Stc to Branch Tube Oring Leak

[cutbow]

My 05 died while running. No hp oil pressure. Took it to a shop to be repaired. Several injector o rings leaking and the stc to branch tube connection ( has the updated one piece stc) leaking. The alum engine cover was also cracked. So the o rings where replaced and the branch Oring , it started fine but it died again. The Oring at the branch tube connection blew out. It has been pulled apart three times and replaced with a new Oring part. Each time it blows out after first start up. The last time the tech built a jig to bolt to the branch tube connector and adjusted it a little to allow the connection to be aligned straighter. Also, he said the original bolts where bent, so he drilled out and tapped the bolt holes up to the next size, said he polished the face before reassembly.

The last Oring replacement lasted for a few more starts, I drove the truck home, about four miles, shut down, the next day, it started and ran for about 10 seconds then shut off, after this, it would start for about a second until it would not start at all. I hooked up my AE computer to it, 5-6 psi at ICP at 85% IPR. No low pressure oil.

I am asking for any suggestions here on why this Oring keeps blowing out.

The tech is trying to tell me that there is a problem with the branch tubes and they need to be replaced! After spending 3K on this repair and another grand on a rental car. The bent bolts and cracked rear engine plate tells me that there might be something to the branch tubes needing replaced.

Thanks for any help with this.

[fordsforever73]

Hate to say, but when the original STC fitting let's go, it can cause the branch tubes tubes to bend. With that very high pressure pushing the branch tube block outward, it can also cause the rear plate to crack. I remember when I replaced my STC fitting with the upgraded piece, the bolts would not line up with the block. I knew then, my branch tubes were bent, but I managed to gently pry the block back in place and had no issues after that.

You say your bolts were bent. That should have been the indication the branch tube block is out of place. Unfortunately, it's a huge job to replace that piece, as the trans has to be removed, unless someone has come up with an easier solution. Good luck.

[cutbow]

Thanks for the input.

The tech gently bent the branch connector slightly on the last attempt. This is what I am trying to figure out, why the Oring keeps failing.
Bad oring?
Stc to branch faces not aligned?,
Over torquing the bolts (says he torqued to 18 ft lbs.), manual says 125 in lbs ?

Frustrated, with the cost to own this truck after 100K miles, 250K on it now. After this is repaired, I need to invest 1.5K on the front end and shocks...

[djshum]

As previously stated, if the cover is cracked, the branch tube is bent. With a bent branch tube, the block on the branch tube and the stc fitting do not mate flush together, allowing for the o-ring to blow out. You will need to replace branch tube for effective repair.

[dcovaleski]

Also, if he torqued those bolts to 18lbs/ft,wether or not they are the original size, or next size up, there is a good chance that there is nothing left to those threads, there for weak clamping force. Especially after 3 times.


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[cutbow]

Thanks for the input.

I am going to do an air test on it tomorrow, and pull the oil filter to verify low oil pressure pump working. I am going to end up tearing apart if its leaking again at the branch connection and try to align the connection faces with bending persuasion , before giving in to replacing the branch tubes.

[cutbow]

Pulled the oil filter out tonight, no low oil pressure while turning over. Pulled it back to the shop, tech is going to tear down and replace the lp oil pump. Hope that fixes this . Thanks for the help.