STC Fitting destruction (2)

[BLittle500]

Hey guys,

 

Got a no start in today, stc fitting blew apart and took out the rear engine cover. This is the 2nd one I've seen that took out the rear engine cover, is this common? Well maybe not common, but atleast not unheard of?

[Keith Browning]

I haven't seen any recently but it seemed that for a while it was common for the fittings to blow apart and leave a mark on the rear cover. I often thought this was causing stress on branch tubes leading to those failures. Some seemed to rest on the cover which held it together for a while and created an odd noise that was detectable at certain RPM's. I have some pictures of a few and here are a couple of pics that Steve Mutter posted:

 

 

[Steve Mutter]

I have done two, all others have been bent back into place. I think you can say its common. I think somewhere at Ford they have a big container of rear covers they are sitting on till the price of aluminum goes up.

[BLittle500]

.... all others have been bent back into place.

Talking about the branch tube? I figured if they dont bolt up to the HPOP that they needed replaced, could it just be bent back into place w/ a wrench?

[Steve Mutter]

On one of the two trucks that I had a damaged rear cover was a service truck that they needed back on the road asap and did not have time to replace the rear cover or the branch tubes. This was a retail job. They came back later and I at least replaced the rear cover but at the time I just started the 2 bolts to the branch tube adaptor and then cranked down on the pump bolts till the pump would draw back into place. I guess most of the time when I have a stc fitting that has failed the branch tubes have not been that far out of place or cracked.

[Keith Browning]

I have gently bent all of mine back with no known issues.

[eastendpowerstroke]

I use a punch/drift that fits well into the hole in the branch tube and bend the tube back into place so all bolts can be started by hand, tighten all to spec and air test BEFORE installing the hpop cover. I've replaced 3 branch tubes 1 in a F-650 (not to bad) 1 in an LCF (not bad at all) and 1 in a E-bus ( )

[Jim Warman]

I have gently bent all of mine back with no known issues.

+1...

 

I have replaced branch tubes - this is not a real fun job. But the ones I have replaced have been leakers, anyway. A couple of them failed without the STC fitting being a concern.

 

YMMV.

[Jeff Clyde]

Gently bent back way too many to recall with no adverse issues. Another tip I use is when the pump is out, I apply regulated shop air via a rubber tipped blow gun directly into the branch tube. Find it a good way to eliminate any further air leaks without having to remove valve covers.

[mchan68]

Gently bent back way too many to recall with no adverse issues. Another tip I use is when the pump is out, I apply regulated shop air via a rubber tipped blow gun directly into the branch tube. Find it a good way to eliminate any further air leaks without having to remove valve covers.

You mean like this?

 

[eastendpowerstroke]

I got an old stc fitting and welded a 90 deg fitting onto it with a air hose fitting so I can bolt it to the branch tube and hook up the shop air, listen for leaks hands free and can disconnect it without the fear if an oil spray bath.

[Matt Saunoras]

Is there a mileage when you guys start to see this failure more often? My 06 has 52k. I have the solid fitting kit ready to go in but I'm worried I might not get to it for a few months

[mrbudge]

Tick tick tick tick tick.........

[Bruce Amacker]

Personally, I don't seem to associate a particular mileage with STC failure, I've seen them at low mileage, high mileage, and anywhere in between. I do recommend replacing them as maintenance on ambulances and emergency equipment. If it were my own truck and I were in there I might consider putting an updated metal inlet screen under the oil cooler.

 

Good Luck!

 

[mchan68]

Personally, I don't seem to associate a particular mileage with STC failure, I've seen them at low mileage, high mileage, and anywhere in between. I do recommend replacing them as maintenance on ambulances and emergency equipment. If it were my own truck and I were in there I might consider putting an updated metal inlet screen under the oil cooler.

 

Good Luck!

 

Now I wonder if Navistar will update the oil pickup screen to a similar style so that any roller lifters or injectors that blow their tops won't make its way through the pump.

