320i heats up quick

[Tigerstyle]

so finally bought my e30 cabriolet been after one for ages. Seem to be having a few issue which is expected for the age of the car. My main concern at the minute is my car will heat up very very quickly.

From starting the car I can drive less then a 1/2 mile and the heater will be blowing out very hot air, temperature gauge stays at quarter coolant levels are fine ( just had it flushed last week )

with the heater temperature gauge turned all the way to red and if I turn off the heater to zero I can still fell hot coming in from the vents every so slightly?? Any ideas

[Brianmoooore]

First of all, you have bought a BMW from an era when BMW concentrated on quality as much as profit, and issues should NOT be expected.
The design of the heating system is such that I would expect heat to be coming from the heater within half a mile, and would suspect a problem if it wasn't. I'm assuming the temp. gauge goes to just past the middle and stays there.
Concerning your second point, from where the temp. knob is just off of its stop, to full heat, the temperature from the vents is controlled by mixing heated and unheated air together, but when the knob is turned to full cold, an electrically operated solenoid valve should cut of the flow of coolant to the heater completely. There will still be some heat from the heater, until the hot coolant trapped in the heater matrix goes cold, but after that there should be no heat from the heater at all.
The unpowered state of solenoid valve is fully 'on', so if it wasn't getting power, the symptoms would be as you describe.
The valve has its own fuse, which is the only fuse on an E30 that isn't in the fusebox, so the first thing to check is this fuse, and whether power is reaching it when it should.
Fuse and valve can be seen by removing the RH access panel in the glovebox, buit for full access, the centre consoles need to come out as well.

[BenHar]

For a six cylinder car the gauge should sit at just over the quarter mark.

With the heater temperature turned to hot and the heater fan on zero you will still get some flow of hot air caused by the movement of the car unless you close the vents by pushing all three sliders to the left.

Yours sounds normal to me.

Ben

[Tigerstyle]

Regardless of the build quality by BMW it's inevitable with anything that's 25yr old you will run into issues...

i ve cleaned out the expansion tank today, well as much as I physically could ( could do with replacing ) heard all the gunk & crap build up in there can cause overheating.

Benhar thanks for confirming its normal, guess its advantage in the winter then

[Brianmoooore]

If the car doesn't have aircon, then it's fairly obvious that the air coming from the vents won't be below the ambient!
If there's 'gunk and crap' in the header tank, then the cooling system has, or has had, a problem. The problem may cause overheating, but the 'gunk and crap' won't.
As BenHar says, the normal temp. gauge position for a 6 pot E30 is just above the 'quarter' mark. 4 pots use a slightly higher temp. thermostat, which puts the needle on the centre line.

[Tigerstyle]

The top rubber hose had a split in it, I ve had all the hoses replaced with black cilicone ones flushed the system added new blue coolant cleaned the expansion tank, never changed the thermostat because the temp gauge is bang on quarter.

What about the fan clutch... If this is faulty will it cause a lot of heat build up in the engine bay but then again the temperature gauge would shoot up would nt it... Will do the newspaper test later today to check the fan

I could BBQ a chicken under the hood after 5 min of starting maybe I m just being paranoid

Not had a chance to look at the solenoid valve yet

[Brianmoooore]

maybe I m just being paranoid

Nothing you have said is anything other than normal, except a possible problem with the heater solenoid valve.

[stu328is]

Sorry to hi jack, my 325i sits at just over the half way mark, does this mean there's something wrong?

Also noticed that if I put the heaters on the temp drops on the gauge, is that normal?

[Cloggy Saint]

No and yes.

[stu328is]

Very concise answer lol, I'm worried because I ran it for a couple of months with a dodgy expansion cap, someone had crossthreaded the cap, so it wouldn't tighten properly and seal never had any problems or high temps though

After a good run to the inlaws giving it it a good toeing it lost some water through the overflow pipe which it has never done, I've replaced the cap and now notice the temp drops considerably when I stick the heaters on, was worried this was hg probs as that's how I used to cool my fiesta down with a knackered head gasket when I first started driving, not had anything overflow since

So you think that is normal behaviour?

[Brianmoooore]

If the temp. gauge on your 325 M20 sits at just over the half way point, then it's possible that the wrong 'stat has been fitted at some point. This is not necessarily a problem if the cooling system pressurises itself correctly - an engine should be run at the highest temperature possible that does not result in local boiling at the hottest parts of the cylinder head.
If you run the heater at full blast when the engine is not under any load, then you may be extracting more heat from the coolant than the engine is putting into it, so the gauge may drop back a bit, but when driving the gauge should exactly at the temp. marked on the thermostat, and not move either way, except when moving very slowly, when it will move up slightly to the point when the viscous fan coupling engages.

[stu328is]

Maybe the wrong stat then, it will sit at the half way point in traffic then as I move off and cruise at say 50 it drops down maybe 5mm towards cooler on the guage without the heaters going and the heat from the heaters is burning hot

The temp guage moving about only really started once the cap was sorted, never really noticed it moving apart from normal moving up to temp before.

I've got no signs of mayo or anything like that just wondering about the guage moving about so much

[Brianmoooore]

Now you're saying the gauge needle sits 5mm to the left of the centre mark under normal running conditions, which can't be far away from "just past the quarter mark", which is where it should be. There's no cooling airflow in traffic, so the coolant gets hotter until the viscous coupled fan cuts in, and maintains the temp. at the half way mark. When you move off, the engine thermostat takes control again.
All sounds normal to me.
One thing you could check is that the small brass nut on the back of the instrument cluster, immediately behind the temp. gauge hasn't gone missing. If it's loose, the gauge will jump over and back a few millimetres, as it makes and breaks contact, but with it missing, the needle will always read a little high.

[stu328is]

Ah ok, wouldn't bother me so much if it hadn't spat some coolant out that time, I've been a bit paranoid since then

Your suggestion of the cluster sounds interesting as my fuel guage has mind of its own as well at the moment, it likes telling me it's full when it isn't, it reads better when it's over the half way mark and will have fits and starts of being correct, been concentrating on fixing other bits so it hasn't been at the top of the list tbh

Sorry for the hi jack op, thanks for the help brian