Renix radiator cap hose mod?

Some time ago I saw a pipe T with a radiator cap on it, designed to go in the upper radiator hose of previously closed systems like renix, but I can't seem to find the beast. I am looking to try one, but need a source for it? Any one now where to get them? Part number?

I think it was either in Summit or Jegs.

DansGreyMj said:

I think it was either in Summit or Jegs.

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Jegs???

Ecomike said:

Jegs???

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Here's a few
http://www.jegs.com/c/Cooling_Thermostat-Housings-Filler-Necks-Water-Restrictors/10129/10002/-1

Bear in mind that the fill cap should be /the/ /very/ /highest/ point in the system! That's why RENIX puts it on the volume tank up in the corner - and the HO setups have the overflow tank sitting a bit below the radiator fill cap. even through it's not part of the pressure system.

Just sayin'...

You might find one at Summit by searching "hose filler".

I recall seeing (but don't remember where) someone using the inline filer neck to convert to an open system. He plumbed the over flow tube from the neck back to the stock coolant bottle. I think he also swapped out the heater valve.

My plan is to use it to help speed filling the Renix cooling system, and getting ride of air bubbles in the upper radiator and upper radiator hose where they like to park themselves.

I plan to use about 18- 20 lb cap on it.

Then I will continue using the stock 16 pound cap, capped plastic bottle open system bottle for the real breathing. I will probably use a very small overflow bottle for the filler cap nipple just to make sure it sees coolant if it ever tries to pull a vacuum there. May set it below the Renix bottle. If the vacuum becomes a problem I may look for a way to seal that area, or just plug it ( the overflow nipple on the neck). I think the one I ordered has 1/4 FPT, NPT on it, so a pipe plug there would be easy. If I ever give up on the open Renix system bottle, I will be one step closer to being able to connect the plastic bottle hoses, with a sealed metal tank (or just pipe), and a bleeder valve near the top.

I ordered one from jegs. 1-1/4" pipe size.

like this one? i believe its bluexj whos running theirs like this

Yep. That is probably where I will put mine.

i did the mod, and mine looks just like the picture but...if i had to do it again, id just save the money for a radiator. chances are you could use a new one anyways...

bluejeepkid said:

i did the mod, and mine looks just like the picture but...if i had to do it again, id just save the money for a radiator. chances are you could use a new one anyways...

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Mine is only 40,000 miles, and 4 years old. I am shopping for a new R-134a AC condenser and a HD, 3 row all metal, copper / brass radiator too, or a 2 row with extra wide tubes making it equal to 3 row. Hopefully it will be overkill. I don't like fixing the same thing more than once.

Just got mine in, installing it today.

I forgot to mention earlier that 1 of the 2 reasons I am installing it is to be able to pressure test my Renix closed system with a standard radiator pressure tester rig, and to be able to watch actual system pressure while it is hot and running in the driveway!

The cap threads and thread size on the Renix poly bottle does not fit standard radiator tester rigs. I may also spring for an after market cap that has the pressure and or temperature display in the cap!

1990JEEPXJ said:

like this one? i believe its bluexj whos running theirs like this

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I just noticed that you added the garden hose 'T's to both heater hoses. Nice idea, great for flushing heater core that way. If you added a ball valve(s) on the heater core side, you could force flush just the engine, and then the radiator too with the heater core isolated.

I completed the hose mod on my Renix system and love it. I kept the POS Renix bottle. So far the 16 lb cap on the filler neck has not released any coolant (even with 4 hours of highway driving in 95 F ambient, with AC on Max) , which confirms my recent observations that we can have the closed system, with an open system filler neck and radiator cap for getting air out of the system, and keep the closed system air /coolant surge bottle. Rigged up this way, the cooling system runs at a lot lower pressures as the air is more compressible than liquid!

I also upgraded to the 97 parallel flow AC condenser, and CSF 3 row brass/copper radiator, with a ZJ clutch.

Been about 6 weeks now (87 Renix update). Yesterday we got back up to about 95 F ambient, >90% humidity, and I got stuck in mid day traffic for an extra hour of crawling traffic on 33 mile trip. AC on Max, no problems. Renix bottle with Volvo cap is holding up nicely. Coolant temps unchanged, and the 16 lb cap on the inline filler neck has never opened or vented as I theorized, renix coolant bottle is still 1/2 full, unchanged, so my closed/open Renix mutant hybrid cooling system is working perfectly. Holding 180-200 F at the thermostat housing for 60 F to 95 F ambient days. Note my thermostat is 180 F.

Summary of relevant changes I made. Installed a new CSF 3 row Brass/copper radiator, new 97 parallel flow AC condensor on the R-12 converted to R-134a AC, new ZJ (grand cherokee standard FC) fan clutch, new standard water pump, and new POS plastic Renix Coolant bottle with a Stant brand Volvo bottle cap on the Renix bottle.

I have also determined that my renix is indeed running leaner, and thus hotter, which is why I had to clean up and make improvements to the cooling system. In spite of the 1 hour traffic jam and poor mileage I still got a 15% higher mileage on the last tank of gas than I got anytime in the last 4 years. I have had a bout 20% increase in mileage since my renix started running hotter.

Also note worthy is that just before it started running hotter I replaced the harmonic balancer. The jeep sat up for 4 weeks during that time. When I started it back up it had a terrible, very load valve train noise, much worse than valve-tappet-lifter noise I had gotten use to the last 40,000 miles and 4 years. So I did a trick that 5-90 taught me that had worked to some extent the last 9 months, which was to run the RPM in park up to 3500 and hold it for a minute to free up the stuck lifters. Well ever since I did that the last time, just after replacing the HB, the 4 year old lifter noise (always worse in cold weather, and first days start up) has been gone completely, and the engine runs hotter, and leaner, and gets better mileage ever since that day.

I'm curious.. with the hyrbrid open system, when It over pressurizes and the cap allows coolant to flow to the over flow tank, is the system ever able to recover the coolant that has gone to the over flow tank? Or are you just having to empty the tank if it gets too full? I believe on my camaro, there is a hose from the over flow tank, back to the radiator that allows the coolant back in after things cool down....

Also.. what year/model Volvo does the cap come from?

stephenspann27 said:

I'm curious.. with the hyrbrid open system, when It over pressurizes and the cap allows coolant to flow to the over flow tank, is the system ever able to recover the coolant that has gone to the over flow tank? Or are you just having to empty the tank if it gets too full? I believe on my camaro, there is a hose from the over flow tank, back to the radiator that allows the coolant back in after things cool down....

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I think there is just one Volvo cap. I told the counter to pick a a mid 90s volvo and randomly pic an engine and bingo it was the right cap. I got mine from the radiator cap rack in an isle. Stant Brand.

If you search for the thread I started on the "Renix bottle Cap", search "renix ecomike bottle cap" in google, and I posted the Stant brand part number for it in that thread.

As far as over pressure goes, the Renix closed system has air in the bottle, so with a 16lb cap on the inline filler neck the coolant system never gets to 16 lbs, and never overflows with mine. I think with air in the taht renix bottle coolant has to get to 260 F to open the in line filler neck cap.

I have run this hybrid for 3 months in Houston at ambients up to 100 F, with no loss of coolant out the 16 lb cap!

Here is the info you posted in the other thread:

Stant Volvo style cap for $8.95, #11244.