Interesting observation....

Jim Warman · September 16, 2006

I was helping one of the other diesel techs chase a coolant puking issue the other day... late build with an Edge programmer with the fancy electronic readout... chip was set on "3"..

When I got on the throttle, the Edge reported 32 PSI and the PDS reported only 22 PSI MGP. Remember, this chip has the cheater T'd into the MAP connector....

More food for thought...

Keith Browning · September 16, 2006

Jim,

I am curious as to what the actual boost reading would be had you tee'd in a manual gage to the MAP sensor.

Jim Warman · September 17, 2006

With my luck, it would have been a third different reading.... then I'd be confused instead of interested.

I wish I had thought to check MAP volts (suddenly remembering that PSI will be a computed - or possibly substituted value in this case)since this should be the value af the sensor.

I wisj I had a little more time for experimenting but that's just not in my schedule these days.

Paul BDP · September 20, 2006

I know this may sound elementary but, Did you replace the coolant bottle cap? They're a "one time" design.

Jim Warman · September 21, 2006

No real reason to change the cap, Paul - the system holds pressure quite well. Besides, company policy is to avoid working on units if a chip is installed.... They can take it home and remove the chip and return - but we don't do anything if the chip is "there".

FWIW, where did you see that these caps are "one time only"? I'm sure that'd be news to most of us...

Paul BDP · September 22, 2006

I was attending one of our 6.0 training classes and the instructor said the caps were good for only one bypass. Something to do with the material used inside the cap. He said the material used on the atmosphere side was not compatible with the coolant. He called it a one time cap. I've contacted him and asked for it in print. He said it's in one of the service manuals. He'd look and get back to me.

Jim Warman · September 22, 2006

Perhaps Manuel Patron could shed some light on it...

I would have thought that one of the coolant loss TSBs would have mentioned it.... either that or I fell victim to "flat rate reading" again...

Paul BDP · September 24, 2006

I received this back from the trainer...

" 2004 F-Super Duty Service Manual page 303-03-5 (Book/Volume 2) about the middle of the page."

Keith Browning · September 24, 2006

From said service manual:

CAUTION: Vehicles with a 6.0L diesel, with the engine cold, fill the degas bottle only to the MIN line. The correct fill level on these vehicles is between the MIN line and 15 mm (0.59 in) below the MIN line. This fill level will allow for coolant expansion. Overfilling the degas bottle may result in damage to the pressure cap, which can cause the engine to overheat.

While this does not provide an answer as to WHY this is, it may suggest that the very presence of coolant overflow (staining) at the coolant bottle would warrant replacing the cap. Now, if the explanation about the materials used to produce the cap being incompatible with the very chemicals it's supposed to hold in, then I would say that there are some really freakin stupid people spec-ing out parts at Ford.

Paul BDP · September 24, 2006

Ford Doctor wrote:"if the explanation about the materials used to produce the cap being incompatible with the very chemicals it's supposed to hold in, then I would say that there are some really freakin stupid people spec-ing out parts at Ford."

I asked the same question about materials of the instructor... He thought it was stupid as well but had no further explanation.

Jim Warman · September 25, 2006

Picking the service manual apart.... it says "MAY" result in damage..... We see these sorts of warnings scattered all through various documents and they are, I have to assume, inserted for the benefit of some of the more sophomoric techs simply because they are so basic in nature as to be nearly insulting.

Thus far, the only degas caps I have had to change are after an oil cooler failure. All of the ones with the tattletale white streaks have held pressure as evidenced by the distinct hard hoses after a road test and the tell-tale hiss as the cap is removed.

Also absent is the word "WILL" damage the cap...

Many of these warnings are inserted into publications to ensure that there are no opportunities for litigation or to "scare" the gullible into being sure that they don't make basic mistakes...

That's one old farts view, anyway....

LARRY BRUDZYNSKI · September 25, 2006

Correct me if i'm wrong... But aren't pressure caps rated to a certain psi, and if the pressure exceeds the rating that they are designed to release the excess pressure?????

Keith Browning · September 25, 2006

Right. But this discussion brought up something we, or at least I was not aware of. In theory, if the system expels coolant though the cap, there is something on the atmosphere side of the valve that is made from something that is not compatible with the coolant. Perhaps I'll start checking them to see if they hold at the rated pressure after letting coolant pass.

LARRY BRUDZYNSKI · September 25, 2006

I don't know if this makes a difference or not but Ford has used the same cap on all the light trucks will diesel engines since 1995-2007 7.3 and 6.0 F6DZ 8100 A. Rated at 16psi. and on the F650's with the 6.0 4C4Z 8100 AD rated at 10psi.

LARRY BRUDZYNSKI · December 13, 2007

Maybe it's like alot of the orings that need to be replaced when parts are disassembled they tend to swell. Just a thought, but obviously trucks aren't designed to overheat or piss out the degas bottle, could be a safety thing, or maybe a liability thing Ford doesn't want to have to deal with. Re: truck overheated, killed engine because of faulty cap, could be Fords way of kicking back a warranty. Does this sound more like it?

Sorry for taking so long on a response to my own post but I had to think about this one..