Technical engine problems when engine is hot

[PaulSpe]

Hi Guys ím trying to fix the old mans 500 C topolino (1950)
My native language isn't english so to translate into specific mechanics jargon is going to cost me some effort but i'll give it my best shot.

The car used to run fine, a bit neglected but fine. Untill my brother(not techincal!) took it for a spin, the car started to make noise and he drove it home.....
Afterwards me and my dad diagnosed a broken piston pin sleeve on cyl 1, I replaced this sleeve myself and put everything back together and it worked again. Afterwards we never took it for a drive for the next 8 yrs and it became stuck in the garage.

Than we wanted to drive it again and brought it to a garage because i lacked spare time.

Its had a complete overhaul from a specialist garage:
- Compression check
- Engine oil
- Gear oil
- Replaced the ignition, sparkplug condensator, rotor contact etc.
- Fuel pump

And also everything to make the car safe to drive(not mentioning details as they arent engine related)


The problem:
The car (cold) starts fine and runs like a charm. Once it gets to the temp range of 70-80 celcius (158-176F) the car start to hicckup, lose power and fire from the exhaust. As the temp rises further te car becomes undriveable due to lack of power. (176F+)
I find it weird as this is related to engine temp.

I sprayed around the carb with some engine start spray and the engine doesnt seem to be pulling in 'false air'.
Checked the spark plugs and they were black.

the carb is a Weber 22 DRS, using needle: 45 and 92.

Looking for some advice as where to look.

 

[PaulSpe]

Spark plug

 

[IanEmery]

Looks and sounds to me like the choke (enrichment control) on the carburettor is jammed in the on position.

BTW, Your English is just fine, well done.

 

[the hobbler]

These sort of problems are very difficult to diagnose from a distance. Looking at your spark plug,I would say that part (if not all) of your problem is that the engine is running very rich---is the choke staying on? I do have a workshop manual for the A + B + C Topolinos, (my first car was 2 Topolinos which I stripped and built into one car) so will have a brouse through it in case I can see anything that might be pertinant. After a reasonable run, with the engine at correct operating temperature the central electrode of the spark plug should be a light brown colour---not black as it is in your case.

 

[PaulSpe]

Thanks for the reply, externally looking the choke is releasing. The carb was ultra sonic cleaned.

Is there a possibility that the choke gets stick internally?

 

[the hobbler]

Yes. the choke could stick internally. I have had a look at my w/shop manual and it seems that the 'choke' lever operates a small piston in the carb. I say 'choke' as technically it is NOT a choke--it is a fuel enrichment device---there is no second 'butterfly' in the venturi.
Do you have a workshop manual? Although mine is in French, if you would like a copy of the Carb pages, e-mail me direct ( [email protected] )with your home address and I will copy out the relevant pages and post them to you.
As Ian Emery mentioned, your English is excellent---well done.

 

[PaulSpe]

Thanks hobbler, first i will check if i can find a workshop manual at my dads. If not i will definatly mail you.

Ill check for a jetting kit as i should problably go a bit smaller. Any suggestions on how many sizes down i should try?

 

[PaulSpe]

Look what i found, german users manual, it has the tech manual aswell and a manual for the pre war model 500 too. Its made up in english/dutch/german. All i can understand so should get me going.

22nd of august a fellow 500 club member will help me take a thurough look at it.

Ill keep you guys posted.

 

[PaulSpe]

Sooooo. The engine wont ŕeally start,

We checked compression hot and cold, both were ok.
Timed the ignition

Took the carb off and cleaned it. Refitted it with some liquid sealant (and original sealing).
So the car wont start.

Any suggestions as to where this thingy came from? I think its from the carb but i cant find where...?

 

[PaulSpe]

See:

[ame]https://youtu.be/s5XPFmvx0Vo[/ame]

 

[Sirdewd]

Hi Guys ím trying to fix the old mans 500 C topolino (1950)

My native language isn't english so to translate into specific mechanics jargon is going to cost me some effort but i'll give it my best shot.



The car used to run fine, a bit neglected but fine. Untill my brother(not techincal!) took it for a spin, the car started to make noise and he drove it home.....

Afterwards me and my dad diagnosed a broken piston pin sleeve on cyl 1, I replaced this sleeve myself and put everything back together and it worked again. Afterwards we never took it for a drive for the next 8 yrs and it became stuck in the garage.



Than we wanted to drive it again and brought it to a garage because i lacked spare time.



Its had a complete overhaul from a specialist garage:

- Compression check

- Engine oil

- Gear oil

- Replaced the ignition, sparkplug condensator, rotor contact etc.

- Fuel pump



And also everything to make the car safe to drive(not mentioning details as they arent engine related)





The problem:

The car (cold) starts fine and runs like a charm. Once it gets to the temp range of 70-80 celcius (158-176F) the car start to hicckup, lose power and fire from the exhaust. As the temp rises further te car becomes undriveable due to lack of power. (176F+)

I find it weird as this is related to engine temp.



I sprayed around the carb with some engine start spray and the engine doesnt seem to be pulling in 'false air'.

Checked the spark plugs and they were black.



the carb is a Weber 22 DRS, using needle: 45 and 92.



Looking for some advice as where to look.

Did you ever find the solution, was it the oil filter?

 

[the hobbler]

At the moment I don't know where the little cone comes from(but probably the carb). When I get back home (away looking after little grandaughter at the moment) I will look in my w/shop manual to see if I can ascertain what the part is/does.
The fact that the engine originally ran fine with the 45 and 92 jets would lead me to suggest that you leave them 'as is'. The fault is elsewhere---have you checked the spark-plugs after a 'non-start'? If you are getting fuel but no spark, the plugs will be very wet---if you have spark but no fuel, the plugs will come out dry. Knowing which of these scenarios is apparent will be necessary to know in which direction to proceed.

 

[PaulSpe]

So yes I did find out what the problem is (we think).

It was the ignition coil, a friend of my fathers noticed a small dent on the coil. that probably hotwired it giving way out of spec ohm readings.

After replacing the ignition coil for a new one she purs again.

My dad is going to give it a proper test drive coming sunday, I'll keep you informed!

 

[Sirdewd]

So yes I did find out what the problem is (we think).



It was the ignition coil, a friend of my fathers noticed a small dent on the coil. that probably hotwired it giving way out of spec ohm readings.



After replacing the ignition coil for a new one she purs again.



My dad is going to give it a proper test drive coming sunday, I'll keep you informed!

Nice, and is that the same solution to the low oil pressure? Mine seems to do the same starts one tick above 25 then drops as it warms up.

 

[PaulSpe]

I havent noticed that the engine oil pressure is low....