Some issues with my 1997 z3 1.9

[deadlyminimee]

I have just got the mrs a z3 and she is chewing my ear off because their seems to be some issues.

Please help!!!

First of all... Most of the time the temp gauge is sticking at just above the blue and subsequently the fuel gauge seems to drop rather rapidly. It does sick in the middle of the gauge sometimes and the fuel seems to be better when it is in the middle.

Secondly their seems to be a slight misfire and strong smell of petrol. When I rev it hard as the revs drop you can hear the slight misfire.

Could this all be do to with the temp/coolant sensor or is it likely to be the thermostat?

I picked up a temp sensor which had two prongs for the connector but when I looked at mine its got 4 prongs and is circular.
Euro car parts shows two coolant sensors do guessing I've just got the wrong one.

Would be great if someone can shed some light before tomorrow. Would be great to get it sorted.

Thanks

[Jonco]

Probably the stat sticking on temp issues if it's a gradual change. You can try the simple `feel' test on hoses in/out of stat to see is there are any temp changes which co-incide with gauge variations - mind your fingers in the fan!
If you have access to INPA diagnostics then coolant temp is one of the things that can be monitored.

[Robert T]

Hi and welcome to the forum.

Slow to warm up, is often reported as a symptom of a thermostat which is stuck in the open position, so that would be my first guess.

Coolant temp sensor reading can be checked using the odometer self-test mode - it will give a reading in Celsius. The Z3 temp gauge is not linear - it is buffered so that the straight up position covers a range of "normal" operating temperatures. The test mode won't tell you that the sensor has failed, but if it gives a reading which slowly increases, then the likelihood is that there is nothing wrong with the sensor.

Misfire is best checked by reading engine codes - could be any number of things from camshaft sensors to coil packs. It may not have logged a code, but if it has, it will normally tell you which cylinder.

As for the smell of petrol, where is this coming from? If it is from the exhaust, it could be a unburnt fuel from the misfire, and if so, it will potentially be damaging the cat.

Cheers R.

[deadlyminimee]

Hi,

the radiator and hoses feel the same warmth all round. is their two coolant/temp sensors one with a two prong connection and one a 4 prong and is it worth changing these?

I dont have access to a meter to check codes etc... It also feels like its sluggish pulling away and picks up once the revs are high if that makes sense.

thanks for the responses so far. Im not sure where the smell of fuel is coming from but it is when you rev it hard.

i wish things were easy to sort out!!!

[BladeRunner919]

Definite thermostat - they regularly fail open. In fact, has anyone bought a 1.9 on which the thermostat wasn't stuck open?

Fuel gauge is not very linear. In my experience they are consistently inaccurate, in other words will drop rapidly, then more slowly, then more quickly, but will always act the same way. It really isn't a good indication of how much fuel is left. You're better off learning how many miles you get from a tank and then using the trip meter combined with the fuel gauge to know how much is left.

[BladeRunner919]

Coolant sensor is almost certainly a red herring.

[deadlyminimee]

If it is the thermostat would this cause the missfire and smell of fuel?

[BladeRunner919]

I guess if the engine never gets up to temperature it would make the exhaust smell of fuel as it always be running rich. That could also have led to the plugs being pretty dirty and give a misfire.

Is the fuel smell under the bonnet, or could it be coming from a rich exhaust?

Might be worth pulling the spark plugs and having a look to see how they are.

[deadlyminimee]

I will look tomorrow at the sparks and try to work out where the smell is coming from. Thanks for help so far.

[BladeRunner919]

No worries. And welcome to the forum.

Whereabouts in Bucks are you?

[deadlyminimee]

Im in a village called Ashley Green, near to Berkhamsted, herts.

Are you near? Maybe you can help me out??? just kidding.

[Del]

Definite thermostat - they regularly fail open. In fact, has anyone bought a 1.9 on which the thermostat wasn't stuck open?

Totally agree

For the misfire - Good idea to start by having a look at the spark plugs. I have seen a few posts on this forum where new owners have suffered from neglect in this area by previous owners. Look closely to see if one looks different from the rest i.e. wetter & blacker - this could show either a plug or ignition coil fault. As said already, it is ideal to plug the car into a code reader to check for recorded error codes triggered by the misfire.

