The Datsun 120Y (B210) had that hotbox under the carb as well... When the engine was cold the exhaust heat hit the "roof" of the exhaust which was right under the twin throat carb. There was a bimetallic spring external to the exhaust "box" which expanded as the engine warmed up and closed a flap up under the "hotspot" deflecting the exhaust away from that hot point. Inevitably at 220k kilometres and 13 years that shaft wore out both sides of the hot box and the shaft then jammed either open or closed....and the flap was not replaceable unless some fancy engineering was done. By that time any OEM complete exhaust manifold was unavailable new.... This manifold heat with the exhaust running alongside the long intake runner was also used by the air cooled Beetles to stop "falling out" of the mixture at all times.... and there was a small stub directing exhaust gases on one exhaust header flange to this cross over pipe which was cast into the ali intake runner...and a "return" on the other side of the engine at a similar stub back into that side's exhaust. Many Beetle engine modifiers couldn't understand the need for exhaust heat to aid uniform mixture but after you have seen 6mm of ice on the outside of an aftermarket manifold with no heat on a cold wet winter day...and with a choking blockage inside caused by ice in those intake runners... then you realise. That's why many carburetor cars have that flap that allows hot air off the outside of the exhaust manifold to be fed into the air intake to the air filter and then the carb... with a thermostatic valve shutting that hot air during acceleration when you want there to be only cold air... and when the ambient air temp is high enough to not need heating.
A very common problem with these old type manifolds….. i open the „tin-box“ and solder the rust holes…..works quite well… Greetings from another 2CV-Workshop😉
The GS also had a manifold similar to this, but it was a cast alloy part. The bottom of the manifold will fail after a while. I think the alloy probably wasn't resistant to something in the exhaust... Even worse, later the inside wall between the fuel/air mix and exhaust would also collapse. Then the engine won't be able to idle, and you have F! All power... Even on the 1.2L engine. Can be fixed with JB Weld or similar and a bit of artistry.
Volkswagen aircolds have the same kind of intake manifold where the exhaust bypasses along the intake. When you put on larger carbs, sometimes the fuel can turn into droplets and fall out of atomization travelling in the long intake runners. Ask me how I know :$ also love the mask I should get one
With the carb air leakage you need to precisely drill out and press in a section of brass bushing which stops the air leaking in, SU make for their carbs a kit for this but not sure if they cover Solex carbs. Once you have the bushing pressed in, you then measure your butterfly shaft and ream out the bushing to take the shaft precisely but not too loose or tight and you could do worse than picking up a NOS butterfly shaft and ream the bushing out to that spec measurement and no more air leaks and good for a few decades at least.
I’m driving a 61 Corvair wagon that I recently recommissioned. Engine is tired and while it sat for years moisture got into the passenger rocker cover and rusted the valve springs. Similar thing happened when I broke an exhaust valve spring. The reversion through the intake cancelled out the other 2 cylinders and causing fuel to spit out the passenger carburetor. Replaced all the springs on the passenger side and gathering parts to rebuild the engine but in a way it’s fun to keep the old girl running.
I've had a similar problem with 2 2CV6 engines where the manifold has had a leak but under the front of the box where inlet and exhaust meet ,I couldn't understand what was the problem either but my good friend Jonno at "Peak 2CV "diagnosed the first one for me.I would never have found it.Great work as usual Seppo
Excellent fault finding...The engine sounds nice and French now.. The idea of venting excess fuel onto a hot engine is completely nuts..😮..Really enjoyed the video..
The fuel will evaporate almost as soon as it drips onto the hot engine. There's not enough of it coming out to cause any problems or risk of fire. They did it that way for many years, apparently it worked well...
What an unexpected failure. Your ability to diagnose and then discover the problem is awesome. I've never worked on one of these engines, and wouldn't have had a clue. But I can surely relate to the feeling, a pit in the stomach that developes as soon as you think it was something you blundered during the rebuild... Congratulations, bravo!
The exhaust going through the hotspot is mainly to atomize the air/fuel mixture better to make the combustion more effective to save fuel. Not uncommon at the time when this engine was designed.
