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Urban Knucklebuster
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Discussion Starter · #1 ·
Is there an O-Ring sealing the base of blue plastic radiator plug? What about the engine block drain bolt?

While doing regular maintenance on my radiator, I drained antifreeze from the radiator and the engine block using the two (2) drain plugs/bolts.

I noticed neither the block drain plug (the 13mm bolt @cylinder #2 on the exhuast side), nor the blue plastic phillips screw plug had any washers or o-rings.

So for the engine block drain plug, I added a copper washer. This was tightened until I could feel the washer flatten out. I know this is a good dry fit now. If BMW did not use a crush washer there, they should have. Does anyone know if there is an OEM washer?

Then I double checked the blue plastic radiator plug, looking for any kind of washer or O-Ring on and could not find one. I looked in the drained antifreeze pan, and up into the seat of the plug. No washer or o-rings were present.

There is a very small o-ring near the upside tip of the plug. When I reinstalled the blue plug using that alone a slight leak developed. The plastic plug was then removed and a larger (12mm) O-Ring was fitted to the plug at the sealing end.

That seems to have stopped any leaks; but I want to know if there is an OEM washer or o-ring on that plug??

Any body got experience with this? Gordo

Added washer and O-Ring to rdrain plugs
 

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Is there an O-Ring sealing the base of blue plastic radiator plug? What about the engine block drain bolt?

While doing regular maintenance on my radiator, I drained antifreeze from the radiator and the engine block using the two (2) drain plugs/bolts.

I noticed neither the block drain plug (the 13mm bolt @cylinder #2 on the exhuast side), nor the blue plastic phillips screw plug had any washers or o-rings.

So for the engine block drain plug, I added a copper washer. This was tightened until I could feel the washer flatten out. I know this is a good dry fit now. If BMW did not use a crush washer there, they should have. Does anyone know if there is an OEM washer?

Then I double checked the blue plastic radiator plug, looking for any kind of washer or O-Ring on and could not find one. I looked in the drained antifreeze pan, and up into the seat of the plug. No washer or o-rings were present.

There is a very small o-ring near the upside tip of the plug. When I reinstalled the blue plug using that alone a slight leak developed. The plastic plug was then removed and a larger (12mm) O-Ring was fitted to the plug at the sealing end.

That seems to have stopped any leaks; but I want to know if there is an OEM washer or o-ring on that plug??

Any body got experience with this? Gordo

Added washer and O-Ring to rdrain plugs
There should be an aluminium washer on the engine block drain plug (I think it is item 5 on this diag http://www.realoem.com/bmw/showparts.do?model=EP33&mospid=47730&btnr=11_2166&hg=11&fg=10&hl=27)

Did you check that the washer wasn't still stuck to the engine block when the drain plug was removed?
 

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I just drained my coolant this weekend and my engine block drain plug had a washer on it.. it's silver and might be stuck onto the bolt or engine and camouflaged itself.. ?
 

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Urban Knucklebuster
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Discussion Starter · #4 · (Edited)
Thanks, I examined the rim of the engine block hole pretty carefully, but I'll double check it one more time. Meanwhile, the copper washer is working very well. In fact, even if the Aluminum washer remained in place, there is no short term problem with 'doubling up. I'll keep and eye on it over the next few weeks.

Of more concern is the radiator drain plug:


I added a second rubber o-ring [to the right] underneath the lip of the plug. It seems to work fine. I should have replaced the existing [smaller] 0-ring on the tip, or bought a new plug.

Originally This is the part that I thought was the problem. It appeared the leak was coming between the radiator tank and the bottom of this assembly;


Thanks for your help. I will post a followup on the results. gordo
 

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The drain plug AFAIK only has the small o-ring at the pointy end, there is no larger o-ring towards the head of the plug.

When I drained my coolant, I noticed that the radiator plug leaked slightly when it was tightened securely . However, when I backed the plug out so that it was only loosely screwed in, the dripping stopped. I think I'll go look for an o-ring and try your solution, although I've been driving around for weeks now and the plug has not leaked.
 

