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2004 X3 3.0 Radiator Fluid & Transmission Leak Questions [Update]

9K views 31 replies 4 participants last post by  awdrev 
#1 · (Edited)
Hello all,

I recently purchased a 2004 BMW X3 3.0 with 98k miles and an auto transmission.

I have searched tremendously before posting my question as I hate to be one of those users that posts before reading so I wanted to confirm and then ask some questions about pricing.

The car BTW does not seem to have a lot of the maintenance done, not from what I can tell from the Carfax anyways.

I am pretty sure that my coolant expansion tank needs replacement.
1) Is Turner Motorsport what most of you would recommend to get the replacement part from? I could not find a specific DIY to replace this part, is there an old one someone with pictures that could link?

2) I have heard that replacing the thermostat is also wise, is that recommended? Car heats fine as far as I know.

Now to a more serious question: when I topped off my coolant earlier (due to the leak) I noticed small brown spots... in my experience, that's usually transmission fluid leaking onto the radiator system.. but upon further inspection it seems that the oil heat exchange is actually located outside the radiator unit...

1) I am not sure how to proceed now, I mean, I can replace the coolant expansion tank but what in the world can I do about the tranmission leak? Is there a way to confirm it...

2) Is this a common occurrence or is this something else?

Thank you, I look forward to contribute to this community.

AWDREV
 
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#2 ·
#3 ·
Thank you. So the good news is that apparently there is no way that transmission fluid can get into the cooling system because they are totally independent. This is a great relieve because I had an old Ford (yea i know) that had a radiator that was used for both oil and water... of course they were separate systems but all within the same radiator... and what ended up happening is the inside system for the transmission started to leak badly and the transmission ended up being destroyed because of insufficient cooling.

Now that I have a better picture or what needs to be done, I will be replacing the coolant tank. Fortunately, I did confirm that it is what's leaking, which again is good news because it seems quite simple.

And after consideration, I will be getting the BMW OEM part from the dealer which actually is almost double the price but I can't risk any damage to the engine.

As far as the water pump, I'm intrigued as well. I'd like to replace it with a new one, and also to replace the hoses, etc but I need to do a little more research. I think taking the mechanical fan will be a pain, a minor one I reckon but I'll definitely want to get an idea of taking that part off. Fortunately, it seems that after the mechanical fan is off, it's an easy process.

Now, as I said I just got the car and thought about the transmission but I keep reading that it's "lifetime tested" and there is no need to do anything to it.... of course, that's really unpersuasive, cars need maintenance, simple as that. But when I called the BMW dealer, they refused to do it and said tranny would break. I'll prob leave that as is for now, tranny works fine even at 100K and I'll really hate to get the fluid switch and have it slip, etc.
 
#4 ·
..... I think taking the mechanical fan will be a pain.....

Now, as I said I just got the car and thought about the transmission ....
The engine cooling fan is electric - quite easy to remove by releasing a few plastic clips from what I have read.

Brown spots in coolant be from someone in the past topping off with green coolant.
Just a guess, but doing a good flush and fill should be the first priority after replacing the expansion tank and its A/T thermostat.

Personally, I wouldn't stress over the A/T lifetime fluid if it has never been changed.

Water pumps and thermostats appear to last longer in the E83 than they do in the E46, so not too much risk in delaying that if no symptoms.

Hoses are definitely worth replacing if any signs of degradation after 9 years and 100K miles.

If the vehicle has not had the best of care under the previous owner(s) may be best to err on the side of caution though.

The first thing I would do is a transfer case fluid replacement, even before the coolant repair.
 
#5 · (Edited)
Thank you for the reply.

I'll replace the coolant tank and I will do a flush or have the dealership do it. I will prob change the water pump in the summer though... and maybe replace everything including the radiator.

If it's only an electric fan, it'll be really easy to pull out but do we have a mechanical one? hmm, I'll have to double check... if not, then even easier to replace water pump.

I'm leaving the A/T fluid as is.... but talk to me more about the transfer case fluid replacement what's the deal with that, as I said, tranny feels strong and I have checked out all the features such as the DSC, etc and they seem to work.

1) Are there major issues with the transfer cases?
2) I'll look for a DYI but if you have one, feel free to please post it along..

