1990 316i M40 rad bleed

Post Tue Jun 04, 2019 5:15 pm

So
I'm awaiting the coming of an OEM thermostat from our friends at Cotswold. After the second thermostat failure, from other suppliers, not Cotswold.
This means I'll have to bleed the system.
Now I've not done this on an E30 and would like to ask, after some time searching, and reading, I'm confused, I just want to know how does one bleed a 1991 316i?
I've read the Haynes manual and no mention on there, for heaters on, lifting the front of the car, etc, which is why I'm asking
I have a bleed screw on the radiator and on a hose at the rear of the engine bay near the scuttle. Pictures attached.
I think years of working on my camper van air cooled engine has fried my brain!

Post Tue Jun 04, 2019 5:33 pm

I've not seen the one at the back (on the heater pipes) before so can't comment on that. But the M40 is quite a simple engine to work on.
No need to jack the front up (normally recommended on m20 engines) Just drain, flush with a hose, refill and leave to settle. Turn heater to full and start engine. Let it run for 5-10 mins and make sure your heater is putting out warm air.
And a link to the wiki for M40 servicing.
https://www.e30zone.net/e30wiki/index.p ... _Servicing
HTH

Post Tue Jun 04, 2019 5:39 pm

stones wrote: ↑
Tue Jun 04, 2019 5:33 pm
I've not seen the one at the back (on the heater pipes) before so can't comment on that. But the M40 is quite a simple engine to work on.
No need to jack the front up (normally recommended on m20 engines) Just drain, flush with a hose, refill and leave to settle. Turn heater to full and start engine. Let it run for 5-10 mins and make sure your heater is putting out warm air.
And a link to the wiki for M40 servicing.
https://www.e30zone.net/e30wiki/index.p ... _Servicing
HTH

Do you know what? Why the hell did I not look there first!?

And stones a thank you, to you sir

Post Tue Jun 04, 2019 5:56 pm

No worries. Keep us posted and car looks good, more pics please.

Post Tue Jun 04, 2019 6:51 pm

Thanks and will do.
When the weather is nicer here in South Wales, ha! I'll get some pics up in the reader rides.
I wonder if the screw on the heater pipe was added by someone?

Post Wed Jun 12, 2019 9:42 am

Sorry stupid question alert, taken point 9 to 13 from e30 wiki M40 service.
Does the radiator cap go back on after point 11 or 9?
Or does it stay off whilst bleeding via the bleed screw?
Thanks

9. Pour the coolant into the header tank (at LHS of radiator) SLOWLY and give it time to settle. (should take about 4.5l to get to cold level marker)

10. Set the heaters to full (HOT and no. 4 fan setting, open all vents) and start car.

11. Let the car idle for 5-10mins keeping an eye on the temp gauge

12. Open the bleed screw (next to the expansion tank cap) WATCH OUT FOR THE COOLANT SPRAYING!!!! (use a cloth to cover it!)

13. Repeat bleeding until all air is out and only water comes out when bleed screw is opened. Top up if required.

Post Wed Jun 12, 2019 11:50 am

Since it says "WATCH OUT FOR THE COOLANT SPRAYING" in step 12, I would assume that you put the cap on before then.

I reckon after 9 and before 10.

Ben

Post Wed Jun 12, 2019 6:37 pm

BenHar wrote: ↑
Wed Jun 12, 2019 11:50 am
Since it says "WATCH OUT FOR THE COOLANT SPRAYING" in step 12, I would assume that you put the cap on before then.

I reckon after 9 and before 10.

Ben

Thanks, for the reply. Not sleeping much with child number 4, who's 9weeks old tomorrow!
Everything seems a blur!

Post Fri Jun 14, 2019 8:21 am

Just a thought. The radiator fluid is less than a month old.
Do I have to drain the whole system, or jcan I just replace the thermostat, top up whatever spillage there is then bleed?

Post Sun Jun 23, 2019 11:46 pm

Bleed screw on the heater hose is somebody's mod. An alternative to pulling off the top heater hose and letting air out to clear an airlock at the back of the head.
System should slowly be filled cold, opening bleed screws, until the coolant starts to come out, with a little massaging of the large radiator hoses to help as well, before the engine is started. There's a bleed screw on the thermostat top housing as well, which often needs unblocking with a piece of thin wire.
Nine times out of ten, this will be sufficient, with just a top up of coolant required after a few hours of running, but do monitor the output from the heater from first start up.
No reason to drain the whole lot down just to change the 'stat.

Post Mon Jun 24, 2019 8:07 am

Brianmoooore wrote: ↑
Sun Jun 23, 2019 11:46 pm
Bleed screw on the heater hose is somebody's mod. An alternative to pulling off the top heater hose and letting air out to clear an airlock at the back of the head.
System should slowly be filled cold, opening bleed screws, until the coolant starts to come out, with a little massaging of the large radiator hoses to help as well, before the engine is started. There's a bleed screw on the thermostat top housing as well, which often needs unblocking with a piece of thin wire.
Nine times out of ten, this will be sufficient, with just a top up of coolant required after a few hours of running, but do monitor the output from the heater from first start up.
No reason to drain the whole lot down just to change the 'stat.

Thanks for the reply
I didn't even use that screw on the heater pipe. And I didn't drain the whole system.
I bled it by filling up to the cold level in the rad, starting up the car, heater's on full heat and level 4, then opening the bleed screw on the radiator. Had to do this about 4 times, only topping up when engine was cold.

Everything working lovely

Also there was no thermostat, when I fitted this one!