car along with the darn simplicity of the engine. I believe it is really a major part of the cars experience, everyone who asks about the car wants to see the engine. lol... I have seen others do electric conversions on the 500, and although i would never want to rain on someones parade, to me, it feels like they removed a major part of the charm of the 500. Seeing videos of folks riding in a electric 500 to me sounds and feels like riding around in a wheelbarrow. The interior echo noises and lack of feedback from the power train really leaves alot to be desired as a complete experience. Some cars can gracefully encompass electric drive conversions, other do not in my opinion.

Do what you want to do that gets YOU the most enjoyment out of your vehicle