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Urban Knucklebuster
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409 Posts
Discussion Starter · #6 ·
I also discovered if the blue radiator plug is tightened too muc it leaks. FSM specs a torque rating of 18-26 INCH pounds.

It is counter-intuitive to NOT tighten that plug; but that seems to be the case. I have no idea what 18 in-lbs even feels like. I used a phillips head screw driver and tried to find the mid-point between too far (which started a leak) and the point at which the plug felt like it was beginning to snug down. There are serrations in the cap which you can feel as the plug begins tightening up.

FYI the blue radiator plug screws up into a second assembly called the radiator adjustment valve, which in turn fits up into the overflow tank using a twist seat with o-rings. Apparently when the blue plug is tightened too deep into the adjustment valve, either the o-ring distorts, or more likely, it passes beyond the range in which it is meant to seat.

I went to the BMW dealer and bought a new plug. The mechanics said when it leaks from there it is almost aways the the O-ring, which is a non-standard size. New plug was $11.50 from dealer. I saw one of the Pelican parts link for $7-8.

They also said the radiator adjustment valve is rarely the cause of any dripping. Witnessed by the fact the dealer did not even have any in stock.

here's to drip-free driving, Gordo
 

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Urban Knucklebuster
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Discussion Starter · #7 ·
I also discovered if the blue radiator plug is tightened too much it leaks. FSM specs a torque rating of 18-26 INCH pounds.

It is counter-intuitive to NOT tighten that plug; but that seems to be the case. I have no idea what 18 in-lbs even feels like. I used a phillips head screw driver and tried to find the mid-point between too far (which started a leak) and the point at which the plug felt like it was beginning to snug down. There are serrations in the cap which you can feel as the plug begins tightening up.

FYI the blue radiator plug screws up into a second assembly called the radiator adjustment valve, which in turn fits up into the overflow tank using a twist seat with o-rings. Apparently when the blue plug is tightened too deep into the adjustment valve, either the o-ring distorts, or more likely, it passes beyond the range in which it is meant to seat.

I went to the BMW dealer and bought a new plug. The mechanics said when it leaks from there it is almost aways the the O-ring, which is a non-standard size. New plug was $11.50 from dealer. I saw one of the Pelican parts link for $7-8.

They also said the radiator adjustment valve is rarely the cause of any dripping. Witnessed by the fact the dealer did not even have any in stock.

here's to drip-free driving, Gordo
 

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Is there an O-Ring sealing the base of blue plastic radiator plug? What about the engine block drain bolt?

While doing regular maintenance on my radiator, I drained antifreeze from the radiator and the engine block using the two (2) drain plugs/bolts.

I noticed neither the block drain plug (the 13mm bolt @cylinder #2 on the exhuast side), nor the blue plastic phillips screw plug had any washers or o-rings.

So for the engine block drain plug, I added a copper washer. This was tightened until I could feel the washer flatten out. I know this is a good dry fit now. If BMW did not use a crush washer there, they should have. Does anyone know if there is an OEM washer?

Then I double checked the blue plastic radiator plug, looking for any kind of washer or O-Ring on and could not find one. I looked in the drained antifreeze pan, and up into the seat of the plug. No washer or o-rings were present.

There is a very small o-ring near the upside tip of the plug. When I reinstalled the blue plug using that alone a slight leak developed. The plastic plug was then removed and a larger (12mm) O-Ring was fitted to the plug at the sealing end.

That seems to have stopped any leaks; but I want to know if there is an OEM washer or o-ring on that plug??

Any body got experience with this? Gordo

Added washer and O-Ring to rdrain plugs
Hi Gordo,

I'm having this exact same problem. Were you able to get the leaking to stop. I broke the Raditor Drain Plug (not the blue plug), and purchased a new one from the dealership, I seated it properly, spoke to a tech at BMW on this, however, it's still leaking. Can advice?

Thanks!
 

