Cam timing set and double checked.

Ignition timing checked.

There is a good spark at all the plugs.

There is fuel delivery, as the plugs have petrol on when pulled out.

Compression is good. The lowest was 75 and the highest over 100. That was with the tester only screwed in finger tight.

Good battery, so it turns over nicely.

BUT, IT JUST WONT BLOODY START ! ! !

Even tried spraying some easy start down the carb, just in case there was something wrong with the fuel.

 

The best I can get at the moment is a hint of ignition, like it was thinking about it.

 

Someone suggested the tappets might have lost pressure ?

 

Can anyone help ?  Any suggestions ?

So you've got compression, a good spark & fuel being injected, the only thing that can be stopping it is either the spark or fuel isn't arriving at the correct time.

HT leads on the distributor cap in the correct firing order 1,3,4,2 ?

 

Nothing to do with loss of pressure in the tappets as the valves must be opening for the spark plugs to be getting fuel on them

 

I checked where there's a small notch on the disi marking number 1 and followed it in the right direction, 1342 and yes, they're all right.

What determines the fuel delivery timing ?

The ECU based on the signal from the distributor 

23 hours ago, Polo3 said:

The best I can get at the moment is a hint of ignition, like it was thinking about it.

Can anyone help ?  Any suggestions ?

Hi

You need oxygen as well. So, 2 things

1. Check the air filter

2.I know its a job, but take the plugs out and dry them.

Good luck.

The air filter is good and I've lost count of the amount of times I've whipped the plugs out to be polished again and have the fuel wiped off them.

 

Towed it to a workshop yesterday so they could plug it in. Nothing came up and the conclusion was that it must be mechanical. They hooked it up to a booster starter and sprayed brake cleaner into the intake whilst cranking it at a good lick.

Nothing.

 

It was suggested that I double check the ignition timing. Get number 1 to TDC and check the rotor is pointing to the right part of the dizzy.

 

I'll just have to double check it all with a fine tooth comb. Although I feel that I've been quite thorough already.

 

One of the many things I dont get about this, is that it was running very well before the initial problem, which turned out to be a seized auxiliary belt tensioner. It appears that this caused the cambelt to jump a couple of teeth. But after putting the cambelt right, I've got good compression on cylinders 1 and 2, not bad on 3 and Ok on 4.

 

Oh well, I've had a good coffee, so lets get back at it.

Well, it looks like the cam timing didnt jump out 2 teeth. I was checking it on the wrong mark. I took the plug out of number 1 and got it to TDC. Put a screwdriver in the plug hole and turned the engine back and forth until I was happy that I'd found the centre of the dwell angle. Looked on the bottom pullley to see where the chamfered tooth was and it was lined up to a mark that I had thought was a just a casting mark. Doh ! What a idiot !  I dont know what the other mark that I used is for ?

So I put that right and thought "Great", I'm going to get it sorted now.

Not a f****n bit of it.

To cut a long story short, she still wont fire, although does seem to be trying with no throttle. As soon as I press the throttle, it sounds less likely to start.

Also, when turning it over with the air box off, there seems to be more pressure and vapours coming out of the crank breather pipe than I would have thought.

 

I'll check the compression again and if it's still Ok, then I'm totally stumped.

Faulty Hall sensor ?

16 hours ago, Polo3 said:

Faulty Hall sensor ?

The OP has already stated getting a good spark so that rules the hall sensor out 

Hi

The only other thing that comes to mind is 

it is petrol vapour that catches fire, not petrol liquid.

So can we put it down to the cold weather not vaporising the petrol in the cylinder.

1 hour ago, vwfan3 said:

 

So can we put it down to the cold weather not vaporising the petrol in the cylinder.

????

9 hours ago, vwfan3 said:

So can we put it down to the cold weather not vaporising the petrol in the cylinder.

 

 

The fuel injection ensures a fine mist.

Four stroke petrol engines will still start at -60

I reckon we've only got to about -4 at night recently and when I've been working on the car, the coldest has been about 1 or 2 degrees.

 

Thanks for your input though.

 

Just going to recheck the compression and try to start it with hot plugs, courtesy of a blow torch.

Compression is

No 1, 100 psi - 7 bar

No 2, 110 psi - 7.5 bar

No 3,  80 psi  - 5.5 bar

No 4,  65 psi  - 4.5 bar

 

3 and 4 are a bit low, but with 1 and 2 Ok, is the overall condition good enough for starting ? Head swap if not ? ? ?

 

Heated the plugs up until the tips started to glow, got them in as quick as poss and just managed a couple of half hearted attempts at firing and that was it.

 

Off to the local V dub garage in the morning to be plugged in.

The limit is 3bar difference so you on the limit, was that a wet or dry test ? as if there was any change between or no change that would tell if its a head or bore problem, but even with the figures you've got it should still run 

When the hg went on mine comp was 9 12 3 3 so keep an eye on that

10 hours ago, nige8021 said:

The limit is 3bar difference so you on the limit, was that a wet or dry test ? as if there was any change between or no change that would tell if its a head or bore problem, but even with the figures you've got it should still run 

 

What is a wet test ?   I didnt disconnect anything to do with fuel delivery.

Yes, I thought it should run with those figures.

 

As I walked out of the V dub garage, I asked what the hourly rate is.  £96/h     I told them to just use their specialist test equipment and leave it at that, as I've gone through all the mechanical possibilitys

Wet test is when you pour a small amount of oil down the plug holes and if the compression increases its an indication of worn bores but if it remains the same then its head/valve/gasket related

Ok, cheers Nige.

 

When I next passed the VW garage, my Polo hadnt moved, so I decided to pop in and have a chat with the mechanic who would be looking at it. I explained the history of the current situation and he said the he would only be doing what I'd already done.

Also, that the diagnostics would be the same Snap On device that the other workshop had used. He did suggest that the coolant temp sensor could be faulty, causing it to dump too much fuel into the pots. So I unplugged it, whipped out the plugs for a wipe off and tried it again. Nothing.

After a quick bit of reconsidering, I decided that £96/h was too much to pay for what had already been done. So yesterday,  I decided to tow it the 12 miles to the best mechanic I know and leave it with him.

His receptionist phoned me today to say it was ready for collection.  I couldnt believe it. I asked what the problem had been and she said that it was so flooded that it just prevented it from starting. It had also washed all the oil off the bores.

I've not had a chance to chat with him yet, but I did wonder if he'd stuck a camera into the cylinder for a look ?

 

I dont know how it had arrived at this state without starting, but I did think that VWfan3's comment wasnt so far off the mark. I reckon that in warmer weather, all the cranking with the plugs out would have got rid of the excess petrol, but in this cold weather, it wasnt vapourising quickly enough ?

 

I'm just very pleased to have it running again.

I just wish I'd spotted the seized aux belt tensioner on the first inspection. It would saved a lot of arsing about.

Oh well, lesson learnt.

5.5mm endoscope camera is about £10 on amazon and can connect to mobile phone or laptop.

 

Not used one but a piece of kitchen towel in through each spark plug hole with pistons at half-height will soak away quite a lot of petrol -especially  in warm workshop.

Diagnose. Disconnect fuel pump. EasyStart into air filter while cranking.

 

Easy with hindsight. Mechanics from 60 years ago did not have computers. But then again, neither did the cars!

 

 

 

Edited 28 February, 20188 yr by dvderlm

Thanks for the pointers dvderlm

Like you say, easy with hindsight.....................Cheers to everyone who commented and made suggestions.

15 hours ago, Polo3 said:

I'm just very pleased to have it running again.

Hi

So pleased for you.