97 previa with bloan headgasket, do I have to replace the whole engine, 165k miles and is it worth it?

you need to get your tires balance.

Hello. Welcome to FixYa.

The easiest way to remove the cylinder head is to lower the engine/transmission combination out thru the bottom of the vehicle; ie support the engine/trans, and raise the vehicle off of the powertrain assembly.

Working on the cylinder head whilst the engine is still in the vehicle is a VERY difficult endeavour.

Even though it looks like more work, by lowering the engine out; it proves much easier to work on and access all of the necessary bolts.

Thanks for choosing FixYa for assistance.

The speed sensor on the transmission maybe bad, replace it and see if that is the problem.I had the same problem with my previa and replaced it and it worked great!

You have a blown headgasket. Unfortunately a very common problem with these vans.

more than likely just headgasket. you wont know for definate until you pull the head off.

I believe it has a timng belt and the interval for replacement is 100,000 miles.

here is a picture:
http://media.photobucket.com/image/97%20toyota%20previa%20diesel%20timing%20belt/Fabitop55/TimingBeltDiagram.jpg

Look the engine over and see if you can find any external leaks, change the thermostat and make sure that fan(s) are operating.
Check the oil for water...loosing that much, it has to show up somewhere. Blown headgasket usually puts oil in coolant or coolant in oil, causes an external leak from between head and block or goes out through the tailpipe as steam.
look carefully and you will find your problem!!

Yes. I would clean the engine with engine cleaner and then watch for any oul leaks. For you to use that much oil there would be a major leak. If no leaks check to see if blue smohe is coming out you tailpipe. If not keep an eye on is I this it will be fine if none of these things are wrong. I hope this helps. Don't forget to rate my answer. thanks.

A used engine that may have less mile than yours will cost anyway from $500.00-1,000.00 plus and additional 500-850 more labor to install engine. Here is amy advise if your engine is in good condition I would definitely do the head-gasket job on it. That should come out to be less money and you know what your getting. More than likely you would only need a head gasket job and have head cleaned and polished and would NOT need to replace actual heads. Good luck and Thanks for using FIX YA

check fuel pressure and check exhaust for leaks. exhaust leaks caqn play with the o2 sensor readings