Dying golf

[Jay]

Hi All,
Had my golf now for 6 months, great car, drives brilliant. That was until 2 weeks ago. The car was over cooling and lost all power through the whole rev range. Took it to the garage and had new temp sender fitted. Was working fine for 2 days. Now it's doing the same but worse.
The temp gauge goes down quckly and then comes back up, it's lost loads of power and there is a funny smell (similar to coolant). It gets worse if you give it a good run.

If anyone has any ideas at all please,please post thread as i'm tearing my hair out .

1999 mk4 golf 1.6s AKL

Ta

Jay

[RickT]

Hello and Welcome to the forum!

Cheers

RicKT

[JohnnyBee]

The thing to do here, Jay, is to ascertain whether the temp gauge is telling the truth or not; given the symptoms you describe I'd tend to go for a thermostat first, being the cheaper option.
Check the temp of the hoses and interior heater as the engine warms through, and how they correlate to what's showing on the dash.
Once you've established that the temperature is stable and under control, the next avenue is the ECU temp thermistor, which is the one with three pins in the plug as opposed to the one-pin temp gauge sender.
What you're getting is essentially the ECU dropping into limp-home mode because of the actual engine temp being out-of-range or the thermistor input being similarly outside acceptable parameters.
JB.

[Jay]

Don't think it's thermostat, engine feels warm all the time. Fitted new temp sender unit over weekend. Running better now although temp gauge still going up and down and also a funny sulpher smell.

[JohnnyBee]

Funny Sulphur smell?
That sounds a bit ominous, Jay; H2S emissions tend to point to the Cat not getting up to temperature and/or being partially blocked.
It may be that the 'brick' inside the Cat has begun to break up and is causing a buildup of back-pressure in the exhaust gases.
Thing to do here to check out that possibility is to remove the air filter from the housing and run the engine, then snap the throttle open a couple of times, allowing the engine to rev through to the ECU hard-cut.
If there's a sharp rasp or crackling coming from the inlet side when you do this, it is a sign that excessive exhaust pressure is bottling the engine, and not allowing the cylinders to blow down adequately on the exhaust stroke.
It might run OK on light throttle, but the more you open it up the worse it gets.
Give that a try and see how you get on.
JB.

[Jay]

Is this a difficult thing to rectify and is it expensive??

Thanks for the help.

[Jay]

If this is the problem, and i continue to run my car will it cause any damage???

[JohnnyBee]

I wouldn't think so, Jay; as long as you don't try too hard with it and keep the revs down it should run fairly sweetly.
The one thing to avoid is big throttle openings as the Oxo sensor will be feeding the ECU a whole heap of mixed messages, which will then put the system into limp home mode.
As far as difficulty goes, well, it ain't ever easy getting old rusted nuts off old rusted studs, but with a blowtorch and a couple of tighly-fitting sockets you should be able to get the old Cat off the system without breaking anything.
For my money (if I had any, that is!) I'd take it to a normal garage and get them to do the job on a ramp - far easier than rolling around underneath the thing on your backside, getting cold, wet and frustrated!
JB.

[Jay]

Cheers Johnny Bee,
I think you could be right about CAT, I tried what you said and had the air filter off and had a listen. Could hear a rasping noise,when revs coming back down, but only very slight, still making bad smell from exhaust, (only when revs are over 3000.) The thing that is puzzling me is the temp gauge is still going up and down, i'm almost certain it's not thermostat cause the hoses and engine heat feels normal when gauge goes down. Had VAG code reader on it again (5th time now!!) still showing no faults. I think it may be possible that there are two faults going off at once, but i don't know as my knowledge of engines etc is limited.

Anyway thanks for the advice, it is most appreciated.

[perks]

I'mexperiencing exactly the same in a 1999 Cordoba. Only mine dies when you try to put any load on it when cold and is fine when warm but my economy is shot! Getting between 20-25 mpg on a standard 1.6! Changed the thermostat which was knackered along with the housing. My next step would be the coolant sensor. Did you get anywhere with this in the end?