Yeah very common, particularly on air-cooled engines with long inlet tracts, VW beetles/type2s etv have a similar(ish) setup, but it's a small bore pipe that feeds from the exhaust rather than the complete exhaust pipe
That box in the manifold is known as a 'hot spot'. It's there to stop the petrol condensing out on the wall of the manifold especially in cold damp weather. Also stops carb icing. VW used a similar idea on their aircooled engines. Lots of British cars had a combined inlet and exhaust manifold for the same reason.
Good work, Id say all engines with carb's use some sort of preheating of t the intake, to prevent the carb to freeze over. But Citroen used an odd solution ;-)
@@kosir1234...or even electric 'hedgehog' heater in the manifold on many VAG Pierburg carb equipped vehicles. Edit additional. There's manifold heating and separately air intake heating via trunking from the exhaust heat shield which helped to prevent ice forming on the idle control jets. Manifold heating helps with vaporisation when everything is cold. 🥶
My bike *should* have been fitted with glow plugs that screw into the carb throat's metal bits to heat up the parts. It is not. And i suffer from carb freezing at least twice every winter, when it's foggy or rainy and cold. And everytime i'm like 'i should do something about it'. And every time i'm like 'Ugh, i don t feel like it'.
I have seen throttle body heating with a coolant passage on a Fiat Seicento 900 which had a single point injection (one injector before throttle body). It also had the intake air heating. On a Skoda Felicia 1.3 mpi with multipoint injection there was no throttle body heating anymore, but the intake air heater was still present.
The reason for the joined pipework was to aid in vaporising the fuel as it came out of the carburettor, making for a cleaner burn (for a carburetted engine, of course!), I guess over time the partition between the exhaust and intake sides just rotted away causing the engine to breathe it's own bumgas... :P
13:53 if you could translate starter noises into French, that's what they would sound like. Most French cars start like "vivela vivela vivela FranceFranceFranceFranceFrance..."
In the old days (early ‘70s) when even in the Netherlands we still had to make do a friend of mine ran a 2CV specialised workshop, where I started to absorb the ins and outs of fixing cars; at the age of 13 I could do a complete front DRUMbrake overhaul on a 2CV, including centering the brakelinings!!! This guy had a length of fuelresistant transparant hose, and whenever a 2CV came up with this carburetor problem he simply drilled out the bore in the housing so it’ld be sort of round-ish and fitted the shaft of the throttle with a bit of the hose around it…. It worked a treat and that bit of hose was worth every penny it never cost….. BTW PLEASE replace that plastic fuelline with a canvas/rubber type of hose; at times under the bonnet it is too warm for this kind of hose!!
@@kosir1234 But there are specific kits that have Teflon lined steel bushes that can be reamed out for any shaft size that will fit the throttle plates back exactly where it needs to be. They have these kits even for old single cylinder gasoline engines on lawn tractors etc. e.g. Kohler engines
You don't have to tell us why it was designed like this. The answer is well known. It is a French car that has so many totally unique design features throughout the vehicle that not one other manufacturer ever used or copied.
What an unexpected failure. Your ability to diagnose and then discover the problem is awesome. I've never worked on one of these engines, and wouldn't have had a clue. But I can surely relate to the feeling, a pit in the stomach that developes as soon as you think it was something you blundered during the rebuild... Congratulations, bravo!
3:54 wasn't expecting that!. 😅
An accidental EGR system! Nicely diagnosed and fixed. Well done.
The Datsun 120Y (B210) had that hotbox under the carb as well...
When the engine was cold the exhaust heat hit the "roof" of the exhaust which was right under the twin throat carb.
There was a bimetallic spring external to the exhaust "box" which expanded as the engine warmed up
and closed a flap up under the "hotspot" deflecting the exhaust away from that hot point.
Inevitably at 220k kilometres and 13 years that shaft wore out both sides of the hot box and the shaft then jammed either open or closed....and the flap was not replaceable unless some fancy engineering was done.
By that time any OEM complete exhaust manifold was unavailable new....
This manifold heat with the exhaust running alongside the long intake runner was also used by the air cooled Beetles to stop "falling out" of the mixture at all times....
and there was a small stub directing exhaust gases on one exhaust header flange to this cross over pipe which was cast into the ali intake runner...and a "return" on the other side of the engine at a similar stub back into that side's exhaust.
