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Stalling when pulling away after head gasket change


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NebulaicToaster

I did a full head gasket change recently, new gaskets seals water pump belt and skimmed serviced head. After putting her all back together and fixing an ignition problem she is still running a little rough I think (I can't tell if it's a normal running sound because I've never owned a polo before and she was in this condition when I got her). I took her for a test drive yesterday and after starting up and putting the choke in she kept stalling going into first. I had to put a load of revs on to get her to move. After driving for a bit it stopped being an issue. I colourtuned the engine before the head change, should I retune now the head has been done (the leak was on cylinder one front right), and could it be a mixture problem? I also put a pierburg carb on to replace the old one (another 1b but with manual choke and no external reservoir, maybe the reservoir is causing the lack of fuel to the cylinders)? Sounds like it could be a misfire but I've got the timing bang on and all the plugs are getting electric (got a stroboscope) so maybe I've cocked up the head gasket? I've got a compression tester now and I'll do one after the weekend, I really hope it's something carb related though because the head was a pain to do . ..

It's a MK2 1.05 HZ bready

Thanks for all your help with her, sorry for the mountain of questions, just want her to be the best she can be!

 

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Hooray! Enjoy your polo.   You can swap the speedo over to keep same miles; it's mechanical behind all that bendy circuit board. Just be very careful of the reset button passing through the

Topran (Hans Pries) are variable. Their switches are top banana. Birth spa are solid.   You can get a block tester kit to detect oil in coolant (actually Co2 from combustion in header t

battery light in dash is from smallest wire contact at alternator. It turns on at key to acc/ignition and off when engine running. Comes on at low batt or poor charge cause regulator brushes

kiran_182

Cant hurt to colour tune it, could be an air leak. Go back and check all inlet bolts are tight and work up from there, also the dizzy position needs to be right too

 

Check the battery terminals and earths are tight too

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Replacement carb idle jet flow and throttle plate position and float level will all be slightly different so colourtune for perfect burn with hot engine.

 

Stall when up to temp can also be vacuum leak.

 

Fuel reservoir smooths flow removing bubbles, but carb needle valve and float-well does that job too so not needed, but more fuel will now heading down return line to tank. It can affect high speed running not idle usually.

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NebulaicToaster
12 hours ago, kiran_182 said:

Cant hurt to colour tune it, could be an air leak. Go back and check all inlet bolts are tight and work up from there, also the dizzy position needs to be right too

 

Check the battery terminals and earths are tight too

 

Any definitive place where all the earth's are? Carb to engine and engine to chassis I know...

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NebulaicToaster
9 hours ago, dvderlm said:

Replacement carb idle jet flow and throttle plate position and float level will all be slightly different so colourtune for perfect burn with hot engine.

 

Stall when up to temp can also be vacuum leak.

 

Fuel reservoir smooths flow removing bubbles, but carb needle valve and float-well does that job too so not needed, but more fuel will now heading down return line to tank. It can affect high speed running not idle usually.

I'll tune her up on Monday, which vac lines should I check, the fuel lines aren't leaking? My new 1b carb didn't have the idle adjustment vacuum screw surrounding that comes from the dizzy so I put the old one in...

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any thin vacuum lines to carb, plus the basemount.

 

Easy start spray will speed up idle  and carb cleaner will slow idle if sucked in.

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10 minutes ago, NebulaicToaster said:

Is it possible the timing is 180 out and it would still run? I don't think it is but might be possible? 

no.

it might try to start, but you'd get a big bang as fuel in exhaust burnt.

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caretakerplus

A common problem, is a (partially) blocked idle jet - fortunately, this is easy to access, being the small jet at the top of the carburettor (you can see it if you remove the air cleaner top)

To be honest, you would think that if this jet wasn't completely clear, it would affect the idle at any temperature, but as it is such a simple job, it might pay to look.

If you hold the jet up to the light, you should be able to see a cylindrical hole right through it - if it has an obstruction, you will probably be able to see it.

WARNING 1 - Make sure that the screwdriver blade that you use actually fits the slot (not too narrow, not too wide) - The screwdriver blade should also have a reasonably square end (like a new screwdriver) Badly fitting screwdrivers can damage the jet, as can over-tightening.

WARNING 2 - These jets are so small that they are easy to loose, so take care.

Regards

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NebulaicToaster

Had another go tonight. Connected the vac line from the idle screw to the 2 way valve and another from the back of the 2 way valve to the dizzy vac. Is this correct? It seemed to help. Otherwise there were no leaks I could detect. The stalling only happened when cold, otherwise the engine was pretty sluggish but it might just be the puny 1l?  I've not actually driven a polo before so I've no idea what she's supposed to sound or drive like?  I'll tune her again because I suspect that might help.

