JohnR

Hello all, I have replace the cooling system parts t-stat, water pump, hoses ect. I went to refill system (8qts 50 50 mix) got no heat and engine got warm acts like there is air in the system. Is there a place to bleed the air out of the system? Also my micofich says that the cooling system holds 12 liters is this correct? Thanks everyone for your help!! I LOVE this site!!
JohnR

JED

Hi

Flattery will get you everywhere!

Ive never had to bleed the system, and I understand that it is designed to self bleed. When I have done it it does make a differance how quickly you fill it up though. I usually do half a litre at a time and let it settle to get the air bubbles out. Then run the engine up to temp and check and top up as necessary.

However, other people have posted the need to bleed the system. There is a bleed screw in the coolant line near the left side (passanger side over here) bulkhead which can be used when the system is under pressure. Full procedures for bleeding have been posted before, and a quick search should give you some results.

farrell

I am betting that your car is a 3.6.
All E34 M5's are the same ?
No they are not.

Usually, the cars will drain & self bleed.
More so with a 3.8.
There are significant reasons why this is the case.

The very early 3.6 had some significant changes to heater matrix along
the initial production curve that seemed to have been ironed out
with a part change to the cooling system which would have been attended
to by a service bulletin in the cars first couple of years.
1990 cars & earlier seem to most affected.
However that does still make them more prone to air locks in within the
heater matrix.**

However.
When the cars coolant is purged almost completely, there are still
issues that can screw you.
If there is not an airlock in the heater matrix, then you have silt & mineral
deposits blocking the heater valves & degas vent tubes.

First.
When coolant is refilled & bled, you must run the heater on full hot.
This ensures the heater valves are open & circulating water into the heater
matrix under pressure.

My advice.
Fill the engine to the level.
Start engine with pressure cap removed.
Now look at the neck of the of the tank.
Is there any water coming out of the two breather tube that vent from
the coolant gallery & above the cooling pack (radiator) top hose.

I suspect not but if there is & the cooling system still blows water out of the
header tank after a couple of minutes, then you have air locks.
Switch off immediately
I would remove all the degas hoses from that vent into the degas tank neck.
Blow them or rod them through ( air line is recommended)
I would remove the screw in connector on the exhaust side coolant
gallery ( the degas hose you already removed was fitted to it)
Is it blocked with silt & mineral deposits.
Unblock it with a needle & blow it to clear.
You should be left with a 1.2mm hole through it.

Now move to the vent tube that exits the back of the cylinder head into the
top hose ( thin brittle black hose that always breaks so buy a spare)
carefully remove & clear it.

Now, once this is done, re-attach hoses & refill with coolant & de-ionised
water slowly.
As you do this, go round squeezing all the coolant hoses to release any air in
main hoses.
Start engine.
Do you get a stream of coolant from the coolant gallery vent tube into the
neck of the degas tank now ?

If yes, wait a couple of minutes longer & run engine.
See if the coolant blows back out of the tank ?**
If not, attach pressure cap & move to bleed screw by the heater valves
on the american / European driver side of the vehicle.
unscrew the M6 size screw a turn & any excess air should vent here,
evident by bubbling etc.
Once you get a clear stream of coolant, nip up the screw & check coolant temp.
It should be stable now with no over heating.
Continue to run at idle & fast idle @ 2,500 rpm.
Still good ?
No bulging of hoses or over heating ?
Good.
Switch off & allow engine to cool.

Top off with coolant as necessary.
Take vehicle for test drive.

**If vehicle continues to blow coolant out of the Degas tank,
remove hoses from heater valves & additional water pump.
check hoses from & to heater matrix that exit & enter through firewall.
clear by blowing hoses & topping off with coolant.
Check that water valves & additional water pump are operational.
( Heater valves should be warm to touch indicating they are opening)
Water pump can fail completely or membrane around pump impeller
can leak which will be evident.)
If you have diagnostic equipment, the heater valve or wiring fault will flag up.

This is a quick & dirty approach to coolant check when bleeding the coolant.

Got to go sort another //M now.
Farrell


Credits.
Mr Ivan Dias
Mr Raymond Woertman.
Thankyou for your insights on the early 3.6 cooling & the technical bulletin data.

Alan Archer

When filling the system initially, set both heater
controls to max heat, fan to at least Position I and have ignition on
position II (lights on) to enable heater valves to open fully.

If you are lucky (and it works ) you will hear the aux pump whinning
away..and it should go quieter as water makes it's way around the matrix.

If your aux pump works.....you can crack open the bleed screw for a while
to assist with purging before start up.


Best Regards,


Alan.

__________________
///M5 the only substitute for capacity is even greater capacity...

JohnR

Thanks guts!! Mine is an early 3.8.