Overheating M20 :(

[Nay]

Right guys.....! (been a while since one of my retarded posts!)

Today my car (the 320i slushybox) decided to start overheating.

Build up to the problem....
1. Coolant light has been on for 1/2/3 months? Its always topped up and the light just remains on. I think/thought it was like my washer fluid check light that just doesn't seem to disappear, even when attended to. What actually makes the coolant check light appear, surely just the levels of fluid?

2. Recently my engine oil light came on for a night (of delivery driving...) then disappeared. So I disregarded it like the lazy retard I am. It came on again, then went. Disregarded...

For a few days the car has been going up in temp when at standstill, but goes to just under half on the meter when driving. Today, it just didn't go back down (after a few hours of pizza-boy'ing). Drove it back from a mates tonight and it sat in the red for half the journey (once it got warmed up!)

So, nakered thermostat?, cylinder head/gasktet gone?, or what? Where should be the first point to check....??? (and how does one retard check such a problem?? )

Any help is grately appreciated, as usual!

(p.s., I would have searched for this, but my internet is being very tempramental, so I wrote this in notepad and copy/pasted into here the second I got a chance!)

[mrLEE30]

coolant light is a simple sensor located in the coolant bottle. they are prone to failure and are cheap to replace, but shoudl not be used as a substitute for regular inspection of engine fluids.

Oil light - do you mean the one in the dash board or on the overhead check panel. the first one can flicker when cornering which is not much of an issue, but if it remains on then your oil is dangerously low or the pump is knackered - or both. the check panel is simply a level meter, so again if you stop on a slope it will trigger it. does it go off if you turn off and on the ignition? yes then OK - no thenyour oil is low or the sensor is knackered.

as for overheating as will asks above.

yes then sign on leak or HG, NO then check the viscous coupling on the fan

[Nay]

Is it using water?

Dont know, will check today. (I take it you mean burning up/loosing the water around the car)

Sorry, its the check panel oil light. Not the dash board one. I'll check the levels today.

I'll check my viscous today (newspaper test right?)

Is it alright to rinse and fill my coolant with just water? Especially at this time of year (bearing in mind its cold, but not quite as low as the UK temps!)

[Brianmoooore]

First thing to appreciate is that red means stop! If you want your car to remain to have a serviceable engine, then you do not drive it with the gauge in the red!! If you've driven it any distance in this condition, you'll be very lucky if you haven't caused serious damage. Just once is all it can take!
Antifreeze does much more than just prevent the coolant from freezing. It's essential to prevent the aluminium parts of the engine from rapidly corroding.
Re, your original faults: the oil level light is probably the level slightly low, and the overheating in traffic does suggest a viscous fan coupling problem, but these may be the least of your worries now.

[Nay]

Thank you mister moooore!

You could be right. I didn't get a chance to check her today, but I'll have to tomorrow. I did drive it for a little in the red (only stayed in the red for a tiny bit, twice, as jerseys a small island to get around, but it wasn't going down!)

My 320i is on the verge of car heaven anyway, so even a new viscous coupling could be enough to say thats enough. Any more damage and its a gonner.

There's a few turds up for sale in jersey atm, so I might look into them as a replacement. Sucks for my job though

[Brianmoooore]

It will make the car noisy with the fan howling but it will cool the car.

It will also do nothing for the 320 auto's less than impressive fuel consumption figures!

[Nay]

Right, round two.

The car had drunk some water, yet to find out if its 'drinking' though. Oil topped up too.

The fan survived my mighty attack involving a thick magazine (no newspaper to hand) and still seemed pretty strong.

Car started to overheat on a little journey round the block after a tiny idling 'warm up'. Stuck behind slow pokes it was moving into the red (for < min) and when I pulled into my drive appeared to be sitting right on the bottom of the red. Didn't dare test that it would go further, but I think it would if given the chance....

How can I test if the head gasket has gone, or if the cylinder head has been cracked?? I know you can sometimes get 'mayo' under the oil cap, but how long till that would start to form anyway? (as there aint any yet, if any will form at all....)

Basically, how can you tell if the car is now knackered?

Ideas? Could it be something else?

[dickster]

You could get a hydrocarbon test done to check for potential head gasket.

Is it getting warm when your driving or does it cool down when on a run? you want me to have a quick look at it? my Sport has a knackered viscous so I've got a few heating niggles myself at the mo, you just need to keep the faith!

[Nay]

Richard, if you could swing by when your free mate, that'll be great.

It just slowly gets hotter and hotter. Before it was cooling when on a run, but now (over the last 2 days) has decided to fail.

