89 525i oil in coolant, coolant in oil? Help!

[ShadeTreeBill]

The other day my car suddenly blew the bypass hose, and overheated in traffic. I limped into the pit, and found a hole in the hose spraying oily coolant everywhere. I got a new hose, let it cool a bit, and went about replacing the hose. When I pulled the old one loose it was obvious that there were black globules of oil in the nice green coolant. When I checked the oil, I swear its tinged a bit green also....

Can someone confirm for me my suspicion that I (probably) have a blown head gasket? or could this be something more sinister and serious...?

Thanks!

[AlmostStock]

If you're lucky it's the head gasket. When my oil and coolant both looked the same (milky gray) it turned out to be a cracked block. The only way I know to find out what's wrong is to take it apart. Let us know how you make out.

[ShadeTreeBill]

Well it took some time but it's all done now and back together. I took it all apart first to see if it was the head gasket, or something worse. When I pulled the head off, the gasket was not "blown" as i would expect, that is, it was not damaged or missing any parts or pieces, but it was wet with oily coolant on both sides. Some (3 or 4) of the head bolts, Torx style, broke loose pretty easily compared to the other ones on the head. I know that we torqued them on to spec last year when I replaced the head (another story) but I never did go back and re-torque them..... didn't think I had to....

Anyway, I did not see any damage to the head or block, so I took a chance and ordered a new gasket set and timing belt. This time I spent a good deal of time cleaning the block and head surfaces, and also made sure that I degreased them with brake cleaner before mating them up with the new head gasket. The intake and exhaust manifolds of course got new gaskets, and I also replaced the leaking gaskets where the exhaust manifold joins the exhaust system. I also put on new v-belts as the old ones were pretty oily from when the bypass hose had burst.

Since I had a bit of a time getting the bolts off of the exhaust manifold, both at the head and at the exhaust system, I decided to follow the recommendation in the Bentley book and replace all these nuts. Of course I had to get them at the dealer ship, so I shelled out the $30 or so to replace twelve nuts to the head, and six on the exhaust side.

When it was all back together I started the thankless task of bleeding the cooling system to try and get the coolant all flowing again. I ran though about 2 and 1/2 gallons of 50/50 mix but still could not stop it from overheating. Then I noticed that the bottom radiator hose was cool as cucumber... The radiatior was clogged up with jellied oil, so I broke the cooling system apart again, and took the radiator out. I tipped it up on my "catch pan" and oil goo began to drip out of it, I set it up like that and between a pint and a quart must have run out into the catch pan. I then decided best to get it professionally cleaned.... Two days and $50 later I had a nice clean radiator to put back into the car.

Topped it off with coolant, and since I had already run all the air out of the block I didn't even have to bleed it this time. In fact, I had to siphon off some excess coolant from the rad to get it down to the cool (Kalt) mark.

I am nervous that I didn't replace the water pump when I was in there. Its obviously working, but I do hear a whining sound coming from that direction... can't tell if its the WP though.... Of course, everytime I put this motor back together and run it I always hear little noises that worry me.... but it actually running better than ever. When I reassembled the throttle body, I put some new clamps on all the vacuum hoses, and sealed a leak in the air intake boot with silicone. As I mentioned I also fixed the known exhaust leak with new gaskets. During the last twelve months the car has gotten new O2 sensor, new TPS, new rotor and dist, new plugwires, new idle control valve, and new air mass meter. So all I had left were some leaks causing rough idle, and it seems I may have cleared up most of these on this reassembly....

There is just the slightest percepitble irregularity in the idle now. Barely noticeable, but still something there not quite perfect. RPM seems a bit low, about 600, but it does not budge now when shifting from Park to Drive, or when I turn the AC on or off. Of course its a sixteen year old car, so I guess I can allow for a little imperfection.

Anyway thats the saga.... any advice for an amateur? Should I re-torque the head bolts later? How would I do that given the way they are torqued? They are the torx head bolts, torque'm to 22 ft lbs, then 90 degrees, and then 90 degrees again. Someone said these are "stretch" bolts. Does that mean they will stretch and loosen?

Thanks to all.

[pada]

Wow Bill, sounds like you just about covered all the bases ... with a couple of possible exceptions.

You didn't mention replacing the T/Belt Tensioner when you re-assembled. That should always be done with the T/Belt. Also, the water pump. A little extra money spent while it's already disassembled can save headaches down the road. One of these two things might well be the source of your noise.

As for the idle, seems to me it should be in the 700rpm+ range. It'll probably smooth right out if you boost it just a bit.

Angle torquing the "stretch" bolts like you did eliminates the need to re-torque ... and "stretch" means they'll stretch to a pre-determined limit on torque and maintain proper tension to eliminate the re-torque. By the way, you didn't re-use the old bolts, did you???? You can never, EVER re-use stretch bolts...


Paul (pada)
89 e30
204k and still looks new!

[ShadeTreeBill]

Hey Paul:

Thanks for the info. I did not replace the tensioner on this job, since I did just replace it about six months ago. About a year ago I put on a new head, but failed to replace the tensioner then, so six months later it was really squealing, so had to dig in and replace it then.

And, yes, I know you are right about the water pump.... and I worry about that. But I considered the factors, and I do know that the one in there is two years old, so I thought I'd chance it.

Thanks for the advice about the idle. Do I adjust it on that screw adjuster on the top of the throttle body? I'd love it if that was all it took to smooth it out....

And ditto on the head bolts. Yes... I do know to buy new head bolts everytime.... Thanks for clarifying the "stretch" thing. What a strange concept, "stretching steel bolts!"

I started working on this car seriously about a year ago when the timing belt broke, and ruined the head. I was faced with possibly losing the car since I could not really afford to pay someone to fix it. So with some encouragement from friends, and a lot of internet research, I dug in and got it done. I really have learned a lot more about the car this past year and really enjoy driving it....

Regards, Bill.
'89 Cirrus Blue Auto

[pada]

Kudos to you, Bill. You got in there and did it! I've learned a lot from research and hands-on-get-your-fingernails-grimy-wrench-turning, too.

And that's what this forum is all about, sharing...

On the idle, you can adjust it on the Idle Control Valve or the Base Idle Screw on the Throttle Body. Some BMW sharpies would probably slap me for saying it, but I think I'd do it on the Base Idle Screw by cranking it clockwise one-half turn at a time and watch your Tach each time. Those IC Valves can be touchy.

Good Luck .. Cirrus Blue, nice color...

Paul (pada)
89 325iA (Bronzitbeige)
204k and still looks new!