1HZ/1HDT/1HDFT Owners: reroute your valve cover breather. Here’s why.

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Nov 12, 2003
Truckee, CA
This 1HDFT motor has 100k miles (mas o menos). The factory oil breather (off the top of the valve cover) is plumbed into the intake manifold.
20 years of sending fumes into the intake results in this mess.

Mine looked even worse than that with only 120k. I think the EGR was to blame for most of it, but maybe made stickier with the oily air. EGR gone and breather hanging open to frame now.

Ive never seen that in a 1HZ and I have had several high klm air intakes in my shed over the years. I have one there now that did 143000klms before the engine spun a bearing and its as clean as a whistle.
These are probably JDMs that spent half their running time sitting in heavy traffic smouldering away
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Yeah, it's primarily the EGR that does that. The PCV on it's own just leaves an oily film everywhere (like what you'll find in your intake system before the EGR inlet).
My last engine had no EGR and looked as bad. Just say’n.
At the very least putting a oil catch can in the system would help. I prefer to vent mine to atmosphere.

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