Author Topic: Strange problem on 126 aircooled 1977  (Read 185 times)

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prkahrvat

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Strange problem on 126 aircooled 1977
« on: July 06, 2019, 02:19:40 PM »
Hello guys after long long time!

First about car:

126p from 1977 with 600cc engine. Engine have 120000 km.

Now about problem:

Two years ago this problem started. When engine is warmish i cannot start it.

Why is it strange? When engine is full cool or full hot it starts like whirligig but when i stop for few minutes it just don't want to start. It spins and spins and there are some signs of life but not enough to start. Now, if i try to start car by pushing it ( few guys push and i try to start) it again starts like whirligig!

It runs like a charm, i even managed 118km/h on highway, runs on idle like a charm but when i stop the engine it just don't want to start if it is warmish. If i stop the engine and after few seconds try to start it (when its full hot), it starts without any problem.

When it is warmish it has spark on both spark plugs, i can see gasoline flowing from fuel pump to carburetor, and starter spins it like it should, fast and strong ( this method is not so accurate because measuring tools are my eyes and ears)

New installed parts:

fuel pump with new hoses
carburetor
air filter
ignition coil (Iskra ATA)
distributor with new capacitor (220nF measured with Fluke instrument), cap, rotor and platinum points
starter
spark plugs (super bosna F65P)
Spark cables and cable from ignition coil to distributor

I exchanged part by part to try to see if there is any difference but without success.

I removed rubber around spark plugs to see if they became conductive somehow but they didn't.

Connected fuel pump to bottle with gasoline to see if it is problem with gasoline or hose from tank to pump, but it wasn't

Connected 10mm2 cable from - battery to ignition coil housing, and from ignition coil housing to engine, just to be sure i have good connection with - battery (even thought i have spark on spark plug all the time). That also didn't help.

Removed air filter and its housing, didn't help

Removed gasoline tank cap (don't know english term for that sorry) so there is no vacuum in tank, didn't help.

I am desperate, really don't know what to do anymore...
It is not so big a deal to wait 30 mins to start it again or find few guys to push me but i cannot pass vehicle registration because they stop the engine on some point...




Sorry for bad english!

Rusty's Uncle

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Re: Strange problem on 126 aircooled 1977
« Reply #1 on: July 06, 2019, 04:01:03 PM »
Have you checked the valve clearances ?

prkahrvat

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Re: Strange problem on 126 aircooled 1977
« Reply #2 on: July 06, 2019, 04:08:52 PM »
Nope, as i remember it should be 0,2mm for inlet and 0,25mm for exhaust?

But if valve difference is bad, shouldn't that make engine run bad cold and hot?

Never the less i will do it. I have nothing to lose. Thank you!
Sorry for bad english!

prkahrvat

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Re: Strange problem on 126 aircooled 1977
« Reply #3 on: July 06, 2019, 04:17:04 PM »
*valve clearance not difference sorry
Sorry for bad english!

DEYAN IYI

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Re: Strange problem on 126 aircooled 1977
« Reply #4 on: July 06, 2019, 07:39:18 PM »
Hi, Tomislav! :)

It sounds not likely a common issue, but check if the push rod of the fuel pump is in a good shape - long enough and not twisted. A friend of mine change 2 fuel pumps,  an used and a brand new one, before he found out that it was not the pump or any electrical problem. It was happening when hot.

Also make sure that the pump or the coil are not overheating. You can cool the pump in case of emergency by using a wet cloth and a bottle of water.

I hope it helps!

Best,
Deyan

Bar Vitelli

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Re: Strange problem on 126 aircooled 1977
« Reply #5 on: July 06, 2019, 10:41:42 PM »
1. Double check (visual check) the spark plugs to make sure that they are still okay
2. Give the carburettor a quick clean (even if it is new) with some carburettor cleaner
3. Check the CO2 using a gastester
Every cloud has one...

dajwid

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Re: Strange problem on 126 aircooled 1977
« Reply #6 on: July 08, 2019, 10:28:37 AM »
Capacitor, do not use cheap ones. always carry a couple. so many are useless.

I'm assuming you have the heat shield in place over the exhaust. if so try wrapping the exhaust.
 when was the oil filter last cleaned out, maybe lack of oil cooling, getting hot very hot?

prkahrvat

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Re: Strange problem on 126 aircooled 1977
« Reply #7 on: July 08, 2019, 08:52:44 PM »





I believe this is a problem. I forgot that i had same problem with my 89' 650cc. After i replaced gasket everything was perfect. Wednesday is a day to test. Car must be finished to 19.7.2019 for Hungary. Wish me luck

Thanks for all support!
Sorry for bad english!

prkahrvat

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Re: Strange problem on 126 aircooled 1977
« Reply #8 on: July 10, 2019, 09:46:17 PM »
It was head gasket... now start like charm! Few more things to do and after that to registration
Sorry for bad english!