Hello everyone, after the last post and the issue solving my favorit started to give me headaches again. I drove it for some 1500 km and everything was fine, but yesterday after my trip to the capital of Croatia the engine started stuttering, violently jerking in the 1st 3 gears, so from 1st all the way to 3rd gear. The jerking seems to be only between 1000 RPM to 2000 RPM, once the engine is above 2000 RPM, there is no jerking/stuttering of the engine while in motion. I checked the distributor timing today and it was spot on, I have checked all of the spark plugs, they are fine as well. I cleaned the carb with carb cleaner but that did exactly nothing, I changed the ignition coil, but still nothing, no improvement. I'm not sure what the issue is, does anyone have an idea?

Ps, there is also strange noise coming from the engine when accelerating hard, it is like a low rumble, at least that's how it sounds to me. I don't have a vacuum gauge, but my last though was that it might be the head gasket as I read on the forum that the engine will either missfire or jerk when accelerating with a damaged head gasket.

Also, for the love of god I cannot find a fuel filter for my fuel pump, I have been to every mechanic in the town and searching online for a fuel filter for my pump but cannot find it at all

This is what my fuel pump looks like, can anyone help?

Have you put petrol in recently, I have no idea of the quality of petrol supplied from petrol station in Croatia just thinking of possibilities. Any work or parts or add-ons devices to the car recently. Have you checked the HT leads. Have you checked inlet and exhaust manifolds, exhaust system too.

I forget what distributor and rotor arm and distributor cap you have, if any are Chinese made suspect them.

Jerky between 1-2,000 rpm could be a lot of causes.

For head gasket failure you could check for other signs oil in coolant, coolant in oil, coolant loss or bubbling in expansion tank, stuff coming out of the exhaust end and it's colour, engine running warmer. temperature gauge needle showing higher than usual especially when the engine has been put under more load and stress, misfires you might have but for other signs check for what I have forgot with internet lists of 'head gasket failure' - HGF.

For filter do you mean a filter to go in that white fuel bowl - or you could fit a disposable clear see-through in-line filter in the fuel hose before or after the pump.

A video/audio recording of the strange noise might help as would possibly clear good (landscape) photos of your engine bay.

1 hour ago, nta16 said:

Have you put petrol in recently, I have no idea of the quality of petrol supplied from petrol station in Croatia just thinking of possibilities. Any work or parts or add-ons devices to the car recently. Have you checked the HT leads. Have you checked inlet and exhaust manifolds, exhaust system too.

I forget what distributor and rotor arm and distributor cap you have, if any are Chinese made suspect them.

Jerky between 1-2,000 rpm could be a lot of causes.

For head gasket failure you could check for other signs oil in coolant, coolant in oil, coolant loss or bubbling in expansion tank, stuff coming out of the exhaust end and it's colour, engine running warmer. temperature gauge needle showing higher than usual especially when the engine has been put under more load and stress, misfires you might have but for other signs check for what I have forgot with internet lists of 'head gasket failure' - HGF.

For filter do you mean a filter to go in that white fuel bowl - or you could fit a disposable clear see-through in-line filter in the fuel hose before or after the pump.

A video/audio recording of the strange noise might help as would possibly clear good (landscape) photos of your engine bay.

Yes I did. On my way back from Zagreb I poured petrol to the top (spilled some on the floor as well lol). As far as my Skoda has been able to tell me, the best petrol in Croatia is from Shell petrol stations, next in line comes Petrol/Crodux and the last place is INA. I worked for 3 years there and the rumours were that their fuel was the worst which by my experience I can totally confirm. As far as the HT leads go, they are brand new and I did check them, they are fine. I did not check the inlet/exhaust manifolds, except I did spray a good ammount of carb cleaner around the inlet manifold in hope of finding a vacuum leak. Today the car has been acting weird in neutral, like it has a vacuum leak, but there was no success on my part in finding one. I didn't try the soapy water method yet as I am currently scared of turning on my Skoda. A little bit before I read your response I was looking for a possible vacuum leak and looked right towards the coolant expansion tank and noticed some bubbles, but didn't think much of it. As soon as I read your post it all kinda clicked together. The loss of power in 5th gear on highway when I went to Zagreb. I noticed that as I go higher in gears the tachometer goes lower and lower (I was driving the car in 5th gear and it took me like 2 minutes for the car to reach from 80 kmph to 100kmph and the tachometer did not go above 2100 rpm, which I found really strange ( it went like this, in neutral the tachometer can go to the red line, in 1st gear it goes to about 4000 rpm, in 2nd gear it goes to 3000 rpm, in third hear also 3000 rpm but gets stuck at 2500 and then jumps to 3000, in 4th gear it goes to 2500, not any higher and in 5th gear it goes to 2000 - 2100 not any higher even if I am flooring the gas pedal. Regarding the distributor, the original one that came with the car is fitted. As far as the video of the strange noise goes, as I said I won't be filming that until I change my head gasket, even if it is in good shape somehow I am still going to change it just so that my mind can be at peace about the head gasket.

