When replacing the head gasket on my 92 Previa. Is it neccessary to remove the timing chain or can I avoid messing with it?
Um…Have you ever done this kind of work before??? This is a basic auto question.
If it’s a overhead cam engine (which I’m pretty sure it is) then NO you can’t. The cam is built into the head. If it’s not a overhead cam the cam is in the block and the valves are controlled via push-rods, so you don’t have to worry about the timing chain or cam.
I have a friend who is experienced going to help me. He was hoping that we didn’t need to remove all the hardware on the front of the engine and just pull the head leaving the timing chain on the gear.(i.e. waterpump,etc.)
Are you sure that your friend’s experience qualifies him for this job?
This would be a great way to ruin both an engine and a friendship if he screws it up.
Yes he has experience on many v8’s but had questions on the Previa since it is a horizontal flat engine unique to the vechile. Have you done a Previa before?
Overhead cam on the Previa. It’s gonna be a big job but not too bad. The real bitch is that they didn’t use aluminum on the top or bottom of the engine so it is HEAVY. VERY unusual to replace a head gasket on these puppies unless you overheat them. I owned a '95 Previa and drove it 230,000 miles before selling it.
If your friend thinks that this is a “horizontal flat engine”, then he is definitely not very experienced around engines. This vehicle has a longitudinally-mounted 4-cylinder engine located under the floor between the front seats, and it is actually a fairly conventional I-4 that was also used in some other Toyota models, not a horizontally oriented “flat” four.
For the record, the manufacturers who currently make an engine such as you described are Porsche and Subaru. And, of course, the original VW beetle had an engine of that type. Toyota has not made any engines of that type.
Perhaps his confusion resulted from the fact that the engine is tilted toward the passenger side in order to conserve interior space, but outside of this canted alignment, it is a conventional I-4 engine.
If your friend is confused about the type of engine, are you sure that he is qualified for this repair job?
Not only do you have to remove the timing chain, but both camshafts before you can even get to the head bolts. Yes, there are two. I highly recommend using the factory manual as it details all the other little things you need to remove.
If you do a google image search for “toyota previa timing chain” you’ll see several parts drawings showing the overhead cam - and hence you’ll need to remove the timing chain.
As AlanY noted, you may want to get a factory manual, or at least have good documentation to guide you.