First of all, when I posted last night at:

https://www.ford-trucks.com/forums/1...nts-degas.html

I didn't realize I was adding to a thread in the Tech Folder, sorry about that. I found the thread by search, my mistake...

Coolant reservoir is topped off, took about 2 1/2 quarts of 50/50 mix to get it back to the Minimum line.

Headed to the dealer to get new caps for the coolant reservoir and oil filler neck (it was all pitted and I've been meaning to change it out.) Switched out the caps and went on the same drive I went on yesterday. After getting the EOT/ECT up to operating temp, I noticed they stayed much closer to one another. The end result of my test was EOT/ECT delta of 8. A little better than yesterday. The ambient temp was 94 today and 84 yesterday. Both of these tests were on a flat stretch of freeway at 70-80mph.

I am really beginning to think it was just a bad cap. Waiting for everything to cool down so I can do the vacuum test.

I rented a radiator pressure test kit. I have no intention of putting positive pressure into the cooling system, but I wanted to test my old cap and new cap, out of curiosity. The old cap would not hold any pressure with this kit. I don't think it is sealing properly on the test adapter though because the Degas bottle was building pressure when the coolant heated up. The new cap sealed fine on the test adapter and lost pressure at 20psi. I assume this is OK since it is rated at 16psi.

I have also noticed some white residue at the top of the radiator along the seam on the passenger side. I am wondering if it could be leaking there very slowly maybe? Anyone else seen or heard of a leak there?

So far I am hopeful that I've just had a bad Degas cap. I suppose that means the water was actually boiled off, causing the coolant level to drop. If that is the case, by adding 50/50 mix, is the coolant concentration going to be too high?

I'll post later after the vacuum test...

 

Getting nowhere really, I only got about 15 in HG vacuum, the pump I got doesn't hold vacuum even so I stopped.

Truck started fine, no steam coming out the exhaust so that is a good sign. It is a trip watching the radiator hoses collapse as vacuum is applied. Made me nervous too.

Maybe get a new pump tomorrow

 

THAT would be the (hopefully) second area of concern. They can and do leak and the seams are a great place for that to happen. Personally I'd rather have it there than inside the engine or parts leading there to...

 

Me too.

The EGR time bomb is always in the back of my mind though.

I really don't want to tear into anything right now if I don't have to. Trying to put together a plan to make the change to ELC this fall/winter but I will have to see how all this turns out. Maybe that will be a good time to replace the radiator with a BPD unit.

 

Clean up all the white residue and watch that thing like a hawk. I went thur 2 new raditors going crazy before I got it to stop, and it was the seams. If I had to do it over again I would have bought the all aluminium rad.......my 2 cents

 

Appreciate the advice. Will definitely keep a close eye on it. Did you get the BPD rad? Seems to be the way to go price wise and sounds solid?

 

Finished testing today, 19 inHG vacuum applied, lost a little over 15 minutes. Final reading 15inHG. So the system is not at 100% according to the test, but I am pretty well convinced that the EGR cooler is OK. I think some of the vacuum may have been lost from air being evacuated out of the system during the test. My forearms couldn't pump anymore, and I was happy with the test so not going to repeat.

After applying vacuum to the system, I noticed the ECT/EOT are closer to one another. I've been monitoring them for a couple years and haven't seen them this close. Driving around town there is a 1 or 2 degree spread. Occasionally, they were the same. My spread has always been 5 to 10 degrees. I'm thinking air was in the cooling system, causing inefficient heat transfer.

Just wanted to share with you guys. Maybe it will help someone else out down the line.

Thanks again to everyone who did the writeup for this testing procedure

 

I decided to go ahead and get my radiator fixed instead of waitt il fall, so I didn't have to worry about losing coolant anymore. Pulled the radiator last week and took it to a local radiator shop, they replaced the upper tank and re-crimped the lower one. End result - no more leaks and haven't lost any coolant!

I was shocked at how much coolant was sprayed all over the inside of the fan shroud. None of that was visible until I had everything removed, and there were never any signs of coolant leaking under the truck or visible wet spots under the hood. It was all coming from the upper tank seal/crimp area.

Time will tell how long the radiator lasts...

 

FWIW, though it's too late, I have found that cleaning the area nicely, then applying an even coating of a high-temp epoxy (I use the self-mixing dispenser to make sure it's mixed correctly) has worked well on the first seam leak I fixed, and I am going to do the other one this coming weekend (assuming my work or wife don't take it away like they tend to.)

 

Good to know as a back up plan, cheaper than the radiator shop no doubt.

Know what you mean about the weekend disappearing, sometimes they are gone before they every start