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JohnW

M50 thermostat housings-interesting news.

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Guys

Got to change the thermostat on my M50 engine so was advised to change the (VERY OLD!) plastic housing. I remembered hearing about them being available in aluminium (A much more suitable material IMO!) but when I enquired it seemed that they are no longer available.

So I bit the bullet and ordered a housing from "Car parts for less"- CIRCOLI brand-much cheaper than anywhere else I could find. It just arrived, and it's aluminium ! I'm well pleased!

For anyone else ordering, the housing comes with the gasket-I didn't know this so I now have an extra one..... :rolleyes:

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Interesting- They still list it as plastic, but perhaps you were lucky.

I just bought a genuine BMW plastic one, as the pattern-part plastic one has cracked on mine, and it was only fitted quite recently by PO.

I hope the genuine one is better, but I'll perhaps try your supplier and hope for a metal one just in case...

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Yes-I thought I would be getting a plastic one-thats whats listed, but this is the right Circoli brand. Worth ringing them to check. Carpartsforless is of course the Euro Car Parts budget brand.

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Well moulded plastic > poorly cast alu. Just cause its metal don't mean it's stronger/last longer than plastic.

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Well moulded plastic > poorly cast alu. Just cause its metal don't mean it's stronger/last longer than plastic.

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Well, mine is on now, so the clock is ticking.

1 mile driven so far without failure... :-)

I did take some pics, but not downloading them now- The one I removed was very similar to the genuine one, but slightly different shut lines on the moulding, and the patten part looked to be plastic with some aluminium powder in, but the BMW one did not sparkle, and looked like it had fine fibres dispersed though the polymer.

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No, but I bought the vehicle after a recent new thermostat and housing had been fitted, and the thermostat looked fine (It is an 88 FWIW).

I fitted the thermostat with the arrow upwards, with no modifications.

The topic has been covered many times of course (including here... http://forum.bmw5.co...coolant-system/ ) but, if you are interested, here are some rambling observations on what I did:

Near the arrow is a little swage in the metal, though it did not seem to be a clear path when the thermostat was cold, but would rapidly become one as it warmed (i.e. before it opened properly)

I replaced the thermostat o-ring and the orange profile seal, and did not use any additional sealant.

I spent some time carefully cleaning the block face, as there were some corrosion deposits, and the housing needs to be able to sit perfectly flat against the block to ensure even loading on the seals and avoid bending stress on the housing.

I filled slowly through the top hose, with ignition on so the auxiliary pump was running, and heater controls both on full hot (overkill, but nothing to lose setting both).

I also used a combination of squeezing the bottom hose, and blowing gently into the header tank until the water almost came out the upright hose, then letting it drop back freely.

Squeezing the bottom hose with the radiator ports sealed set free some air up by the heater valves as I heard the auxiliary pump noise change.

I used the blowing method only once the system seemed to be full, and it freed a couple of air pockets, allowing some more coolant to be added.

Started with cap off and used some fast idle to get the coolant whizzing around (the level in the expansion tank dropped then rose again when I let the revs fall back).

I repeated the rev-cycling a couple of times, tidied up a couple of things so it had a few minutes idling.

Still no waterfalls, there was some warm air at vents (not hot yet), and needle off the blue.

Quick run up the road then double-check followed by a longer test drive in a toasty cabin, and no overheating or leaks observed.

Of course the toughest test is when the Mrs uses it today... :?

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Thanks-that's useful.

A couple of questions if I may:

1. What auxiliary pump? I wasn't aware of this ..........

2. I can see how the profile seal sits against the block, but the thermostat has only the one O ring-how does that seal to the block AND housing with only one?

Thanks.

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The auxiliary pump lives by the heater control valves up against the bulkhead by the fusebox.

It circulates water even when the engine is not running, so will get it through the heater matrix, as long as you have full heat set.

The o-ring sits against the front face of the thermostat flange, and sticks out proud of the block. The shape of the thermostat supports the ID of the o-ring, so it is constrained as if it were in a groove.

When the housing is fitted the o-ring will be squeezed between the housing and the thermostat flange, which prevents water getting past the flange and past that bit of the housing.

(The diameter of the hole in the housing is smaller than the o-ring, so it forms a face-seal against the o-ring)

A bit hard to describe, but it works :-)

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Nice job to do, though refilling was bit painful.

I did wonder about draining the block, but could not get under the car without major hassle, and need to have it usable again this morning, so went for a flush out with water.

I was worried about overtightening the bolts, so I used a torque wrench.

Apparently the three smaller bolts should be 10Nm, and the larger one that holds the lifting eye should be 22Nm, and I did them to this.

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Beware aftermarket thermostat housings!

I replaced my thermostat in the summer and noticed the housing looked a bit knackred- there was a chunk missing out of one of the spigots and it was obvious that it had been re-fitted at some point with sealant, so I opted to change it. Unfortunately it was a saturday evening so my only option for a replacement was ECP. They sold me an aftermarket one for £17 including the rubber seal but straight away I wondered if it was going to seal- the mating surface was rough, it looked like the manufacturers had missed a finishing machining process. Sure enough it didn't seal and has been leaking ever since. This weekend a BMW OEM replacement is going on, a tenner more but looking at it you can tell it's much better finished.

Ally is nice but I read some negative reports on the 'net about the quality. Hopefully yours is good, OP!

Edited by J4M35

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I don't really seem to have any issues bleeding mine!

I'll share my method:

1. Reconnect all pipes/hoses and secure all clips.

2. Remove reservoir cap and bleed nipple.

3. Switch key to ignition '2' and heaters to hot with blowers on max.

4. Begin to fill reservoir with coolant slowly until coolant/air bubbles appear from bleed hole.

5. Replace reservoir cap and bleed nipple.

6. Start engine and run with heaters on full blast until temp needle is at 12 o'clock. By this point, the heaters should be running hot or at least getting there.

7. With engine running, crack open bleed nipple and release air bubbles. Close bleed nipple.

8. Switch engine off. Allow to cool fully. Top up coolant.

9. Fire up engine, bring to operating temperature with heaters on full blast etc, crack open bleed nipple. By this point, mine is fully bled.

I'm running a genuine BMW housing with a BMW seal. The thermostat is from GSF.

I know everyone's car is different but I honestly don't have any issues bleeding.

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Fitted my OEM BMW 'stat housing on Saturday, wish I'd never bothered with cheap ECP christmas cracker rubbish! a good clean up of the mating faces, a slight smear of grease on the rubber seals and a sensible hand-tighten, and the jobs a good'un. I'm really enjoying being able to turn the heater off now because for the last week I have been using the heater to prevent the 'stat from opening and speeding up the housing leak! Hope your ally one goes well OP.

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