EDIT: FOUND A DYI so will probably do that too... but do tell me how the transfer cases are in these vehicles... etc
 
#6 ·
BMW engineers like to avoid accessories that are a drag on engine power, so electric cooling fans area no-brainer.

For the 2007+ model they moved to an electric water pump.

Not sure where they are with electric power steering across the current model range.

Transfer cases are thought to be a weak point with the X3 based on discussion in this forum.

Mostly it's the separate actuator that wears out, but some owners have had bigger problems either as a consequence of that, or lubrication issues.

For part of the 2004 model year X3 transfer cases were filled with A/T fluid as the newly-developed xDrive fluid was not available then.

Dealers did not replace the fluid unless a wear value code was thrown based on monitoring of resistance in clutch plate operation.

Fluid costs about $50 so any cautious owner should have had it done regardless.
 
#8 ·
Not really, but if your build date is prior to March 2005 the factory fill was certainly Dexron III A/T fluid.

When you drain it, you should be able to tell from the reddish color.

The xDrive fluid is a very light color.

It's not like other instances where there is a concern that some of the old fluid remains in passages and may be incompatible with the new fluid.

Opinions vary, but changing it about every 50K miles seems right.
The other concern is, for any model year, the factory fill for both the transfer case and the 2 diffs. (synthetic 75W90 gear oil) has been observed to be on the low side.

This may or may not have been a factor in the few cases of early transfer case and diff. problems (clunking, outright failure).
More likely just variances in how well the supplier assembled the gears at their plant.
 
#9 ·
So even if the factory used DIII fluid, I should just go ahead and put xDrive fluid?

I will keep the factor that you mentioned about the differentials... unfortunately, I prob won't be getting to that anytime soon. I'll do the coolant expansion tank, and then the transfer fluid change soon and we'll see how it goes from there.

Assuming the car gives me no problems, I will start saving up to do a full cooling system upgrade by the summer which is right where I should be hitting 100K and I'll also try to take care of other fluids... but I am death scared to touch the tranny, especially if it's working fine.
 
#12 ·
So even if the factory used DIII fluid, I should just go ahead and put xDrive fluid?
Yes, most certainly. ASAP
ATF has always been used in transfer case applications for any vehicle maker, but if BMW felt that all the interventions of xDrive demanded a more complex fluid formula, that's perfectly believable.

.... and all I have to say is who in the world thinks plastic will hold up to extreme conditions? would it cost that much more to make the little part out of metal?
Not standing up for BMW, but the general industry direction is to reduce weight wherever feasible.

Might not seem much in isolation, but it all adds up.

Cost to the car maker certainly comes into it, but I think they would argue that's not their primary reason for using plastic impellers, plastic expansion tanks, etc.

Not sure which is preferable for the average owner, a metal impeller that corrodes down to nothing because the coolant didn't get changed often enough, or a plastic one that fails through old age.
 
#10 ·
BMW changed its tune on the tranny's in 07 and now recommend 100,000 mile fluid change. Keep in mind while the GM transmission is different for post lci refresh its the same fluid dexron iv...some food for thought...

I change mine every 30k...but auto are like a box of chocolate...you never know what your going to get.

As for the electric fan, it comes out super easy once the air snorkel is removed. It's only like two clips that hold it in place.

For the cooling system for the m54 motor it is recommended to change water pump and thermostat at the same time as expansion tank. They are known problem areas. Some also like to replace radiator too so it's a 1 and done solution. I know with the e39 it was like clock work every 76k miles the cooling system would fail.
 
#11 ·
BMW changed its tune on the tranny's in 07 and now recommend 100,000 mile fluid change. Keep in mind while the GM transmission is different for post lci refresh its the same fluid dexron iv...some food for thought...

I change mine every 30k...but auto are like a box of chocolate...you never know what your going to get.

As for the electric fan, it comes out super easy once the air snorkel is removed. It's only like two clips that hold it in place.

For the cooling system for the m54 motor it is recommended to change water pump and thermostat at the same time as expansion tank. They are known problem areas. Some also like to replace radiator too so it's a 1 and done solution. I know with the e39 it was like clock work every 76k miles the cooling system would fail.
Point well made. I'll speak to the dealership about the tranny but this is an 04. Or you meant to say that their minds change in 07 about what they said regarding auto trannys in general.

