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Use the correct coolant and your pump will be fine. Use the wrong coolant (i.e. not-BMW) and you'll be replacing your pump. The coolant contains special ingredients required to maintain the seals in our engines (I don't recall what, but I'm sure someone will tell us).
Wait, we have to use BMW specific coolant too? I just refilled mine with Prestone after doing this the other day.
 

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Discussion Starter #42
Wait, we have to use BMW specific coolant too? I just refilled mine with Prestone after doing this the other day.

I have been told by EVERYONE that using anything but BMW radiator fluid is a big time NO NO. I used the BMW fluid and distilled water.
 

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Wait, we have to use BMW specific coolant too? I just refilled mine with Prestone after doing this the other day.
I have used the DEX Cool (I think by prestone) for years on my other BMW's. Never a problem. I even deleted the fan on my E36 and still never a problem. Just make sure the coolant is safe for "all metals." Dont get teh cheap green junk though.
 

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Wait, we have to use BMW specific coolant too? I just refilled mine with Prestone after doing this the other day.
I don't recall exactly what, but there is something about BMW coolant that is different from most of the off the shelf brands. I think it has to do with silicates, but honestly, I don't recall if it is supposed to have them or not. Whatever it is, it maintains the health of your water pump.

With that in mind, it is much like oil or any other part - if you can find a comparable aftermarket product that meets the same specs/requirements, there is no reason not to use it, but I wouldn't grab a random bottle off the shelf and hope it works out.

d-
 

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Wait, we have to use BMW specific coolant too? I just refilled mine with Prestone after doing this the other day.
You should use BMW approved fluid. Too many variables with seals and metals for me to take the chance just to save a few dollars. If you go aftermarket, I'd seriously look into Zerex G-05. Supposedly it's factory fill for many European cars these days, only w/o the huge dealer markup. Zerex G 05. There is a Pat Bedard article on this on Car and Driver online.
 

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So how hard would it be for me to drain ALL of the coolant and refill it with the BMW stuff? When we did the t-stat replacement, we didn't drain the block, so right now there's just an amalgamation of fluids in there - old BMW coolant, new Prestone coolant, and DI water. I really don't want to have to take it to someone; that's the whole reason I did it myself. I guess I should have researched the coolant issue beforehand.

Edit: After some research, it looks like I just have to pull the radiator plug and the plugs on both sides of the block and refill 50/50 with coolant/water. I need 6.5 quarts of coolant since we have a 13 quart capacity, right?
 

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So how hard would it be for me to drain ALL of the coolant and refill it with the BMW stuff? When we did the t-stat replacement, we didn't drain the block, so right now there's just an amalgamation of fluids in there - old BMW coolant, new Prestone coolant, and DI water. I really don't want to have to take it to someone; that's the whole reason I did it myself. I guess I should have researched the coolant issue beforehand.

Edit: After some research, it looks like I just have to pull the radiator plug and the plugs on both sides of the block and refill 50/50 with coolant/water. I need 6.5 quarts of coolant since we have a 13 quart capacity, right?
You've got the drain method down. Just remember that the radiator drain plug doesn't unscrew the whole way (1/4 turn then pull down I think) - ask me how I know... I bought 2 gallons and had plenty, so you're 13quart number sounds close...

d-
 

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If youre going to drain it from the block I suggest new crush washers when you do.
 

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Yes Douglas. It is MANDITORY that if you drain from the block you get new crush washers. That would suck to get the thing drained all the way then only to realize you didnt buy 2 $.60 parts. So while youre buying the MANDITORY OEM coolant ask them for some crush washers for the block.
 

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Yes Douglas. It is MANDITORY that if you drain from the block you get new crush washers. That would suck to get the thing drained all the way then only to realize you didnt buy 2 $.60 parts. So while youre buying the MANDITORY OEM coolant ask them for some crush washers for the block.
Much better :)

d-
 

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Thanks Doug and Chris. I'll be sure to pick up the crush washers. How soon do you guys think I need to drain this stuff? Should it be an immediate concern?
 

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Thanks Doug and Chris. I'll be sure to pick up the crush washers. How soon do you guys think I need to drain this stuff? Should it be an immediate concern?

Did you get a premix type? As in 50/50? Or, did you mix your own? If you mixed your own and used tap water I'd say get it out as soon as possible.

If you bought it premixed or you used distilled water I would say yes its a priority but get to it when you have a spare hour or so.

The mineral deposits from tap water will ruin your internals faster than off the shelf anti freeze. I wouldnt wait too long though if you bought off the shelf 50/50 mixed.
 

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Thanks Doug and Chris. I'll be sure to pick up the crush washers. How soon do you guys think I need to drain this stuff? Should it be an immediate concern?
I'll go with: as soon as possible. The longer you leave it, the greater the risk, but I don't think any severe damage will be done in the short term. I'd say if you get it out in a week or two you'll be fine...

d-
 

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Thanks for the DIY!
M5 is out in the garage on jack stands right now, ready for the new t-stat install.
Except I think I only bought 4 o-rings, not six, so will see how that goes.
 

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Replaced on 2 M5s today the thermostats,only the inner metal sealing ring in the housing was a PITA...
Edit:Both don't run original BMW coolant and not even TWS:2:
 

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did the thermostat about a month ago. when putting housing back on I didn't seat the thermo in the housing till after i slid it in place over the water pump. This allowed me to be able to tilt the thermo at an angle to move it in proper place over the pump. once i hade wiggled it over the housing i pushed the thermo in place and now had the 3 pipes completely level to be seated. this will keep you from pinching or knocking an o-ring out of place. just a gentle push and they all popped right in to place. you will feel if they go on right or not. without doing this it looks like it will be a significant angle to push on.


never replaced the inner gasket unless it is trashed not really nec. would highly recommend bmw fluid or another HOAT for an aluminum block and no tap water use purefied. this last one failed in partial position fyi. also fill from the temp switch hole if you can all while squeezing both hoses will keep you from getting an air pocket of needing to bleed.
 

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Couple of things of note from my replacement:
-Yes, TIS says you don't need to disconnect the VANOS oil lines. But not worth the aggrevation, order up the replacement crush washers (2 ea of #07119963072 and 2 ea of 07119963129) for the banjo bolts and flop the oil lines out of the way, makes it much easier.
-Had to really pull and wiggle to get the housing off, the water pipes did not want to pop out.
-I replaced the inner seal, I'd agree with the previous posts that its probably not necessary, but I had already bought the damn thing. MAJOR PITA to get out.

Should replace your oil seperator drain lines while you have the t-stat housing off. Have to have the t-stat housing off to get at the drain lines, and our engines are old enough now that rubber hoses are starting to deteriate.
#11151407344 and #11151406902 along with the clamps for the bottom end, 2 each of #07129952107

I had to borrow a big socket from a friend to press the new inner seal back into the t-stat housing.
He says the M5 thermostat design is identical to the one Caterpillar has been using on their big diesel engines for the last 20 years or so.
 

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Inner thermostat gasket.

I finally replaced my thermostat based on this thread and other on this site. It all went well and my temp is now back to 85 C. Thanks to everyone for posting your experiences! It's a great help for someone like me who has not done this type of job before.

Anyone, I will strongly recommend that you don't waste time on replacing the inner seal. I have not seen any good arguments why this needs to be replaced and I have not found anybody who had problems because they didn't replace it. So if it looks fine, just leave it even if you have already bought a new one. Just my 5 cents on this issue...

Jesper
 
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