Trying to solve engine not cooling down

[dodj]

While I don't know if that is ALL of your problem. Fix that first.

[blown motor]

While I don't know if that is ALL of your problem. Fix that first.

But how do I fix that? Can you get a longer rad cap? I have another thread going to try and ID the rad so I can contact the company. Otherwise I might have to have a new neck welded in I guess.

I think I'll try to get this solved and put a spring in the lower hose and wait until spring to try it out.

[RUNCHARGER]

Pretty easy to tighten up. Large washer with rubber glued on one side to seal to filler neck. I can't tell by the photos if your core tubes are plugged but I bet this rad cap problem will fix your car. I'd put a spring in the hose too but at my age I'd try to get the rad cap squared away before dumping the water and putting a spring in the hose.

[blown motor]

Ya that photo wasn't so good. The tubes are clean.
@RUNCHARGER  Just so I understand you correctly are you suggesting a rubber washer in the bottom of the filler neck with a steel washer in top for the cap to seal against?

[RUNCHARGER]

Yes: To take up some height and ensure the cap seals. Right now it is too short. Unless I misunderstood.

[blown motor]

No you didn't misunderstand. Good idea, I hadn't thought of doing it that way. Thanks. 

[MoparLeo]

You said in the beginning that you had a coolant recovery system, not just an overflow.
The radiator cap for a recovery system is different and you must use one designed for a recovery system or the system will not function. The recovery cap has a 2 way valve system. This allows coolant to go into the bottle when the system heats up and then allows the vacuum in the system to draw coolant from the bottle back into the radiator when it cools down.
A far as the cap not reaching the bottom of the neck to seal, what does the old cap look like?  Is it longer than the one you bought ?
Simply measure the neck depth of the other 2 radiators that you have in the other 2 cars and compare.[/font]

https://www.allpar.com/threads/cooling-systems-the-surprisingly-wide-range-of-radiator-caps.229050/

[RUNCHARGER]

That remind me. My washer as a spacer idea won't work if it blocks the overflow line, you'll have to make sure the overflow line would be above the spacer for it to work properly.

[blown motor]

@MoparLeo  The old cap, the other two caps and the new cap are all loose on the Charger and all tight on the Challenger.

@RUNCHARGER  Good point.

[MoparLeo]

Odd. Most manufacturers use a standard sized neck to avoid just these problems. This shows that the radiator was never holding pressure which could be causing most of your cooling problems.
You may have to replace the radiator or have a competent shop TIG weld a new neck on this one.
Fix the cap and the problems may just go away.

[Cudajason]

I would try here.


https://knowledge.northernfactory.com/en/articles/24-how-to-choose-the-correct-radiator-cap

looks like there are different size rad caps!

[blown motor]

Today's report: we noticed that the flange on the top of the neck was bent up a bit on the right side, see pic. This would prevent the cap from seating deep enough and once we fixed that we could start to build pressure but we lost it quickly. Then we cut a rubber washer and put it in the bottom of the neck and that was a little better. So we found another, better price of rubber and that was better still but we still have a very slow leak down. The search is on for the ultimate rubber washer.    But that still doesn't explain why the neck is weird unless it was just a manufacturing hiccup.

[dodj]

I'd be researching for a suitable replacement rad.....

[blown motor]

@dodj  Yes I just might. I was talking to an older gentleman this evening who has been in the radiator business all his life and he's pushing 80 and still working. He said I need a at least a 2" core and mine is 1 3/4". That extra 1/4" doesn't sound like a lot but it's 14% more capacity. Time to do some shopping while I watch the Leafs.

[jimynick]

You shouldn't need a lot of thickness Murray. I've got some sheet rubbers in various sizes that a friend gave me and if you've got a # then let me know and I'll take a caliper and go looking. I'd buy a stock replacement cap and dry fit it to see how that fits. Let me know.