Changing the coolant ? any tips please

[Shiz]

Looking to service my e30 318i M40 this weekend, I am happy enough with the oil change, air and spark plugs. With the fuel filter change, i believe that my filter is a skinny cylinder located below my brake reservoir on the passenger side of my car UK spec.

Now on to the confusing part. Coolant change.

First thing, do you have to change your thermostat when changing your coolant, is it essential or can you change it at a later stage.

Now my understanding is that I would disconnect top and bottom pipes, then drain the fluid into a pocket with loosing the screw at the bottom of the radiator passenger side.

Ok that sounds easy enough.. However my understand is that you have to turn all your dials to cold. And bleed from the 'block'.. or there is another screw on the other side of radiator to make sure the fluid is fully drained. Is this correct on an m40 engine..

Once coolant is fully drained. connect back up pipes and fill 50 50. Now coming to reading max & min, there is no markings on my radiator reserviour... Just lines, I pressume the last line is max?.

Once filled to the 'max'.. Do I turn the dials to hot and let the car run for a wile. Stop car and top up.

Now at this stage I believe you might have to bleed the radiator ?.. Is it just a matter or opening the drain screws and making sure theres fluid comming out..

If you can add your feedback I would appreciate it.

Thanks guys.

[Grrrmachine]

Simple:

http://www.e30zone.net/e30zonewiki/inde ... ant_Change

[polsta]

its easy mate, i did it as a total novice 1st go at it, when its all drained out - i put a hose in the block and rad and gave it a good flush out, bleeding it was easy too didnt have any trouble

[Brianmoooore]

There are errors in that wiki article! You cannot drain anything like all of the coolant from an M40 engine since there's no block drain plug, or any provision at all to drain the heater. The M20 engine does have a drain plug, but it's very difficult to get at (under the exhaust manifold) so rarely gets used.
The technique is to drain out all that will come out, flush everything with plain water, at which point there will be no old coolant left in the system, then refill as per wiki, but with the correct total amount of neat antifreeze first, followed by plain water.
A coolant change shouldn't normally result in airlocks as long as you have the car level or slightly nose up, but it's good practice to watch the temp. gauge as it warms up, and have the heater on, so that you can confirm it starts to blow warm air after a couple of minutes.

[Shiz]

Yeah i was thinkin that there was no bolts on the block. Ok so finally is it essential that u change the thermostat when changin the coolant?. Is it just a matter of bolting on and off.. Back to measuring is there any indications to a full mark?

[polsta]

check the coolant capacity and put that in, didnt change the thermostat on mine, they are only cheap mind ,mine was an m42 engine and never used the hard to reach drain plug, all i did was drain it via the rad and pipes off the block, and get a hose in there, flush the lot right out from both sides, the rad, the lot- give it all a good blow through

[Brianmoooore]

Correct coolant level is marked on versions where the tank is attached to the rad., and is the seam half way up on M20 separate coolant bottles. Many E30s seem to settle at about 10mm below the correct level, which is nothing to worry about.
You need to know the total amount, though, to calculate how much neat antifreeze to put in.
Total quantities are:
6.0 litres for the M40.
6.5 litres for the M42.
10.5 litres for the M20.

[polsta]

out of interest brian, as ive only ever done it on an m42, is a 325i engine done in just the same way ? or is there an easy access drainage plug on the block or anything ?

[Shiz]

cool. Thanks Brian and Polsta for your input. Things are clearer now. However when you say flush out the block I pressume you mean where the hose that connects to the radiator and goes back into the engine, do you stick the hose in there ?.. Id be scared incase I put to much water in, but I suppose it would just drain out at the bottom ? correct yeah.. Thanks

[polsta]

yes mate, once the 2 hoses to the block are dissconected, just put the end of the hose in and flush it right out for a bit, then the other side, in the rar, the lot - give it a good flush through , you cant put too much in as like you say it just drains out again, hence flushing a load of cold water through !

[Brianmoooore]

out of interest brian, as ive only ever done it on an m42, is a 325i engine done in just the same way ? or is there an easy access drainage plug on the block or anything ?

There's a block drain plug, with a 19mm hex. head on the M20 block. It's at the rear right of the block, and is impossible to undo while still retaining a full covering of skin on your knuckles.

[polsta]

ok thanks brian !

[Shiz]

Thanks Brian for the descriptive information.. I done this on the weekend there and followed the procedures. Mines is the M40 engine.

