Don't wanna blow coolant system! 23 psi for Pressure Leak Test?
 

I don't want to blow the coolant system! Is much higher 23 psi rating true?

Please help! My pressure leak testing is delayed only because I found differing PSI numbers for the radiator SYSTEM. I will be using the Powerbuilt tester loaned from Autozone. I found the following numbers from various sources below:

...Leakage Test Pressure 157 kPa (23 psi), Cap Relief Pressure 81-109 kPa (11.8-15.8 psi) from sources:
+Villager [Chilton online via public library]
+Quest: [Chilton online via public library: can't seem to find spec]
+Quest: [FSM [factory service manual]


...16 psi???
+Haynes book for Quest/Villager, which didn't see mention of 23 psi:
page/section 3-1 "radiator pressure CAP rating" = 11.8-15.8 psi
page/section 1-2 "radiator CAP pressure rating" = 16 psi


Printed psi on cap itself:
+current on van: no spec. I don't know if OEM or 3rd party
+Oreilly, Autozone: 13 psi
+dealer: cap no longer available and no spec

Regarding the Mercury Villager -- ALL Years :
DO NOT test at 23 psi !! Test at 18 psi.
The operating pressure range of your cooling system is12 -- 16 psi.
ALL available brands of Pressure Caps for the Villager are rated at 13 psi.
Motorad offers a Stainless Steel model -- part #- MOTORAD T13R -- pressure rating = 0.9 atmospheres, or 13.23 psi.
Motorad is a quality manufacturer of cooling system parts, which I have used successfully over many years on different engines and types of vehicles..
Available at Rockauto.com ; Amazon.com ; and Carid.com for around 4 dollars.
https://cimg9.ibsrv.net/gimg/www.mer...d8bb92bac3.jpg
95 MERC Engine Bay

Nice clean engine bay for a '95! So, why the significant discrepancies among the various documentations including your feedback (13, 16, 18, 23)?

Radiator Issues
 

Thanks -- That's my 95 MERC Restoration, as seen here: 1995 Grand Marquis Restoration - Mercury Forum - Mercury Enthusiasts Forums
I don't know exactly what you are asking -- BUT --
The "13" is the working pressure of the Cap.
The "16" is the upper range of the cooling system spec.
The "18" is the upper limit for the "Test" setting,
The "23" is where you should not go -- unless you wanna blow up the radiator.
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Colorado Rte. 82 - East of Aspen, Colorado -- 12,095' -- Highest Driveable Pass in USA.

Like what I've stated in my initial post, the 23 is in the various manuals. Then, Haynes stating between 11-16. Then, you saying 18. Another person in another thread saying 13. Specs from manuals and online posts are all over the range. How did you come up with 18? Thx

Coolant System Pressure Testing
 

O.K. -- I'll try again.
The Working Pressure of your Villager's cooling system is 13 p.s.i.
The Cap's range is 13 -16, with the highest pressure being 16.
Testing at 10% over the spec is an industry testing standard.
16 + 10% = 17.6 -- rounded up to 18, in your case.
Of course, ALL vehicles will not test at the same number, however YOURS should be tested at 18 p.s.i.
There is NO SENSE in testing at 23 p.s.i. -- that would be like 44 % above the spec -- and dangerous to your cooling system.
WHERE did I come by this info ??, you ask .
It took quite a while, as I'm 82 years old, and have been wrenching on imported and domestic vehicles for about 70 of those years.
And THIS, from an automotive website that I saw this morning:
Avoid pressure above 18 pounds so you do not damage the cooling system by causing a rupture.
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95 MERC Right Front Brakes - ACDelco Drilled & Slotted Rotors; Eclipse Calipers; Police Pads; ESI-6 Brake Fluid; Raybestos Hoses.

Ok, now you are bragging about your clean car! Too clean for a '95. I understand that you have been wrenching for a long time. 10% above industry standard makes sense. I'll give that a try. Curious if your manual indicate a spec. Any thoughts on why the factory service manual spec at 23 psi?

Thank you kindly and muchly -- The 95 MERC will be 26 years old in May, with NO RUST anywhere on or underneath the body and/or chassis.
And yes, I brag -- A lot of planning, shopping, installing, and modifying went into the build, and I have reaped the rewards over many years and miles of long-distance, high-speed touring throughout the deserts and mountains of the American West.
The 95 MERC is getting a bit long-in-the-tooth, but so am I. ;>;)
Now, back to radiator test pressures:
The first thing we need to remember is that all manufacturers do not test at the same pressure -- AND that even the Factory Service Manuals have errors and/or mis-prints. I use Factory Service Manuals whenever I can -- those Chilton and Haynes Manuals are not reliable, in my experience.
As I am not boned up on the Mercury Villager's V-6, I consulted the official FOMOCO Service Manual for the 95 MERC's V-8, which states that cooling system components should be tested at twenty (20) p.s.i. --
I use the "Cap Range + 10%" method as a safety net, regardless of manufacturer, as it allows leak testing without putting un-necessary strain on the system.
Besides, blowing up a customer's radiator and/or heater core will definitely ruin your day. ;<;)
As for the 23 p.s.i. in your manual -- it may be correct, but it makes no sense unless the working pressure of your cooling system is near 20 p.s.i.
A premium-quality Radiator Cap from Motorad or Gates is recommended.
A Prestone Coolant Flush Kit lets you reverse-flush the cooling system, which gets the nasty out of the heater core and improves both heating AND cooling.
Lemme know how you make out with your cooling system issues -- I'm always open to learning. ;>;)
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Classic Style -- Relaxed Comfort -- Modern Performance.