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Urban Knucklebuster
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409 Posts
Discussion Starter · #9 · (Edited)
Radiator and engine block drain plugs

I am not certain if you are talking about the plug or the adjustment valve.

But yes they both use o-rings. In my situation, replacing the blue radiator plug by itself did not fix the leak. (I think this is the o-ring you are talking about.) Consequently, I bought the complete assembly, the blue radiator plug and the unit it screws into. This assembly is called the radiator adjustment valve. This the adjustment valve fits up into the overflow tank using a twist seat with o-rings. The o-ring was supplied separately, and it seemed to be too big too large to fit into the overflow tank. l carefully ground the outside diameter very lightly until it was a tight slip fit using petroleum jelly. That stopped the leaking, and its been six months w/o problems.

In addition, I remember many people said they also replaced the overflow tank as a matter of preventive maintenance, whether it shows signs of leaking or not, when they perform this job.

FYI in my post I said I used a copper washer on the engine block drain plug. OEM uses Aluminum crush washers, but the copper ones are showing no signs of leaking.
 

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Yes there is an o-ring on the blue radiator plug. However, in my situation, replacing the blue radiator plug by itself did not fix the leak. Consequently, I bought the complete assembly, the blue radiator plug and the unit it screws into, this is called the radiator adjustment valve. This assembly fits up into the overflow tank using a twist seat with o-rings. The o-ring supplied seemed to be too big, so l lightly ground the outside diameter very lightly until it was a tight slip fit. That stopped the leaking, and its been six months w/o problems.

Regarding the engine block drain plugs, they use Aluminum crush washers. I think you'll be OK with the coppers.
Hi, thanks for getting back to me. Yes, I purchased a new Radiator Adjustment valve and seated it properly, I broke the one that was on there. However, it's still leaking.
 

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Hi Gordo,

I purchased a new Radiator adjustment valve, it came with a new blue drain plug, the o-ring is at one end, where I'm assuming it fits into the expansion tank. It came with the o-ring, but you keep referring to an o-ring that you had to purchase separately. I've seated the new radiator adjustment valve, and my radiator is still leaking, you can clearly see it leaking between the whole plug and the base of the radiator. It's snapped in and turned clockwise as far as it will go. I've also taken it out and re-seated it, same problem. I started the car and coolant poured out the bottom of the radiator.

Would there be a problem with the expansion tank, I had no leaks until I broke the adjustment valve. I've installed new belts, water pump, and thermostat.

Do you have any other advice?
 

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Urban Knucklebuster
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Discussion Starter · #12 ·
I remember thinking how poorly engineered this part of the cooling system seemed to be. BMW is a very well engineered vehicle, and these parts disappointed me. It sounds like you did the same things I did, but my leak stopped. If it were me, then I would probably install a new expansion tank. gordo
 

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Radiator Adjustment Valve

I had my cooling system flushed and after it came back the radiator adjustment valve started to leak. I tried removing the radiator adjustment valve but could not figure out how to get it out. I ended up breaking it. The adjustment valve part that houses the blue drain plug screw completely came out leaving the two O-rings portion with the plastic and the long stem inside the radiator. Any tips on how I can get it out?

Attached is the pic of the broken adjustment valve and a new one. You also see two small bits of plastic--those are part of the adjustment valve on one side that broke completely off and the other two pieces opposite of them on the adjustment value stayed intact, so as to why the other piece with the O-rings do not just fall down, is beyond me--maybe physics?

I tried taking a small long screwdriver and sticking it up into the drain hole to try and pry it out, but it does not budge. As soon as I unscrew the expansion tank cap, coolant comes starts to drain of course by the laws of physics.

Would starting it up be enough pressure to force that part of the adjustment value out?

I had already planned on replacing the entire cooling system but that was after I replaced the oil filter housing gasket, plus replace nearly the entire power steering system too, since there are multiple leaks. However, I had planned on doing the cooling system last since I did not want to get oil all over the hoses, so I figured I could just replace the radiator adjustment valve for the time being so if I needed to test drive it with the other repairs, then at least I would not have to deal with leaky coolant issues.