I'd love to change the water pump and thermostat now but I won't get the chance... I'll just replace the expansion tank and hope that it holds up! And talking about the water pump, is the BMW OEM part still using the plastic part? I know some aftermarket water pumps upgrade it to METAL but I'd like to stick as OEM as possible if I can... and all I have to say is who in the world thinks plastic will hold up to extreme conditions? would it cost that much more to make the little part out of metal?

Gee
 
#13 ·
Okay, I'll ask for some of that good xDrive liquid tomorrow and replace it too.

So I get your argument about weight reduction but when it comes to critical parts that directly affect the reliability and resilience of the car, that thought is just unpersuasive coming from BMW's part. Yes, weight has a direct effect on a variety of factors such as MPG, etc but a metal propeller and a metal gear for the actuator would have been more beneficial than detrimental... I suppose you are right about whether is it preferable for the average owner to have a metal impeller that corrodes down to nothing because the coolant didn't get changed often enough, or a plastic one that fails through old age. But I think getting a coolant change is far easier and cheaper than getting the whole water pump replaced.

Anyways, you've been great mate and I thank you for your time. I will be getting the parts and doing the swap hopefully soon... I got to finish these finals first.
 
#19 ·
It's funny you mention that because I was just looking for an old pump but I can't find it! UGH this is annoying.... what other way are there? I think I remember hearing that there was enough clearance to just fill it up using the bottle but I could be wrong...
 
#20 ·
Here's an ancillary question: I notice a little bit of jerking before the car comes to a stop... this seems to be a software issue from what I've researched. How true is that? and what's the overall range to fix something like that at the dealer... I feel this should be complementary because it's software, I mean, who charges for firmware upgrades..

Anyways, I will be doing the coolant tank and transfer case thing tomorrow morning, I gotta get it done early!
 
#24 ·
Here's an ancillary question: I notice a little bit of jerking before the car comes to a stop... this seems to be a software issue from what I've researched. How true is that? and what's the overall range to fix something like that at the dealer... I feel this should be complementary because it's software, I mean, who charges for firmware upgrades..
The dealer charges! Lol. Figure $150 if you need an update. However try the transmission reset procedure first. I'll need help from the folks with a gm5 tranny to walk you through it, because I have the gm6. I am not sure if the steps are different.

If that doesn't help, at 98k miles I would then drop the pan and change fluid and filter.

Another possible culprit could be your drive shaft.
 
#26 ·
You could probably do it without raising the car. I find it easier to get the bottom cover off by jacking it up. As a side note, I am pretty thin and I couldn't get to the transfer case without jacking the car up.

For your transmission, I don't consider 100k too long of an interval to drain fluid. That is the normal duration GM recommends for its cars and what BMW recommends for 07 and up. Now at 140k I would side with the dealer. As a side note, I would put this low on my priority list. If it shifts fine wait.

The more I think about it, that clunk sounds more like the driveshaft and guibo. I would ask an indie not the dealer for them to look at it after you fix the expansion tank.
 
#27 · (Edited)
You could probably do it without raising the car. I find it easier to get the bottom cover off by jacking it up. As a side note, I am pretty thin and I couldn't get to the transfer case without jacking the car up.

For your transmission, I don't consider 100k too long of an interval to drain fluid. That is the normal duration GM recommends for its cars and what BMW recommends for 07 and up. Now at 140k I would side with the dealer. As a side note, I would put this low on my priority list. If it shifts fine wait.

The more I think about it, that clunk sounds more like the driveshaft and guibo. I would ask an indie not the dealer for them to look at it after you fix the expansion tank.
hahaha OH MY more research to do... okay, i'll keep that in mind. I briefly did a search and notice the issues were "clunking while going from 2 to 1" which is what I have.... except, it doesn't do it in manual-mode, only in auto mode

Will try to get it at LEAST the transfer case done by tomorrow... apparently that tops the list of things to do.

EDIT: I'LL INSPECT THE GUIBO TOM WHILE I'M UNDER
 
#28 · (Edited)
Okay so what a heck of a long day.... started at 9 AM and finished around 3pm.

I know, sounds like a long time but a few things came up.

