I think long term I'll need to replace the motor in our Previa.
I found a couple two or so hours away on car-part.com for around $300.
if I go the used motor route, what work would you do to it before installing?
I figure I would do the head gasket and all tune up parts, and clean out the egr and icm and all.
Am I missing anything important?
If you have the wherewithal to remove the engine and put it back in, and the tools and courage to take off the head, I'd say the rest of the way down to the crank is easy. Then you can clean the block, hone the cylinders, clean the pistons, replace the rings, replace the bearings (if needed), cam chain guides, etc. It might cost you another few hundred bucks, but you'll have an engine good for another quarter-million miles. Get the FSM and have an adventure.
Hey Pdgizwiz,
But what about a JDM engine? I recently purchased a JDM engine to replace the old neglected engine. The PO of my Previa put straight water in the engine, causing rust galore, so decided to replace it. Surprisingly enough, it was still running when I removed it.
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The JDM engine I got looks like it was well taken care of, but twenty years ago. The valvetrain looks very clean, no varnish, but there is some surface rust that has me wondering. The company I bought the engine from did a compression test, but didn't provide me any numbers. They said it was "good." The surface rust, let the pictures speak for themselves.
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My mechanic said "It's not ideal, but it should run ok."
My question comes down to this: In general, are JDM engines capable engines, for perhaps 100k miles? Does mine look like it needs machining work to go the distance? I have already spent $3000 in parts, and I am not looking to spend a lot more. I have purchased already like 40 different OEM toyota parts.
I am not confident enough to do machining work. I have a cramped garage, and no machining tools. I mean, I am borrowing an engine crane and stand. I don't have much beyond wrenches and sockets. Should I look to getting the engine refurbished by a machine shop? I only interested in doing this if I would get significantly more life out of the engine. What is your opinion? Anyone else can chime in also. Thanks guys.
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Do you have access to a borescope to see what the inside of the cylinders look like? Also remove the brainy caps to make sure they aren't rusty.
if they are all fine, I'd clean up whatever rust comes off easily and then run it. Fill with cheap oil and a good filter and do two or three short interval oil changes, with some MMO thrown in for good measure. Like a couple hundred miles. Then, maybe 3k with Mobil 1, and after that the usual (I do 5k).
No borescope. Brainy caps?
I bought and installed one JDM engine and it ran just fine. I sold the car to a friend who gave it to his son and so I'm still sort of connected to the van - it's still running fine some three years later. When I got it I had to strip it down to a short block, and I noticed that the intake runners were pretty dirty. According to lore, JDM engines generally see a lot of stop-and-go use. Of course who knows what kind of maintenance they get, but they don't get many miles. And they may have been sitting in a warehouse on a pallet for years before landing in your shop. But they are OEM and so you can count on them to have at least been built right in the first place.
I've rebuilt two Previa engines since. One was a high miles engine that had a known maintenance history. I found that the crank and rods were still to spec, and the bearing were still in servicable condition as well but I replaced them with OEM parts of the same size grade, just because I could. The cylinder walls cleaned up with a quick hone. The pistons were fine too, but took some cleaning - the oil passage holes were all clogged with deposits. I had the head freshened up by a local auto machine shop: cleaning, facing, kissing the valve sealing surfaces, and replacing the seals. No new guides were needed. This engine came out well too, and is still running around town - I sold it to the same friend.
The third engine I rebuilt was out of a van that only had 140k miles but had had a hard life. The cylinders were worn and I had to have the block bored. I found oversize pistons and my shop bored the block to suit them. The crank and rods were fine but the bearings needed replacement. Same routine on the head as before. This engine is in a van I still drive. It runs fine, but it cost me more to rebuild - I blame that on the previous owner and wonder if they ever changed the oil at all.
Cam chain guide parts wear out and I've had spotty luck with after market part quality. One set flat out didn't align correctly and so I shelled out for OEM parts.
So back to the JDM. I've wondered if the best engine might be a JDM that has been torn down and cleaned, given the same treatment as the high mileage but well-maintained one I did. But it's a lot of work and extra money. You really have to assess your needs. How likely are you to drive a Previa another 20 years? My history has been to have them a year or two, sell them to a friend and buy another. I have other cars as well so it's pretty unlikely that I'll ever put 100k on any of them - I can only drive so many miles total. I like rebuilding engines, but it's more out of obsession than practical need.
The JDM engine I just plopped in was the easiest project, by far, and so far as I can tell, every bit as satisfactory.
Oh, one other engine I did was out of the van that got the JDM donor. It's head was warped and I bought a rebuilt one on ebay. I don't have a van for it, though, so it needs a home. It's taking up space in my shop.
Thanks for the response. So you're telling me you haven't had any troubles with the JDM engines. I intend to keep mine for many more years, but only use it strictly for road trips and load hauling. It won't be a DD by any means. I don't want to spend the money to do the full rebuild. I have already spent $3000. I just wish there was something I could do while the engine is out, to give me more confidence that it is ok as is. I am irritated though that i have spent all this money on parts, but the most important part is a shot in the dark. I think If I replace the engine again, I may want to do a proper rebuild.