[deadlyminimee]

Now I'm worried....

I thought I may as well replace the coolant sensor because I had it and only a 2 min job. Took it out for 10 min spin and The gauge has gone right up to the red!!! I don't want to knacker it so any help would be greatly appreciated.

[BladeRunner919]

Put the old one back in and see what happens.

[deadlyminimee]

Once its cooled down ill try the old one again!!' This is so annoying!

[BladeRunner919]

I take it the gauge started at cold and moved into the red rather than just going straight there (ie bad sensor, bad wiring etc)?

[Robert T]

I think it is more likely that you have the wrong sensor and that it is now giving a reading which is somewhat higher than the old one. What exactly did you buy and did it have a part number?

I can see two items labelled "Double Temperature Switch" on BMWFans - one is on the radiator and appears to be for aircon only - the other is on the cylinder head, which I am assuming is for the temperature gauge. The latter seems to be the same part for the entire Z3 range, with the exception of the S54 ///M engine. See here for details.

Cheers R.

[deadlyminimee]

Good point. The first time I saw the gauge it was in the middle. It had been ticking over for a couple of minutes so maybe bad wiring? Could I have put the connector on wrong? Not sure if its possible to have it on the wrong way round and if that would cause that? Once I can get my hand down there to check I will.

[deadlyminimee]

http://www.gsfcarparts.com/929bm0240


The one I got. The connector has 4 prongs on it.

[deadlyminimee]

It seems the connector can only go in one way so i will change it for the old part shortly.

[Del]

When I was chasing some mystery misfire issue in 2011, I speculatively changed the coolant temperature sensor with one from GSF. The electrical prongs inside were too narrow and it did not come with the fixed seal washer and leaked coolant. I replaced it with a new BMW OE one which only cost about £13.

I quite like GSF but sometimes these pattern parts simply just don't do the job correctly.

[deadlyminimee]

Funny you should say that. I've now got the new bit off and looking at the part it says Rover MEK 100160.
The box it came in has the part number that corresponds to the correct part on the website for the z3 but the actual part does not have any think other than MEK 100160.

I called gsf and they said it will be the right bit because range rover use the same engines???

I just wonder if the original will do the job.

[Del]

The problem is with some (not all) aftermarket bits is that they are an "approximate best fit" for several vehicles. As you have already gone down the route of replacing the sensor, I would personally fit a new BMW one and see what happens - you have then got the peace of mind that you have definitely eliminated one possibility.

As said above it really is common for the original thermostats to stick open - it is a common posting on this forum.

[deadlyminimee]

where can i get an original part from?

[BladeRunner919]

where can i get an original part from?

From BMW, but I honestly think you're focussed on the wrong part. Change the thermostat and leave the old sensor in.

[deadlyminimee]

where can i get an original part from?

From BMW, but I honestly think you're focussed on the wrong part. Change the thermostat and leave the old sensor in.

ok, will this part do? http://www.gsfcarparts.com/176bm0130

Why would the temp gauge change so dramatically when i put in the other sensor if it is fine?

Also,

Is it a DIY job to change the thermostat? I just dont have the money to throw at a garage so if i can do it myself i will have a go!!!

thanks for all your help...

[BladeRunner919]

Yes, that's the thermostat. It's an easy DIY as long as you have basic skills.

The sensor may just not be right for the car - as a rule I'd always suggest a BMW dealer for sensors as there are too many stories of problems with aftermarket ones.

[deadlyminimee]

Yes, that's the thermostat. It's an easy DIY as long as you have basic skills.

The sensor may just not be right for the car - as a rule I'd always suggest a BMW dealer for sensors as there are too many stories of problems with aftermarket ones.

just hope the thermostat works ok if i buy it from there

[Robert T]

General rule of thumb, get a price from BMW dealer first, and then compare with aftermarket/ebay prices. On the more generic parts, BMW are not badly priced, especially when you take postage into account (you won't pay any if you collect from you local dealers parts desk). Parts that only fit the Z3, or only one Z3 model are usually quite a bit more expensive. To get a quick price guide, I use Coopers. M44 Thermostat looks to be £51.38. I always get the parts desk to check the part numbers for me, as then it is their fault if they order the wrong part. Parts are usually available for collection in a couple of days.

