BMW E32 735I Overheating Problem

[bmw328]

Hello Guys,

We bought a 1991 E32 735I a few months back as a second car.
Car is really in a very good condition with just over 220 000KM on the clock with FULL SERVICE HISTORY,

Problem is, after a few weeks of driving the car, We noticed that heat gauge will start to climb to 3/4, ext & go down again.

To my amazement I discovered that the car was shorting 4Litres of coolant!!! Filled it up & the problem went away for a while. 3 Weeks later, same problem!
Checked for leaks, nothing!
We then filled it up, and drove from Rustenburg (North-West) all the way to New Castle (Kwazulu Natal). (More than 600KM before car burst a water hose just outside New Castle.
I replaced blown water hose, ordered all new water hoses from agents & bypassed Air conditioner heater.
Drove all the back to Rustenburg without overheating.
Took the car for its next major service and requested that a pressure test be done (Just to check that the head gasket is not blow)
Service DONE,
Pressure test done, All check out all-right.

I spent about R10 000 already on replacing water hoses, water-pump & thermostat gaskets, new thermostat, water-bottle, water level sensors, emergency fan switch.

After doing all of this, she still manage to lose enough water for the temp gauge to raise!!!!

No mixed oil & visco fan is funtioning aswell, Its not missfireing at all.

Any ideas?

 

[zaleonardz]

Are you physically losing water that you are not seeing.

Did you do a combustion gas test of the existing water. It could be that you are either losing water into the combustion chamber through a cracked head. May not always appear on a pressure test.

Couls also be that its leaking straight onto the exhaust and burning up before you see it.

 

[bmw328]

[/quote]

I told the guy @ bmw that we are losing water somehow & to do a "Pressure Test". & they did ajust the CO of the engine. Won't it show up on that?

According to them, There is nothing wrong with the engine. So I' am like WTFudge?

Is there a way to be 100% sure? Perhaps a compression test?
But is it possible for a cracked head to be drivable more than 500KM before it overheats?

It must be losing the water somewhere i can't see!

 

[Nic_s]

I'm just thinking here, but if it's a hose (Even if new) that's leaking somehow, you could try and pull slightly on them while the engine is running to try and aggravate the leak. Best to do this while still cold.

Maybe you can leave it idling for some time and check after a while if there is any water. I'm talking about leaving it idling for like 30min+.

If you can't find any visible signs of water leaking then there is a very good chance that it's leaking into a combustion chamber or exhaust.

 

[zaleonardz]

Go to any silverton radiators.

They phyiscally take a sample of your water and chemically test it to see if it has combustion gasses mixed in, it costs like R50 to have done.

Alternatively, its leaking.

Also, I assume its an auto (being an E32), have you checked by the gearbox for leaks, I dont know the 735 that well, but the gearbox is water cooled as well im sure.

You can pick this up by seeing if there is two pipes going to gearbox from the back of the block.

You can do a compression test as well if you still cant find the problem, but the exhaust gas mix will give you a clue,

I just recon its leaking close to the firewall where you cant see it, and being burnt away by the exhaust

 

[bmw328]

Go to any silverton radiators.

They phyiscally take a sample of your water and chemically test it to see if it has combustion gasses mixed in, it costs like R50 to have done.

Alternatively, its leaking.

Also, I assume its an auto (being an E32), have you checked by the gearbox for leaks, I dont know the 735 that well, but the gearbox is water cooled as well im sure.

You can pick this up by seeing if there is two pipes going to gearbox from the back of the block.

You can do a compression test as well if you still cant find the problem, but the exhaust gas mix will give you a clue,

I just recon its leaking close to the firewall where you cant see it, and being burnt away by the exhaust

Ill try and take it today to silverton,
As far as i know of, the transmission fluid is cooler via the radiator (2 hidralic hoses from the g/box to the radiator.

Yes, you are right, its a auto.

Im going to rip it apart tomarrow & see what is going on!
:argh:

 

[zaleonardz]

Good luck bud.

Rick540 is our resident E32 expert...

 

[bmw328]

Thanks, Zaleonardz & Nic_S, did take her to Silverton radiators on Friday afternoon. Combustion Gastest came back positive, Took the car straight home, she is grounded until we have all the prices we need for repairs. Guy at bmw claims they did a pressure test on cooling system, therefore can't detect blown headgasket. Now the stress begins!!! Have to rip her apart and see if its blown head gasket or cracked head!!!

Will keep u guys posted on the repair.

 

[zaleonardz]

Sorry bout your troubles dude

Did she overheat, do you know if its a cast iron or alloy block ?

 

[bmw328]

Sorry bout your troubles dude

Did she overheat, do you know if its a cast iron or alloy block ?

Jip, she did
Its a cast iron block

 

[zaleonardz]

Refer then to PM...

Could then be head gasket or cracked head. :thumbdo:

 

[bmw328]

Good morning ALL!!!

Im having a slight :argh:!!!

I stripped the car last week and Wednesday, and found a really brittle head gasket, that came apart on removal from the cylinder block.
Took the head to engineering for a pressure test & came back perfect. Had it resurfaced, valves re-seated with new valve stems the works. (Basically renew the whole head!!!)
Ordered 14 new head bolts from the agents
Ordered Victor Reinz head set (Changes all gaskets)
Took my time with the re-assembly of the engine.
Torque the cylinder head according to the Bentley workshop manual for the car.
Stage 1 - 60NM
Wait 25 Min
Stage 2 - 80NM
Run engine for 25MIN (until car reach normal operating temp)
Stage 3 – 35 degrees.

