post the video address but take out the end actually = http//video address.com = you post http//video address dot com

are you EGR deleted

 

Yes I’m egr deleted. Ok let’s see if this works:

https://m.youtube.com/watch?feature=youtu.be&v=u9rPet8LHeA

 

Thermal expansion and maybe too full of coolant
The cap reliefs at 16psi
Once warm(not hot) and you relief the pressure, does it re-build to 16 within a few minutes?

Normal for the pressure to drop as you rev the engine, ...the degas bottle is on the heater return, that goes to the suction side of the water pump

 

Yes It builds to 16 over a few minutes while warm.

 

Sounds like it's headgaskets time...

-jokester

 

Jokester I know that’s definitely a strong possibility, however, I am reading everywhere that with a head gasket failure, pressure in degas goes up under load. Mine actually maintains current pressure and even drops slightly under load and increases with my foot off of the gas. Will a blown head gasket do that as well?

 

hit an incline and push it WOT I bet it will spike the psi

other than that i cannot figure a way for PSI to climb in the cooling system once the coolant reaches temp ( unless it boils)

i have been monitoring psi and a bad HG for a while I also can see a drop in PSI when letting off the throttle but attribute that to the gasket letting pressure bleed off into the cylinder

the suction side of the water pump should not be able to "suck off PSI in a closed system in my non fluid dynamic professional opinion "

 

...
the suction side of the water pump should not be able to "suck off PSI in a closed system in my non fluid dynamic professional opinion "

Here ya go

 

Thanks so much for your help. I’ll drive it through the winter and park it when it gets wArm and turn my garage/ driveway into a disaster again. At least now I know from the first time.

I see shops do cab off. I can probably run an I beam across my garage to do it. I swore to myself that If this happened, I’d never work with the engine in the truck again. Any other way to get the engine out or at least get more access to the back without taking the cab off? Thanks for all of the replies. You guys have really helped my “please don’t be head gasket please don’t be head gasket, why did I take that shortcut” thought process.

 

I pull out the fender wells, put the frame on 12 ton jack stands back behind the doors, and pull the front wheels off. I have an extra long armed crane jack (I modified mine by extending the arm as far as I could and drilling extra holes for the pin) and load leveller. I pull the left side motor mount and lower that side of the engine to get more room for the right side head. Pull the CAC tubes and air cleaner before doing this, and replace them after the motor mount is reinstalled.

 

thanks for posting that
but I honestly don't think that multi-tank and pipe sytem correlates to the automotive system we have here, and it would suggest that while the pump is running( all the time in our case) it would read different PSI depending on where the sender was located but that is not the case with a typical engine cooling system and normally you will see no PSI drop on a healthy automotive cooling system when letting off the accelerator in my experience anyway

please note

Automotive Water pumps are not positive displacement pumps. The water pump is a centrifugal pump that can move a large volume of coolant without increasing the pressure of the coolant. The pump pulls coolant in at the center of the impeller. Centrifugal force throws the coolant outward so that it is discharged at the impeller tips.

 

The OP vid shows a pressure drop at higher pump speeds, that is normal and expected. Even in a 'hard' piped system this will occur. There only needs to be a small amount of fluid displacement to show on the gauge.

The vid I shared illustrates why the degas bottle is placed on the suction side of the automotive system. The pump in the vid is oversized for the piping to exaggerate the effect.

The pressure drops in the automotive system because of expansion of the hoses and plastic parts, the degas bottle is located on the suction side of the system and serves as a pressurized reservoir.

Cavitation of the water pump can be caused by not having enough pressure in the degas bottle(as seen on the 6.4) or too soft of hoses(lowering the pressure)

 

@ZMANN what pressure do you see wile normal driving. And im also woundering if i get o ringed heads and and a new gasket if i could have to do it all over in a year or 2. I dont hotrod it but do pass slow drivers some times. Just time for a decision on new truck or get it repaired.

