Injector Gaskets, Where Are You?
You just finished installing reconditioned injectors on a HPDI VZ225TLR. You were letting the engine idle while checking fuel pressure and noticed a sound coming from the engine. It sounds like a compression leak near the cylinder heads. You don’t see any indication it is the head gaskets and don’t
think it was there before. What’s the problem?
This is a common question after a service procedure that required injector removal on the 2.6L and 3.3L HPDI motors. The noise you are hearing actually is a compression leak. Compressed air is blowing out around the injectors. Usually this is caused by missing injector gaskets on the injector nozzles but could also be old gasket material left in the cylinder head pocket where the injector seats. Obviously. this compression leakage could lead to other concerns if not addressed quickly.
When you remove the injectors from the cylinder head, the old injector gasket material needs to be cleaned from the cylinder head pockets and from the injector nozzles. 12 new injector gaskets come in a powerhead gasket kit if you have one for the job, otherwise the gaskets can be ordered separately. Why 12 gaskets – there are only 6 injectors, right? Yes, only 6 injectors but, by design, there are two gaskets per injector.
Ok, the missing injectors have been located, everything has been
cleaned, and you ready to reinstall the injectors with the gaskets.
Wow, wait a minute, the injector gaskets are different on each side.
Which way do they go? There is a special orientation for the gaskets.
There is a metal reinforcement ring in the center of the gasket with
a wide flange on one side and a narrow flange on the other. The two
narrow (smaller) flanges face each other; the wide flanges contact the
cylinder head surface and the injector body.
Make sure the injector packing is all OK, then install the injectors with
gaskets, and fuel rails. Torque the bolts for the injector holders and the
fuel rails to spec. Run the motor again to check the leaks are resolved
and you’re back on track to deliver that boat as promised.