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Discussion Starter · #1 · (Edited)
I recently purchased a 2007 320d with an overheating problem and i'm after some advice

The car starts (Very slightly hesitant but that could be a weak battery) and the runs and drives very well

I haven't had much time to investigate but it got to about 100 degrees sat idling on the drive without the fan coming on (Fan does work when you turn A/C on) and shortly after spat water (Looked bubbly) out the expansion cap vent. I also noticed some white smoke coming out the exhaust once its hot which the seller never mentioned

I also have a mechanics report saying they pressure tested the coolant and does a chemical test on the coolant to eliminate the head gasket. However this was at 90k miles and the car now has 95k so i understand if its been driven 5k miles with the problem it could now be much worse.

One thing i find strange is when i open the coolant cap (From cold) i cant see any coolant circulating. Its just spits bubbles out the small pipe at the top but no stream of coolant like my mates (Newer shape) 320d does. Its a mechanical fuel pump on this car not electric.

Not sure if i should start spending on thermostats etc or look elsewhere? Once i have time i will be bleeding the system again but as far as i can tell it should self bleed

Cheers,
Dan
 

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I would start by getting the codes read, record them, post them and delete them. If there is plain water in the cooling system clearly that would boil at 100C, yes the system would need to be bled. Why is the cooling fan not running?

Maybe you can not see coolant because its all boiled off?

White smoke can indicate blown head gasket.

You say you purchased it what do you mean look elsewhere?
 

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Discussion Starter · #4 ·
I have read codes earlier today and the codes read were all to do with the EGR being removed and blanked. I have reset the engine light and see if anything re emerges.

There is defiantly some sort of anti freeze in the system as it is a green / yellow colour but i agree it needs draining and re filling as i am unsure what mix it is. Could have been diluted with a lot of water over time.

I have been doing a lot of research on the fan not coming on. I have found a post saying the e46 320d fan comes on at 98C. Temperature of my car was reading up to 100C but i believe this is oil temperature - so maybe the fan needs 98C coolant temperature (Which i'm not sure if its getting too, but it looks bubbly rather than steamy so maybe the coolant is not getting to 100C / Boiling point)

The system is full of coolant and i have done a basic bleed. Let the car get up to temperature and open the bleed screw until just coolant comes out. But i haven't had the time to take it on a drive yet

When i was bleeding the system earlier there was a little white smoke on start up but it cleared quickly and i did not see any more. So hopefully before it was just moisture in the exhaust system.

Looking elsewhere in regards to a more major problem. I guess eliminating the simple stuff is just part of the process.
 

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If the coolant is now full and bled, run it and see if the water pump is working, water flowing through the radiator. The fan will come on below 100C, the engine should be running at 86C I think when up to temp. Check you do not loose anymore coolant
 

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Discussion Starter · #6 ·
I will try do a proper road test tomorrow. I cant see that the guy sold it as cheap with a problem as simple as air in the system but fingers crossed 😅

The car got up to 97C earlier on the drive and the hose going into the rad was just starting to get warm but i expected it to be much hotter as the thermostat should start to open at 88C. Maybe i have a sticky / slow reacting thermostat if that's possible. Again a good road test would give me a better idea of what's going on
 

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You can not check if the fan is coming on if you are driving it. If the block was getting to 100C without the fan coming on there is a problem as the temp sender is in the block.
 

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Discussion Starter · #9 ·
Previously I let the car get up to 100C, stopped the car and popped the bonnet and the fan was not running.

The last post on the following thread suggest i could be just under the threshold for the fan kicking in so i will keep a close eye on it: 2004 E46 320D What temp should rad fan cut in | BMW Forums : BimmerForums

There is a possibility the previous owner deleted the overheating codes. I have got the car hot enough for the coolant cap to over pressurise but no temperature lights come on in the cabin. Do you know what temperature would be classed as overheating. From what i have read i think 125C / 135C is about the point a light might flash up and go into limp mode.
 

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No dont know the temps for warning lights or limp mode. How are you checking the temp? If you have a scan tool, you could check the fan operation with that.

If there is not sufficient coolant and there is just water it could boil and over pressure the cap or the cap may be faulty.
 

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Discussion Starter · #11 ·
I’m checking temperature through the hidden menu on the dash.

For codes I’m using a cheap obd2 tool, so doubt this would be able to do much with the fan?
Hopefully my head gasket DIY test kit turns up tomorrow and gives good news
 

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Shouldn't go above 88/90C on the dash. Maybe the water pump is shot, they only have plastic impela. Also did you bleed the bleed screw on the egr thermostat.
 

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Does the cooling system suffer with high pressure? When carefully releasing cap when at operating temp does it give a slight whoosh or is it under a lot of pressure giving a big whoosh? Also any loss of coolant or any loss of cabin heat?
 

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Yes need to do a block test from cold to see if there is any co2 gasses in the coolant system.

Check for the water flow from cold and hot the thermostat may be stuck closed all the time.

Does your heater inside the car stay hot as you can use this to keep the engine cooler.

You can also get white smoke if the dpf has been removed and the software not calibrated correctly which I see a lot of the time.

To damage the head gasket by wrapping the engine needs to go over 135 degrees for some time.




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Mine runs at 90/92 when on a run.
If i stop and sit it will cool (i have a readout plugged in the obd port sat on the dash).
Never seen it ever go past 93 ans never had the fan come on.
Me personally i would fit a new thermostat fill with 50/50 mix of antifreeze and make sure it is bled 100%.
 

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ive done a few tests over the years for hg failure,car cold,very cold,,,open bonnet,,take rad cap off,,start car,rev to near nmx for 30 seconds or so,,replace rad cap,,leave car over night,,open bonnet and take rad cap off,if there is any pressure/hissing then eother air lock or hg gone,or even car has had the likes of k seal put into it to mask any probs,,this stuff is lethal to cooling system,can block stats/galleries/water jacket etc..very very rare for hg failure tho,as jason said,would need to be silly temps for a while to distort head etc
 

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Discussion Starter · #17 ·
Thanks for all the replys, all very good suggestions and info.

I have done the head gasket block test today and it looks like i have a head gasket leak, or maybe worse.

I have started stripping so hopefully its not a crack in the block. I have also started reading about cam chain failures on the N47 engine and thats got me worried. Hopefully its not all a waste of time :cry:
 

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If you are having the head off do the chain kit at the same time,far easier to pull engine out as you need box off to access the lower chains.

yes the chains fail but with a new chain kit you have a clean slate,change oil and filter regularly and don’t follow the stupidly long bmw schedule and you will greatly improve chain life. Also not sure when start/stop was introduced but if your has it then disable it as that causes more wear on chains
 
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