The temperature sensor is likely to be some kind of thermistor who's resistance changes with temperature. There are all manner of these available and their temperature/resistance curves vary dramatically, some even change in the opposite direction (i.e getting more resistive instead of less). If the sensor is not the right one for the car, the instrument cluster will not be calibrated correctly to show the correct reading. If the gauge moves at all, I would expect that the sensor is fine. I certainly don't think you car has gone from running cold to overheating like that.

Cheers R.

[deadlyminimee]

Just spoke to Coopers and is £52 so a bit more but genuine part at least. Any guides on changing the thermostat? Do i need to remove fan, hoses, drain coolant etc?

[Robert T]

See the knowledgebase: http://www.zroadster.net/forum/viewtopi ... =18&t=3631.

It's not an M44 engine, but looks very similar.

Cheers R.

[BladeRunner919]

If you have a viscous fan you will need to remove it. That will probably be the most challenging part of the job as it can be tricky (Thank goodness I have an electric fan!!).

You will need to drain the coolant down, at least part way.

From memory I don't think there's much else that you need to take off just to do the thermostat - I did my waterpump at the same time, so had to dismantle a bit more anyway.

[Jonco]

Changed my thermostat recently along with pump and belt. The pump was nightmare to get out and as it turned out did not need changing. It's worth checking the condition of your drive belt in advance as if its' worn you might as well change that when you have the rest out.

I bought the stat and housing from http://www.carparts4less.co.uk at £30.60. It was a Behr unit so good quality. Same unit from Eurocarparts was £42.

You will need the 32mm flat spanner to get viscous fan off - plenty on Amazon - just search under `viscous fan spanner'. Note: fan thread is opposite hand i.e clockwise to undo.

[deadlyminimee]

I don't suppose you live close to bucks? Sounds like you will be a dab hand at it now!!!

[Jonco]

I don't suppose you live close to bucks? Sounds like you will be a dab hand at it now!!!

Sorry up in the Northwest but if you fancy the drive up!!!

If you take the fan shroud out you can actually get at the stat bolts between the fan blades with a long extension bar - bit fiddly but can be done without removing fan - depends what else you want to look at.

If you have access to a Haynes 3 series manual there are some reasonable illustrations on stat change for the 44.

[Del]

•Remove black plastic cowling at top of radiator (4 X 10mm? bolts)
•Remove the black foam air intake pipe – unclip carefully from air filter box and grill intake scoop
•Drain coolant as required – I actually drained from the plastic plug at the bottom corner of the radiator – care as this is plastic and can be over-tightened and broken.
•Disconnect hoses from thermostat housing
•I managed to unbolt the thermostat (two upper and two lower 10mm? bolts) without removing the fan assembly. I used a small socket and extension and reached the bolts through the fan blades.
•Suggest cleaning the surface (wipe with a clean rag) before replacing the new thermostat, which from memory needed to be tilted slightly to get it into position. The thermostat housing should have a rubber seal sunken into the surface that mates with the engine.
•From memory the two lower bolts were difficult to see and so I replaced them “blind” screwing them in by hand. They are torqued quite lightly (not sure of torque off hand).
•Refill with appropriate coolant mix and do the air bleeding process which personally I found a little tricky.
•As mentioned by others, whilst you are “in there” so to speak, you can note the way the auxiliary belt is looped, lever back the tensioner and fit another (if it looks cracked). Also, you can check and top up the power steering reservoir with ATF oil. Finally, lots of owners like to change the water pump as well – from what you say you may not feel inclined to do that at this point.

[Jonco]

........From memory the two lower bolts were difficult to see and so I replaced them “blind” screwing them in by hand.......

Good point Del - the casing cover bolts are next to them and same size -I locked on to wrong one on removal but realised my mistake in time - compare with new unit to get right position.

[deadlyminimee]

Nice one guys , appreciate your help