Bearing caps lol. Autocorrect.
No I haven't had any issue with the JDM engine I've installed, but that's a sample of ONE! Can't draw sweeping conclusions from my one experience! Maybe we can take a poll here - Any other JDM Previa engine reports out there?
Good advice.Originally Posted by pdgizwiz
The problem for me is I don't have the tools required to remove and reinstall the pistons nor a cylinder hone.
I will check and replace, if necessary, the crank bearings.
You'll need to remove the pistons and rods to remove the crank if you replace the bearings.
You'll also need a ring compressor to get the nice clean re-ringed pistons back into the block. But both cylinder hones and ring compressors are inexpensive tools that are generic and will last through many more similar projects. I've had mine for a very long time.
I guess I'm also assuming you have a hoist and a sturdy engine stand, both of which I regard as essential to avoid calamity and injury.
From my perspective, getting a Previa engine out and in again is the hard part of this deal. That's why I prefaced my comments about going all the way into the engine with the assumption that you're crazy enough to take this on and that you have or will find the tools you will need.
But there's a reason that most Previas have already wound up in the shredder - it's because there aren't many people crazy enough to fix them when the engine goes bad. They certainly aren't worth hiring it done - especially given your odds of getting it done right by a run-of-the-mill mechanic in your area.
Maybe I'm obsessive, but when I commit to a job this big, I go all in. I spend a little more money and the extra time to fuss over the details. I've a full-blown case of acute Previosis.
My problem is lack of self confidence and experience. I have never rebuilt an engine. I am afraid that there is so much opportunity for me to mess up. I am somewhat tempted to go in deeper. I purchasd several micrometers years ago that I never used. And I would love to give this engine more life. But what if this JDM engine is fine? I have used a ring compressor before, but never a borin tool. I do have an eletric drill. I am thinking it may be worth it. What are the odds of me screwing this up badly?
Well, I have done a lot of mechanical work on cars over my 47 years. And I have pulled and installed motors before. But not on the previa, of course.
But I have not rebuilt an engine before.
Pulling to motor in the previa doesn't SEEM to be very difficult. I plan on pulling both the motor and tranny together rather than trying to separate them belowdecks.
Drain coolant and oil, disconnect exhaust, fuel lines, SADS shaft, throttle, shift linkage, and electricals. Support motor & tranny, remove mounts, and lower. Am I missing something?
It's not a job I really want to do (I'd rather it not need any attention). But I don't think this motor is long for this world. And this 1992 is super clean--no rust on the body at all, and really solid underneath. Clearly not an upstate NY car its whole life.
The first couple of times I dropped the engine and transmission together using the same rationale you have. But I've switched to pulling the transmission first now.
The reason has to do with the amount that you have to tilt the back end of the engine downwards to get the upper rear of the engine to clear the body before you can pull it back to get the engine mounts off of the supports they bolt to. With the transmission still attached, the back end of the transmission winds up a lot lower - thus the need to get the van up so high. With the transmission off you still have to tilt the engine back to get it free of the body but you just don't need as much ground clearance.
A professional shop would of course have the van on a lift high enough to walk around underneath, and some kind of fancy hoisty thing underneath to tilt and guide the engine out and down.
There's more work to do underneath to get the trans off of the engine, and yes, you're working underneath the van so it's less pleasant. You have to remove the starter to get the tin cover off and unbolt the flex plate from the torque converter, natch. Again, the same work, just in a different sequence and in a different position.
I've found that if you lift the rear of the van more than the front, you can undo the transmission mounts and allow the engine/transmission to tilt back until it's about level. This gives you enough clearance to get to the upper bell housing bolts. While supporting the weight of the engine from above and the transmission on a cheap HF transmission jack, once you remove all the connections you can just roll the trans back and out from underneath the van.
I haven't yet come up with a way to control the tilt of the engine well enough to suit me. I've busted more than one temperature sensor - the one on the upper right front corner of the engine. Pull that sucker out first and tape the connector out of harm's way!
If and when I do this again I'll spend more time and contrive something better than the simple strap I've used before (see this thread)
I would return any motor with that rust.
Definitely a full tear down otherwise.
A ready to go swap seems like the best route for you.
Don't forget, there's never enough time to do it right the first time but always enough time to do it over.
All but a few tools can be borrowed from AutoZone, and who doesn't need another tool
I just turned on my JDM engine, and it's working great! Smooth as a baby's bottom. Here's another positive experience for JDM engines. It seems that the Japanese took really good care of these old Previa engines. I think all that rust was just simple surface rust. I cleaned it up with WD-40 and shop towels.
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See my video below of it running. The ticking sound is the timing light...
https://www.youtube.com/watch?v=TALeasMuTBE
BTW, my method for installing the engine was pushing a crane through the passenger door.
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Like others, I also used straps to support the thing, while I pushed it into position.
good job. i didnt post my install pics. because i worked off a car hoist at a garage. kind of cheating. good install set up for future reference.
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