535i coolant system problems.
 

I have recently bought a 89 535 and i had done a few work to it because the previous owner had absolutely no idea what they were doing. i had to had the starter rebuild, they replaced the fan and clutch with an electronic fan. i had to install a thermostat since there was no thermostat to begin with. now when i run it and get it to operating temp., the hoses going to the radiator becomes stiff like theres a lot of pressure in the hose. and every time i bleed the coolant, only coolant comes out and no air. so as of right now im stumped. should i be looking for a clogged hose, or should i replace the radiator. also will this cause the engine to run rough after warm up when pressure is build in the hoses?

It is normal for the radiator hoses to be under pressure when the engine is at operating temperature. I prefer the engine driven clutch fan to an additional electric. With the proper thermostatic swtich the electric should work fine.

Is the car overheating? Is the car losing coolant?

Is the car running rough as well?

its not losing coolant and the temp gauge stays at the middle line. the hoses seems to have a lot of pressure though. sometimes it feels hard like a rock and i know that isnt normal to any car.
once i start it up the engine will run fine idle like it should, then once i drive it for a little bit and when the temp gets to the middle line on the gauge, it starts to idle rough. but when i give it gas sometimes it smooths it right out and sometimes it seems like it dropped a cylinder or two.

Is the thermostat in the right direction and right temp ?

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The cooling system can presurize to 15 psi and still operate normally. Beyond that you will get pressure release from the cap at the resevoir at the base of the windshield.

If the car is not overheating, and not losing coolant, there isn't likely a problem.

The one thing that can overpressurize the system is a blown headgasket but it would also cause overheating and coolant loss.

This could be any number of tune-up items, plugs, wires, cap, rotor, fuel filter, injectors, vacuum leaks, idle control valve clogged or bad, throttle position sensor, O2 sensor, valve adjustment. Download the Bentley manual for the car and start diagnosing and replacing worn tune up items as needed.

Whatever you do, I wouldn't put diesel fuel where it wasn't intended to go, in hope of finding some miracle liquid cure for your car.;)

well i decided to leave the cooling system alone and drove it for a while. and just until a few hours ago it started to over heat on me. as in the temp kept going higher, so i pulled off and open the hood and saw steam and dripping coolant from the coolant expansion tank. i let it cooled for a little bit and started it up and right away the gauge went right down to operating temp and was fine... so my question is what the F@#* did i get myself into buying this car?!?!

Relax man, its just a car, they all have issues at one point or another. At least you saw this coming and got feelers in there.

I start with a coolant flush, fill and bleed and take it from there.

I already flushed it last week with a new thermostat. and while i was looking up similar problems, i was thinking, is it possible that the thermostat didnt open to begin with and cause it to over heat?

Just curious...

Did you rule out a head gasket problem?

Is your heater control valves working properly?
Does it make a difference when you turn on the heater?

My car has been going about a needles width over TDC on the guage, and causing me some concern, so I'm paying attention to the advice of posters.

Supertech777, I had to go to RealOEM, just to assure myself that I had installed the thermostat correctly, even though I was quite certain I did.
New water pump, and new rad, but still the same on the guage.
What, in your opinion, is the proper temp degree for the therm?

I am having another interesting thing happen concerning the cooling and A/C, but I will start a new thread.

Thanks for the continuing education.
Hb

A 23 yo BMW may need a cool system over haul, rad,pump,fan clutch,hoses,housing. I would go back to stock HD Clutch fan. I think that coolant channels in the block can de obstructed with debris/corrosion ,witch also can clog Radiators.

the cooling channels in the block are so thin and small, given the amount of coolant passing through the block (not sure if youve ever drained the block but its alot) would cause a pretty good deal of pressure which would make the chances of something small enough to fit in there get stuck slim to none. a radiator block or clog is much more probable.

I agree with the system overhaul. New sensors and hoses and clamps and housings and gaskets and all of that with a true flush (block included) and proper bleed.

Did you bleed the car right? the heated air left in the system could expand causing all of that pressure you feel in the hoses, and ultimately an overly hot engine...

I'm not sure of the exact way to bleed the air out of an M30, or if its similar to an M50. I know the M60 is a self-bleeding system...

Was there a reason why the previous owner removed the thermostat ?

You need to do alot of troubleshooting before you jump to conclusions, and it is likely that you'll need to do stuff anyway just to be safe. Since the overheat ocurred after your repair, there's a good chance that you either did not do it right, or the thermostat was busted though new (it happens).

Try removing the thermostat and driving that way. There's no harm to the car with the themostat removed.....the engine will just take longer to heat up to operating temperature.

You should check to see if your WP (water pump) is working. Pull out the top radiator hose off the radiator, start the car, and see if water spurts out. If it doesn't, then your wp is busted.

On lunch break so I'll be quick.
I will go into detail if not understood later.

For there not to be a thermostat already in the car is a tell.
Usually done to cover up a bad WP, clogged radiator or worse.... BHG (blown head gasket)

However let's not get ahead of ourselves.
Test your current thermostat in a pot of hot water.
If it opens your good.
Let it cool (this is where people don't pay attention) If it doesn't close the thermostat is bad.
Make sure you have a high temp thermostat.
If you don't have one get one.