Disconnected lower coolant pipe on the driver side.
Released some fluid
Then released the upper and lower pipe on the passenger side and drained what seemed the rest of the fluid.
Ran cold water through the expansion tank till I noticed clear water returning out. Also ran water through the upper pipe that connects to the block.
I filled the expansion tank up and opened the bleed screw. I did notice that it only took 4.5 litres and is filled right to the top. I had turned the heater to cold to make sure there was no blockage in the heater core. So I then started the car for 4-5 mins and turned the heaters up full. There is HOT air coming out, i then opened the bleed screw a couple of times and noticed air bubbles coming out. Now my problems are, the temperature gauge was creeping up to 3/4 today, only when i turned the heaters on and blew warm air out she started to cool down then.

Secondly i noticed you saying M40s take 6.0 litres of coolant and water, mines only has taken 4.5?

Is there a possibility that there still is air circulating causing the temperature to go above half.

Thanks in advance for the help man.

[Brianmoooore]

It only took 4.5 litres to fill because there was still 1.5 litres of liquid in there. Hopefully this liquid would have been well flushed, and was just fresh clean water, rather than old antifreeze mix. That's the reason you should add the correct quantity of neat antifreeze when filling, followed by clean water.
If you were aiming for a 33% mix, then you should have started filling with 33% of 6 litres = approx. 2 litres of neat antifreeze, followed by 2.5 litres of water. This would then mix inside the engine to give 6 litres of 33% mix.
Note that the whole thing should have been done with the temperature control of the heater turned to full hot, although this only becomes relevant when the ignition is turned on.
It sounds like you had a small airlock in the heater system which has blown itself clear. There will be further small pockets of air that will purge from the system over the next day or so, as well as air that was dissolved in the water, so keep an eye on the level and top up with ready mixed coolant.

[Billwill]

When bleeding the system it is advisable to have the front of the car facing uphill or jacked up a bit.

Bleeding must be done with the heater turn to full hot.

Run the engine while the plastic bleed screw on the expansion bottle is opened and squeeze the hose pipes to get all air out of that bleed screw. Now turn off the engine and loosen the metal bleed screw that is in the bent metal pipe near the thermostat...now run the engine for a while to get air out of that metal bleed screw.

Switch off and tighten all bleed screws. Take for a run and repeat the process the next day when engine has cooled down.

The expansion bottle is marked halfway down with a "cold" level and that is where the water should sit...more or less.. when the engine is cold.

Test that your viscous fan clutch is working properly.

[Tommek]

I would like to make a correction, on the m40 engine there is a block drain plug, it is on the exhaust side of the engine, near the gearbox bellhousing. It is actually a 17mm hex screw, it is a bit hard to get at but is doable. I know because i flushed my coolant today.

[Brianmoooore]

I would like to make a correction, on the m40 engine there is a block drain plug, it is on the exhaust side of the engine, near the gearbox bellhousing. It is actually a 17mm hex screw, it is a bit hard to get at but is doable. I know because i flushed my coolant today.

You know; He's right! I've never noticed one there before, but I've just been out to the workshop and looked at a scrap M40 in the corner and another in the design cab. on the ramp, and there a plug there. Smaller than that on the M20, and even more, I'd say almost impossibly, difficult to get at with an exhaust in place, but it's there.

[Tommek]

I would like to make a correction, on the m40 engine there is a block drain plug, it is on the exhaust side of the engine, near the gearbox bellhousing. It is actually a 17mm hex screw, it is a bit hard to get at but is doable. I know because i flushed my coolant today.

You know; He's right! I've never noticed one there before, but I've just been out to the workshop and looked at a scrap M40 in the corner and another in the design cab. on the ramp, and there a plug there. Smaller than that on the M20, and even more, I'd say almost impossibly, difficult to get at with an exhaust in place, but it's there.

Thank you for confirming Mr. Brian. As for removing it, i used a tubular 17mm socket and removed it easily enough on my LHD '93 Touring but for RHD cars could be tricky. I think jacking the car up and removing it from underneath the car will be easier

[Brianmoooore]

Thank you for confirming Mr. Brian. As for removing it, i used a tubular 17mm socket and removed it easily enough on my LHD '93 Touring but for RHD cars could be tricky. I think jacking the car up and removing it from underneath the car will be easier

The car I looked at is up on a four post ramp, and while I can see the plug from underneath, I'd struggle to find a tool to fit it.
It's likely that the exhaust on LH drive cars runs a bit further out, without steering shaft issues to consider.