Hi guys,

1998 4Runner 3.4 5speed manual

Last year, approximately in June while on the freeway, I heard a loud pop and then observed smoke through my rear view mirror. I immediately pulled over, looked underneath and all the oil was pouring. I had the car towed home. The following day, I inspected the engine and observed a hole in the block. From reading this forum, it was caused by a broken rod punching a hole in the block.

Due to funds, my car has been parked in my driveway since the incident. I will be replacing my engine next month and wanted to ask you guys what else I should replace/ upgrade at the same time while the engine is out. I look forward to your responses and thanks in advance for your help.

This by no means is what you should do, but rather what I did when I had to replace my engine 1 1/2 years ago.

If you are going with a USDM (United States Domestic Market) engine, the swap is simpler. If you want to go for a JDM (Japanese Domestic Market) engine the swap gets a more complicated and you'll be replacing a lot more things and transferring them over from your old engine.

Things to consider that are much easier to do with the engine out:

• Valve cover gaskets
• Timing belt (if replacement engine has not been done, easy to check)
• Starter contacts
• Spark plugs and wires

Some optional items to consider:

• Rear main seal (I didn't do this)
• Knock sensor harness (I wish I had done this but it a lot more work)

There's lots of good info on how to pull an engine on here. I can also go into detail on what needs to be swapped from the JDM engine if you want.

Thanks for the response.

I’ll be going with USDM engine. I’ ll start looking to purchase the parts you suggested.

As far as the timing belt. I recently had installed a timing belt / water pump kit on the 4Runner. Has less than 3k miles on it. Do suggest swapping it into the replacement motor or buying a new kit?

That’s what I did when the 96 engine I put in my 97 took a crap. I had the 97 rebuilt and put all the front engine parts on from the 96.


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I replaced all hoses that car coolant and the heater valve. Some of the smaller hoses can be replaced with bulk hose others not. The O ring for the oil cooler some just reuse the disk on the otherside of the cooler. Radiator if you have not done it yet. Any fluid you that need to be serviced. Drive belts.

I did the rear main seal and the front seal. It was well worth it and now i dont have to worry about pulling the tranny later on. I also did the engine mounts, oil cooler seal and hoses, and TB, because its way easier when the engine is pulled. It was easier than i thought and look me about a week from start to finish. I would recommend buying an engine lift instead of renting, then you could sell it and get most of your money back.

I also had just done the timing belt right before mine blew, about 2k miles. Coincidence? Hmm... Anyway yes you can re-use all those timing belt parts. If the timing belt marks are rubbed off completely you might need to get a new belt to line it up right.

Great suggestion about the motor mounts RuggedRunner. I wish I had replaced mine when I had it out.

Thank you all. I appreciate the responses.

How difficult would it be to do the job on my own.

Some of the work I’ve done on my own on the 4Runner includes:

- Tundra caliper/ rotor upgrade, lower ball joint
- alternator
- starter
- cv axles
- Radiator

I’m trying to gauge how difficult the job would be based on my experience and whether or not I should let a mechanical handle it.

Looks like you have enough under your belt to do just fine. I'd never changed the engine out in anything until just a few years ago when my son's 2000 Celica did the Toyota piston ring crapper.

He and I changed our first engine together and it really wasn't all that tough. Just took it a step at a time and helped each other remember what goes where and which way around. Take video all the way through on anything you are likely to forget the order/orientation of.

It's no small feat, that's for sure. I have a day job and I did mine over the holidays. Took me about 5 weeks of tinkering in the evenings and spending Saturdays replacing and fixing things. The JDM engine slowed me down by about a week and a half though due to some parts not wanting to come off that had rusted and all the parts that I couldn't use that had to be swapped over. Well that and the fact it was the holidays and didn't want to spend all of December in the garage away from my kids.

You can do it if you take it slow and take lots of pictures on how it's supposed to be before you take anything apart. That and plastic bags & sharpies to mark all the brackets and parts that need to come off. Pulling an engine is simple enough, only takes time. Putting one back in is difficult. I would go as far as to say putting the engine back in is not a one man job. Takes a spotter/positioner and someone manning the jack to do it right.

Some things to add...

1) As mentioned previously, ziplock bags and a sharpie are your friend! I just replaced the long block on my 97 with an LKQ reman from RockAuto; during the process I started by labeling all the hoses (both ends) and wire connections with zip ties that had small tags. And I mean ALL the hoses/wires! It made re-install sooo much easier. And when I removed bolts/nuts from an engine component I would put them all in a ziplock and label the bag w/ a sharpie.

2) Timmy the Toolman on YouTube is your friend, lots of great info, along with a Toyota Factory service manual.

3) One thing that is often overlooked during an engine swap is the motor mounts, they do where out and while everything is out you might as well replace them.

4) The top Bell housing bolts can be a PITA. Get some long extensions (Timmy covers it in his auto transmission replacement video)

5) Speaking of tools, Flex head ratcheting box open end wrenches are extremely helpful. There’s a lot of tight places you’ve got to get your hands (like the transmission access panel, torque converter, etc).

6) If your going to do a junkyard swap, make sure you know what year model the motor came from. I know that some time after 97 they changed the design of the fuel injectors, so if your unsure, just pull yours from the blown motor and install them into the new-to-you motor. Otherwise hello error codes.

7) as mentioned before, both knock sensors and the knock sensor wire harness. Also, be sure the knock sensors you install are the same style/brand (denso or the M ones) of knock sensors in your current motor unless your swapping ECUs too.

8) if you do pull the intake manifold really inspect it for electrolysis erosion on the water journals. I ended up having to by a new OEM intake cuz it was so bad.

9) take your time and be patient.

10) if you label, bag and can take your time you’ll look back and think it wasn’t as big a deal as you first thought. Just sorta fun, rewarding and time consuming.

My build and repair thread has the entire engine swap. Both times.......


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I swapped a 99 engine into my 97 SR5. The ECM connections are different on a 99 vs 97 so I had to swap the engine harness's (had to use the stock 97 harness on the 99 engine). Everything on the engine side plugs in just fine, including the injectors (no codes, no issues).

I also just did a timing belt kit before the HG blew on my 97 so I reused everything minus the cam seals, front/rear main seals and the water pump gasket. The hardest part is getting the engine back in and lined up (make sure your torque converter is fully seated!!). Also, the motor mount bolts/nuts are a PITA to get to. I really wish they used studs instead of a bolt and nut, it's a total nightmare to get to them.