Radiator Cap, Pressure/Temp Questions - JeepForum.com
 
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post #1 of 14 Old 03-02-2018, 09:58 AM Thread Starter
CatAndTie
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Radiator Cap, Pressure/Temp Questions

Hey All,

I recently tore into my 96 ZJ 5.2l a few weeks ago to fix my timing chain cover leak. Along the way I swapped a bunch of stuff. So over the past couple of years I pretty much have replaced my cooling system including radiator, water pump, fan clutch, thermostat, gaskets, various hoses.

My ZJ at one point had boiling coolant in the reservoir, and occasionally would creep up to a mark or so above the 210 mark (guessing 220ish+ range from memory). After changing everything out it's now sitting more around the 210 mark, which I'm pretty sure is an adequate temp for my ZJ, yes? I seriously don't know how to get it any lower at this point?

So after all of the work I did recently getting to the timing chain the ZJ developed a gargling sound around my passenger side dash. Figured there was still air trapped in there so I burped it again. That solved the gargling noise. But every since I did that I now am having issues with leaking at my radiator cap. I got the all aluminum radiator from Radiator Express about a year and a half ago with no issues/complaints: https://www.radiatorexpress.com/prod...aia_id=1182215 I just used my original ZJ radiator cap with it, too without issues. So I figured I'd try a different cap - went with a cheap-o from Autozone that still leaks. It even felt a bit lose on my radiator. I bent in the tabs, which helped a little I think.

I just talked with someone from Radiator Express to see what kind of caps they had and the sales guy just recommended trying a couple different styles. Specifically he suggest Stant 10334: https://www.amazon.com/gp/product/B000C8227E

Questions condensed:

1996 ZJ 5.2l

1. 210 is an appropriate temp to run at, yes? After replacing most of my cooling system that is where it runs, sometimes a hair lower but mostly hovers around 210... any way to get that a bit lower and keep it there? It seems some people are able to get theirs lower but some are at 210.

2. Is the Stant model I posted with the little lever any different from a regular besides the fact that you can release pressure if you need to open it hot? In other words, does it automatically release pressure through the lever or is it just for me to open the cap? Any reason not to get this style?

3. Any other suggestions to get a better seal at the radiator cap besides trying different brands, etc. Or anyone have a go-to brand that worked for them?

4. Could it be possible that there is now too much pressure in my system? Is this a sign of another issue at hand?

Thanks!

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post #2 of 14 Old 03-02-2018, 10:08 AM
StPaul59
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Get a cap that fits. Can't use oem on rad express aluminum radiators. Their caps suck. I had the same issue. I found a cap from an 07 accord will work, but you have to get the correct one. The accord has 2 styles. Get the bigger one that matches the rad express one.
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post #3 of 14 Old 03-02-2018, 10:27 AM
BorderWalker
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I've had no issues using the Radiator Express Rad cap that came with my All Aluminum. It works perfectly fine and has no leaks or overheating issues.

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post #4 of 14 Old 03-02-2018, 10:56 AM
kg6mov
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1) Yes, 210 is what it’s designed to run at. You could probably get that down a bit, but I see no reason to.
2) A radiator cap is supposed to regulate the pressure in the system, that’s what they all do. The lever is a bonus for opening it hot.
3) I just used the one that came with the radiator? Dunno why they didn’t ship one with yours?
4) If there is too much pressure in your system then the radiator cap isn’t doing its job correctly.

The thought occurs though, how recent is the t-stat? I’d throw a good stant in there if it isn’t recent, and if you put a fail safe or similar in there you want to replace it with a normal stant.


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1984 F250, 460 BB, T19, work truck/future tow pig
1987 Mercedes 300D Turbo, the diesel daily, 30mpg in style

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post #5 of 14 Old 03-02-2018, 11:31 AM Thread Starter
CatAndTie
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Quote:
Originally Posted by kg6mov View Post
1) Yes, 210 is what its designed to run at. You could probably get that down a bit, but I see no reason to.
2) A radiator cap is supposed to regulate the pressure in the system, thats what they all do. The lever is a bonus for opening it hot.
3) I just used the one that came with the radiator? Dunno why they didnt ship one with yours?
4) If there is too much pressure in your system then the radiator cap isnt doing its job correctly.

The thought occurs though, how recent is the t-stat? Id throw a good stant in there if it isnt recent, and if you put a fail safe or similar in there you want to replace it with a normal stant.
The t-stat is a Crown that went in only a few weeks ago when I had everything torn apart.

I seriously don't remember there being a radiator cap that came with the radiator... maybe it did but I misplaced it or something?
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post #6 of 14 Old 03-02-2018, 11:56 AM
kg6mov
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I vaguely recall that it was in the styrofoam packing and kinda easy to miss.


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Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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post #7 of 14 Old 03-02-2018, 12:21 PM
BorderWalker
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Kg's got it. Mine was stuffed into the Styrofoam packaging which surrounded the Radiator.

