Can't find coolant leak!

[ecalder]

Hi everyone. This is my first post....

I bought a 1991 318i back in December. I can't believe how much satisfaction this car has brought to me, especially considering it cost less than 10% of what my x3 cost! I bought it as an autocross car, but I've fallen in love with the car and now I'm thinking I might even fully restore it. I'm a little jealous seeing all the nice specimens in all of your signatures. I know I have a long way to go, but I'm in no hurry.

Let me make something clear before I pose my problem: prior to purchasing this car I had never even changed my own oil. But when I bought the car I also made it a point to start trying to figure out the mechanics of automobiles. I took the little garage that I have here at my complex and turned it into a workshop of sorts. Bought some tools, tiled the floor, added some better lighting, and now I have just about everything I need for simple to medium complexity projects.

OK onto the problem. I've run across a lot of leaks on this car. The first few were fuel related, and I'm afraid of gasoline getting everywhere so I took it into the shop. I've been trying to figure out why I'm leaking oil. It's not as obvious as I might have thought, and since I started trying to find the source of these leaks (I'm thinking there are various leaks because of the pattern on the floor) I've run across a more serious leak... coolant. I first noticed it on Sunday morning as I was getting ready to take the car to a friend of mine who was going to help me install new shocks and springs! Over the course of the day it got progressively worse, and by the time it was back in the garage and sat overnight I was looking at about a puddle around 12" across.

I looked all over the engine, and could not see where the leak was coming from. I can see green stuff on the "ledges" of the transmission, but nowhere above the upper manifold, and only on the driver side of the engine. I read some posts about the faulty profile gasket but I'm pretty sure with over 150K that has been taken care of, plus I can't see any coolant coming from anywhere near that area.

I decided to take a big jump into auto repair and followed some instructions on how to remove the intake manifold. It was really different on my car compared to the one I was reading, but I dumbly just started unscrewing things and although I have a huge mess of hoses now I think :eek: I'll be able to get it back together...

OK so after everything was out of the way I reached what I THINK is the bottom of the cooling system... a plastic pipe attached to the block. At this point I can tell that nothing is leaking from the hoses at the back of the engine (closest to the firewall), everything is bone dry. Nothing is leaking to/from the radiator either. All of the hoses along the system were clamped really tight too, so I don't think it is the connections themselves.

Here is the problem: nothing was broken/deteriorated/gashed. All of the hoses look fine! Well there was one problem, the plastic pipe, but only inside the engine where it connects at the "o" ring. When I removed it part of it was left behind in the hole, I had to scrape it all out with a screwdriver.

I can't tell for sure, and sure as hell don't have the expertise to rule anything out, but it seems like the leak could not have come from anywhere but this part of the cooling system.

Is it possible that these hoses or the plastic tube were leaking even though there is no visible damage (except for at the plastic pipe connection to the block)? Is the coolant under enough pressure to squeeze through non-visible imperfections? If I replace and re-tighten ALL of the coolant hoses and the plastic tube, can there somehow still be a leak that I can't see? I ask because I'd like to replace everything but since it looks like nothing is broken I'm afraid it won't do any good.

By the way, I WILL eventually fix the "mess under the intake" but for now I'm satisfied with returning everything to the way it was and then making that a project for the future, once I know that everything is working OK as it came.

Yikes, thanks for reading my life story, for any of you that are still reading, thanks in advance and I look forward to being a contributing member to the forum, not just an information leech!

Erick

[ghoulama]

since you have it apart buy a new one. they're fairly inexpensive (around 10$)
i believe the part # is 11531714738. use new o-rings. have fun

[3bvert]

yes replace that plastic pipe, and when your putting it all back together get rid of all that throttle body heater crap, all the vac hoses and water hoses related
use the search or look under the diy, many many of us have done it with only one person that I have read haveing trouble with deleting it, but he is in some very frigd area
it was put on, some say, to help pass us emissions, as pics of  the original factory vrsion, british versions, aftican, and ausrailain cars, dont have it

[ecalder]

Thank you both, I ordered all new replacements (hoses, plastic pipe) and we'll see how it all comes together. I guess if it still leaks I'll take it to the shop because I'll be clueless as to where the leak is coming from at that point.

