Rad bleeder screw still leaking

JimD

JimD

Waiting for Godot...
Moderator
This is a followup on my thread about the initial leak from the bleeder on install of my BobG aluminum rad. I thought I had it fixed, but after living with it for a week or so it is still leaking pretty steadily. I believe what I thought was the fix turned out to be a temperature related phenomenon. It just so happened that the last thing I tried (stock bleed screw, no washer) coincided with the car getting up to temp.

Here is what I am experiencing. It seems to leak when the rad is cold and the water level in the cooling system is high enough to reach the bleed screw. Once the car warms up the leak stops, then I can drive around, come home and park and watch it. No leaks. Come back a few hours later when the car is cool again and there is a big puddle under the bleed screw area and usually at the other end of the rad as well. (The water travels in the lower tray of the rad to get to the other side.)

I have tried two different stock bleed screws. Tried using the fiber washer MWB sent (until I destroyed it). Tonight I took the rubber o-ring from the screw the manufacturer used to block the bleed hole during shipping. It is a stout o-ring, but it didn't stop the leak. Maybe it's too big? It did kind of cover a bit of the cross drilled holes.

Thru all this testing I have fought the urge to over tighten. I stayed away from a socket wrench and just used a standard short allen to make it harder to get overzealous.

So I guess the next step is Greg's suggestion to get a copper washer and see if it helps. And I guess a selection of smaller o-rings would be another thing to try.

I really don't want to have to pull the radiator and put in the second BobG rad I have on the shelf. Anyone else have a good idea? :help:
 
Bob, proceed with the copper washer, and

Just by chance, use some virgin teflon tape on the threads.
When you tighten, take note the washer needs to crush a little.

My :2c:
 
+1 what BB says... or use some Permatex...

gasket sealer on the threads.

Sorry you are having so much trouble here... but it does kinda sound like it is NOT tight enough. I would do the tape or Permatex thing first though.
 
Personally

I would remove the bleed screw, chuck it in a lathe and turn a cup under the head of the screw/bolt to captivate the O ring. This will allow you to tighten the screw that will now capture the o ring from being forced out by tightening. The O ring is soft and it will form to the shape under the bolt and the face of the bolt flange. Copper may be okay but the surfaces must be true and smooth. Also tightening or over tightening will stretch and then strip the threads in the aluminum radiator, which will present a whole other problem. Sealing with sealing compounds may work but will not allow you to bleed the rad and resealing now becomes problematic.


TonyK.

Grimsby Ontario Canada.
 
No lathe

I must have left my lathe in the pocket of my other pants. ;) Even if I had a lathe, I would probably just make a hash of the project. Good idea though Tony. I do have a friend that I believe has a lathe in his shop. I will see if he wants to give this a try.

TonyK said:
I would remove the bleed screw, chuck it in a lathe and turn a cup under the head of the screw/bolt to captivate the O ring. This will allow you to tighten the screw that will now capture the o ring from being forced out by tightening. The O ring is soft and it will form to the shape under the bolt and the face of the bolt flange. Copper may be okay but the surfaces must be true and smooth. Also tightening or over tightening will stretch and then strip the threads in the aluminum radiator, which will present a whole other problem. Sealing with sealing compounds may work but will not allow you to bleed the rad and resealing now becomes problematic.


TonyK.

Grimsby Ontario Canada.
Click to expand...
 
shipping bolt

Black-Tooth said:
gasket sealer on the threads.

Sorry you are having so much trouble here... but it does kinda sound like it is NOT tight enough. I would do the tape or Permatex thing first though.
Click to expand...

It is a real PITA Tony. I only put water in when I refilled since it's summer and I needed to check for leaks. So it isn't making a huge mess at least.

I am contemplating going back to the bolt/o-ring set up that the radiator shipped with. It isn't a bleed screw, but right now I really need it to seal.
 
I'll look into some options.....