Edited 4 June4 Jun by Joja2k

Edited 4 June4 Jun by Joja2k

Here is a link of a short test on my yard.

As you can see in the video, I am holding my foot steady on 1500 rpm but the engine starts to lose power, it is noticable and then when I let go of the throttle, it almost stalls.

Regarding the previous pictures, the ignition coil is new, and I changed it yesterday, the ignition amplifier as well, I know the ignition amplifier is a Chinese one, but there is absolutely no difference in the car's operation between the new one and the original one ( I took them both for a test drive).

Also there are pictues of the engine bay and the instrument board as well.

I lost my post so this will be a shorter version of it.

You have made your mind up on HGF so when the head is off you can closely look at the cylinder block and head and all that is inside both. When you have all back together again of course you will need to check and adjust as required the valve clearances again and check and adjust as required all that follows in the set up chain of checks.

Despite what I put later in the video the "rev counter" needle is steady and moves well.

I am not criticising you just trying to help you now and for the near and further future, the things I highlight in the following photos may not at present be causing any issue(s), or they might, but you would be best to tidy up the wiring and cable routing and secure as required, independent of other cables, wires and hoses, so as not to possibly cause issue(s0 in the future and to tidy up or redo crimp connections for better more secure fit and location and prevent moisture or other ingress, shrink-wrap over secure good crimped joins or use connectors with shrink-wrap covers already on them. The wire to connectors has to be a good solid clean connection that is secure and protected.

You don't want wires and cables touching or other wires or cables or against other items particularly metal items like hose clips.

Hose clips are best as close to fit size as possible (allowing for getting them on).

Coolant level in photo is between 'Max' and 'Min' lines so OK as long as that level hasn't drop too much and too fast from where it previously might have been (subject to levels taken at about same temperatures).

That's all I can remember, so on to photos.

If these are for the "rev counter" then at least it seems to be working good, but more thread protruding passed the nut would be good (without damaging anything of course)

Under the 'Media Options' symbol added to the photo, very top right - see below., Oversized cheap hose clip would be good to replace at some point perhaps. HT lead pushing against wire may not be good for either, if you pull a little of he HT cable back behind the HT leads separator comb this might be sufficient.

A poor looking connection on this, that could get contaminated and the wire(s) could get fatigue and break causing poor connection and readings, that needs sorting as soon as possible and reconnecting or new connection with wire insulation inside connector sleeve and wire(s) firmly connected to connector.

On coil, again yellow wire to crimp connector is poor and unprotected. At hose clip the "king lead" HT cable from coil to distributor the HT lead is touching the hose clip screw, so too is the white wire, both are touching each other and one is wrapped round the other, both want to be clear of each other and the hose clip, the white wire obviously want to avoid being near the drive belt if it needs securing.

Poor electrical connection can cause all sorts of issues and be intermittent and difficult to find so it is best to prevent as many possibilities of this as you can and it is good practice to have wires, cables and hoses as well routed and not crossing or touching as possible. Also to keep all electric and other connections as clean, secured and protected as possible.

HTH.

As always let us know how you get on.

Edited 4 June4 Jun by nta16
resize photo

17 hours ago, nta16 said:

I lost my post so this will be a shorter version of it.

You have made your mind up on HGF so when the head is off you can closely look at the cylinder block and head and all that is inside both. When you have all back together again of course you will need to check and adjust as required the valve clearances again and check and adjust as required all that follows in the set up chain of checks.

Despite what I put later in the video the "rev counter" needle is steady and moves well.

I am not criticising you just trying to help you now and for the near and further future, the things I highlight in the following photos may not at present be causing any issue(s), or they might, but you would be best to tidy up the wiring and cable routing and secure as required, independent of other cables, wires and hoses, so as not to possibly cause issue(s0 in the future and to tidy up or redo crimp connections for better more secure fit and location and prevent moisture or other ingress, shrink-wrap over secure good crimped joins or use connectors with shrink-wrap covers already on them. The wire to connectors has to be a good solid clean connection that is secure and protected.

You don't want wires and cables touching or other wires or cables or against other items particularly metal items like hose clips.

Hose clips are best as close to fit size as possible (allowing for getting them on).

Coolant level in photo is between 'Max' and 'Min' lines so OK as long as that level hasn't drop too much and too fast from where it previously might have been (subject to levels taken at about same temperatures).