I'll eliminate that throttle body heater too, I'm in Houston, and although it got down to the teens here last week, happens RARELY so it should be OK I guess. Other than less crap under there, are there any other advantages to removing it?

Finally, I drained the coolant from my radiator, and a lot of coolant came out when I disconnected the hose from the plastic pipe (the one that is inline with the pipe and goes to the firewall). Do I need to drain the rest of the coolant out or can I just add more coolant? I'm thinking I want to do a full coolant flush (get rid of the green stuff and switch to the blue bmw type), but everyone talks about having lots of trouble with it I might take it to a professional shop for that. In the mean time, just to get the car started again, is there anything special I have to do before I start the car other than add more coolant in the resevoir? I've heard a lot about air bubbles and overheating.

Thanks again!

Erick

[DesktopDave]

Make sure you get the rear block drain out.  It's on the extreme rear passenger side.  Turn the heater on to full hot too.  I power flushed the whole deal with a garden hose, then filled with distilled water & coolant mix.  The BMW blue stuff is supposed to be the best.

Bleeding the car is a bit tricky.  I had good luck with back-filling the lower hose, then putting that back on the passenger side of the coolant flange.  Then I filled the upper hose; buttoned that up when it starts overflowing.

Finally I ran the car & bled the system as usual, being VERY careful not to break the bleed screw on the radiator.  If you get heat you should be OK.  I learned an important lesson...DON'T USE A PHILLIPS HEAD!!  It's meant for a large flat head screwdriver.  BTW, replacement screws are about $3 at the dealer.

[ecalder]

OK so I'm waiting for my parts, so in the mean time I went and bought various cleaners for various parts in the engine compartment. I thought I'd make myself useful and clean in the mean time. Everything is super gunky, so I used engine degreaser on the block and other black areas. I then sprayed all of the electrical connections with electrical component cleaner. Finally, I sprayed the throttle body with throttle body cleaner. I'm curious about the ICV (I think this is what it's called, it sits between two air hoses at the firewall). Can I spray anything in there to get the residue out of there? Can I use the throttle body cleaner or is there yet another agent that I need to use? What can I use on the inside of the intake manifold?

I also realized there was a copper colored lubricant type substance between the upper manifold to lower manifold gasket. Same on the throttle body gaskets. I don't have this stuff, is this necessary to put everything back together?

I also went and removed the coolant drain plug in the back of the engine. Damn that was not easy but finally figured out that I can reach in over the steering rack from the front of the car. To my surprise nothing happened when I removed the plug.

When it came out it looked like this:

At first I thought it had broken off in the engine because I can't believe it is so short! I was expecting that uncontrollable spray that many people have posted about. So I re read your post and realized I need to turn the knob to heat and turn on the vents inside the passenger compartment. Here's my dilemma: my entire wiring harness under the manifold is unplugged. Do I need to plug everything back in to turn the key? Or is the HVAC system independent enough to just start the fan as is? I guess draining the coolant can wait until I have the rest of engine back together if that's necessary.

I'm not sure if I fully understand your trick to refill the coolant by pre-filling some of the hoses. I've got some time before I try to put the coolant back in so I might wait to get more details on that. I'm scared to refill the coolant because I'm afraid of the air bubbles. I want to make sure I do it right the first time. Also, the previous owner filled it with the green stuff, and I have a bottle of the good bmw stuff, but I'm told they can't mix. So when you say you power flushed it with a hose, you literally put a hose into the radiator and let it run for a while until no more green comes out (just water)?

Finally, while I was in there I thought I'd try to replace the thermostat (my car needle NEVER gets past the 1/4 mark, even after an hour drive). I tried removing the radiator shroud but couldn't get it off around the fan blades. Do I need to remove the fan first? Even without the shroud it seems like it will be a really tight fit to get the thermostat housing out. I'll take any advice on that in case anyone has ever done this.

I really hope replacing the hoses and platic pipe gets rid of the leak. I still don't see any obvious reasons why it could have been leaking.