I look into finding the correct size crush washer. I currently have 3 installed with no washer of any kind. On one bleeder I did have to tighten the bleeder more than the others. I guess in my head I chalked that up to the bleed valve itself. Sorry for your trouble Jim.
 
It's only a little issue

bg82x said:
I look into finding the correct size crush washer. I currently have 3 installed with no washer of any kind. On one bleeder I did have to tighten the bleeder more than the others. I guess in my head I chalked that up to the bleed valve itself. Sorry for your trouble Jim.
Click to expand...

It's just annoying Bob, not a big issue. The fact that it seals up when hot tells me that it will seal, its just finding the magic combo of bolt, oring, crush washer, etc. I may even look for one of the fancy button valves. Then I could really lay on the tape or thread sealant.

Do you know the thread size of the bleeder off hand?
 
Ya know Jim... You need to have a "Lathe-Clip" and...

chain and wear it around your neck... like TK does!

He is really quite a remarkable man... Have you seen his "shop"? Looks like a Class A Industrial Complex where he actually casts his own parts.

I wouldn't be surprised if he has one of these portable 200 ton panel stamping machines to punch out his own quarter-panels!

LASTLY, as TK states, sealing it with Permatex would not make it easy to purge... but then you can at least DRIVE THE CAR!

As you well know, there are at least 10 other ways to purge the air out... and I have been afraid to touch my bleeder for over 30 years!
 
Yes, the drain plug size is M10 x 1.0

My original prototypes had the same as the drain cock for the bleed valve. Plastic with the O-ring. Which also worked fine actually.

On the second run I changed it to use the original plug size M10 x 1.0 I will test a few different options and post the findings.
 
Trip to HF at lunch

Hi Bob,

I went to HF at lunch and picked up the copper washer asst and a metric o-ring asst. I found one size of copper washer that seems like a good fit and a few o-ring sizes that fit from really tight to slightly loose. I will do some experimenting of my own. If it wasn't pouring down rain here I would get the car out in the driveway and get started. Unfortunately if it starts leaking it puts out more water than I care to chase indoors. :)

Just to clarify, the top bleeder screw is M10x1.0... the drain cock is the plastic with o-ring plug at the bottom of the rad. Correct? I almost ordered a button bleeder valve, but it was an NPT size, so good thing I restrained myself.
 
Rad comes with a screw in that bleed hole

The radiator ships with all its holes plugged. The screw in the bleed hole has a large o-ring on it. I am sure this was also part of a pressure test during the manufacturing or QA process.

If all else fails, I will load up that original plug with PTFE tape and hopefully be able to get it in the top of the rad thru the frunk access hole. I might need to get creative to make that happen, but I bet it wouldn't leak. Of course, bleeding would be pretty hard, but once bled I don't plan on messing with it often.
 
I "think" it stopped leaking

I did some experimenting this morning. I tried the large rubber o-ring that was on the aluminum plug that came with the rad. I was quite surprised that that did not work, it actually leaked pretty bad. I found out why when I pulled it. Sorry for the fuzzy picture, but we lost our good camera some how.

In the upper left are the two shipping plugs from my two rads. You can see I removed one o-ring to test with and you can see that installing it shredded the ring. That's not good.

Next I tried a copper washer. It still dripped, but was better. When I pulled it, I found a raised lip on the outer rim of the washer. I drew a little arrow pointing at the shine reflecting off the bent rim. It seems like there is a little peak somewhere on the mating surface for the bleeder. Enough to catch the large o-ring and shred it and also deform the rim of the copper washer when I tightened it. I can see where the inner rim of the washer tried to seat and conform to the bleeder, but couldn't sit flat enough. The drip was very slow, but wasn't going to stop.

Finally I tried a small o-ring that was very snug passing over the threaded area, but sat very nicely against the smooth part of the bleeder where the threads terminate. You can see it in the picture. I hand tightened it on the spare aluminum rad I have here and it seemed to fill the gap nicely. So I tightened it a little more and then pulled it. It was not marred at all, so I put this combo in the rad in the car.

