Bleed Screw Threads Stripped In Radiator...Repairable?

[bmwman91]

So I was sitting at a light this afternoon and noticed that the temp needle was creeping towards the 3/4 mark. Once I started driving the temperature went back to the normal middle position. I assume that that means that it is just really low on coolant and not empty. There was also a coolant smell at the light.

When I got home and popped the hood, coolant was sprayed all over. The system seemed to be missing a good half gallon of coolant based on what I put in, and I have not run it since the bleed screw is the culprit, so more may be missing once I get the pump running. Adding coolant + squeezing the top hose repeatedly seemed to push a lot of air out of the system, so I did that until bubbles stopped being pushed into the expansion tank / the level stabilized. I can see bubbles come out around the bleed screw just from squeezing the top hose, so I am certain that the leak is serious enough that I shouldn't drive much until it is fixed. The threads in the radiator itself are what has been stripped.

My question is: Are the threads in the removable top bracket thing, or the radiator itself? Does this mean that I need a new radiator? If so, then I am going to seal the bleed screw in with some high temp RTV so that I can use the car until the new radiator comes, and I sort of need to drive it to somewhere besides my apartment since they get uppety about car repairs!

[Slowered318]

I believe the screw taps into the radiator itself and not the expansion tank or plastic cover... unfortunately. I had a similar problem with my old radiator. The plastic around the bleeder screw was cracked, I managed to get by a whole season by removing the plastic cover and placing a hose clamp around the bleeder screw housing. You could try something similar and use a good amount of plumbers tape.

For only $5 you could also try a brass bleeder screw in the future, just be careful when you tighten. I think I might add one to my next order from ECS.
http://www.ecstuning.com/BMW-E30-318is-M42_1.8L/Engine/Cooling/ES2608507

I've had a great experience with the Behr radiator I installed last summer, the whole cooling systems seems to function better now. If I had the chance to do it again I might splurge on the Zionsville radiator, but I think the stock rad is already oversized but has some design problems. http://www.zionsvilleautosport.com/store/screen/prod/store_code/6134/product_code/CCCK.htm

Good luck!

[bmwman91]

Well, I just went and pulled the little cover plate thing. Sounds like I have the same issue as you. Time for a new radiator. The stupid screw boss thing has a nice big crack in it that runs about 5mm off into the plastic body of the end cap. I smudged Ultra Grey RTV all over it, but I don't think that it'll help a whole hell of a lot. Hopefully the biggest part of the leak is dealt with (crack around the bleed screw itself).

I may just aim to do the radiator swap in the middle of the day when nobody is around lol. Would leaving the radiator cap loose help to keep pressure from building up in the system, or would that just be another place for coolant to piss out all over?

[Slowered318]

If the crack is running down on 2 axis there is pretty much nothing you can do.

Just have your new rad and coolant in the trunk, wait till it just rained, park over to a storm drain and let it rip! A little glycol never hurts but don't leave pools of it around for wildlife to drink. They finally added a bitter agent to antifreeze but I'm not sure if the BMW blue has that.

[Nick_318is]

I just replaced my radiator this weekend due to the same thing.  From what I found searching you can seal the screw up with some RTV but it may interfere with bleeding.  If you have a crack next to it I think you're going to be stuck with putting a new one in.

I would stay away from the brass bleed screw, sure it looks nice, but that's how I messed up mine.

[E301000]

Same thing happened to me and I was also tricked in thinking that the bleader screw thread was a part of the cover. You could try some epoxy in the area and use the brass screw to cut new threading..............The same brass screw that damaged mine in the first place.

[bmwman91]

Thanks guys. Yeah, placed the order for a new Behr radiator at Pelican last night. Now I just need to decide if I should try to drive the 5 miles to my house (just bought one and ma fixing it up a little, still living in apartment for another month) or if I should try to do it in the apartment parking lot without being caught lol. It should make it the 5 miles to the house if I keep the RPMs low and drive over at lunch time when there is very little traffic.

[Slowered318]

Ok so scratch the brass screw idea, I didn't know it's caused so many problems for people.

