If indeed it is a head gasket that needs to be changed, its fairly easy, a few tools you will need is as follows, Jack stands, floor jack,2-ton,Breaker-bar, torque wrench, 10,12,13,14, 17 mm 12 point sockets to remove head bolts. First off the engine does not need to be removed, you can do it right from the access cover over the passenger seat, and from underneath, things you do not need to disconect are front driveline, water pump and timing chain cover.

First jack up the front of the car on your two stands with floorjack, get as high as your conforatable with, I also use the floor jack as a secondary support and do not rely on the stands only, then remove the passenger seat, and then the stepup rim covering the carpet at door entrace, then peel back the carpet to expose the access cover, remove all screws and cover plate, keep the bolts separate from others, I usally put the bolts back in there respective holes as not to lose them and some are not the same size so is good way to remind where they go. ok, now were onto the disconnect exhaust just past the header system, there are 3 bolts and two bolts connecting the mount, this is where the breaker bar will come in handy, you can use your leg to push back the muffler enough to break the system apart you'll need to separate it from the header, then move on to the header assembly and take out the 5 bolts and drop the header. ok lets remove the engine mount just at the front and at below the valve cover, theres 3 bolts that hold it to the block, and another two that you will loosen or take off, make sure you prop up the engine so as it does not but anythin in a bind, once all are taken off jack up the engine enough to pull this out, onec out, you'll have access to the other items that will need to be taken off, remove the timing chain tensioner, now lower the jack slowly and relive the load, take off the oil assembly line, two bolts attach it to the head, and two clamps will remove it, make sure your oil has been drained and your anti freeze sealant, you'll now have plenty room to reach in and above the engine to get to the intake, more later..ok, now you can move up to the access hole, and take off the spark plug cover to expose the valve cover, tape and mark your wires, hoses, and anything that requires taking off, if your not sure comfortable with removing the distributor then mark it as to where it is, or start from scratch with TDC I'm assumming you already know about this so will not cover it, once the distrib is removed you'll have better access to the egr valve and the two bolts that hold it onto the head, remove this and 2 bolts holding on the wire harness at the top of the head, now remove water jacket assembly from the head , two bolts at the top block, no need to pull it off just out of the way, leave the hoses connected to it, ok, now you'll need to disconnect the intake from the head, open your gas cover and release the pressure of the cap and leave it very loose, this will keep the gas from comming out the lines when you take apart. there are two intake brackets that the bolts will have to be taken out, there far back so a small ratchet and 13mm will do it, I only removed the top ones and left it at that, once those are removed take out the 6 bolts holding down the intake you may have to also take loose the bolts that hold down the wiring harness so that you can move out of way, you cannot take completely off so just keep moving aside as you need to, also disconnect the vacume hose to valve cover, and the gas lines, no need to taqke the injecter plate off, ok the intake should raise high enough to clear the bolts do not need alot, now remove the valve cover, and expose the two cams, here is where you'll need to follow in order a procedure outlinning the sequence of lossening the cam bolts, and then remove the bottom cam first, keep in order the bolts and the bearings that you take off, now, I think its a 17mm wrench take lossen the bolt from the front of the cam, make sure you slip something into the sprocket so that when taking bolt lose you do not stretch the chain or put in bind, at this poing you cannot take bolt out, but just lossen, ok same procedure on the upper cam for taking off, once loose you'll be able to take that sprocket bolt out and take sprocket off as well and set aside , again I am assumming you know how to have set it up for TDC for alignment on the timing chain and cams. you can now take the sprocket out and let the chain lie in the head. you can also at this time take out the valveshimes and keep in order as to where they go. you now have all the head bolts exposed, this is a 12 pointer socket, remember to take loose in the order it calls for so that you do not ruin the head, onec all the bolts have been taken loose as well as the two inside the timing area, do a double take and make sure everything is disconnected from the head, there will be some misc bolts that hold some lines to the intake that you might find easier to remove if you want. Take a pry bar and very carefully pry the head loose, just enough to break the seal, prop your floor jack up and under the head with a block of wood and continue to now take off the head, its very heavy in this position and the floor jack helps in doing it very slowly and carefull, no need to get in a hurry. Once out you'll see expose the pistons and head gasket, this is where the fun begins you'll need to clean all the gasket material from all exposed parts, intake, head or block, water jacket, egr, oil line assembly, There you have it, is good idea now to have your head checked for cracks etc, or do valve job.. to put back is the reversal of this order.

here is link to get your head gasket kit for 38 dollars and is good kit.

<A href="http://cgi.eBay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130271354856&ssPageName=ADME:B:EOIBSA:MT:11">http://cgi.eBay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130271354856&ssPageName=ADME:B:EOIBSA:MT:11</A>

This is a good link for your assembly order and or lossening bolts on the cams and heads.

<A href="http://www.justanswer.com/questions/1jhz-engine-removal-Toyota-previa">http://www.justanswer.com/questions/1jhz-engine-removal-Toyota-previa</A>

I have step by step pics if your interested, e-mail me at <A href="mailto:mike@dalephill2.com">mike@dalephill2.com</A>

P.S> do not forget to change your oil filter and add 5 quarts of oil, and your antifreeze, start her up and check for leaks and or water. and job well done

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