Hi, I'm new to this board and to the 740il. I just got this car and love it so far. Today after installing some denso plugs I took it for a FAST test drive which the car performed very very well. But afterwards I turnred off the car and noticed some antifreeze leaking from the bottom of the car. I had lifted the hood and heard a "hizzing" noise (like when there is a hole on a hose) and aferward is when I looked down and so the leak comming down.

The leak is near the back of the engine which to me is weird since most of the leaks from other cars I have had always were in the front. Any idea where this leak is comming from? What I need to replace?

Thanks for any help you guys can give. I hope it's nothing big.

Come on people I know you guys must have some clue,please.

It's not that nobody wants to help you, but there are quite a few possibilities for leakage from the rear of the engine. The coolant hoses that run to the housing on the rear of block, the auxillary water pump/heater valve assy, the plate on the top of the block under the intake etc..... Some information from you is required. We don't have a crystal ball.

Thx for your reply which was very helpful. At least now I have an idea as to what it may be. The crystal ball comment was not really necessary, I was not trying to be rude. I tried to give all the information I had. If more info is needed all you guys need to do is ask and I will do whatever it takes to get that info.

Thanks for posting.

What year 740. I woiuld start by looking at the expansion tank (the plastic coolant holding tank on firewall at rear of engine). There is probably (based on year) a large hose coming off of the bottom of this tank on drivers side, and the hose clamp my be loose or the hose split or the tank split at the hose attachme4nt (on my 1988 750 there was a metal sleeve in the tank outlet and the outlet had a crack and allowed the sleeve to slip toward outlet and I could not tighten hose clamp on the sleeve. I took tank off and tapped the sleeve back upstream and was able to reconnect and tighten the hose clamp). New tank is about $40.00. The outlet hose is "T" shaped and goes down behind the engine block and then tees off to the pasenger side and to the auxilary heater valve (the plastic cover next to the B+ jumper post on drivers side). Lift the cover off and look for a leak on hoses off of the aux heater valve and to the firewall to heater core, I had several leaks on thes hoses and ended up replacing all of the heater hoses which is a beach on the V12.

Get yourself a small inspection mirror and a flashlight and start probing around the back of the engine, check all connections.
Let us know what you see.

Thx bear and grettahouse! The year is 1995,I will try the mirror idea in the morning and let you guys know what I find. It will be great if it's just a craked hose!

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Ok, I found the hose that is leaking. It's the rear top left hose that is mounted to the block. It seems to go to the driver (right side as you stand in front of car) and down. I need to lift the car to be able to see the other end of the hose. But for now I need to get a part number so I can order it from the net.

Does anyone know where i can see a picture of the back of the engine with the hoses hooked up. Or does anyone know what hose this would be? I cannot go to the dealer as it's to far away and the leak has gotten very bad.

Any help is GREATLY APPRICIATED.

OK, go to www.realoem.com/bmw
Then go to parts lookup and select your series and build date, after that go to lookup parts and select engine, in the pull down menu select engine cooling, find the picture with your hoses and click on it to expand it, and see if your hose is there (the menu will also have the part number for the hose).

Good luck.

Thx Bear!

Finally fixed the water house and no more leaks. I did it myself and saved $109.00 that pep boys wanted to charge me. Thanks everyone!

I have one last question for this thread. Where is my cooling sensor and air sensor in this 95 740iL?

Great news. Now, if you used the realoemparts website, go back to that and engine cooling and hose and pipes, you will see the two sensors that you mentioned, both are in the back of the engine at firewall and on passenger side. OBC temp sensor is in the front lower fascia either on drivers or passenger side and next to the fog light.

Many thanks Bear! I have to ask you guys what MPG are you getting? When I first bought the car the computer told me 7.3 MPG. I changed the plugs to denso's and now it say 9.3. This is the only thing I'm not liking about this car.

I filled the tanm up with premium gas and now it's close to half tank with only 69 miles! I drive this car pretty slow so it's not the way I drive. Is this normal for a 1995 mbw 740iL with 123,000 miles? Please say no.

Btw, the previous owner put in a K&N filter, does this waste gas more than the regular air filters?

Thx.

The only experience I have is with a 1988 750 and that MPG was 14.0 city and 20.5 highway (at 75 MPH). K&N should not affect MPG, how are the 02 sensors?

