Question about 1992 Toyota Previa
1992 Toyota Previa van, replace head gasket
The toyota previa uses a formed silicone gasket for the valve cover and the cover is held in place by metric shoulder bolts ( 10mm). The valve gasket leaks because you can't get enough preload on the bolts to re-seat the old gasket when it gets old and shrinks. The shoulder bolts only allow you to tighten the gasket enough to seat the shoulder on the bolt. If you continue to torque down the suspected bolts, you will snap the bolt off ( don't ask me how I know this ). You can either 1.)replace the old gasket with a new one or 2.) remove the existing bolts around the leak area and put in new metric bolts that do not have a shoulder. You may want to put in a small sleeve into the existing bolt hole but shorter than the thickness of the valve cover to account for the smaller diameter bolt. You can now torque down the bolt and get enough preload to seal the valve cover without removing the old gasket. Make sure you use a torque wrench ( in-lbs) or be very careful not to snap these small valve cover bolts.
Posted on Jul 15, 2009
Our family -- same problem. I have a '91 (435,000 miles), dad's '95 (160,000 miles) both leaked almost profusely. There are 2 major reasons for these leaks. 1) As mentioned above, the valve-cover bolts (actually 6mm - with 10mm head) are too long after years of pulling the gasket tight. a couple washers under each will get you on the 'road to recovery' with this issue. 2) Next if not replaced with the valve-cover gasket, replace the distributor O-ring. This is more easily done at time of VC gasket replacement. And, "yes", use the Toyota silicone. gasket sealer. NOTE: It is ABSOLUTELY recommended that you DON'T use a heavier grade oil, northern climes or not, than that specified (5W30). See (Search: Ferrari Chat Oil)
Posted on Sep 27, 2011
You will need a new head the block is bomb proof consider a second hand engine also consider the cost and value of the car
Posted on Jul 14, 2009
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Posted on Jan 02, 2017
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