Wouldn't it leak coolant if that were the case?

 

no I don't believe so. Ive heard of this happening before. My buddies civic was having cooling issues resembling hg's and ended up the water pump sucking in air. Just something to look at.

 

Was your cooling system under pressure during the test or vented to atmosphere? I could only see air ingestion as a possibility if your system is atmospheric pressure during the test.

 

Under pressure and held pressure when cap was on. If it was taking air in it would bleed off pretty quickly which it doesn't.

 

Did you use the test fluid that was specifically designed for Diesel engine testing? If not, you might want to retest. Also take fluid and run it n the exhaust stream to see if it changes color. When I did mine using std test fluid, it never changed color even when running and vacuuming exhaust gas directly in the exhaust pipe air stream. Using diesel specific fluid, it would change color in a minute or two of exhaust gas sampling which verified it was working correctly.

 

You'd have to be drawing a vacuum at pump suction to pull air in. I don't know the hydraulics of the system but it doesn't seem likely to me that the pump suction will be under atmospheric pressure when the system is pressured up. Your line losses through your radiator and cover would have to exceed pressure plus head. Typically pump suction lines are generously sized to avoid any appreciable pressure drop (although I have no direct experience with engine design). My gut would be that it is not air. I also don't know any easy way to confirm.

 

Fluid instruction said on a Diesel it would change faint yellow to greenish, which it did. I think you can see it in the video.

 

Fluid color change definitely indicates combustion gases present. I think you have a head gasket problem. Another unlikely possibility is a cracked head. Ford heads are pretty well made so that is uncommon in a stock motor.

 

So, is this the truck in your signature? If so, this would be the first case I've ever heard of that lost a headgasket using o-ringed heads. Hopefully just a leak on the cooler....

 

Yes it is. Shop is going to warranty it and figure out what happened. Heads were decked and oringed, new valves, guides, the whole works. I think I'm going to break a record for how many times my truck has been torn apart and put back together. I'll update with what he finds. He's been super good about taking time to figure it out but I think he's been hesitant to call it head gaskets because of the oringed heads.

 

If you don't mind me asking, what warranty do you have on the heads? I talked to a local shop about o-ringed heads and they hinted at warranty, but in my haste to get my list in front of them I didn't actually ask them. I'm curious for additional data points.

Good luck with your truck.

 

3 year unlimited miles. That's on all the work he did including the heads.

 

Did they measure pertrusion when they did the head work, and how did they prep the block?

A simple test is to warm it up, then release all the preasure and drive it. If it gets back to 16psi again then there's a good chance the gaskets are leaking.

.

 

I'm not a fan of o ringed head on a stock truck. I've seen a bunch of them fail due to the ring cutting the gasket and leaking. Fel Pro don't hold up well to being o ringed for sure. Only gaskets that work well with o rings are Cometic.

 

Yes. And as such, the pressure due to the 50/50 ethylene glycol water solution operating at 190 (ish) temp should only produce around 7.5 PSI pressure.

I thought it should be more so I had to dust off my thermodynamics books and do a little searching around in the Dow Chemical engr stuff on ethylene glycol + water mixture properties. using their own chart, a 50/50 mix @190F should be right at 7.2PSI.

Because it sounded "low" I went to the actual equation for determining vapor pressure of an aqueous solution of eth-gly and got 7.01xxxxx psi....

(Nice to know because I want to use a 10psi cap with my new 4-row rad in my 55 F-600 + 292 Y-block)


For all of us Power Strokers (can we say that?) with "16" psi caps, the vapor pressure of a 50/50 ethylene glycol mix reaches 16 psi at around 230 degrees F.

If the cap is even a a little "defective" on the low side, it could start "puking" as temps exceed 230.

If you're producing 16 psi running the engine at ANY power level (but operating at 190 deg F assuming your gage is NOT defective........) That pressure is coming from somewhere else other than the hot coolant. I.E a leaking EGR cooler that is doubling as a "steam generator" or a leaking head gasket.

Regards,


Rick