V6 cooling system

[toby noble]

I'm doing my first coolant change and dropped the bottom radiator hose on my '84 280i. I only got around 3ltrs of old coolant out.

Presumably this is because the thermostat housing is at the bottom of the engine and was closed when I tried to drain the system.

All I drained was the contents of the radiator so can someone tell me if it is necessary to pull off the thermostat housing to drain the block?

I can't believe this is the only way to fully drain the coolant.

Steve's book does not shed any light so I'm thinking I'm missing something simple....

I'm hesitant to let the car idle until the thermostat opens releasing the rest of the coolant so what's the answer.

I've phoned a friend without success so now I'm going to the audience.......

[280bod]

Toby,
There should be a drain plug screwed into either side of the cylinder block to let coolant out without removing thermostat - but must admit I've only found the one on the drivers side of mine!

[Boosted LS1]

Some rv8's have a factory drain plug as said on both sides of the block. Some builders get rid of them and fit a blanking plug instead which you can unscrew with a spanner. Look between the middle cylinders at core plug level or thereabouts. The blanking plug is quite small but it stands proud of the block.

[toby noble]

280 you've given me hope. Where exactly was the plug you found? Presume I'm looking for something resembling a sump plug?

Another reason for staying away from the thermostat is that the original housing was rotten and a replacement was manufactured from steel last year. When fitted they used blue gunk of some sort instead of a gasket.

Therefore I won't get a gasket to fit and will have to cut one etc etc...

Cheers.

[york33]

you couldn't just pull off the hose from round the back of the housing could you? IIRC this should let all the remaining water out. Just trying to picture mine which is in bits atm.

[grady]

Why change the coolant now? I would have thought it would have all (or most anyway) drained out when they changed-out your thermostat. But otherwise, I think the thermostat would have to come out Sorry Grady

[toby noble]

Coolant was looking rusty and It's summer in Aust so I decided to do the deed.

I have improvised and taken the advice of one of the above posts.

Took off the hose into the thermostat housing from the engine. Blocked all other holes incl radiator and pushed water hose into the housing. Flushed it out nicely. Actually blew into the hose to ensure no water left in system ( nice oily smile now...)then sealed all up and added the coolant. It took about 6.5 litres which sounds right as I have bypassed the heater.

Until proven wrong I am firmly of the opinion my engine does not have any drain plugs.

Thanks to all for your advice. "Darling, I just have to take the car for a run to check for leaks...."

[jchase]

When I changed my coolant about 2 weeks ago, I split the heater matrix delivery tube (comes out of t.stat housing, and goes to cabin heater valve) . I then put the end connected to the t.stat in a bucket, and reverse flushed the engine with a hose into the matrix end (with the cabin controls on HOT !). Took ages to get all the brown rust out, but appears to be okay now. ( I removed the radiator and backed flushed it too ). I also seem to remember putting the garden hose into the top tube where the radiator would have been.
No removal of t.stat, or core plugs required, and now have a happy 2.8 V6, with anti-freeze anti-corrosion in it.

Hope this helps.