Air Pump Check Valve/Tee Hoses

1990 XJ-S and 1991 XJ-S Classic Collection Coupes (US Spec, 5.3L V12)



Check Valve

2 Tee Hoses (Part Number EBC 1488)

6mm Socket/Wrench or Flathead Screwdriver

Long Screwdriver

Adjustable Wrench

Grease Cleaning Solution


After I got my Air Rails off, I figured I might as well check the “check valve” – good thing I did, it was NG.  The Air Pump Check valve is part of the “air injection” emissions control which injects air into the exhaust for 45 seconds after the engine is started cold, helping the O2 sensors do their job (the 12 tubes coming down from the Air Rail pass right through the Intake Manifolds).  It’s a lot of heavy hardware for something that is designed to be useful for a very small fraction of the time (some have chosen to remove it all, but that may or may not be legal in your state).  The Check Valve is supposed to prevent exhaust from “back-flowing” into the air injection system, allowing airflow in one direction only.


The Tee Hoses are the hoses connecting the Tee to the Air Rails.  In the picture to the right you can see the old Tee hoses underneath the rear of the Fuel Rail - the Throttle Pulley is out of the way and the “boot” for the Oil Pressure Sender is removed (center of picture).  If you loosen the four clamps (6mm socket or flathead screwdriver), you’ll be able to slide the hoses further onto the Air Rail and free the Tee pipe.  The Tee pipe is screwed into the Check Valve, the bottom of which is clamped to a hose.  Patience is needed to loosen that clamp and take the Check Valve and Tee out in one piece.


The picture below shows how I really did it – with the Air Rails, Fuel Rail, Intake Manifolds, etc. removed.



Once I got the assembly out, I spent a bit of time cleaning it.  Afterward, I blew into the bottom of the Check Valve and air came out the Tee – good.  Then I put my hand over one end of the Tee and blew into the other end.  Air came right out of the bottom of the Check Valve – not good.


Old Check Valve and Tee


It was off to my local auto parts shop for a Borg Warner CV-8 Check Valve ($18.00).  For my ’91 they got me a Standard AV7 Check Valve ($19.92) – considerably less expensive than the Jaguar part, including the one available from (their part number IN101295).  Once I got the new one, I could see that what looks like a nut on the check valve is not – it is part of the valve – so don’t try to loosen it.  On the old assembly, I put an adjustable wrench on the “nut”, put a long screwdriver into the tee, and disassembled.  I cleaned the Tee a little more and reassembled everything (many places sell replacement Tees if needed, including – their part number IN102151).


On my ’90 Coupe, one of the original Tee Hoses was red and the other blue (they were both Blue on my ’91).  Both Hoses were shot.  They are almost like a garden hose – squishy, multi-layered rubber (red inside) with some reinforcement strands. sells the Tee hose (their Part Number IN101302) - $10.82 each - $21.64 a pair.  That seemed like a lot, so I asked on the Jag-Lovers XJ-S Forum if there was any thing special about them and it was suggested to me not to use any substitute.  Installation is the reverse of removal.  Next project…



New Blue Air Rail Tee Hoses

(Rear Center of Engine from Left Side – Throttle Pulley is Lower Left)



Questions/comments: Email me.