Low Compression Issue

[Phil Gti 10]

Morning all, I need some advice regarding a non start issue. I have a 1.9 Gti that I have finished rebuilding and it refused to start yesterday. I drove the car that the engine was taken from so I know it was in good condition. I replaced the cambelt, water pump, inlet, exhaust, rocker, sump and thermostat gaskets, new plugs, HT leads, battery and fuel filter before fitting it. The timing is correct and all fluid levels are good, no leaks. I disconnected the HT leads and it turned over on the key. All ok. I reconnected the ignition system and expected it to roar into life, but no joy. There is fuel arriving at the fuel rail. I checked each HT lead and plug and they are fine. I then thought it would be sods law that I hadn't changed the head gasket and it may be at fault. I did a compression test and all 4 cylinders failed to produce more than 60 psi and would not hold the pressure, they quickly lost pressure, reading 0 psi within a few seconds. I then noticed a small amount of fuel around the bottom of injector 1 & 2. I refitted the plugs and leads and turned the engine over again and noticed a hissing sound ( air escaping) from around the injectors. I suspect that the o-rings are leaking. Would these cause compression loss? I hope so as this will be an easy fix. If not what else could be the problem?

[Phil Gti 10]

Any ideas?

[jackherer 543]

The injector O rings wont leak compression. Did the cambelt change happen without issues?

[Phil Gti 10]

The cambelt was changed along with the other items because I didn't have all the service history for the car the engine was taken out of. I did drive the car before hand and it idled and ran very well, without issues.

[erbs 42 1 Cars]

is the ignition timing correct?

 

the reason i say this is because this can be easily overlooked

[Phil Gti 10]

I checked the mechanical timing before and after fitting the belt, and again before turning the engine over on the key. The Ignition timing should be roughly correct. I marked the distributor body so I could line it up with the mark on the cylinder head I made. My issue is leaking injector O-rings and no compression.

[jackherer 543]

Like I said the injector O rings don't affect cylinder compression, it will be a leak via either the piston rings or more likely the valves. Did you turn either the crank or cam at all while the belt was off?

[Phil Gti 10]

No I left the crank and cam locked in position whilst changing the belt.

[jackherer 543]

You need to do a leak down test to find out where the compression is leaking then.

 

http://en.wikipedia.org/wiki/Leak-down_tester

[Phil Gti 10]

I am sure I locked both cam and crank before removing the belt and know not to move either independently. I understand that if the two holes in the sprockets allow a 8mm dowel to be passed through them and the holes in cylinder head and block casing that is the timing correct. I will check the timing holes on both line up tomorrow when I go over to my garage and replace the O-rings, check all connections then compression test again. If I have the same results I will do a leak down test I guess arrrgh. Cheers for the advice I thought that being direct injection the O-rings would have been the answer.

[pugdamo 111 2 Cars]

These engines are indirect injection. Good luck, hope it's nothing to serious

[Phil Gti 10]

Ohh : ( cheers for clearing that up. I will post my results later.

[Phil Gti 10]

Evening, I have discovered that my compression tester had a faulty pressure release valve. I bought another today and re tested with an average of 120 psi across all 4 cylinders, to say I was relieved would be an understatement. I removed the fuel injectors on the rail and tested them, all 4 spray evenly. So I thought the engine would start. I tried and nothing. I used an in line tester and the spark plugs are getting a spark, but I am not sure of their condition and if they are firing so I will replace them and try again tomorrow. I know the cylinders are 1-4 left to right when facing the engine. Can someone confirm which number cylinder each HT lead connection is on the distributor cap as my cap has no markings and I want to be sure I have connected them correctly.

 

Cheers ​

Edited May 6, 2015 by Phil Gti

[pugdamo 111 2 Cars]

The cylinders are the other way round, 1 being the flywheel end. Is your car even trying to fire?

[Phil Gti 10]

My bad, I have man flu at the mo. I have cylinder 1 as flywheel. No it doesn't sound like it is firing. I could do with knowing distributor HT lead connection numbers

[pugdamo 111 2 Cars]

I'm sure someone will know off the top of their head, I'm not near my car at the mo. Has the Haynes not got anything useful in it?

[Phil Gti 10]

All the Haynes manual tells you is to remove each lead one at a time to avoid confusion. A bit useless if you haven't started from that point! lol.

 

I searched online, and nothing apart from opinion not fact. I thought asking 205 owners, they would know or would be able to check.

[welshpug 1,627]

google search is epic.

 

 

http://forum.205gtidrivers.com/index.php?showtopic=116578

[Paul_13 212 1 Cars]

http://www.205gtidrivers.com/info/techspecs.html

[Phil Gti 10]

Well done that man, cheers. I blame my lack of success to man flu.

[Phil Gti 10]

I checked the HT lead connections and they were correct. I bought some NGK plugs and fitted them, turned the key and it ROARED into life. I had forgotten how good 205 Gti's sound with a stainless steel system lol The Bosch plugs I removed look new but were obviously faulty! The only issue I had was that the engine kept reving from idle to about 3000rpm and then dropping back to idle and then repeating this cycle. I adjusted the throttle cable without any change. It will rev cleanly to the red line which I tried once before turning it off and rolling it back in the garage for tonight. Any suggestions what might be causing this?

Edited May 7, 2015 by Phil Gti

[Phil Gti 10]

I spoke to Dianne @ Ecosse today. She knew what was wrong straight away. Supplementary Air Device apparently. I will test it tomorrow and fingers crossed it is that and is repairable, otherwise I will be on the look out for a new one if possible or 2nd hand from a forum member ; )

Edited May 8, 2015 by Phil Gti

[oldkiteman 6]

I would be supprised if its the SAD.An air leak is more likley.

[Phil Gti 10]

The hoses are all new, I have checked they are secure. I started the engine, squeezed one of the hoses coming from the back of the S.A.D and the over reving cycle stopped. The engine idled roughly for about a minute then stalled. I re started it a few times, and each time it ran for less time before stalling again. If I tried to save it by pressing on the accelerator it would not increase the revs. That leads me to believe the faulty S.A.D is causing an over fuelling issue. I removed the S.A.D and cleaned it with brake cleaner, there was a little bit of dust but otherwise it was ok. I started the engine and no improvement. It will idle around 1000rpm, it will not increase revs with the throttle open and stalls. I haven't tried waiting for the engine to cool down and re start it to see if it will idle for longer as it did when I first started it at the weekend. Based on Ecosse's advice and the symptoms I have found I will replace the unit and fingers crossed I can finally drive it!

[welshpug 1,627]

SAD will not make it over fuel directly, its purely a bypass valve to raise the idle speed when the engine is cold, that's all it does.

 

 

Sounds more like a faulty AFM to me.