Went to change my reservoir tank cap and noticed the rubber oring was melted and see some light brown gunk floating around on top?

Just by chance I was reading this could be cracked cups?

How do I tell this and or rule this out?

What are my next steps ?. Advice please

7.3 150'000 miles

Kyle

 

If it's cracked injector cups, you'll have diesel fuel floating on top of the coolant. Stick your nose down there and see if it smells like diesel fuel.

It could just be time to flush your coolant.

 

I tried the smell test and could not tell
I'll have to get my wife sniffer involved since hers is way better.

I was mainly concerned about the mushy rubber oring in the reservoir cap
Thought maybe this was a tell tale

Thanks for your help

Kyle

 

To relive this thread.. shortly after this I had ALL my injector cups replaced..
Not on mileage but its been just over 2 years and BAM . fuel in the coolant again.
I was thinking this time I would only get the faulty cup changed..
What are your thoughts on this ??
Seems to me like a good idea since 7 cups are likely still good.. Why do all 8 when a single 1 could fail again at any time ?

Kyle

 

I dont think there is anything wrong with changing one cup,people go thousands and thousands of miles without changing all of them

 

make sure you change all of the o rings and the copper washers

 

Since my truck is an excursion .. It would be nice if the issue was in the drivers side bank..
Since there's a nasty heat box to remove on the passenger side.

Any other tips ideas.

Kyle

 

Check your injector hold down bolt torque before you pull the injectors. Tugly had mentioned that he saw in the Ford service manuals that an injector hold down bolt that has loosened to below 50in-lbs should be pulled to have the cup checked for cracking. That could possibly help narrow down the offending cup, and give a reason as to why it failed.

 

I don't recall the heat box on the Ex being any different than on the P/U, but I certainly remember that fender well not letting me at the VC bolts from the side.

13mm flex socket took care of the VC bolts down low, and 1/4" universal joint took care of access to the #5 injector bolt. Other than that, foul language helps when the heater stays in place. Ex owners - please correct me if needed.

Yes... check the injector torque - that's what likely killed my cups in the first place.

Replace only the cup found to be bad - good luck isolating that without removing all your injectors. I drained all coolant from the engine, exposed the cups, sprayed them with silicone spray, then pressurized the coolant system to 15 PSI:


I can't stress this enough: Loose injector or poor cup prep will have you in there again. The cup needs a factory-new clean surface to adhere to for a reliable seal.

 

Update..
Was not diesel in coolant..
Was a line of Gunk but my mechanic did find an issue with injector number 8.
Did test of coolant and was less than 3% diesel.
Just thought I would update for reference in the community

Kyle