"how are the 02 sensors"

I have no idea, how can I trest them? Also, does short distance driving affect fule economy? I hardly drive long distances, short stop and go I do alot of.

Thanks for the help!

Short distance driving does lower fuel economy, but not to the extent yours is lowered. I would go to Auto Zone and see if they can computer scan your car (it is free). Getting 02 sensors checked is difficult as t rewquires going under the cart and locating the sensors and then doing a voltage/ohm check.

Thanks. I'm just going to buy the sensors, figure it can't hurt. Some people say that their good only gor 60,000 miles and should be changed. I will also do the auto zone on monday. Btw, my computer on the dash now says 10.3 mpg. Seems to be rising slowy. Thanks for all the help bear. I will post if I get the car to do better gas milage. Goping to do the tornado fuel saver thing. I'm going to make my own and see if it helps. On my benz I bought one on ebay and it did give me a little better mpg but sure did give me better performance.

Do not beleive that there is a mileage limit on O2 sensors, when they fail the computer should alert you that one or the other (upstream/downstream) has gone bad. I had 1000,000 on my 1988 750 before I changed them and I bought some from oxyensensors.com that were warranted for 100,000 miles. The BMW has essentially a CAI (cold air induction) system as the intake air is taken through enclosed fiberglass tubing to the throttle body or DKW (whatever). A low restriction filter might help (??) and no, the oil will not screw up the MAF. My daily driver is a (may I say this on a BMW board) 1998 Dodge Neon with 2.0 lter DOHC engine, a reflashed PCM, a underdrive pulley, front and rear sway bars from the Dodge ACR (American Club Racing series) car and a home made CAI. I can really feel the underdrive pulley as the revs build and I want to believe that the CAI works (It does roar at WOT). I went from 150 HP (using premium fuel) to about 170 hp with all of the mods. Oh I also debaged the car and put in 1.5 degrees of negative camber up front.
Perhaps TMI but keep in touch, I am interested in what you find out.

The Bear in Virgina
AKA Bubba

The neon has great gas milage (what like 24mpg when it first came out). From what I hear they are like VW, FUN to drive. Back on topic, now you got me worried, I certainly don't want to spend $200.00 on two parts I won't need.

I don't know what to do now, today I saw in a dealer a 1998 740il (all black, VERY NICE). The dash computer said 20 MPG just like my brothers 740il which also says the same. My computer today went up to 10.6 mpg.

This really stinks, it seems EVERY car I have ever bought have had bad gas milage! My last mercedes gave me 10mpg when everyone else was getting 15-18.

Hope to hear more suggestions as to why I might be getting such bad gas milage before the weekend is over.

Thx.

The first thing I would do is get the car scanned, if Auto Zone cannot do that then find an independent TECH (I spent $90.00 at a dealer to find out one of my MAF was bad and that put me in limp mode). Yes, $90.00 but at least I knew what the issue was and was not just throwing money at the car. In my opinion you should be geting in the range of 15 MPG to 17 MPG city and over 21 MPG hghway (if my 1988 750 would do 14 city and 20.5 highway, your 740 should do as well if not better).

As to the Neon (not a Bimmer by any means) , I get 27-29 MPG city and 38.5 to 40 MPG hghway.

15-17mpg sounds soooo good! Bear, I just took apart the hose from the maf. I saw something that I have never seen on any car before and wanted to know if this is normal. After the maf I can see a ROUND flap that opens and closes to let in air. Every car I have seem this is always closed until gas is given, correct? On my bmw it is fully opened when the car is off? Don't know what happens when the car turns on. I find this to be wierd that this thing is opened. Please let me know what you think. If this is always opened I suppose this would wast alot of gas??

Aft of the MAF should be a rubber boot that links the MAF to the Throttle Body (sometimes called a DKW). Remove the boot and see if you can rotate the butterfly or flapper valve by hand, if not, get some throttle body cleaner (in aerosol can at any parts store) and lubricate the shaft that the butterfly valve rotates on and see if you can free that up so the butterfly moves freely. On the 750 there are two MAF and two DKW and they are motor controlled from a solenoid on the throttle pedal, yours, I believe are a direct connection from gas pedal, and the butterfly at rest, should be closed. The hot wire in the MAF should burn all contaminents off prior to them getting to the Throttle Body. I beleive the butterfly should rotate freely by hand (with engine off) and should snap shut when you release hand pressure. A butterfly haning up at rest will surely feed too much fuel to the engine.