1) I was able to replace the coolant expansion tank but as it turns out, it seems that it was the TOP RADIATOR hose that was leaking... that's my judgment right now but that's okay. I am happy I replaced it anyways, hose was extra 30 bucks..... but it was a mess. First, I did not have as much clearance as the pictured DIY showed, maybe it's because we have xDrive but I def did not have the whole front end open like that... in any event, I did it but I got coolant everywhere, ugh, even on my face. Def a learning experience... Good news is that I believe the leaking situation is solved (finally)

2) The transfer case fluid was also done... it was black, as I expected it to be. This also took me forever... I made a big mistake and started taking apart the transfer case metal support so I can get more clearance to put a socket, that didn't work... I realized when I took that down that the transfer case came down with it, so I had to get a carjack and put it back up and tighten the mount.... FINALLY went to Advanced, picked up a 16mm and worked out fine. So the transfer case took almost all of my quart bottle but it didn't start coming out and if so, very slightly.... should I buy another one and put it in until it's definitely coming out? I have just a tiny bit left and I think when I finished pumping and couldn't get more of it into the transfer case, it was coming out pretty slowly... which, to me, it meant that it was good to go. Thought?

3) Replace air filter (it was awfully dirty and gross); and also the cabin filter... (also disgusting)

Test Driving: So far the car feels good; overall, I actually think the car feels smoother... also, the clanking from 2 to 1 has disappeared for now and I'm still taking it easy driving wise to ensure that the transfer case gets fully fully lubricated. The coolant issue seems to be fixed which I am very happy about, now I need to save up and get a radiator flush.

Car just hit 98.5k today, I plan to do the remaining maintenance schedule but I need to drive the car for at least three months without spending more money in it. Hoping it lasts!

Thank you to the both of you for the help!
 
#29 · (Edited)
Good work! You should be good on the fluid in the xfer case. If it was slightly dripping out or if you could feel it it at the top you are fine.

Glad to know about that support! Taking it down crossed my mind once too. I ended up using a box wrench to remove the fill plug.

Haha about the coolant. Same darned thing happened to me. I filled the coolant with the bleeder open and then stupid me used to domestics turned the car on to fill it up more with expansion cap open. I was given a pretty waterfall of blue coolant every where. Lesson learned...that's what the bleeder is for.
 
#30 ·
Good work! You should be good on the fluid in the xfer case. If it was slightly dripping out or if you could feel it it at the top you are fine.

Glad to know about that support! Taking it down crossed my mind once too. I ended up using a box wrench to remove the fill plug.
Yea if you do take it out, just do know that it will come down too. Not that much but enough so that you can't get it up without a jack... just use the wrench.

By the way, I did buy the rear diff fluid but need to read more about it.... I didn't see a fill plug when I was down there and I think it's on the side... I may get a shop to do three things:
both differentials fluid change; and radiator coolant change...

Do you have any idea how much fluid I would need? I got two quarts for the rear, how much does the front take and how much coolant should I give to the shop? I'd rather give them my own stuff to put in instead of trusting them.. it's the shop of a buddy of mine anyways.
 
#31 ·
There is only one plug on the rear diff. It's for both drain and fill. What I do is remove the spare tire, pull the drain plug and then jack the front of the car up. I use my pump to get what's left out of there. I then refill with redline 75w90.

The front diff has two plugs. I bought 3 quarts for front and rear and used about 1 3/4 quarts between the two. I definitely wouldn't pay a shop if you were able to change xfer case fluid.

For the cooling system it takes about 10 quarts so you need two gallons. Also not hard to flush...you just need about 4 gallons of distilled water and to find the block drain.
 
#32 ·
There is only one plug on the rear diff. It's for both drain and fill. What I do is remove the spare tire, pull the drain plug and then jack the front of the car up. I use my pump to get what's left out of there. I then refill with redline 75w90.

The front diff has two plugs. I bought 3 quarts for front and rear and used about 1 3/4 quarts between the two. I definitely wouldn't pay a shop if you were able to change xfer case fluid.

For the cooling system it takes about 10 quarts so you need two gallons. Also not hard to flush...you just need about 4 gallons of distilled water and to find the block drain.
Yea that's gonna be a lot of work for the time being... I'll have a shop do that and the front... I have heard of Red Line but I'm just getting all OEM fluids from the dealer.

My next, I guess "slight concern", is that humming sound. I do not think it's the wheel bearing, it increases and decreases with the touch of the pedal so I am thinking that the rear diff needs to be flushed or the "guibo" issue... ugh, but I can't take care of any of that for like a month. It's just gonna be like for that a 2-3....
 
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