Thanks
 

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I had my cooling system flushed and after it came back the radiator adjustment valve started to leak. I tried removing the radiator adjustment valve but could not figure out how to get it out. I ended up breaking it. The adjustment valve part that houses the blue drain plug screw completely came out leaving the two O-rings portion with the plastic and the long stem inside the radiator. Any tips on how I can get it out?

Attached is the pic of the broken adjustment valve and a new one. You also see two small bits of plastic--those are part of the adjustment valve on one side that broke completely off and the other two pieces opposite of them on the adjustment value stayed intact, so as to why the other piece with the O-rings do not just fall down, is beyond me--maybe physics?

I tried taking a small long screwdriver and sticking it up into the drain hole to try and pry it out, but it does not budge. As soon as I unscrew the expansion tank cap, coolant comes starts to drain of course by the laws of physics.

Would starting it up be enough pressure to force that part of the adjustment value out?

I had already planned on replacing the entire cooling system but that was after I replaced the oil filter housing gasket, plus replace nearly the entire power steering system too, since there are multiple leaks. However, I had planned on doing the cooling system last since I did not want to get oil all over the hoses, so I figured I could just replace the radiator adjustment valve for the time being so if I needed to test drive it with the other repairs, then at least I would not have to deal with leaky coolant issues.

Thanks
Hi!

Well, it sounds like whoever flushed your radiator broke the Radiator Adjustment Valve the first time around. This plug only requires a quarter turn, if you break any of the little "winged tabs" your screwed. It will start to leak, and will not hold. I had a rough time with this. I went thru two new Adjustment Valves from BMW, installed them correctly, and the radiator stilled leaked. I ended up installing a new radiator, with the new style plug. Also, word of advice, go ahead and replaced the expansion tank, it's easy, and good pre-ventive maintenance.

As far as how to get that out, I've never been in that situation. I'd just replace everything if you have the budget for it. Peace of mind is always better, knowing it's all new and sound.

Good Luck with it.

-JP
 

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Hi!

Well, it sounds like whoever flushed your radiator broke the Radiator Adjustment Valve the first time around. This plug only requires a quarter turn, if you break any of the little "winged tabs" your screwed. It will start to leak, and will not hold. I had a rough time with this. I went thru two new Adjustment Valves from BMW, installed them correctly, and the radiator stilled leaked. I ended up installing a new radiator, with the new style plug. Also, word of advice, go ahead and replaced the expansion tank, it's easy, and good pre-ventive maintenance.

As far as how to get that out, I've never been in that situation. I'd just replace everything if you have the budget for it. Peace of mind is always better, knowing it's all new and sound.

Good Luck with it.

-JP
Thanks for the thoughts. I figured they must have broke something or that one of the O-rings went bad, but I wondered why they had to mess with it in the first place. Why not just unscrew the blue plastic drain screw? The flush service they did perform was with one of those professional flushing machines. When I had ordered a spare adjustment valve for the new radiator I ordered and have on hand, I wondered how is it that BMW engineered such a fine piece of work--out of all things, plastic!

I have never seen such a odd piece for a radiator before--the radiator adjustment valve. What purpose does it serve? What does it adjust other than seeing how before it broke, I turned one way and it leaked, and turned the other way and it leaked some more. To take it out, do you which way are you supposed to quarter turn it (from the perspective of facing the front bumper), then after the turn is it supposed to be pulled down easily?

I got an idea this morning...maybe after draining the radiator, I will take a large and long enough self drilling screw and screw it up in that drain hole and then yank that sucker down.

I'll be installing a new radiator, expansion tank, hoses, thermostats--the works, but I was hoping to do it in a certain order...cooling system last after all the other preventative maintenance I was going to do, so I just need it to last through that, but at this rate I might have to do it first. The oil and ATF fluid leaks I have I wanted to tackle first since I did not want those oils to get on my new hoses :)
 
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