If you feel the parking lot job is going to be rushed then maybe you should make the drive to your own property and do a complete job. Maybe run the heater on full just in case, if you have to stop and top up the fluid then do so. I thought you had a new $7,000 MM engine in there? If that's the case personally I would say ignore the superintendent and do it at the apartment or have the car towed.

[bmwman91]

Yeah, there is a nice MM power plant in there. It was a big "WHOA" when I noticed the temp needle approaching the 3/4 mark on my way home yesterday. I assume that while I was on the highway things were OK (wasn't looking at the gauge then) since the needle dropped as soon as I was moving again.

But yeah, I'll have to think about doing this at my apartment. If nothing else I need to keep a gallon or two of water in the car just in case I need to pull over and top it off. I'll probably turn the engine off at stop lights lol.

[Slowered318]

Yeah, there is a nice MM power plant in there. It was a big "WHOA" when I noticed the temp needle approaching the 3/4 mark on my way home yesterday. I assume that while I was on the highway things were OK (wasn't looking at the gauge then) since the needle dropped as soon as I was moving again.

But yeah, I'll have to think about doing this at my apartment. If nothing else I need to keep a gallon or two of water in the car just in case I need to pull over and top it off. I'll probably turn the engine off at stop lights lol.

Our cars really need a big siren to go off when the temp hits 3/4, I have never had it get that hot without something major like a broken belt, air lock or sudden loss of coolant. If I just installed that motor I would be washing my hands before I open the hood and straining the oil and coolant with cheese cloth. LOL

Good thing you caught it in time!

[bmwman91]

Definitely...I am resisting the urge to get all paranoid that it somehow overheated on the highway when I was not paying attention, but if driving at 30MPH was enough to cool it off then 70MPH certainly was.

Anyway, I am going to drive it about 200ft down my street, away from the apartment and park in front of a sort-of empty lot. Changing it in the street should be fine lol. I'll just get a few gallons of cheap water to dump on whatever spills.

[Gabs]

Your temperatures were likely normal on the highway. To make a long story short, e34 dd decided to drop its gas tank off at the pump (literally)  ,   unfinished 318 had to take over dd with no cooling fans installed. My experience is that even at slower speeds in the city the engine temp stays nominal, highway speeds I wouldn't even have to look at the temperature. At stops lights though, I looked more nervous then a teen getting pulled over for the first time. Anyway I'd put to rest the idea that you we're over heating on the highway.

Also if it makes you feel any better, I once redid all my brakes including caliper rebuilds on the side of a relatively busy street. I didn't think much of it at the time but in retrospect it seems like a silly idea  and it was

[bmwman91]

Haha roadside brake-job...nice!

Yeah, I assume that coolant leaks are one of those things that can only get worse with time. If the engine was still cooling itself off at 30MPH at the end of the drive, then there was certainly enough coolant in there when I was on the highway before then.

Radiator was delivered today (living 50 miles from Pelican's NorCal warehouse FTW) and I will swap it at lunch tomorrow.

[ti_tony]

I had a bleed plug strip out, the threads were 10mm x 1.5 which is only about .006 different than a NPT 1/8-27 pipe thread. I tapped it out and put a brass stop-cock similar to part #4921K41 in the link. It's a back up radiator now and hasn't been used but everything is tight and strait. I put a head gasket on and replaced the radiator then. I hate those plastic threads, I elevated the front of the car with the heater on high when I refilled it, massaged the top hose and didn't need to bleed the second one.

   http://www.mcmaster.com/#stop-cocks/=nr3fs7

[bmwman91]

I got the new radiator swapped in at lunch today. Talk about bullshit though...the bleed screw on the new one stripped. I can't tell if it is the screw or the threads in the radiator. It is not like I overtightened the thing...I've done this a zillion times. WTF? It does not leak, but I assume that it is only a matter of time before it does. My assumption is that the bleed screw is what should strip since it is made from a softer plastic. Maybe this is why people use the brass bleed screws?

Can I use a little RTV around the rubber O-ring to keep it sealed? It does not leak now, but who knows if the screw will decide to "jump" a thread at some point and lose compression on the O-ring.

I'll get a better look tonight. Maybe it is just the screw threads (fingers crossed!).