That's all I can remember, so on to photos.

If these are for the "rev counter" then at least it seems to be working good, but more thread protruding passed the nut would be good (without damaging anything of course)

Under the 'Media Options' symbol added to the photo, very top right - see below., Oversized cheap hose clip would be good to replace at some point perhaps. HT lead pushing against wire may not be good for either, if you pull a little of he HT cable back behind the HT leads separator comb this might be sufficient.

A poor looking connection on this, that could get contaminated and the wire(s) could get fatigue and break causing poor connection and readings, that needs sorting as soon as possible and reconnecting or new connection with wire insulation inside connector sleeve and wire(s) firmly connected to connector.

On coil, again yellow wire to crimp connector is poor and unprotected. At hose clip the "king lead" HT cable from coil to distributor the HT lead is touching the hose clip screw, so too is the white wire, both are touching each other and one is wrapped round the other, both want to be clear of each other and the hose clip, the white wire obviously want to avoid being near the drive belt if it needs securing.

Poor electrical connection can cause all sorts of issues and be intermittent and difficult to find so it is best to prevent as many possibilities of this as you can and it is good practice to have wires, cables and hoses as well routed and not crossing or touching as possible. Also to keep all electric and other connections as clean, secured and protected as possible.

HTH.

As always let us know how you get on.

The pictures of the instrument board were taken just before I reassembled it back, to everything should be fine there. I will secure the electrical connections in a few days when my parts arrive. Then I will also change the head gasket.

But a quick question. I am also suspecting a vacuum leak at the carburettor spacer plate as it's a cheap one. When I was replacing the carburettor spacer plate I did everything as Ricardo said in a certain post but recently I got a hold of gasket paper of 1.5mm thickness and I feel like that would do a much better job at sealing rather than Reinzosil alone at the spacer plate. As I wrote in a previous comment I couldn't find a vacuum leak with a carb cleaner, and I don't understand why, I even tried using a homemade smoke machine but still no luck. It was like that even on the first try when there actually was a vacuum leak. Can anyone explain why I couldn't find the vacuum leak at all? I tried the carb cleaner method on the first try and spent 2 500ml bottles but no luck, then 30 minutes trying with a smoke machine but still no luck. Anyways back to the question.

Can a vacuum leak cause the jerky engine as it's in my case and could it be that after just approx 1500 - 2000 km driven the seal broke on the carburettor?

Cheers!

Others, particularly those with Favorits or late RWD, might have different ideas, explanations and answers than me.

Any electric connections that are not good I would redo, the wires want to be clean, fully and firmly connected and fully protected, same for connectors as appropriate, you don't want to have potential problems even if they are not problems at the moment, poor connects can be very restrictive or intermittent.

I would not want to speculate why you didn't find a leak as I don't really remember the engines and carb set up at all and I was there with you when you were looking. Using carb cleaner is perhaps an expensive choice particularly after the area is cleaned.

I have no idea if 1.5mm gasket paper is as good choice or not and don't know if you are using it only one or both sides of spacer but if using a sealant that does have to be applied correctly with both surfaces clean and not have excess sealant going inside where it might come off and clog or stick elsewhere internally whereas paper if you cut it right (scissors, hole punches, ball pein hammer) paper should stay where it is put.

You have not said you have a vacuum or any other sort of leak yet this time so they might not be any to cause the issue. Have you checked all nuts and fixings on carbs and manifolds are all tight, can you hear any hissing or blowing, perhaps using some sort of ear-trumpet.

In your video the engine was being held back or restricted from going above 1500rpm, with just a leak I would have thought revs would have been fluctuating more, but never discount contributing (even contra) factors or issue(s).

If you still have the old coil and it works OK you could try swapping that back in. As well as electric/electronic you could also check all mechanical operations move freely and are unrestricted, sometimes need two people for that, one operating from drivers seat and other looking engine bay end.

But you might just as well wait now until you remove the head, as you disconnect and remove parts take you time before removing them and have a good look at their fitting and movements if appropriate as you might see issues, then when remove check part and attachment and fittings for being correct, note anything that might not quite look or operate correctly or fully. Same for when you got to put things back together - don't just take thing off and put them back on again the same, check the parts and the fitting and attachments to the part. You are not in a race with anyone else or yourself to get the job completed as quickly as possible your aim is to successfully find and sort your problem(s) and not potentially leave or introduce more problems now or later.

Do not dismiss or ignore anything that doesn't fit in with your assumptions or theories of what might be wrong or the causes.

Others will know more than me but I do have decades of experience of old car problems and owners with less time and experience fault finding and repair - but of course I am often wrong and/or don't know other than the basics which can rarely be ignored.

Good luck.