Many Beetle engine modifiers couldn't understand the need for exhaust heat to aid uniform mixture but after you have seen 6mm of ice on the outside of an aftermarket manifold with no heat on a cold wet winter day...and with a choking blockage inside caused by ice in those intake runners... then you realise.
That's why many carburetor cars have that flap that allows hot air off the outside of the exhaust manifold to be fed into the air intake to the air filter and then the carb...
with a thermostatic valve shutting that hot air during acceleration when you want there to be only cold air...
and when the ambient air temp is high enough to not need heating.
2CV Engine: "Clatter, rattle, clank clank clank chug chug"
2CV Mechanic: "Sounds lovely!"
When it's all bolted back together it will purr like a kitten
A very common problem with these old type manifolds….. i open the „tin-box“ and solder the rust holes…..works quite well…
Greetings from another 2CV-Workshop😉
The GS also had a manifold similar to this, but it was a cast alloy part. The bottom of the manifold will fail after a while. I think the alloy probably wasn't resistant to something in the exhaust... Even worse, later the inside wall between the fuel/air mix and exhaust would also collapse. Then the engine won't be able to idle, and you have F! All power... Even on the 1.2L engine. Can be fixed with JB Weld or similar and a bit of artistry.
Volkswagen aircolds have the same kind of intake manifold where the exhaust bypasses along the intake. When you put on larger carbs, sometimes the fuel can turn into droplets and fall out of atomization travelling in the long intake runners. Ask me how I know :$ also love the mask I should get one
With the carb air leakage you need to precisely drill out and press in a section of brass bushing which stops the air leaking in, SU make for their carbs a kit for this but not sure if they cover Solex carbs. Once you have the bushing pressed in, you then measure your butterfly shaft and ream out the bushing to take the shaft precisely but not too loose or tight and you could do worse than picking up a NOS butterfly shaft and ream the bushing out to that spec measurement and no more air leaks and good for a few decades at least.
@@dodgydruid
S.U Part numbers:
AUD 3079 1/4" bush
AUD 3080 5/16" bush
Teflon coated split steel bush. 🙂
Fit the carb on the manifold first then fit manifold to engine 😊
Getting the engine running correctly is quite a lot of progress in my book. Nice.
3:51 thanks for that, i nearly spilt hot tea on my nuts 😅
I’m driving a 61 Corvair wagon that I recently recommissioned. Engine is tired and while it sat for years moisture got into the passenger rocker cover and rusted the valve springs. Similar thing happened when I broke an exhaust valve spring. The reversion through the intake cancelled out the other 2 cylinders and causing fuel to spit out the passenger carburetor. Replaced all the springs on the passenger side and gathering parts to rebuild the engine but in a way it’s fun to keep the old girl running.
I've had a similar problem with 2 2CV6 engines where the manifold has had a leak but under the front of the box where inlet and exhaust meet ,I couldn't understand what was the problem either but my good friend Jonno at "Peak 2CV "diagnosed the first one for me.I would never have found it.Great work as usual Seppo
Excellent fault finding...The engine sounds nice and French now.. The idea of venting excess fuel onto a hot engine is completely nuts..😮..Really enjoyed the video..
I think it is supposed to have a copper pipe soldered to the hole and the pipe gets routed down clear of the engine
The fuel will evaporate almost as soon as it drips onto the hot engine. There's not enough of it coming out to cause any problems or risk of fire. They did it that way for many years, apparently it worked well...
I thought that was a lot of progress. Well done! What a quirky unique engine.
Interesting little engines aren't they? Some good detective work saves the day.
What an unexpected failure. Your ability to diagnose and then discover the problem is awesome. I've never worked on one of these engines, and wouldn't have had a clue. But I can surely relate to the feeling, a pit in the stomach that developes as soon as you think it was something you blundered during the rebuild... Congratulations, bravo!
The exhaust going through the hotspot is mainly to atomize the air/fuel mixture better to make the combustion more effective to save fuel. Not uncommon at the time when this engine was designed.
