I updated my gallery to include the pics I took while fixing the coolant leak in the DS head of my 98 4.6L. This is the first time i have ever seen a coolant leak due to a hole and not a crack. My best guess is that it was a poor casting, possibly with a trapped air bubble that finally gave way. As i was cleaning the area with a wire brush, the hole increased in size do to the incredibly thin cast. Marine Tex saved the day!

Summary of events:
Dealer: Replace both heads Cost: over $7K... PASS!!
Dealer: OK, how about a whole new new engine? Cost: $5100... PASS!!
Me: how about Marine Tex? Cost: about $8... SCORE!!!
Dealer: but it will never hold up to the temp and pressure, you should buy a new engine.
Me: BULL. Temp should not exceed around 200 degrees which is well within the parameters published by Marine Tex, and I'm sure that it can hold back the 16lbs of pressure. Even the plastic overflow tank can hold 16 lbs!
Dealer: let me know when you want that new engine.
Me: Don't hold your breath waiting for that to happen.

So here are the pics I promised so everyone can see exactly what i was talking about in my earlier post. (Coolant leak from an odd place)

I also emailed them to the Dealer that was yanking my chain and charged me $70 to tell me he couldn't help unless I dropped at least 5 grand.

If anyone has any questions, please feel free to ask!

 

I am glad to here that everything worked out. I would keep a close on eye it also. So keep us updated on what happens with it. It should hold.

Good job not letting your dealer screw you!

Bryan#50

 

What a great fix! $8 sure beats 5K. Great job!

 

What is Marine Tex?

 

I would say it's similar to JB Weld.

Click here for Marine Tex site

 

It's a 2-part epoxy that when fully cured, can be drilled, tapped, sanded, painted, etc, etc, etc. You can even apply it under water! I have some left over on my mixing board, and let me tell you- it's never coming off. I abused it by hitting it with a hammer, chiseling it, etc, and couldn't even make a mark in it. Check it out- $8 and an hour saved me big bucks. I tried JB Weld in the past and didn't have much luck with it. Marine Tex rocks!

 

yyz87- (Rush fan? YYZ, La Villa Strangiato- awesome instrumentals!) Thanks for the info and pix. This happened to me today in my workvan- a hole in the head casting under the thermostat. I was going to try JB Weld tomorrow, but I will try to find Marine tex. What is causing this? I have heard- 1- electrolysis from a bad ground or old antifreeze 2- cavitation from antifreeze (maybe an eroding vortex flow under the t-stat?) 3- defective casting bubble. Wish me luck. (...eroding vortex flow- sounds like a Peart lyric!)

 

didn't mention- it's a '99 E-250 5.4 w/ 70,000 mi.

 

dwells, I've read the antifreeze can cause this corrosion along with the two different metal coming in contact. That marine tex sounds like good stuff, especially if it's better than JB.

 

t'sford- yeah, that's what causes electrolysis. The fluid must be able to conduct electricity, and the different metals will "migrate" from one to the other. I talked to an import mechanic yesterday, and he's broken down engines where the aluminum was badly pitted and corroded, and the iron was all shiny with a nice coat of aluminum! He said a bad engine ground was usually a cause of this.
Also, old antifreeze, or antifreeze mixed with high mineral content water, allows electrolysis. Thats why we're supposed to use distilled water to mix.

 

Here's a link to another repair of a large hole in the same spot- http://www.muggyweld.com/alternative.html

 

I found this quote here, http://www.team.net/sol/tech/coolant.html -which might explain why these leaks are always occuring under the thermostat-
"Cavitation is the process whereby pressure fluctuations cause the formation and subsequent collapsing of vapor cavities, which exert high mechanical forces on metal surfaces. Erosion-corrosion is the process whereby a flowing fluid surface destroys the protective film giving corrosion free play. The results of both processes are very similar, namely severe localized damage. Cavitation and erosion-corrosion are difficult to separate under test conditions."

 

Sorry about all the extra posts- I just keep finding more info. Here is a link- scroll down to ken00's post- he has a Ford tsb test for electrolysis- https://www.ford-trucks.com/forums/s...=electrolysis+
I checked mine yesterday, after reading a similar post, and was getting .3V. That post said anything over .1V was bad, but the Ford tsb says over .4V.
Due to the common location of of all these leaks under the thermostat, I'm leaning towards the "erosion-corrosion" cause. If it were electrolysis, it seems leaks would be popping up everywhere.

 

Picture of repair in my gallery. I couldn't find marine tex, and I already had JB Weld. Let's hope it works.

 

dwells if it's less than an hour since you posted something you can hit the edit button at the bottom of the post and add or change things.