A Coolant System Pressure Test (1 Viewer)

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Bambusiero

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Apr 11, 2005
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Location
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As a follow-on diagnostic to an ongoing engine coolant overheating problem, coolant system pressure has been a question.
So, I've finally gotten around to rigging up a radiator / coolant system pressure gauge that can be monitored while driving around at speed, rather than just guessing and interpreting other signs.

The suspicion is a head gasket combustion gas leak into the coolant system, causing load dependent overheating.
Or, maybe it's something else.

The radiator cap is rated at 85 kPa = 0.85 bar = 12.3 psi (but it says 0.9 bar, rounded up).
So, if I see pressure rise up to 12-13 psi and hold, that must mean it's being pressure regulated by the pressure relief cap, and coolant is in the process of overflowing into the tank, right?
If I see that, I'll pull over and check it!

Let's just see about that!

Tapped into the #3 coolant bypass tube at the radiator nipple.
It's easy to tap in there.

Coolant System Pressure Gauge - equipment list :

0-30psi multi-purpose gauge, steel case, 2" dial, panel mount back, 1/8 MPT - McMaster-Carr
1/8" hose push fit to 1/8 MPT adapter - McMaster-Carr
1/8" nylon hose - McMaster-Carr
1/8 FPT-FPT coupler - Ace Hardware
5/16" barb Tee - Ace Hardware
5/16" barb to 1/8 MPT - O'Reilly Autoparts
Custom fab gauge to windshield wiper mount bracket


CoolantPressure_GaugeCockpitView.JPG


CoolantPressure_GaugeMountFrontView.JPG


CoolantPressure_GaugeMountCloseup.JPG


CoolantPressure_TubingTee.JPG


CoolantPressure_TubingAdapter.JPG


No data yet - TBD.
 
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A convenient hole is available in the firewall.
1/8" line just makes it through, and snakes right through the vent.
Easy-peasy.

CoolantPressure_FirewallPassThru.JPG
 
A convenient hole is available in the firewall.
1/8" line just makes it through, and snakes right through the vent.
Easy-peasy.

View attachment 1288543
What happened with this experiment? What was the resolution to your original warm running engine?

I too installed a CSF 2517 a year ago and could report just about the same sort of temps/situations. I have no data previous to the new radiator and cooling system overhaul because that's also when I installed the secondary water temp indicator.
 
What happened with this experiment? What was the resolution to your original warm running engine?

I too installed a CSF 2517 a year ago and could report just about the same sort of temps/situations. I have no data previous to the new radiator and cooling system overhaul because that's also when I installed the secondary water temp indicator.

Same radiator as I put in my '97 several years ago. I've had a ScanGauge on my vehicle for quite awhile so I had readings on the OEM radiator (under various conditions) with which to compare. On average (MY vehicle) runs about 2° F. warmer with the CSF 2517 than with the original radiator (factory).

I'm not a big fan of 'plastic' and crimped seals. The peace of mind is worth the paltry exchange of efficiency (2 degrees) to me.

Used a Spectra replacement radiator in my LX 470 when that unit failed. Now to be fair...the OEM units DO last a long time so I am not disparaging that radiator, but anytime I can put something stronger on my vehicles....I will do so.
 
Last edited:
As a follow-on diagnostic to an ongoing engine coolant overheating problem, coolant system pressure has been a question.
So, I've finally gotten around to rigging up a radiator / coolant system pressure gauge that can be monitored while driving around at speed, rather than just guessing and interpreting other signs.

The suspicion is a head gasket combustion gas leak into the coolant system, causing load dependent overheating.
Or, maybe it's something else.

The radiator cap is rated at 85 kPa = 0.85 bar = 12.3 psi (but it says 0.9 bar, rounded up).
So, if I see pressure rise up to 12-13 psi and hold, that must mean it's being pressure regulated by the pressure relief cap, and coolant is in the process of overflowing into the tank, right?
If I see that, I'll pull over and check it!

Let's just see about that!

Tapped into the #3 coolant bypass tube at the radiator nipple.
It's easy to tap in there.

Coolant System Pressure Gauge - equipment list :

0-30psi multi-purpose gauge, steel case, 2" dial, panel mount back, 1/8 MPT - McMaster-Carr
1/8" hose push fit to 1/8 MPT adapter - McMaster-Carr
1/8" nylon hose - McMaster-Carr
1/8 FPT-FPT coupler - Ace Hardware
5/16" barb Tee - Ace Hardware
5/16" barb to 1/8 MPT - O'Reilly Autoparts
Custom fab gauge to windshield wiper mount bracket


View attachment 1288538

View attachment 1288539

View attachment 1288540

View attachment 1288541

View attachment 1288542

No data yet - TBD.
*BUMP*

EVENING MUD

Any updates or news? I believe I had a factory brand new faulty radiator cap that caused my system to overpressure and boil it altitude, will not boil but overflow the tank in a high pressure sort of way.

Anyway I ended up with some coolant out of my freeze plug above my block drain as well as a couple drops of coolant out of my brand new heater mixer valve.

I've tested the block no exhaust gases I thought that might be a culprit then I started thinking today maybe my system is over pressuring somehow I'm still getting a little bit of coolant out of the freeze plug which never happened before until the incident this summer.
 
My perpetual overheating and the strange overpressure behavior were both solved by installing a TYC 1918 aluminum core/plastic tank radiator.
The whole subject of "which radiator?" has been beat to death :deadhorse: many times over on various threads, but here is the thread where I documented the direct radiator comparison.
Cooling issues with CSF 2517 - what temp does your rig's A/C shut off? - https://forum.ih8mud.com/threads/cooling-issues-with-csf-2517-what-temp-does-your-rigs-a-c-shut-off.1063747/
I'll just invite you to read that.
 

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