water pipe in back of cylinder head
 

Hi guys, well I did it, I totally screwed the pooch. I tried to install a new water pipe on the back of my cylinder head and cross threaded the threads on the bottom bolt hole. when I pulled the bolt back out the threads came with it. btw. I replaced the water pipe because the old one cracked right at the threads, the engine got pretty hot, didn't hit the red line but got up there. any ideas on what to do outside of removing head or complete engine? any help would be appreciated as usual.

Oh man, what a nightmare. Obviously, the best solution would be to put a heli-coil in there, but that would probably require removing the head to get access. You could epoxy a short stud in the threaded hole with some high temp epoxy, then just have a lock-nut or something similar to hold on the pipe. That could probably be done in the small space without removing the head/engine.

Now thats something I didn't think of. epoxying a stud bolt in the bottom bolt hole would also make it easier to reinstall afterwards. hmmm. very good. thanks Biolite. That also would be a hell of a lot cheaper than pulling the head and replacing head gasket etc, etc. going to give that some thought.

just a thought (albeit not a tested one), what if you tried a 1/4 inch by 20 self threading bolt? 1/4 inch is like 6.35mm (I think that bolt is a 6mm by 1.0). it would be like using an oversized bolt (not sure if that is available either). good luck :)

(you could also rethread the hole to 1/4 if you have a tap that short ;) )

Both suggestions are excellent ideas so you don't have to pull the motor. I would try the larger self tap screw first and if that doest work go for the epoxy. I would use JB-Weld. I fixed a cylinder head with JB-Weld when I was a kid.

Good Luck, John S

I would try the self tap screw first and the other suggestions before doing a head pull. Man I feel bad for you though, because that's one of the worst places to have that happen with the amount of room you have to work. I was worried when I was replacing my head coolant connector of doing the same thing. Lesson learned for me is to never get the non oe parts for something like that. I ordered an OEM instead on fcpeuro and the fitting was a pita to get it right versus the oe part. Really BMW should have put a third bolt back there to make sure it sealed.

Hey guys, well I guess am going to have to pull the head. tried both suggestions. either my hands are too big or somethings just not lining up right. tried the epoxy thing. It didn't hold. which is where I'm thinking the pipe isn't lining up right. Mobius, I'm going to do what you suggested too, going to order the bmw part. I've been trying to use the cheaper part.... not good. so ordering the right one now. I tried using the bigger bolt w the self tap but it doesn't want to line up right either I guess can't really tell as again no room to see. soooo, just going to bite the bullet. going to buy the cam tools then pull the head. there's a guy here in springfield mo who works on vw engines machine work. gonna have him helicoil he bolt hole and inspect the rest of the head. if no warpage I'll be lucky as engine did get hot. engine has 165k mi on it. would really like to go ahead and do valve job on it as well if I can afford it. thanks guys. will let u know how it all goes.

Hoping for the best for you man sorry to hear that. For me I had to use a mirror the entire time I fought with that connector. I also had to remove the coil pack and all of that stuff on left side of the motor looking from the front. They don't make it obvious in any manuals but if you work from the left with plug wires coil pack and that tray the wires run in removed theres more room to work. I fought with it for a while from the right side before I decided to remove all of that stuff and go the other side. Much easier. Although like I said I fought with the oem part forever. The oring was the problem. No matter what I did I couldn't get the connector to seal all the way around. I used a telescoping kobalt mirror to look all around the connector. One side would always be not level with the head which I know would leak if I left it that way. I used coolant as a lubricant too hoping that would help. Finally I carefully had to use a pry bar and put some force on each corner to get it seated properly. Then I put the bolts in and tightened them. I tried to tighten them while seating the connector but they would always back out. My friend bought the genuine part and didn't have nearly as much trouble as I did. Everything on this car including the starter has been easy to fix except that part. What a pita.

That IS a nightmare! Sorry man. I think rebuilt M44 motors on ebay are around $800.

Reading through Mobius trouble, I thought that I would mention something.

First off let me say that this is BlackBM's suggestion to me, so I don't take credit. But when I did my cooling overhaul he recommended to put dielectric grease on all those O-rings.

So I treated that dielectric grease like A-1 sauce (or tabasco?), I put that sh*^ on everything!, including those fittings and water pump gaskets. They all popped in there like an old lady on a crowded bus...Point is, they wanted to be seated!

Good luck.

I had the very same problem as mobius did with my o-ring. I guess that's what I meant when it wouldn't line up. and yes I did put grease on the o-ring, it would pop in on one side but not the other. definetly a pita lol !

Granted I'm not standing in front of the car, but I would consider some other options before pulling the head. I think a helicoil should work, but realistically, how much more room do you need to make that happen? I would be tempted to unbolt the engine/trans/driveshaft and maybe remove the fan to see if I can't pull everything forward to gain enough room for adding the helicoil.

I had thought of that but since the car had overheated when the water pipe had broke and I had the choice of doing as you suggested or pulling the head off I decided to go with the latter. I did try and use a bigger bolt and also tried to epoxy a stud bolt in place neither which worked as again just not enough room to go at it straight and true. This way I can have it repaired with a helicoil, the most proper way to repair it, and check the head for any warpage or any other damage. Also, since it had so many miles on it would probably be a good time to do a valve job as well, if I can afford it. I got to wait a couple of weeks till we get paid so I can buy proper cam tools and have enough money to have head thoroughly checked. I now just have to keep my fingers crossed for my 95 ford ranger which has 280k miles on it to keep going until this is all done lol !!!

Hello everyone (1st post). I'm doing the head rear coolant connector replacement for 'preventative maintenance' this weekend, but i'm going to have the valve cover off for a gasket replacement so hopefully it will be a lot easier

Best thing I can suggest trying is a longer bolt. Don't know if it will work but it got me out of trouble when I changed the water pump, felt like a **** when it happened but we've all been there :frown:

The space to work back there is tighter than a nun's ****, good luck mate

so it sounds like i need to replace that pipe again with a factory part got mine from FCPeuro and it's speratic leaking fine for 24 hours then leaks next day from back and pressure is high bleed and its fine for another day.

my question is if there is a pin whole in radiator will it make the pressure build?

water pipe in back
 

Smarkwilson, you might not have to replace it. But what I would suggest is to tear into it again and check to see that the connector is flush with the back of the head. When I used one of the cheaper copies of the OE part no matter what I did (until using a pry bar on all the edges) I could not get it to sit flush with the back of the head which means it wasn't seating properly. If I had left it that way there could have been either a slow or major leak out of the bottom of the connector. I wouldn't have noticed this had I not taken the time to look around the connector with a mechanics mirror. It is a lot of work but better to be safe than sorry when dealing with the cooling system.

I think most people wouldn't catch it either unless they were being careful assuming the two bolts seat the connector properly which they don't. Like I've said before BMW really should have had 3 or 4 bolts on the connector to make it seat properly without any hassle. The best suggestion though like someone else has said is to absolutely coat the connector edge with dielectric grease so it slides in easily.

A pin hole wouldn't do that. The BMW cooling system is supposed to be completely sealed so it can build pressure. Have you checked the dual temperature sensor for the cooling fan? If the cooling fan isn't working properly additional pressure builds up because of the system not being able to cool off. You'd notice this in idle traffic especially. I firmly believe this is also the reason why the expansion tanks will literally burst or explode sometimes. When they are old the plastic has deteriorated eliminating the built in safety factor they are engineered with which combined with an increased pressure over spec, causes the bursting. I haven't run any scientific studies to prove this but as an engineer it's my best guess.