turbo o-ring

[rdodd]

Does anyone know the part # for the o-ring that sits between the bottom turbo flange and the elbow that goes to the intercooler? Mine looks a little flat and i,m concerned that it could be leaking boost pressure. Thanks.

 

[ARhine]

Cummins # 3919852 Approx $18

 

[rdodd]

How can you tell for sure that the o-ring needs replaced. Mine dosen,t seem to be dryed out but it is about even with the top of the elbow flange. How thick is this o-ring suppost to be?

 

[Greenleaf]

Simply pressure test the system and spray soapy water onto it ansd ALL the connections. Use about 15 psi and you will discover just how badly your system is leaking. Truth is, your flange O ring is going to be the least of your concerns.



This test is a real eye opener.



-S

 

[ARhine]

Where do you plug the system at on both ends? I found a 4" ruber sewer pipe cap at the local hardware to put on the inlet of the turbo. Do you pull the other end from the intake or will the engine keep the air from flowing through?



Was wanting to give mine a leak test as well? Need to make a fitting to work in the pipe cap so I can plumb the air hose into it, then set the regulator to pressure it up.

 

[swankmetal]

the head should keep the air in, i believe. theory being that if an intake valve is open, the exhaust should be closed and vice versa. just tested mine to 45psi, and found that two boots needed tightening and there is one hole in my intercooler. i need a bigger one anyway .



dave



edit: i just replaced the oring with one from napa because somehow the old one got twisted and a little mushed. just took the old one in, they found a close match. it is a tiny bit bigger (dia. and thickness), but i was able to stuff it in there. and it was free.

 

[Greenleaf]

No need to plug anything off. Install that sewer cap onto the turbo and install a fitting.



Unless you have no A/C or a conversion, you'll not be able to see the IC. A leak free connection willo help ensure you'r listening for an IC leak or remove the radiator and test the back side of the IC.



Should you do it correctly, test the IC outside the vehicle. You will no doubt reinstall it when you price a new/replacement unit.



-S

 

[ARhine]

Cool, thanks for the tips. I do have A/C so it is impossible to see the IC without removing something.



In the 6 degree weather last week I was able to hit 22lbs of boost at wot in 5th, so I don't have any more major leaks now I don't think.



When I first bought the truck the elbow where the o-ring goes in was cracked and would not clamp tight, one boot had a 1/2 long slit in it, and I still need to replace the fuel supply line to the inj pump, fuel filter, and possibly the lift pump.