GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: cняis on 23 April 2007, 18:25
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Right... what a crappy weekend :angry:
Had the 8v digi timing and CO done last week, but its still pinking when hot. The garage advised me (when i picked the car up) that the head was quite coked up, and could cause hotspots resulting in pinking. When I enquired about de-coking today I was advised against using chemicals (by a third party) to soften the carbon up as a lump may fall off and damage valves etc... As i dont have the tools to strip the head, the car needs to go back to the garage again. £Â£Ã‚£
Then i notice some drops of water on my left foot... guess what, either the heater matrix or a pipe has split, and im getting a puddle in the footwell, and constantly topping up water! £Â£Ã‚£
Also i have a replacement steering column which needs fitting, as the original has dry bearings causing lumpy steering when the car is warm... £Â£Ã‚£
oh the joy of owning an old car!! :cry:
p.s. Anyone know why its leaking in the drivers side footwell (by the clutch pedal) and not the passengers side? I've search and search on here, and all I can find ref leaking matrixes are puddles in the passengers side. The passengers footwell and behind the centre console are bone dry. It has to be heater related as my coolant dropping like mad, and it was dripping through on a dry sunday
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its great aint it. i got my clutch done bout 2mths ago only to find out the main crankshaft oil seal is now leaking so its another gearbox out job!!
but sure its all part of the fun!
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The pinking could be caused by another couple of factors than were discussed before. Check you spark plugs are the correct ones, and that they are not worn. If the wrong ones are fitted, then they could be overheating causing pre-ignition followed by spontaneous combustion. If they are worn, then the electrodes cannot dissipate heat fast enough, which will also cause pre-ignition.
Another thing that I have read on the internet, but would not recomend unless you have a strong engine is to drive the car in second gear to red line for one minute. Keep an eye on your oil temp. It should go up slightly. This is supposed to burn off any coke build up. Again, I DO NOT RECOMEND YOU DO THIS UNLESS YOU KNOW YOU HAVE A STRONG ENGINE. Personally, I wouldn´t do it anyway, but its an idea.
If it is thought that coking may be the problem, then I have also heard that if you pour a small amount of brake fluid into the bores via the spark plug holes and leave it for a while, this will soften the deposits on the pistons, and allow them to burn off, although the engine will smoke for a few seconds or minutes whilst the fluid is being burned off. I have never tried this, but I can´t see it doing any harm.
But look at your spark plugs first.
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under the scuttle, the clutch cable and accelerator come in through 2 holes there, is water getting under the tray and leaking down through there?
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whats pinking? ive asked before but cant remember.
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Pre-ignition i think. The mixture ignites before the piston is in the correct position.
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whats pinking? ive asked before but cant remember.
Pinking is spontaneous combustion caused by pre-ignition, which itself is caused by excessive heat. The maximum pressure in the combustion chamber should be reached after TDC at the start of the power stroke. Causes for the excessive heat source could be a number of things.
Hot spots in the combustion chamber, ie spark plug electrodes, carbon deposits etc.
The wrong grade of fuel being used, ie 95 instead of 98. In old money, the higher the octane rating, the more TEL (tetra ethyle lead) was added to the fuel. Lead helps delay the onset of detonation, allowing higher compression ratios to be used, thus higher combustion temperatures. High altitude piston engined bombers of WWII used to use 130octane fuel with water injection. Lead has now been replaced by another substance which has escaped my memory.
Ignition timing being too far advanced, (pre-ignition effectively) causing the max pressure in the cylinders occuring before TDC rather than after.
Too lean a mixture. This is important as fuel is a volatile liquid, ie it gives itself up as a gas very readily. This is because it is cold, and it is the coldness of the fuel, and how much of it there is that detrmins how hot the combustion is. As said before, excessive heat leads to detonation. If you go the other way, and have a rich mixture, not all of the charge will be burned as there is not sufficient heat to burn it all. (Indicated by sooty black smoke from the exhaust. This is unburned fuel) Bear one thing in mind. The fuel is supplied to burn the oxygen to expand the nitrogen in the charge.
Master class over. I hope you understood it. :smiley:
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erm thanks my head is now very sore! how would you know if your car was pinking what would be different?
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1. Pull the vacuum lead off the airbox, and submerge it in a jug of water and hold the throttle at about 2k rpm. You should hear the engine bog down, if it seems like its about to stall take the pipe out of the water and let it clear. Put a pint or so through, this will clean out all but the worst of the carbon deposits!
2. Wont be the heater matrix, the pipes to it are on the passenger side. Its more likly to be a water leak thru the bonnet release cable grommet or the windscreen!