So far, this seems to be the answer. It has been sitting for 30 minutes or so without dripping. Now I will start the car and try to do a bleed procedure and see if it seals again. I sure hope so. :)

Looking at the mating surface on the spare rad, it is very smooth. I did not look at the rad I installed, but I am guessing that perhaps the weld on the insert went astray on the rad in the car. I am not going to drop the rad if I can stop the leak, so we may never know. :confuse2:
 
But it's good that you did some more sleuthing!


Those who haven't yet installed their rads should have a close look at the bleeder sealing surface of their rads, just to check for any similar irregularity.
 
It's dripping again ARRRGH - rad out of position???

Well its not a dripping lot, but after I took a drive and came home to burp it, it did not reseal 100%. I pulled the bleeder and the little o-ring was busted. I cranked it down a little too much trying to seal the leak.

While I had the bleed screw, out I poked around the top of the rad with my finger. There is definitely a piece of metal covering a section of the bleed mounting surface. So I retract my "bad weld" theory and replace it with perhaps I have the rad slightly out of position. It is in there solid, but I guess I "missed" on the alignment.

The only other rad I have replaced was on my 78. There was a hole into the trunk for the top center post on the rad to go into and you could see it was where it should be. On this 85 there is a bracket, but it doesn't open into the trunk. I couldn't tell if it was in the right spot, but I couldn't wiggle it front to back. I figured it was seated. Either I missed the bracket or just mis-aligned something.

I have an autox in the AM and I really don't want to get too deep into any repairs. I guess I will loosen the lower bracket and see if I can move it a bit. I put on new o-ring on too. If it seals I will just leave it be till I have more time to play with the radiator.

Sigh. Wish I had felt around in there sooner. Or wish I had one of those cameras for looking into tight spaces.
 
Jim, try a short bleed bolt. On my Scorpion the bleed bolt has a normal head, not the elongated one you are showing. Maybe this will help, if the long bleed bolt is up against a part of the car.

You can also use an aluminum washer, might seal more easily than a copper one.
 
Thanks Greg

I am slowly coming to the realization that I have the rad mis-aligned. I might even have the lower bracket on backwards. I tried to see how the 78s bracket is installed, but the two brackets do not look exactly the same.

From what I can "feel" with my finger tip. There is a piece of the body work touching the top of the bleed screw seating are. I would say it is covering maybe 1/4 of the surface. The bleed screw has room to get by this sheet of steel, but not much clearance. I am sure this is what the copper washer bent against to produce that raised corner.

I loosened the lower bracket and really could get much movement out of the radiator. I can reach up between the fans and feel the top of the radiator and contort my hand just enough to get a finger inside that center bracket. The top aluminum post is definitely in the bracket, so at least I had that right.

If I can get it to stop dripping I am thinking it will have to be good enough for today. I will definitely be revisiting this rad install soon. Unfortunately I have something rubbing in the wheels and I need to pull those and see if I can spot that issue. Then I need to align the wheels after that. Or skip the race. It is supposed to storm off an on anyway, but we haven't made one yet this season due to family obligations.
 
Well I guess the rad bracket wasn't on backwards after all

What a waste of time. I have lived with what I thought was a reversed lower rad bracket for a few months and finally decided to take care of it before the weather turns. I spent the afternoon pulling the lower bracket and reversing it, then trying everything I could think of to change the alignment.

I never could get the bleed screw centered in the frunk's access hole. I "think" I gained maybe 1/8" clearance on the bleed screw seat that leans into the nosecone sheet metal, so I guess that is something. The long bleed screw is tipped forward in the access hole, but not touching the body work. I was able to fill and bleed the rad and the screw sealed when I was done. I guess I will just leave it as is till I feel like pulling the whole unit out again.

I did take my multi-tool and cut off the corner of one fan housing that was digging into a hose. I also took the opportunity to drain the system and fill it with fresh 50/50 mix for winter, so I guess it wasn't a complete waste of an afternoon. :(
 
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