OT - 1998 VW Polo 1.6 stalling/temperature issues

[gjm 3258]

Apologies... But at least it is a German car.

1998 VW Polo 1.6, AHS engine (the lower power - 75hp version). Nearly 145000km. Regularly serviced. Economy isn't great at around 12km per litre on 45km runs.

For a little while the temperature gauge has suggested the coolant is not getting up to temperature. Typically, it'll peak when displaying 70 degrees, but with the cold weather over the last couple of days, it's been lower. If sat idling for a period of time the gauge will show 90 degrees, but as soon as any constant speed is reached, this drops back to 70 (or less).

Normal journey length is around 45km, mostly on SH1 at 70-100km/h.

For some time we have had an issue where it would sometimes, not always , stall when stationery. Always restarted without any issue. I'd attributed this to an (apparently) common problem with the throttle body. Costs a small fortune to replace so we've lived with it.

Today, no problem going in to work.

When leaving work, seemed a little reluctant to start, but then would not tick over. Revs smoothly - no problem. Take foot off accelerator and it stalls. Drives well enough, accelerates smoothly, but will not idle without a little accelerator.

So... Has the thermostat gone south and needs replacing (replace the housing on these at the same time), or has the engine temperature sender called it a day? My nitial suspicion is that longer use with low temperature (at least) being reported has 'fooled' the ECU into running the engine much richer than it should, and the excess fuel has caused the cat to become blocked.

Any ideas?

[vtgts300kw 90]

As someone who also has to pay the bills to run a Mk3 Polo, "living with it" about sums it up.

[charles28 136]

It will need a new Thermostat, it will be stuck open basically.. just about every VW i've owned has needed this replaced.

It will be hurting your fuel economy also, as the ECU will be adjusting things to run rich due to it thinking that the engine isn't warmed up.

[gjm 3258]

Thanks. That'll be the first stop.

[Allanw 1071]

Gauge symptoms suggest a faulty thermostat.

They don't get stunning economy either - they're a freakin heavy car for their size... compared to a Jappa anyway! But I do remember a crash test being done between one and a Hyundai Sonata back in the day. Polo was a FAR safer car

I dunno about the stalling issue. Only ever had one of these, in the rental fleet many years ago. It needed a thermostat too though... I remember the VW dealer telling me it was expensive because parts for a premium brand had premium prices. He wasn't very impressed when I said it was only a VW, AND the price was twice the price of a genuine one for dads E30 325i!

[gjm 3258]

I think it is about $80 for a thermostat and housing, from an appropriate source.

The housings are (I think) plastic, and tend to crack/break when you start to 'play' with them.

[Etwenty1 45]

recently bought a 1.4 polo for my sister with the stalling issue. I got lucky and found a good runner at pickapart and stole the throttle body, injector rails, leads, PCV trap, etc.

I tried a new the temp sensor first with no luck. Throttle body swap cured it.

Buggered if I can find the bell housing hole to check the timing tho'.......

[gjm 3258]

Had a nice chat with a lovely lady at Qualitat. (Shane wasn't available.)

Thermostat: $34

O-ring: $4

Top housing: $29.90

~1.5 litres of genuine VW coolant: ~$30 (ouch)

All plus GST.

[Ahmedsinc 414]

+1 for Qualitat. All the dealings I had with them were great, Shane's a bloody good sort too!

[Dn540 67]

Qualitat are great! I bought numerous items from them and also Autohausaz when i had my Golf. I replaced pretty much everything on that engine short of the engine itself, mind you I don't know how well the PO took care of it.

It's definitely the Dub way of life haha. Get friendly with part suppliers.

[Allanw 1071]

Qualitats sponser the VW Nationals every year, and have done so for as long as I can remember.

They really are a great place and stock a lot of stuff too!

[charles28 136]

Qualitat are great! I bought numerous items from them and also Autohausaz when i had my Golf. I replaced pretty much everything on that engine short of the engine itself, mind you I don't know how well the PO took care of it.

It's definitely the Dub way of life haha. Get friendly with part suppliers.

I know all about it, I have a Mk3 Golf VR6, probably the most unreliable of them all

[gjm 3258]

I know all about it, I have a Mk3 Golf VR6, probably the most unreliable of them all

We had a Mk3 VR6. It wasn't a Highline, but had all the Highline bits and then some. Particularly rare as ours was a Dragon Green 5-door automatic.

It went up in smoke on the side of the road. A puff of dust from around the steering column turned out to be smoke. A second and Mrs GJM pulled over and got out. Engine off... Phoned me to say she was concerned, then turned around to see an inferno.

<sniff>

[elmarco 56]

I know all about it, I have a Mk3 Golf VR6, probably the most unreliable of them all

Really? Mine was great - bit lazy in the engine dept & thirsty (swapping the an E46 330 auto was refreshingly economical as well as much more power) but pretty good apart from that. The mk3 diesel i had was a pretty good car too until the A/C compressor lunched itself...

