Cooling Mod - What am I doing wrong?

[Jeronimojc]

One of my two engine cooling mod connections keeps failing. I am using one of those brass fittings to connect to where the freeze plug used to be. I used a couple of different types of RTVs and so far the RTV fails. Sometimes the RTV holds for months, but it eventually fails.

The other cooling mod connection is perfectly okay.

Did I miss something? Was I supposed to use an O-ring on the fitting? Is there some particular RTV type you are all using on your cooling mods? Did I put too much RTV? Too little? Have others had similar issues?






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[Logizyme]

I used epoxy to build my own mod fittings and a few months later it turned to goo and started leaking.

I then pulled them out, replaced them with freeze plugs, then installed two of the cobra style heater supply tubes into the back of each head, no more problems. These are steel tubes with O-rings similar to the COT, the passenger side fits perfect the drivers side just needs a hole drilled in the mounting bracket and the tube going into the head shortened just slightly. Also far more difficult to install, but IMO a much better end result.

I've heard of guys using sodder and epoxy, but don't use RTV, totally not the right stuff for this job.

anyway, good luck.

[MOTOWN]

Cobra Engineering makes the best cooling mod you can buy! and it can moved from motor to motor without leaking! CHEAP isn't always best!

http://www.cobraengineering.net/cooling%20mod.html

[eric jones]

I think with the cobra engineering cooling mod your motor must be out of the car IIRC.

[Zack]

Who's kit before we proceed?

[Logizyme]

The rear of the head cooling mods require engine/trans removal on mustangs as I understand it, but I was able to install the rear of the head fittings on my Marauder with engine and trans in the car, much more room, but the struggle was real getting those freeze plugs out.

[Jeronimojc]

Cobra Engineering makes the best cooling mod you can buy! and it can moved from motor to motor without leaking! CHEAP isn't always best!

http://www.cobraengineering.net/cooling%20mod.html


I am open to using something else, but for now I need to make what I have work. I know others here are using the same setup without trouble.



Who's kit before we proceed?


Your fittings. I tried "The Right Stuff" black gasket maker and also tried the gray RTV. The first one held the longest. Both are rated for over 600 degrees F. One connection has been holding up with no issues. The other one I can't seem to get it right. Any suggestions?





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[fastblackmerc]

I assume your saying it's leaking where it goes into the block.

Make sure the bore is round and there are no "defects" in the sealing surface.

Make sure the fitting is round and there are no "defects" in the sealing surface.

Make both surfaces nice and shiny.

Apply the appropriate sealer, following the package instructions.

Install the fitting making sure it is flush and not cocked.

[fastblackmerc]

I then pulled them out, replaced them with freeze plugs, then installed two of the cobra style heater supply tubes into the back of each head, no more problems. These are steel tubes with O-rings similar to the COT, the passenger side fits perfect the drivers side just needs a hole drilled in the mounting bracket and the tube going into the head shortened just slightly. Also far more difficult to install, but IMO a much better end result.


I've had DR's original cooling mod installed for years, never had any problems. The only thing I want to do is replace the plastic tee.

[Zack]

It's hard to tell the problem without seeing it or knowing how you prepped the hole after the freeze plug was removed. It is also possible you grooved the hole when removing the original freeze plug.

I do know for a fact my fitting or solder is not the culprit. I use 1/4" of solder all the way around, and inspect them thoroughly before shipping.

[justbob]

Mine are greenish at the base but have never caused a concern. I cleaned mine thoroughly and used a small amount of black RTV as well. World ain't perfect. [emoji6]


Builder Of Badassery

[Jeronimojc]

I assume your saying it's leaking where it goes into the block.

Correct. No defects on the bore hole or fitting.


I do know for a fact my fitting or solder is not the culprit. I use 1/4" of solder all the way around, and inspect them thoroughly before shipping.

Agreed, the problem is not with the fitting. Assuming your fitting doesn't require an O-ring, my guess is the problem has been either too much RTV or not enough.



Mine are greenish at the base but have never caused a concern. I cleaned mine thoroughly and used a small amount of black RTV as well. World ain't perfect. [emoji6]


Thanks, at least now I know the black RTV should work. I've always made sure both surfaces are clean, but I'll work on it a bit harder next time.



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