Drain the system and remove the radiator. Then flush it.
Flushing the entire cooling system at once is good. But I've been down that route your on.
So to be safe I remove the radiator and flush it separately first.
Reinstall radiator.
Flush the entire system
refill and bleed, bleed, bleed.

If that doesn't do the trick then check you wp.
Next would be to inspect your sensors (one on the radiator, one on the thermostat housing)
If none of these solutions work... BHG.

The Idle issue can be from various things. Without much detail on what's been done to the car and when does it occur... it can be anything.
As well most m30 cars have a bit of a lumpy idle.

I wouldnt do this. you can feel the coolant flowing through a hose wih it attached while the car is running. Definitely a safer option.

+1:thumbup:

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You won't be able to judge the amount of coolant flowing through the hose as well as with it detached. From what I've noticed, wp failures need not be total failures. They could also work partially, just not well enough to pump enough coolant through to the radiator. This was amply demonstrated by Larrick in a recent thread on an overheating issue, who did pull the hose off and ran the engine to see the water flow, and was neither hurt in the process nor caused an overheating issue (in fact there's nothing dangerous about this, common sense will suffice). He reported that water did flow, and eventually, the dealership diagnosed the problem as being a buggy water pump.

If your engine is an optemp, you have about 2-3 minutes to do this before the temp would begin to climb. This is enough time to make a quick judgment about water flow. If your engine is cold, you have up to 6 minutes. In any case, you can have someone sitting in the driver's seat watching the needle, or you can work something out with your phone video cam setup to shoot the coolant flow while you are in the car.

Of course, shut down the engine once the temp begins climbing. Repeat the test with fresh topups of water if needed.

The likely suspect in this case is the thermostat, since most problems that occur immediately after a repair are related to the repair itself. However, it is also quite possible that it is not, as it is rare to have a new part be defective right out of the box, and a thermostat can only be inserted one way into its cavity, and if there's no visible leak after that, then installation itself was done correctly. From what the op says, this car was not well looked after, which means the wp is probably could be screwed too.....perhaps that was why the po removed the thermostat, to permit a greater flow of coolant out the cylinder head despite a partially functioning wp.

Tim, you might find this thread useful to your issue :

http://www.bimmerfest.com/forums/sho...325&highlight=



rgds,
Roberto

Most points covered here. If the water pump is suspect ditch it rather than 'test' it. Cheap insurance.

You need to find out why it is overheating. Doing another flush, or a flush at all is unlikely to cure the problem, and when you go to fix the problem you will be wasting expensive new coolant. If the radiator, fans, water pump and head gasket are working, it will run on garbage coolant. Just save it for last, save yourself time and money.

I would also FIRST verify the condition of the headgasket. There are chemical tests that detect combustion gasses in the coolant. Check the oil for milky color. Stop driving if you see oil in the coolant or vice versa.

If the headgasket checks out, go for the cooling system overhaul and thorough system flush. It is impossible for us to know from here what the condition of the radiator is, or the water pump, or the H.G. There is more work to do.

I agree with just replacing the WP. If its suspect, replace it, as stated before, cheap insurance...

A poorly flushed non-bled system would cause over heating. Air becomes pressurized with heat (think hot air balloon if it helps; I know it's not a pressure thing, but temperature causes deferent properties for gases). A lot of air in the system could cause many cooling issues which is why there's such an emphasis on the bleed bleed bleeding.

I wish OP would check back, so we can get some closure or an update.

I think that this is the order of events that's needs to happen here OP:

i checked the oil and there isnt a milky color, the exhaust doesnt smell or looks like its burning coolant so i think the head gasket is fine. is it possible that the hose from the rad to the expansion tank is clogged and/or the expansion tank has some issues.

also where on the block is the drain plug?

also i bled the system using the bleeding screw on top of the thermostat housing and after a while of bleeding it it stopped having air come out. it hasnt over heated again so far.

now my last question, if the rad has a little damage to one of the ports but isnt leaking, would that cause a problem too?

Your last question is "possibly". Any details about this "damage"?

The drain plug on the block of my M50 is under the exhaust in between the 5 and 6 cylinders...

We still have not determined the cause of the overheat. The system has reportedly been flushed and bled, not exactly a complex procedure. Vry doubtful that is the cause.

It is highly unlikely that there is a blockage in a hose.

As mentioned, more info on the damaged radiator.

Did it overheat on the highway at speed, or in traffic, stop and go?

It would take a lot of air. No offense but changing coolant to fix an overheating problem is akin to changing trans fluid on an auto trans that wont go into reverse. It just isn't going to fix the problem. Find the probelm first, do fluid maint after the actual fix is made.

Unfortunately, that's not a very thorough inspection. Taking it to a shop and having a technician perform a leak-down check on each cylinder is the best way to go.

On the passenger side of the block, towards the rear, underneath the 5&6 exhaust ports. Don't remove it until you have a new copper gasket to put in place of the old one...otherwise it'll leak.

That's good. Now would be the time to get it over to a shop for a better look. This isn't unique to BMW's, it's just something you have to do with any old car, for peace of mind. :dunno:

What do you mean by, "....a little damage"? :confused: Got a pic?

When you installed thermostat was the little arrow or up? Also check the condition of lower raditor hose. If deteriated it could colapse. Good hunting