Thanks again for all of the advice!

Erick

[ecalder]

Done! I actually did the entire procedure twice because I could still see a drip near the engine block when I put it back together. I was so frustrated that I took it back apart and replaced the one hose I has not replaced (the hose that comes straight off of the plastic cooling pipe). After putting it back together there was still a small drip! I couldn't understand how after changing all of the hoses and pipes it could still be dripping. It was a small leak though so I decided to turn on the engine to see if it would still start up after the surgery that I performed under the hood. It started fine and after some time running the drip stopped. Hasn't dripped since then and I've been driving it all day. I'm completely confused what's going on... Hopefully it's stopped for good this time. Toughest part of the entire procedure was putting the throttle body back onto the manifold. The hoses and clamps kept getting in the way. I'm still not sure how I did it both times. After screwing with it for a while it finally slid on.

By the when I turned the car back on the clutch was dead. Turns out I had to replace the clutch slave. I didn't see many writeups but honestly the Bentley was spot on and the process was pretty straight forward. Helps to have a buddy to help pump the clutch white the bleeder valve is open and to close it before the buddy releases the clutch.

Also changed the thermostat, car actually runs at just under 1/2 for the first time since I got it! It had never made it past the 1/4 line. Hardest part here was removing the fan shroud. I think I might have cracked it a bit on the way out and back in. Couldn't find an easy way to get it over the fan and the other obstacles. Also, I spent some time on figuring out how to remove the cable that went across the thermostat housing. I kept looking for a way to pull it out but couln'd find a way to remove the lower sensor. Finally it dawned on me to work the other way and remove the cable from the engine harness and work backwards. Worked well. No need to remove the fan blades by the way!

So I removed the coolant drain plug on the back of the engine and turned on the heat and put the fan on the first setting. NOTHING HAPPENED. Apparently it was clogged, I stuck a screw driver in there and pulled out some crud, that's when it started flowing.For now I''m running with just water, want to make sure everything is good before I put the fancy bmw coolant in the system. Thankfully I didn't have any trouble bleeding the system... or so I think I didn't. How can I tell if there's still air in there?

Anyways, I'm happy to help anyone in the process of doing any of the above tasks to their car. I'm no pro but happy to help.

Thanks for all of your help! MY next task is the steering rack... yikes!

Erick

[DesktopDave]

Congratulations on your work...make sure you're using distilled water.  You can't use straight water if you're expecting a deep freeze (like us northerners)...it'll pop the radiator or crack the block.

I'm surprised that the rear bolt didn't have more coolant in it...I'd say mine drained a quart or so.

I also used a garden hose to backflush water through all parts of the system.  Mixing the old glycol coolant with newer BMW stuff will degrade its performance.  IIRC the heater valve in all e30s is totally manual (except for some oddball 'verts with their booster pump) but I'm not sure about that.  I didn't have to worry about wiring being disconnected, etc.  With the heater control on full hot I had no trouble flushing all the coolant out of the heater core.

Be sure you use distilled water for re-filling (if you don't buy premix).  I can't say that enough.  It's only like $4/gallon at a grocery store.  Tap water typically has salts and other chemicals that will deplete the coolant's wear inhibitors.

The fill method I was speaking of is to leave both main radiator hoses disconnected.  The rest of the system should be buttoned up.  I'll typically do this on ramps or jacks...makes it easier to fill air pockets (and takes it easy on my back).

1. Fill the lower rad hose first...the one that runs down to the lower passenger side of the radiator.  It'll take a while to fill even with a funnel.  I also tried to fill the thermostat housing.  When full, reconnect them.

2. Then fill the upper rad hose (driver's side) until it's overflowing as well.  It won't take as much but if you hold it up as high as you can it'll siphon a little into the rest of the system.  I then reconnect that too.  The system should now be closed, ready for bleeding.  Heater control must be full hot too.  Be sure the overflow tank is properly filled too.

