Coolant questions

[Gav1234]

Hi, I've been slowly rebuilding my 325I engine, and of all the specialist I've spoke to during year it seems as the common problems that the m20b25 suffers from is getting too hot and nuking the head.

So two questions, does any one run engine ice or pro cool or even maybe an oil based coolant as an alternative and, does anybody know the coolant capacity of the system ?

Thanks in advance

[Gavla]

Theoretically if your water pump, viscous fan, thermostat and blue temp sensor are all working ok an you have the correct coolant and level in the car, then you should have no problems with over heating...

I am no specialist but maybe one of the gurus will leave a comment soon...

[kam-325i]

Overheating is not a common problem on the 325i.

The problem stems from either the water pump or fan viscous failing, which are prone to failure just like any other part....

If the system is in tip top order, then there is no need for anything else other than normal coolant....

[Brianmoooore]

As above. Overheating is not a common problem on any E30, BUT if you do cook a 885 325i head, just once, then there's a good chance it will crack.
Note that the best fluid for transferring heat is pure water. Never take the claims of someone trying to sell you something at face value.
Capacity of the system is 10.5 litres.
(P.S. Don't use pure water, as you will have corrosion problems in summer and freezing problems in winter.)

[Gav1234]

Cheers for the input.
I've stripped down two of these motors now and was surprised to see how clogged up corroded all the waterways were.
Both heads had previously been welded too.
The thermostat housing on both were so rotten I've bought a new one and noticed that at the point where both the previous housings were clogged solid, they have changed the design.

I use pro cool (made by putoline) in all the 2St and 4St motocross engines I've built over the years which make crazy power from small capacity and have magnesium, steel and aluminium components.
It has reduced core Temperatures and I've found absolutely no corrosion issues throughout.

I seem to remember chatting to one engine builder who said that the head has a pocket high up in the water jacket where the coolant can boil and foam. Right under the cam tunnel. This is where they crack.

Of course a engine will only fail at its weakest point once other components have failed.
You would suggest that it's a failure of the viscous coupling and waterpump that leads to this ?

[Gav1234]

Cool cheers for the input, totally agree with the air bleeding I'll have to check it real carefully.
I've seen a few furred up impeller shafts, corroded rubber seals and rotted rads on mx engines. Maybe mx riders are prone to just lobbing neat water in on hot days, who knows.

I've never had any issues using pro cool so I'll probably end up using it in the e30 too.

Not sure about these oil based coolers, read many, very mixed reviews.

I have many trade accounts so the price isn't really the issue luckily. Think pro cool will be my way ahead.