 

0 psi is what I see
I have an aluminum degas that uses a traditional flip style cap and an overflow bottle

I run a o psi cap.

When I was monitoring psi. They readings would spike in hill climbs. And on easy but long uphill elevation changes

If I ran any tick or not find. The psi went to 16. Right away

I am still gathering parts for my HG,s

 

Any reason why my ect and eot deltas are not going crazy? Ect is 190/192 eot will reach 198 max on a 75 mile hilly daily one way drive. I figured excess pressure would make these numbers fluctuate a bit more due to constant pressure build and release.

 

I know my gaskets have been leaking for a wile i think only on a hard exel at highway speeds. Mine runs at 14 normally on highway but if i floor it going up a hill it will get to 16 but not vent yet

 

how do you know it does not vent at wot 16 ?
i bet you actually vent at 14 psi
and the16 you see is because the cap cant vent fast enough so the psi climbs a little

 

It could be venting i guess but there is nu residue around cap

 

The weird part is before i fixed my thermostat temps were at 170 sometime on real hot days 200 but lately this fall always 170 and pressure was always 10 to 11 psi since the new thermostat rides at 13 or 14 on highway at 75mph

 

for discussion sake,

i don't think a compression test will divulge the offending cylinder info

normal cranking cylinder psi does not get the HG to the point of leaking on a typical ( underload coolant psi issue)

and the leak is typically so small it wouldn't drop the cylinder psi enough to show up more than a normal variance

and if it was bad enough it would blow apart the cooling system since the cap could not vent enough

thats my free opinion anyway ;_)

 

I actually did a compression test when I did the studs the first time to see if I had to go change head gaskets. My pressure climbed quickly and rose to 390 on all cylinders. I did it before and after I studded the truck. Same results. That let me to believe that my head gaskets were fine, so I decided not to change them. Bad idea.

Would a cylinder leakdown test have helped?

I already bought the fittings that I need to tee off of the degas line into the cab. I'll let you guys know how it goes.


Can I use one of the open spots on the obd2 to hook up an electronic pressure sensor to my setup? I honestly haven't researched to see if anyone has done this, but I am assuming people have done it for fuel pressure. That way I could always keep an eye on the degas tank pressure.

 

the pressures at combustion are sooo much higher than your going to do on a leak down test
so IMO it will not show up on a leak down

 

Ive had one installed in cab for about a year now. It always starts in the morning at 0 than acorsing to engine temp rises. For the last year the highest ive seen it was 13 untill recently now seems to run at 14 at highway speeds and gets real close to 16 if i push it on a big hill up here in the nh mountains

 

You guys seem to really know the theory behind coolant expansion. Why would my coolant pressure actually start to drop when my thermostat opens? It always seems to do that around that time.

 

My first guess is because that is when the cooling system actually starts cooling.

 

She’s in!! Did a coolant flush and luckily my deltas dropped to 10 degrees( established ten degrees by pulling 40 bales of hay up quite a few hills at 55 mph for about an hour and a half. She didn’t feel it but it IS a load) now she’s in the garage for a while. Head gasket time. I had to take down a wall to get her to fit, but she’s in. Wish me luck.

 

:crazy::thumb:

Driver's side removed.

 

That is some hard work. Do you plan on doing anything inside the engine itself?

 

It is definitely a challenge. I’m not sure what I’m going to to with the engine yet. I’m doing a ton of research to see what, if anything, I’d like to do to it. Things that would make sense for me.

 

When you pull the coolant standpipe from the front of the engine to the heater core, make sure the oring seal (3C3Z 9J469 AA) fits nice and tight around the pipe. If not it's real hard to get back in without cutting the seaĺ. If I can't lube it and push it back in by hand in a minute I replace the seal. I've tried pulling it in with the screw a couple of times only to break the oring. A $5 part isn't worth the trouble. It's the pipe that is screwed to the alternator bracket.