Otherwise, could be car heaven, as I may get a new one (possibly my 3rd E30 ). Maybe help me find another mechanically sound one? A little 4 pot would be nice for the petrolium.

If its going to car heaven, your more than welcome to buy it off me for all the salvaging goodness. I only want the bonnet, bumbers, one of the wings, maybe the SE skirts, dash and the wheels. Boot carpets? Rocker cover? etc. Nothing major. Unless your after some of them.

Is the iS you just bought the red one with black leather, on insight for £1500?

[dickster]

Richard, if you could swing by when your free mate, that'll be great.


Is the iS you just bought the red one with black leather, on insight for £1500?

Ok I'll text you and have a look.

Yes it is, I'm collecting it at the weekend.

[Nay]

Oh, looking forward to seening that. If only i was a little quicker....

Cheers mate, awaiting your text.

[ross_jsy]

if you want to save richard the hassle i shall have a look when you take a peek at my engine on sat?

my sports converted to electric fan, non of this viscous fan hassle

richard, your sport doesn't have a touch of filler on the roof by any chance? if so i may have seen it. mine will be out soon enough if ya fancy a little drive

[Nay]

could do, but ideally I would like to know whats wrong with it asap. Depends on how free you guys are.

[Brianmoooore]

my sports converted to electric fan, non of this viscous fan hassle

An electric fan is going to be many times less reliable than a viscous one!

[ross_jsy]

hmm pm me your number (forgot to save it) and i can probs have a look when im at work tomorrow then.

and i know brian, but now i have to have the fan with the m50

[dickster]

richard, your sport doesn't have a touch of filler on the roof by any chance? if so i may have seen it. mine will be out soon enough if ya fancy a little drive

Nope, although mine is a bit rough around the edges the roof is fine, I know a chap has just bought a tech-1 Sport which had a rusty roof and he was going to track day it so it might've been him- registration J33253. I don't drive mine half as much as I ought to but hopefully that will change. Yeah can meet up, there is a suprising lack of BMW meets in Jersey, unless you are a beard with a perverse desire to hang out with other men with beards dribbling over a 1939 MG TA.

Nathan I was going to have a look tommorrow if it wasn't too wet but if Ross wants to do it then I'm easy just let me know either way.

[Rav335uk]

You sure your thermostat isn't knackered and not opening????

[ross_jsy]

J33253? could have sworn that was a tech 2, saw it for sale ages ago and was tempted as a cheap run around.

i have not driven mine since september the 10th when i blew the m20 it pains me to look at it. but im hoping with in a month all will be done.

[Nay]

Thanks Rav, another thing to look at. Dont know how to check the thermostat though.

During my drive this evening, it wasn't fully warmed up on my way back home, so I continued the run and for a while it sat at 3/4. It then slowly increased (over a 5 min drive) towards the red, so I parked her up again. So it's not savagely overheating....

Richard, I'll message you tomorrow if you dont mind swinging round.

Ross, let me know whenevers good for you, just incase Richard can't make it.

[Rav335uk]

Check the rad, top and botton and be careful of all the moving parts, it should be hot all the way through.
Also see how pressurised the pipes get, if they get really hard then theres a blockage somewhere.

[Nay]

Thanks, haven't been near the car today, so can't check that, but i'll make a point of checking that tomorrow.

I take it I should warm the car up to around half temp before those tests?

[Rav335uk]

Thanks, haven't been near the car today, so can't check that, but i'll make a point of checking that tomorrow.

I take it I should warm the car up to around half temp before those tests?

If it is the stat, it'll warm up pretty quick, as the temp stays in the engine and doesnt get into the rad.

[Nay]

Right, after a 10 min idle (with mini revv holding every now and then) I got the car to about 1/4 up the temp gauge. Remember its about 0 degrees tonight as well.

[If your looking at the engine from the passenger side, facelift cooling system] The closer, top pipe is hot. The one further away (going back into the engine???) is about the same temp. The one under the first pipe is (U shape rubber pipe going to a metal pipe) was/felt stone cold (in comparison, as my hands were getting frostbite whilst trying this lol).

From what I remember from testing my 325i's cooling system, I dont think any pipe was presurising or going hard/stiff (don't think of anything dodgy... )


Could it be the thermostat then? If so, roughly how much are they? Are they hard to replace and do you have to bleed the coolant to change it? If its not that big of a job for me anyway, then I may just try it!

