Famous Previa Valve Cover oil leak: my remedy

[Melisander Wildberger]

After having read the accounts from so many Previa owners who repeatedly have the problem of the valve cover gasket leaking, the oil eventually conducted right onto the exhaust manifold -- and having experienced several Previas that have had petrohalitosis, I decided to replace the spark plug tube gaskets and the gaskets for valve covers 1 & 2. Using a set of new bolts to affix the main valve cover (having read about others having had the experience of old bolts breaking off in the head), applying FIPG as directed, then tightening the bolts in Toyota Shop Manual-specified order, under-torquing ca. 10% to allow for the possibility of snugging the bolts a little more in the future when the inevitable occurs, I am happy to report that there is no leak now. But considering that there is a serious design flaw that always results, sooner or later, in another leaky gasket, and being not overly fond of oil fumes, and downright fearing a vehicle fire, I enlarged the hole in the rear corner of the top "heat shield" (that has the trough that catches the leaking oil) to take an ordinary eighth-inch plumbing pipe nipple, set vertically. I drilled a hole in the nipple's side wall at the level of the floor of the trough, took it to my machinist to TIG-weld it in, then screwed an ordinary 45-degree elbow onto the nipple just below the trough, then screwed a 6-inch nipple into the elbow so that it descends at a 45-degree angle. That 6-incher is held firmly in place with a pipe strap attached to the support for the exhaust pipe. The lower end of the 6-inch pipe comes out directly behind the lowest (large) shield, very slightly above and outside of its left-rear corner. Water poured into the trough was immediately conducted onto the driveway, as I trust will happen to the oil that indubitably one day again will leak past the valve cover gasket. I'd rather clean up a few drips from my gravel drive than have the stink and possible fire from the oil dripping onto the exhaust. It is true that I had to do some filing and grinding to make the 45-degree elbow fit, and I conducted the 6-inch pipe through a hole that I made in the smaller second-level heat shield from whose rear left corner the oil was dripping directly onto the exhaust. I regret that I don't have a camera to show my handiwork graphically, but I think the idea is simple enough that such is perhaps not needed.
Let me hasten to elicit any comments -- especially negative ones warning of some consequence that I may have overlooked.
Mel. Wildberger 1994 Previa LE S/C All-Trac.