[Bruce Amacker]

Now I wonder if Navistar will update the oil pickup screen to a similar style so that any roller lifters or injectors that blow their tops won't make its way through the pump.

I think the reason that screen is so coarse is so it won't starve the HEUI system on a sub-zero start.

 

[mchan68]

I think the reason that screen is so coarse is so it won't starve the HEUI system on a sub-zero start.

 

Understood. But then why is the screen under the oil cooler so fine? Wouldn't oil needing to pass this screen also starve the HEUI sytem if flow were restricted, just the same?

[Matt Saunoras]

I'm doing everything at once. EGR cooler bypass, oil cooler, STC fitting, dummy plugs + any gasket that can be replaced. the truck has already had a chra done under warr so i'm not gonna open the turbo up yet.

 

that reminds me. anyone have an extra oil cooler kit 3C3Z-6A642-CA that they'd unload for cheap? it's the only thing i haven't bought yet

 

thanks guys

[Bruce Amacker]

Originally Posted By: Bruce Amacker

I think the reason that screen is so coarse is so it won't starve the HEUI system on a sub-zero start.

 

Understood. But then why is the screen under the oil cooler so fine? Wouldn't oil needing to pass this screen also starve the HEUI stem if flow were restricted, just the same?

The difference between pressure and suction. The pickup tube is under suction which is much easier lose prime under (terminology?) than the HP screen which is under LPOP pressure.

 

Who is the physics major here- isn't a perfect vacuum equal to -14.7PSI? So you only have 14.7PSI under perfect conditions under the pickup tube compared to 50-70PSI going through the HPOP screen.

 

 

[LARRY BRUDZYNSKI]

anyone have an extra oil cooler kit 3C3Z-6A642-CA that they'd unload for cheap?

thanks guys

Don't know if it's cheap enough for you but I can get you into one for $198.00 plus shipping. And any other gratuities you can provide. LOL

[GregH]

The difference between pressure and suction. The pickup tube is under suction which is much easier lose prime under (terminology?) than the HP screen which is under LPOP pressure.

 

Who is the physics major here- isn't a perfect vacuum equal to -14.7PSI? So you only have 14.7PSI under perfect conditions under the pickup tube compared to 50-70PSI going through the HPOP screen.

 

 

No such thing as negative pressure - Pressure is an absolute value. Maximum pressure forcing oil up the pickup tube is 14.7psi at sea level just as you stated, though. If the pressure drop across the oil screen approaches this number, the flow will cavitate. Some air may be sucked in through the front seal and aerate the oil that does get sucked out of the pan.

 

As for the fine metal screen, Bruce is right - 50-70 psi will blow a lot more oil through that screen than would be possible by suction from the other side alone. Another thing to consider is that the high pressure pump will suction oil into itself... I don't know how much suction it can generate, though...

[Matt Saunoras]

Originally Posted By: Matt_Saunoras

anyone have an extra oil cooler kit 3C3Z-6A642-CA that they'd unload for cheap?

thanks guys

Don't know if it's cheap enough for you but I can get you into one for $198.00 plus shipping. And any other gratuities you can provide. LOL

hey, what a coincidence, that's what my parts guy quoted me. really i'd like to get one over on him. i buy a lot of stuff off him and he still won't cut me a deal for anything less than 10% over.

[Bruce Amacker]

Originally Posted By: Bruce Amacker

 

 

No such thing as negative pressure - Pressure is an absolute value.

 

 

That wasn't me saying that- that was the tequila talking.

 

[Matt Saunoras]

did the stc in my truck finally. it was definitely on its way out. had a lot of in and out movement and you could see the wear mark forming. truck has 54k on it now

 

my oil cooler screen was tore up too and the ipr screen had a few small pieces of crap on it. damn 6.0s maybe i can sleep at night now knowing my truck is better off than it was before........err or not

[Keith Browning]

Did you know that screen filters at 150 microns?