[Rav335uk]

Pi55 easy, I normally used to undo the bolts and let the water drain out, this way you don't loose all your coolant.
Take out the stat, and remeber which way out it came, drop the other one ine, replace either with new gasket or blue gasket sealer, tighten up bolts, and fill up and bleed system.
That's as far as I can remeber, I have the M30 now and it's a bloody nightmare on that.

[alexalloybrokers]

i've got a similar prob. on my 320i
mine uses coolant, (maybe 2 weeks till the coolant light on, then i need to top up like about 1 ltr or so)
usually sits on half on the temp guage. but sat in traffic for maybe 20mins or so it starts to rise. once it gets to 3/4 on the guage i stick the fans on full, and hot. and the guage stays where it is. and engine cools once driving. no water in oil, no oil in water, oil level is fine.
and i cant visiblely see a leak.

i do get a smell of coolant occasionally after a run. so as an addition to this thread can you tell me where are the common points to check?
at the moment im assuming i need a water pump, (maybe seals have gone) but i should also check viscous fan, thermostat and pipes for a blockage? does/can coolant leak from the heater matrix?
for example are there any suspect hoses that are prone to perishing or leaks?

[Brianmoooore]

i do get a smell of coolant occasionally after a run. so as an addition to this thread can you tell me where are the common points to check?
at the moment im assuming i need a water pump, (maybe seals have gone) but i should also check viscous fan, thermostat and pipes for a blockage? does/can coolant leak from the heater matrix?
for example are there any suspect hoses that are prone to perishing or leaks?

First of all, it sounds like you need a new viscous fan coupling.
There are plenty of places a M20 cooling system can leak!
Heater matrix is possible, but a much more common one in that area is the electric heater valve on the LH side of the heater box, and this is often caused by a faulty cooling system pressure cap which still hasn't been replaced more than a decade after BMW issued a safety recall!
Water pumps can leak; often, but not always,given away by a little play in the bearings.
There is a hot water connection to the throttle body, which is weeping, if not actively leaking, on most M20's. This can be disconnected and the flow and return pipes joined together with no ill effects, unless you live in Siberia or somewhere with similar weather, like the north of Scotland.
At the rear of the cylinder head, there is a hose that goes to the bottom heater connection. Because of it's hidden nature, this hose is often overlooked, in spite of it living in one of the more hostile positions on the car. The bolt on connector to the head for this hose has also been known to corrode through.
There's a steel coolant pipe that runs across the front of the engine to the lower radiator connection, which is reputed to rust through, but I've never seen this, and of course, any hose can fail with age, or it can leak from its ends if the clamps aren't tight enough.
That leaves the radiator, and unsurprisingly, a 100,000 mile+ radiator can be prone to leaks. At this sort of mileage, they really should be considered a service item and replaced.
Although you may not be able to see a leak, dried antifreeze is fluorescent, so looking around with a UV light in otherwise darkness may just give clues.

[alexalloybrokers]

you are the man! just the info i was looking for!!!

i am getting a viscous fan coupling anyway and checking the rad when replacing as i had both these go on my E36 coupe M42, but i didnt experience any coolant loss on that one, just overheating in traffic

[nm1]

i had the exact same problem on my sport and it ended up the rad it looked good from outside but inside it was bunged with sh1t, i ended up replacing the engine, after originaly changing water pump and thermostat, after i replaced the waterpump it pumped the water around better but it still heated up, if i was you i would take out the rad and flush it with a hose to see if it is bunged up. wish i had done that, ahh well, i guess i wouldnt have a lightned flywheel if i had of checked this.

[gafta]

HELP PLZ SOMEONE , having problems bleeding the radiator on my m20 engine,2.0 six. I have changed the water pump , thermostate , radiator ,thermostate housing and bleed screw, filled the expansiton tank with bmws own coolant, 50/50 mix , started the car, blowers on full heat , i have poured the coolant in ( quite a lot) had the bleed screw open ,hot coolant was coming out the bleed valve after 30mins of idoling, but the pipes dont seem to fill with water, the car was idoling for 40 mins , the temp was half way, but no hot air, it seems like theres a airblock in the matrix , cant seem to burp the system , when i open the expanstion tank cap, the coolant just rushes out cold, has any one got any tips on a easyier way to do this? what am i doing wrong ,

[Morat]

Try bleeding it with the nose pointing gently uphill, it helps the bubbles filter out. You'll want your heater sliders over to the right as well as the temp set to hot while filling. How much coolant did you put in?

[Brianmoooore]

Take the top heater hose off, and push it back on when coolant comes out of both pipes.

[eta]

I recomend a bentley manual for the E30 to all those with these cooling system troubles. It's like having brainmooore and other experts in a book.