[charles28 136]

Really? Mine was great - bit lazy in the engine dept & thirsty (swapping the an E46 330 auto was refreshingly economical as well as much more power) but pretty good apart from that. The mk3 diesel i had was a pretty good car too until the A/C compressor lunched itself...

Its not really that bad, its just old.. just a lot of little wear and tear things.. Coolant hoses, heater core, just had the steering rack rebuilt as it was leaking, needs new strut top mounts etc. nothing too costly.

Just had the ABS ECU Re-soldered internally.

Its not as good as the newer MK5 Golf GTI I had, but its got more character, it still goes well enough for an old car.

Its using an average of 10.5L/100k, my E39 525i averages 11.3L/100k on the same drive, yet has a smaller engine..

Edited May 30, 2014 by Charles32

[charles28 136]

We had a Mk3 VR6. It wasn't a Highline, but had all the Highline bits and then some. Particularly rare as ours was a Dragon Green 5-door automatic.

It went up in smoke on the side of the road. A puff of dust from around the steering column turned out to be smoke. A second and Mrs GJM pulled over and got out. Engine off... Phoned me to say she was concerned, then turned around to see an inferno.

<sniff>

Mines still looking quite Mint for its age.

[gjm 3258]

Replacing the thermostat appears to have resolved the temperature problem - no sits solidly at 90 degrees on the gauge once warmed up. That's what I'd expect. I took the expansion chamber off and ran some descaler through it to shift some muck that had accumulated in there.

The tickover issue is a funny one. Throttle cable adjustment appears to be rudimentary - slide a ribbed section through a metal ring, and use a clip to stop it sliding back. The clip was the wrong side of the ring to actually do anything - it would let the rubbed section slide and slacken the throttle cable - so I've swapped that and set things so the car ticks over now. Of course, this is tickover adjustment by throttle cable rather than how it should be done - I'll check that later.

I took the opportunity to squirt some cleaner into the throttle body. It was filthy, so that won't hurt. Seemed to make a bit of a difference.

The crankcase breather pipe that connects to the bottom of the airfilter housing has mayonnaise in it. Not unusual, I guess, but disconcerting. I'll look into cleaning that out properly, too.

New airfilter needed. Repco/SCA want a fortune for one, and I can get an air filter, oil fitler, and fuel filter shipped from Oz for half the price of an air filter here. That said, for GBP 15 I can get an airfilter, oil filter, fuel filter and 4 spark plugs from the UK... Even if shipping works out to $50, it'd be worth it!

[gjm 3258]

No doubt that the thermostat swap has worked. There's even warm air through the vents!

Idle needs some work - it's too low. I can fudge it by adjusting the throttle cable, but I suspect the throttle body (with incorporated idle control valve) needs removing, cleaning and replacing. I anticipate there is a gasket involved so that will wait until I can get hold of one.

There is one more issue. When driving at constant speed, level road, constant throttle, there is sometimes a very brief deceleration. No change in throttle position (inside the car) but it's almost as though fuel supply has been cut for a fraction of a second. It's a hesitation. Doesn't seem to be speed related, but is (I think) happening at marginal throttle, so while cruising rather than accelerating.

Could this also be an idle control valve issue?

[gjm 3258]

Well, we've got the WoF behind us. Rear wheel bearings needed adjusting (they've need that for the past two WoFs, too... ) and a steering rack gaitor needed replacing. Not so bad.

A quick poke around this evening suggests replacing the vacuum hoses might be a good idea. Certainly that'll explain the rough idle, but obviously not the hesitation at constant throttle and normal driving speeds.

Still, one thing at a time.

[gjm 3258]

Hmm... And this morning the car was reluctant to start.
Probably need to investigate WURs and ICVs.

[2052NV 43]

the stalling will be you throttle body coked up with soot etc. you will need to have it removed and flushed out etc,

[gjm 3258]

the stalling will be you throttle body coked up with soot etc. you will need to have it removed and flushed out etc,

The top end is much cleaner (I'll not say clean) but I've not pulled the whole thing off the car (yet). I suspect there is a base gasket or similar so obviously want to have a replacement to hand when I do that.

I think the ICV is a part of the throttle body (on this car).

[2052NV 43]

yea there is also a random metal pipe that goes to the exhaust and thats the main culprit you have to clear that one out fully

[gjm 3258]

Swapped the vacuum lines that can easily be done. There's one that goes through the firewall which is going to prove tricky.

This does seem to have helped smooth the idle.

Now I just need to work out how to get the idle speed up. I can bodge it on the throttle cable, but bodge is all that would be.

I've read that the speed is hard-coded in the ECU, but there must be something, somewhere that'll offer a more manual adjustment... Surely?

[gjm 3258]

Still got the hesitation issue. Driving at a constant speed - say, 90kph - and with no conscious movement of the accelerator pedal (no cruise in an old Polo!) it feels as though the engine is starved of fuel. It's a 'nothing' rather than a misfire.

I've fitted new plugs, rotor and dizzy cap already.

Certainly starts easier since replacing the vacuum hoses.