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post #8 of 14 Old 03-02-2018, 12:40 PM
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Mine is using the Gates Stant 31535 18 psi cap. That has been working fine.




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post #9 of 14 Old 03-02-2018, 01:06 PM
StPaul59
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Maybe all I had to do is bend the tabs on the radiator express cap, but it was letting air in within months of putting it on. My oem cap didn't fit their aluminum radiator, maybe bending the tabs would fix that? There was a thread awhile back listing all the caps that would fit the RE rad. My concern is that the neck is different on the inside where the rubber seals it.. I'll have to get an oem cap and see if they are different where it matters.
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post #10 of 14 Old 03-02-2018, 04:16 PM
1996maroonzjf
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Quote:
Originally Posted by CatAndTie View Post
The t-stat is a Crown that went in only a few weeks ago when I had everything torn apart.

I seriously don't remember there being a radiator cap that came with the radiator... maybe it did but I misplaced it or something?
I just got my Radiator Express all aluminum in a few weeks ago.

Funny story about the cap - I ordered the radiator over the phone and the sales guy casually said Ill throw in a radiator cap. I said cool thanks, thinking "throw it in" meant free. I get the invoice and I see $11.99 for the cap and an additional $16 and some change for shipping. I had actually put together a cart on the website to see what shipping would be and the amount on my invoice for shipping was $16 and some change over that total.

I emailed to complain, and their response was the he really meant he would add the cap to my order since they aren't included and he never said free. They also said they charge $16.xx PER item for shipping. They did end up refunding me the extra shipping and the price of the cap in the end, but I'm sure a lot of people wouldn't have caught that.I'm not sure if not including a cap is a new policy or what considering what KG and Boarder are saying.

When the radiator arrived the cap was installed on the radiator fill neck not in with the packaging like others are saying. The filler neck seems to be smaller than an OEM ZJ radiator and the cap is really tiny. at least on the 4.0. It was also slightly bent and seems to be pretty poor quality(the cap not the radiator).

EDIT: I forgot to mention that the new cap is 16 lbs, not 18 like the OEM

-Tim
(2) '96 4.0s
#1-'10-'18
#2- HP30/Ford 8.8 - 4.56, OME HDs, 5100's, IRO Adj Arms/Track Bars
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post #11 of 14 Old 03-02-2018, 04:23 PM
1996maroonzjf
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This summer on the OEM radiator, I was having a similar problem when I was driving in really high elevations (over 10,000') at high RPMs, I was seeing coolant splattered all around the filler neck and hood insulation. I tried a new OEM style stant and the same thing was happening when I went up into the mountains. I ended up putting the original cap back on and bending tabs in, and that seems to have fixed the problem.

-Tim
(2) '96 4.0s
#1-'10-'18
#2- HP30/Ford 8.8 - 4.56, OME HDs, 5100's, IRO Adj Arms/Track Bars
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post #12 of 14 Old 03-02-2018, 04:34 PM
kg6mov
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Yeah, I got mine a while ago so they may have changed somewhat.


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Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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post #13 of 14 Old 03-02-2018, 06:32 PM
StPaul59
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Quote:
Originally Posted by 1996maroonzjf View Post
I just got my Radiator Express all aluminum in a few weeks ago.

Funny story about the cap - I ordered the radiator over the phone and the sales guy casually said Ill throw in a radiator cap. I said cool thanks, thinking "throw it in" meant free. I get the invoice and I see $11.99 for the cap and an additional $16 and some change for shipping. I had actually put together a cart on the website to see what shipping would be and the amount on my invoice for shipping was $16 and some change over that total.

I emailed to complain, and their response was the he really meant he would add the cap to my order since they aren't included and he never said free. They also said they charge $16.xx PER item for shipping. They did end up refunding me the extra shipping and the price of the cap in the end, but I'm sure a lot of people wouldn't have caught that.I'm not sure if not including a cap is a new policy or what considering what KG and Boarder are saying.

When the radiator arrived the cap was installed on the radiator fill neck not in with the packaging like others are saying. The filler neck seems to be smaller than an OEM ZJ radiator and the cap is really tiny. at least on the 4.0. It was also slightly bent and seems to be pretty poor quality(the cap not the radiator).

EDIT: I forgot to mention that the new cap is 16 lbs, not 18 like the OEM
I also noticed this. Back when I needed one it was only about $25 total. I even posted about it somewhere here.. And its not even the correct lb cap lol! 16 seems to work fine though.
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post #14 of 14 Old 03-05-2018, 08:47 AM Thread Starter
CatAndTie
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I'm going to give the Stant 10334 PSI 18 a try as recommended by the RE guy. I still have a small leak around the cap using the cheapo Autozone cap, but I did find bending in the tabs helped that a lot for the time being.
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