cooling system pressure when headgaskets fail?

[makuloco2000]

hey everyone first time poster. I was wondering when you are testing for failed egr coolers or headgasket for coolant loss issues and there is a failure what kind of cooling system pressures reading are you getting. I have one cust swears he lost 2 gallons of coolant and there is some evidence of coolant out the bottle, but every test in 9-8-3 passes. Only thing I got was it goes to 16.38 psi during wot after multiple wots. Coolant bottle never vented nor lost coolant. Did notice cust has a piece of cardboard cover the rad itself fully. he has a hitch with a reciever on it so he must be towing at some point. no smoke no nothin. i would imagine cooling pressure would be in the 20psi plus range if something has failed. Hotline agrees there is no failure at this time. Any experience in figure out these coolant losss issues appreciated, especiallyt psi readings!

[Aaron]

16 is kinda high.... I'd say borderline if anything.

 

I would compare it to a like unit, or a unit with fresh heads and see what you end up with.

[Aaron]

Welcome to the DTS

[Keith Browning]

I typically see spikes to around 19 PSI as the cap vents

[Shlep]

Did notice cust has a piece of cardboard cover the rad itself fully. he has a hitch with a reciever on it so he must be towing at some point.

 

I had a guy come in early last summer complaining of coolant loss and he was hearing his fan ramp up while towing his trailer, like you I found a chunk of cardboard between the CAC and the rad. While at the time nothing was showing as a failed component, just before Christmas the truck came back with a obvious failed EGR cooler.

[Mbl35]

Try pulling the egr valve, jack up the rear and pressure test above 16 psi and let it sit for a while.

[Mekanik]

I think the 16.3psi is too high. What pressure does the cap vent at? I bet it's less than 16.3psi.

[makuloco2000]

vents at 16psi and levels off at 15psi. Never vented on road test. Cust took vehicle and removed cardboard for now shouldn't need it any more temps supposed to be high 30's around here, isn't that the point of the electro viscous fan to eliminate the need for the cardboard and such?

[mchan68]

What was the point of having the cardboard in place to begin with?

[Aaron]

Kinda like a poverty winter front.

[Mekanik]

The trucks I have had that didn't have either a leaking EGR cooler or leaking headgaskets DID NOT have cooling system pressure even close to this.

 

Your cooling system pressure is exceeding the holding pressure of the cap, therefore it is venting. I'm going to assume that you did the on vehicle EGR cooler leak test and it passed. That would lead me to believe that your headgaskets are leaking.