Yeah very common, particularly on air-cooled engines with long inlet tracts, VW beetles/type2s etv have a similar(ish) setup, but it's a small bore pipe that feeds from the exhaust rather than the complete exhaust pipe
Good work. You'll be taking us for a drive pretty soon then.
That box in the manifold is known as a 'hot spot'. It's there to stop the petrol condensing out on the wall of the manifold especially in cold damp weather. Also stops carb icing.
VW used a similar idea on their aircooled engines.
Lots of British cars had a combined inlet and exhaust manifold for the same reason.
Good work, Id say all engines with carb's use some sort of preheating of t the intake, to prevent the carb to freeze over. But Citroen used an odd solution ;-)
not all, some use exhaust, but many use engine coolant for heating :)
@@kosir1234...or even electric 'hedgehog' heater in the manifold on many VAG Pierburg carb equipped vehicles.
Edit additional.
There's manifold heating and separately air intake heating via trunking from the exhaust heat shield which helped to prevent ice forming on the idle control jets. Manifold heating helps with vaporisation when everything is cold. 🥶
My bike *should* have been fitted with glow plugs that screw into the carb throat's metal bits to heat up the parts. It is not. And i suffer from carb freezing at least twice every winter, when it's foggy or rainy and cold. And everytime i'm like 'i should do something about it'. And every time i'm like 'Ugh, i don t feel like it'.
@@kosir1234 I stand corrected, and have updated my posting.
I have seen throttle body heating with a coolant passage on a Fiat Seicento 900 which had a single point injection (one injector before throttle body). It also had the intake air heating. On a Skoda Felicia 1.3 mpi with multipoint injection there was no throttle body heating anymore, but the intake air heater was still present.
Brilliant video as always
Good job getting the engine running.
The reason for the joined pipework was to aid in vaporising the fuel as it came out of the carburettor, making for a cleaner burn (for a carburetted engine, of course!), I guess over time the partition between the exhaust and intake sides just rotted away causing the engine to breathe it's own bumgas... :P
Well done
Godt med gode naboer 😊😊😊👍👍👍
Indeed!!
Seems like this engine invented its own primitive version of EGR :)
brilliant analysis.
More progress that's another job ticked of the list and now your Citroen van starts on the button
This old girl really put up a fight. I like that.
Great work as always!!
You bought that Mask mask just to make that joke, didn't you? 🤣
I liked that as well!!
13:53 if you could translate starter noises into French, that's what they would sound like.
Most French cars start like "vivela vivela vivela FranceFranceFranceFranceFrance..."
In the old days (early ‘70s) when even in the Netherlands we still had to make do a friend of mine ran a 2CV specialised workshop, where I started to absorb the ins and outs of fixing cars; at the age of 13 I could do a complete front DRUMbrake overhaul on a 2CV, including centering the brakelinings!!!
This guy had a length of fuelresistant transparant hose, and whenever a 2CV came up with this carburetor problem he simply drilled out the bore in the housing so it’ld be sort of round-ish and fitted the shaft of the throttle with a bit of the hose around it….
It worked a treat and that bit of hose was worth every penny it never cost…..
BTW PLEASE replace that plastic fuelline with a canvas/rubber type of hose; at times under the bonnet it is too warm for this kind of hose!!
Guess somethings clogging a bit hard, did you messure the tolerances on the Interiors? besides a new shaft and two bushes could save your carb 😀
its hard to machine worn out carbs, if you just drill trough, the butterfly wont be in the precise location it needs to be.
@@kosir1234
But there are specific kits that have Teflon lined steel bushes that can be reamed out for any shaft size that will fit the throttle plates back exactly where it needs to be.
They have these kits even for old single cylinder gasoline engines on lawn tractors etc. e.g. Kohler engines
You don't have to tell us why it was designed like this. The answer is well known. It is a French car that has so many totally unique design features throughout the vehicle that not one other manufacturer ever used or copied.
Air cooled Beetles...and the Datsun 120Y (B210) had similar systems....
Hvad slags blæser har du brugt til dit sug?
What an unexpected failure. Your ability to diagnose and then discover the problem is awesome. I've never worked on one of these engines, and wouldn't have had a clue. But I can surely relate to the feeling, a pit in the stomach that developes as soon as you think it was something you blundered during the rebuild... Congratulations, bravo!