 

In other news the battery light, fuel gauge (she's got 5 l in and not registering) and maybe temp aren't working on the dash. I've tried replacing the voltage stabilizer with one from an old dash but no dice. Any ideas? Thanks so much

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  • 2 weeks later...
NebulaicToaster

Thank you all for the help! After 2 dud carb mounts from topran, I finally got a proper one from Birth. That solved my loss of power and stalling problems. The motor is still sounding a bit rough though. I did the thermostat and housing while I was at it and discovered that the lovely previous owner who I bought the car off had removed the thermostat (telltale blown head move) but luckily I've already changed the head gasket. Hopefully no more leaks. 

 

I'm worried that I might have bunked up the head gasket change though, there was a bit of vapour coming out the exhaust and the cap had some mayo on (i can't remember if I cleaned it before doing the head but I have now so we'll see). The head was off for two very damp weeks in december with a rag over it and my garage lets a bit of weather in through the barn door so could the mayo be because of all the condensation that accumulated on and in the engine? If it is caused by the gasket leaking (which i suspect because of the vapour in the exhaust) is there a definitive way to diagnose this? Should I test the compression? Or am I worrying too much and should I just drive her a bit and see if the coolant level goes down?

 

Sorry for all the questions, I just want to get the girl running properly. Any advice is appreciated. Cheers, after all this I'm definitely bringing her down to the meetup in June (need to give her a name, open to suggestions)

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Topran (Hans Pries) are variable. Their switches are top banana.

Birth spa are solid.

 

You can get a block tester kit to detect oil in coolant (actually Co2 from combustion in header tank).

 

But i think you are worrying too much. I'd drive it to blow away all the condensation from exhaust system.

If you're not confident,  drive in a circle just over a mile from home if you have breakdown recovery service

but no homestart. Or can be pushed a mile if no hills.

 

And it's mayo on dipstick not in rocker cover cap you should worry about.

 

Performance. not sports car, but not sluggish. Better once warm.

Carb mixture can only be set right when really warm engine. 

Check ignition timing is right?

 

Dash ... get a meter and check at the fuel sender below rear seat.

Might be poor earth or that the float is stuck and will move the rheostat once more fuel in.

Temp guage, there's a contact on thermostat housing you've probably disturbed. 

 

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battery light in dash is from smallest wire contact at alternator.

It turns on at key to acc/ignition and off when engine running.

Comes on at low batt or poor charge cause regulator brushes worn.

You need good alternator output for good spark when running, but just a charged 

battery to crank.

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NebulaicToaster

Bingo! Got a dash from the scrappy, plugged it in and everything works. I'd rather keep my old one in as it's got the clock and my proper mileage so any clues as to what could have gone wrong, only the clock and Speedo were working, no power to the rest?

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NebulaicToaster

Gave her 15 miles of test driving today and I think you were right dvderlm, I was worrying too much. Once I'd adjusted the idle and mixture she ran fine (though when I set the idle too low the oil light flashes, only when idling it goes off once some gas is on, what does this mean?). No more vapour in exhaust, I'll check the cap before I leave for work in the morning and no visible leaks with coolant.

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NebulaicToaster

All in all, the Polo is bloody good fun to drive, on my first trip to the petrol station I've already been stopped by passers by for a chat  I'm very happy now, thank you all (dvderlm especially) for helping me get it on the road. I'm sure I'll be back with further worries (anything I should be doing before driving it properly if it's been sitting a while?). This is such a brilliant community, hope to see you all in my polo in June (if she makes it across Europe in one piece)

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nige8021

The fuel and water temp gauges are supplied by a voltage regulator on the rear of the speedo unit,  on some models you can easily replace them

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NebulaicToaster
5 minutes ago, nige8021 said:

The fuel and water temp gauges are supplied by a voltage regulator on the rear of the speedo unit,  on some models you can easily replace them

Already replaced the regulator, no dice sadly

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Hooray! Enjoy your polo.

 

You can swap the speedo over to keep same miles; it's mechanical behind all that bendy circuit board. Just be very careful of the reset button passing through the hole.

Rev counter is electric. Only needs earth, the red/black wire and +ve.

 

Maybe the edge connector contacts are not all good on old clocks?

 

If the oil level is good and there are no oil leaks then it could be the pump is worn, but you would have the high speed oil pressure buzzer (J112 circuit)  ruining your life over 2500rpm.

Oil pressure gauge is only way to tell for sure.

Edited by dvderlm
windows 10 onscn keyboad... oh ffs
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On ‎27‎/‎01‎/‎2018 at 17:29, NebulaicToaster said:

(need to give her a name, open to suggestions)

 

For an old fashioned female name, stick a pin in this page?

https://en.wikipedia.org/wiki/List_of_suffragists_and_suffragettes

 

Or as you are planning a long european journey, Bertha.

https://en.wikipedia.org/wiki/Benz_Patent-Motorwagen#Historic_journey_of_Bertha_Benz

The patent was applied for on this day in 1886.

Edited by dvderlm
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