3. Piece of piss, should take you about half an hour ;)
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1. Pull the vacuum lead off the airbox, and submerge it in a jug of water and hold the throttle at about 2k rpm. You should hear the engine bog down, if it seems like its about to stall take the pipe out of the water and let it clear. Put a pint or so through, this will clean out all but the worst of the carbon deposits!
2. Wont be the heater matrix, the pipes to it are on the passenger side. Its more likly to be a water leak thru the bonnet release cable grommet or the windscreen!
3. Piece of piss, should take you about half an hour ;)
1. This is definately worth a shot, thanks for the reply! :smiley: which lead is the vacuum lead though??
2. It was a hot day, it had not been raining at all and I had not put the washer jets on. Plus im losing coolant. maybe the water is travelling somehow across the inside of the car? I'm only doing 5 miles to work at the moment, so I'm low on coolant hence the leak has stopped.
3. this is being done tomorrow :)
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if rubjonny's treatment doesn't work (or even if it does) check the cable coming from the knock sensor on the front of the block. If its the original sensor, it might need replaced. The cable coming from it is a shielded, coax type and if the shielding or insulation is split, it wont be sending the correct signal to the ecu. Mine used to rattle pretty bad and I got a new one from bosch for about £40 which sorted it. Only rattles the odd time now, on hot days at low engine speed on wot.
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rubjonny which is the vacuum lead you refer to? I take it its number 14 (not 14a)?
(http://www.vagcat.com/epc/etka/B084/036000.png)
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1. 14 is the one aye :)
2. Ah you said left foot, not right :grin: This plus the fact no other water has got in recently does point more to the matrix, if I were you I'd bypass the hoses to the firewall before it blows completly!
The job isn't too hard, but its fiddy. I've since done another and can say that with the dash out the jobs a doddle, and I'd recommend you remove all the heater houisng nuts on the bulkhead and the one next to the blower unit, and remove the entire airbox unit complete including the blower housing, makes like so much easier than trying to split the box off the blower unit, those clips are a nightmare!
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The car is currently in the garage. The leak has been identified as coming from the matrix, not the hoses. its trickling back through the sound deadening and into the footwell.
One question though - is the matrix liable to blow if its temporarily fixed with k-seal/radweld? ive been quoted £120 by the garage to replace it, which i could do without paying!
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That price is reasonable, given the labour involved.
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rad/weld or whatever isn't going to do the car any favours, steer clear. If I were you id get them to bybass it with a length of copper pipe, which will take em all of 5 minutes and its not as if you'll need the heaters any time soon ;)
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rad/weld or whatever isn't going to do the car any favours, steer clear. If I were you id get them to bybass it with a length of copper pipe, which will take em all of 5 minutes and its not as if you'll need the heaters any time soon ;)
thing is i think theyve already done it... :sad: as i spoke to them at 11.
oh well, coolant flush and matrix replacement next week then :angry:
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Ahhh result! they havent done it yet, so theyre bypassing it to avoid any further issues. :smiley:
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Right-o well currently the heater is bypassed (its summer soon anyway) and i have tried rubjonny's "poor-mans decoke" of sticking the vacuum pipe into water and running about a pint through it at 2k rpm...
i have just taken it for a blast and it seems to have stopped 99% of the pinking :) cheers rubjonny. engine temp was up to 98 at one point (and its a cool evening) so should be pretty much sorted... :cool:
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would this 'de-coke' work on a mk1 k jet?? :undecided: :smiley:
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unsure! tbh i am waiting for a baking day to see if its been effective enough. it does seem to have reduced pinking considerably though.
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the "pint of water" trick is very commonly discussed on't other forum, have a look see!
which vac hose would you use on a KR Jon?
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http://www.clubgti.com/forum/forum_posts.asp?TID=13991&PN=5
even the mechanics at work didnt know about this one... :cool:
all i can say is i was impressed by the el-cheapo decoke :)
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Toofunkyhouse: Yep sure will, it'll work on any car! I did this on my 1.6 driver, and it made a HUGE difference becasue it had been running rich for months due to a dead autochoke. It was also dead easy to do, I could just trickle water straight down the carb, unlike a GTI where it wont run without the inlet system attached.
Rowlers: I would use a vacuum hose as close to the throttle body as possible, you should be able to find a handy one somewhere :)
I have to add you don't usually need to do this, but if the car has been running badly for a while and you suspect carbon has been building up, its a nice free thing you can try. When an engine is running well it should be relatively clean inside, though lots of short journeys can cause the carbon to start building up.
Oh and make sure the engine is warmed up before you get it sucking water :)
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i think mine needs another dose! its absolutely fine at an oil temp of 100 degrees or below, but 102...104... (i.e. in traffic, hot day) it starts to pink again!!
we'll see how it goes! :cool:
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if it needs another dose so soon I'd suspect its running quite rich!