3. Turn the engine on and carefully loosen the bleed screw on the radiator expansion tank with a large slotted screwdriver.  Don't use a phillip's head screwdriver!  I'd have a spare on hand, they tend to break.  You'll see some coolant come frothing out.  Keep it open until the coolant flows without bubbles.  Then I snug it down (just until coolant stops flowing) and wait for the car to get nice & hot.

4. Verify that the heater is working.  You might have to rev the car 2-3k rpm for it to get really hot.  That's normal.  No heat at all is not normal...turn off the car right away & locate the problem.

5. Repeat the bleeding being aware that the system is VERY hot & pressurized.  I broke a bleed screw on a running car and 150degF coolant shot about five feet in the air! :eek:  I'm not making that up...I had to walk two miles back to my house AND admit to my wife that I'd broken the car.  :mad: FYI, hot coolant will practically explode out of the system when you do something dumb (like breaking that stupid bleed screw or unscrewing the overflow tank cap) on a hot system.  Just open the screw until it oozes & don't tighten it all the way.  Just until coolant stops coming out...

6. After the car has cooled off, maybe that night or the next day, I check the overflow tank level & look for any leaks.

[ecalder]

Thanks Dave, that was a great system. So after all is said and done what are the signs that you still have air pockets in the system? I didn't feel comfortable with messing with the bleeder screw while the engine was running, so basically I just back filled the hoses as you said then filled the expansion tank with the bleeder screw out until alll of the bubbles were gone. I would let it sit for a few minutes then come back and more bubbles would come out, less and less every time until there were none. Problem is this leaves me with a full expansion tank. Shouldn't it just be filled to the "kalt" line when the engine is cold? Should I drain a bit out?

Also, I flushed the system out with tap water a couple of times before I put the blue stuff in. I didn't have a hose so I used buckets. Then I even ran the engine for a day with just tap water (it's 50 degrees down here). When I drained that out it was still green but not nearly as radioactive as the original coolant. Just before adding the blue coolant I still flushed it one more time with a gallon of distilled water. There was still a faint green tint to the stuff that drained out, is that going to be OK or did I just degrade the performance of my new coolant?

BY THE WAY to any of you out there changing your coolant hoses... when I got it all back together the first time and started flushing the coolant I noticed some drips coming from the same place that it had been leaking before. I was pretty frustrated and took the entire car apart again... after the second time it still dripped, and it is still a mystery why, but now it's been running a couple of days with no drip. SO if you change the hoses and it still drips a little after you put it back together run the car a couple of days and see if it still leaks before you take it all apart again! Mine's completely dry now.

[DesktopDave]

I'm glad that helped.  Signs of remaining air pockets are persistent overheating lack of heat from the HVAC system.  

I'd get a siphon set up & drain the system to the KALT line just for a good frame of reference.  A mechanic might mis-diagnose the full overflow as a pressure leak or clogged radiator.  Too much coolant shouldn't be a bad thing unless your cap isn't functional.  The radiator fills & drains coolant from the bottom of the tank.  I'm pretty sure the rad cap is a two-way valve, so too much coolant won't cause any running issues.

I still have a bit of the green color in my last few changes too, it's difficult to eradicate.  The new phosphate free coolant won't be any worse than the green stuff, I wouldn't worry too much about it as long as you have regular (every year or two) coolant changes.  If I was running a turbo or FI engine it'd be a different matter.

Mine always seems to leak for a day or two.  I'm told that the silicates in coolant take a few cycles to fill the normal hose and alu casting pressure leaks.

[ecalder]

Thanks again!

OK so I'd be happy to help anyone with the following in case you're new and about to tackle these issues!

Oil Change
Clutch Slave Cylinder Replacement
Coolant or Air Hose hose replacement
Thermostat replacement
Shift Knob Replacement (pretty annoying honestly)
Sunroof Leak Issues
Suspension Replacement/Upgrades
Blower Motor/Blower Motor Resistor
Steering Wheel Replacement (with airbag)
Glove Box Replacement

Next on my plate:
Steering rack replacement
Brake Job
Cluster Rebuild
Sunroof rebuild
Painless Dent Repair
Re-upholster the seats
Replace rear passenger door panel/card that has been GLUED in place.

Erick