Hi There, I wonder if someone would please help with a problem i have with my Polo 1.3 6N1 petrol, single injector, 1995. Mileage 50K

 

I had a couple of issues when we got the very low mileage car earlier this year. I fully serviced it and went through brakes, timing belt, water pump and all the filters etc. H.T leads and coil.

Then it ran fine for a about three months. It then developed a couple of problems, a hydraulic tappet or two started to become intermittently noisy. Also from time to time when on a return journey, where it was not fully cooled down and just a bit warm, it would have trouble starting and if you did get it started it would struggle to idle and drive in a jerky manner. It would be a job to get it home. Then the following day it would start and run fine again, until returning from work/shopping after it had a little time to cool down.

So, by suggestion i then changed the cooling temperature sensor, with no differance. Then the Lamda (o2) sensor, no differance. I also checked the thermostat and vacuum lines. 

 

By this time i was beginning to think there might be a head gasket issue. Although there was no obvious sludge/mayo in the cooling system, there was a small amount of milky mess found in the engine breather box. I had to attend to the noisy tappet so i thought it best to have the head off and do the lot. So a new head gasket, Hydro tappets dissasembled and cleaned/checked, skimmed head, re-lapped valves, new valve stem seals, super clean/de-coke, new exhaust manifold studs (one was broken on the noisy tappet cylinder 1).

Also i checked the black block between the hedgehog and the throttle body. It was fine and no cracks or perishing where apparent. I put in a new gasket at the bottom of the throttle body. New inlet and exhaust gaskets where fitted. The throttle body was spotless and shiny new looking throughout. 

 

After the re-build the engine fired up without ANY hesitation.

More pleasing was that the noisy tappets are gone and the re-starting from tepid is fine.

Also gone is the jerking and kangarooing when driving upon re-start, when it decided to play up. In fact, it drives very smoothly indeed.

 

Only thing left to solve is an idle issue it has. It idles fine when cold, but when warmed up, after say 6-8 miles or so, it struggles to idle and maintains about 900rpm most of the time, but every 6-10 seconds or so it will drop to 500rpm and struggle for a moment, then rise up to correct idle again OR will cut out.

My instinct tells me it may be something simple.

 

Can the idle be adjusted or stabilised somehow??

Could this be a timing issue?, even though the car accelerates correctly and there is no pinking when pushing the car hard up a hill.

Or what about disconnecting the breather hose to see if that is sending some condensation to the air intake?

 

ANY IDEAS, VIEWS OR ADVICE WOULD BE VERY GRATEFUL OF course!!!

 

 

Edited 12 December, 20205 yr by timmypolo1.3
spelling

From how you say the car drives, I wouldn't become too concerned about the timing.

 

I have just read another post, which was not too dissimilar to your problem, albeit on a different model.

 

I would suggest that you take a look at the inside of the distributor cap, rotor arm and the ignition coil (especially where the king lead joins to the coil) - what you are looking for, are what might appear to be pencil lines. If there are any signs of these 'pencil lines' there has been tracking of the high tension current across the insulator. The real cure if any of these problems exist, is to fit a replacement part.

 

As you have already fitted new HT leads, we can discount checking them.

 

It is quite possible that, when the engine starts to warm up, any moisture inside the distributor is vaporised and condenses on the insulation, causing tracking.

 

Don't worry too much about any 'crud' on the cap segments, this is caused by the spark jumping the gap between the tip of the rotor arm and the segments - That's right, it does jump the gap, at no time should the rotor arm actually contact the segments - if id did, it would probably shatter the cap. Obviously, if they are really badly burnt, then it would be as well to replace them.

 

Suggest that you check out the above points and let us know if there is any improvement.

 

Regards

Hi

On 18/12/2020 at 16:37, caretakerplus said:

From how you say the car drives, I wouldn't become too concerned about the timing.

 

I have just read another post, which was not too dissimilar to your problem, albeit on a different model.

 

I would suggest that you take a look at the inside of the distributor cap, rotor arm and the ignition coil (especially where the king lead joins to the coil) - what you are looking for, are what might appear to be pencil lines. If there are any signs of these 'pencil lines' there has been tracking of the high tension current across the insulator. The real cure if any of these problems exist, is to fit a replacement part.

 

As you have already fitted new HT leads, we can discount checking them.

 

It is quite possible that, when the engine starts to warm up, any moisture inside the distributor is vaporised and condenses on the insulation, causing tracking.

 

Don't worry too much about any 'crud' on the cap segments, this is caused by the spark jumping the gap between the tip of the rotor arm and the segments - That's right, it does jump the gap, at no time should the rotor arm actually contact the segments - if id did, it would probably shatter the cap. Obviously, if they are really badly burnt, then it would be as well to replace them.

 

Suggest that you check out the above points and let us know if there is any improvement.

 

Regards

Hi and thank you for your reply on the idling matter.

Great idea, i will have a look in the distributer for signs of condensation and in the areas you say for any tracking.

 

When i had a look at the throttle linkage the other day to see if there is a manual screw stop to prevent the throttle butterfly assembly from closing past a point i found one. It lies at the top of the linkage were the throttle cable is attached. You can access it and turn it with a torx bit from behind the carb after removing a plastic covering plug. I turned it in so it just touches the throttle spigot when the engine was warm and idling at 900-1000 rpm. If i turned it in any further it would increase the idle.

 The only other way i could see of stabilising the idle was with another stop screw at the bottom of the spigot that contacts the idle air control valve push rod. It was at that point i realised that it could well be a faulty control valve that is causing the issue.

Anyway,  just for now i will see how i get on with using the top stop screw as a 'cheat' aid to help the idle getting too low.

Regards Tim

I checked out the distributor and its all very dry and stable in there. 

So at least it isn't that!!

Is vapour lock a possibility? Do your fuel lines run close to anything that would cause the fuel inside to get too hot? 

Have you put anything like bg44k or redex in? 

14 hours ago, Eviljohn said:

Is vapour lock a possibility? Do your fuel lines run close to anything that would cause the fuel inside to get too hot? 

Have you put anything like bg44k or redex in? 

Hi eviljohn I don't think so but i will check on it. Yes i am running the Redex cleaner through it.

Cheers