Problem is!!!
When I started the car just after Stage 2, engine had a misfire and was running uneven.
10min later normal operating temp reached, but cooling pipes swollen & hard,
Switched it off.
Checked dipstick, oil filler cap!! , Milkshake!!!! And shorted 4 litres coolant from coolant reservoir bottle. (THE CAR MIXED)
Did the final torque as per manual, but Bentley manual don’t state anything about mixing fluids.
Drained all engine oil, and changed filter @ oil.
Car still misfires!!! And loses coolant,
What ever this cars problem was, I seem to have made it worse!!!!
Need help or suggestions....

 

[Raybimmer]

Car has full service history -If coolant mixture was changed every two years then internal deterioration should not have occurred .Head gasket fell apart - was there any corrosion of waterways visible on block when stripped ?
Oil and water mixing and water loss ( most likely ) means water is getting into oil . Were all hoses put on correctly ? You may need to strip and send head for chemical clean then pressure test -this may show leak between oil and water passage . Was the correct head gasket fitted -may close off water/oil passage ? Was head gasket on correctly ?
Good luck .

 

[bmw328]

The car is 20 years old, Yes there was rust inside the block, The head was sent for a full recon (Including Chemical clean)

The old head gasket was brittle, dry & old. broke apart on removal from the block.

The thing that bugs me is that the car use to lose a bit of coolant, and had to be filled up weekly.

She did not mix oil and water in the past, only loss of coolant. (No missfire what so ever. Now its looses alot of coolant quickly, mixes with oil and misfires. (Classic top gasket symptoms) AFTER HEAD GASKET REPLACEMENT

I didn't even bother taking the car for a test drive and she never even had time to overheat...

It is possible that my surplier didn't surply me with the correct head gasket,
According to what I have have found on the net, There where 2 different heads on the M30 (Early model 68 - 87) and (Late model 87-94 ) mine is a 91, But both use the same head gasket. (Compared it to the old gasket before installation)

The head gasket was fitted correctly (M30 head gasket can only be fitted 1 way)

I personally think:
X Can be incorrect torque settings...
X Incorrect Head gasket... (Stranger things have happend)
X one of the cylinder block gide dwols (Dwols that gide the head onto the cylinder block, might be smashed between the head and the block. causing the coolant, oil and combustion chamber to run.)

The strange thing about my last theory is that i did check that the head was seated correctly, level on the headgasket, before I installed the head bolds and torqued.

All the piped are fitted correctly, I'm not totally a beginner on bmw engines. Ive build my E36 up from scratch and know my way around it... :idea: and with the M30 engine, I double checked everything on the bentley workshop manual. "Every thing was done according to the book."

As I said: Stranger thing have happend before...

I think, I hope the is someone on this FORUM that knows these M30 (333i, 535i, 735i) engines well to advice me.

Thanks in advance.

 

[rick540]

Mmmmmm

It sounds like you know your way around an engine and I'm fairly sure you put it back together correctly, so this is a difficult one.

The fact it got worse after removing the head leads me to beleive there is a crack between the water chamber and the oil return to the sump. Some cracks only open up under hot conditions and will not show up in a cold pressure test.

The fact it's worse now could because after machining the head, stress has been releived and allowed the crack to open up.

Remove the head and inspect everything yourself, do not trust others.

Sorry to see you are having to throw cash at what is ultimately one of BMW's toughest engines ever.

 

[bmw328]

Hello all!!!, I removed the head today, again!!!
I have cracked the riddle that was bugging me out of my mind!!!!
After inspecting the head, and found nothing again, I turned all my focus to the head gasket, noticed something weird about cylinder 6. water port corroded badly!!!! Where cylinder 1 and 2 have about 5mm of walll between ports, cylinder 6, 5, 4 walls between water and combustion chamber is about 1 mm, but stranger is that it is rusted downwards, like a dent on block.

I've someone knows where I can buy a good replacement M30B35 engine, preferably with a garantee, please give me a pm. Thanks a lot guys...

 

[rick540]

At some stage in it's life it was run without antifreeze and thats what happens.

What about welding it?

 

[Raybimmer]

Skim the block and fit thicker head gasket - works on every toyota taxi :roflol:.
This is what makes a guy upset , you buy a car with FSH and it ran years without antifreeze changes and now its your problem .
R200 every 2 years for antifreeze not too expensive for preventive maintenance !!!!

 

[Sankekur]

Dude, R200, what kind of expensive anti-freeze are you using :mmm:

But in all seriousness, I have to agree on that one, I just put in the BMW anti-freeze in the correct ratio with distilled water, it is really not that expensive. Pretty cheap insurance if you ask me.

 

[rick540]

I open BMW engines all the time, and I can say 100% when it's had the proper BMW antifreeze in and it was changed as it should every two years, you can still see the Iron of the engine block, the stuff really works.

BMW antifreeze is about R450 for a 50/50 mix in most engines, but it's worth it. I've seen other aftermarket glycol based ones used on BMW engines and for some reason (probably an additive) they soften the seals in the cooling system to mush.

So here is one place I stick with the OEM stuff made by BASF