Brandon2938

I'm about to do a 3.4 swap in my 94 4runner. I found a wrecked 95 T100 4x4 donor vehicle for $600 that I'm going to pick up this coming wednesday. The truck was a daily driver and from what the owner says it runs very smooth and strong and it doesn't use a bit of oil. The engine has about 300,000 miles on it and the truck was driven mostly on the highway.

The vehicle I am swapping it into is my daily driver 94 4runner. I rarely do any off road driving and primarily just drive about 40 miles a day 4 times a week to work. I'm planning to do the swap mainly for the improved fuel mileage and because my 3.0 has given me nothing but problems since day one.

I plan on doing a compression test on the 3.4 and seeing how it runs before I pull it out of the donor vehicle. If it checks fine should i plan on rebuilding it anyway because of the high mileage or would I be fine with just a good freshening up with new timing belt and water pump.

I'm on a fairly tight budget so I'm trying to save money where I can but I don't mind spending the money on a rebuild if I absolutely have too.



TLDR
Getting a 3.4 with 300,000 miles runs good no leaks and burns no oil could I get away with using it as is and not rebuilding

Sturmcrow

Considering how much easier it is to do a rebuild while the engine is out of the truck, there is no way on Earth that I would swap it without a rebuild, particularly if your 3.0 is still running. Yeah, it'll cost some $$, but the peace of mind will be worth it.

These engines are really pretty good, all things considered, but you're talking about one that has been around the world 12 times, miles-wise.

Brandon2938

That's kinda what I was thinking. The downside is that right now my 3.0 isn't running and I'm borrowing a dodge truck from my dad which is bankrupting me because of fuel costs.

Sturmcrow

Ahh, you didn't mention that your 3.0 is not running. That does change the equation a bit, but I would still do the rebuild.

Would you be doing the work yourself?

I suppose it could be worth it to swap in without a rebuild, if you cannot afford to do a complete job right now. Getting the heads rebuilt and cylinders bored (and new oversized pistons to match) could cost more than you want to pay right now.

Brandon2938

Yeah I will be doing the work myself.

One option I'm considering is Just using this engine for a while provided it has no major problems and once I get a bit more cash just buying a lower mileage engine to swap in at a later date.

I considered just finding a lower mileage engine to begin with but my truck is an automatic and this T100 is such a great price and has all parts I need without needing to source another transmission for my truck and will save me a lot in parts since the t100 3.4 has the proper oil pan and exhaust crossover pipe.

Sturmcrow

You could always do the poor-mans rebuild. Just new bearings, piston rings, head gasket, and seals. You would need to have the heads machined, or at least checked, but that may not be too expensive (adjust valve clearances, but do not replace them).

You will likely not get the max in power and fuel efficiency this way, but should cut down on oil leaks and minimize the potential for head gasket failure. If you are in deep enough for the timing belt anyway, it would be silly not to change out a bunch of oil seals.

In general, this approach would cost a lot of time, but not a lot of money. I believe you can rent a cylinder hone for free from Autozone. I'd estimate about $500 total, which buys a lot of peace of mind and saves you needing to do another swap in the near future.

donomite49

compression check and a leakdown test for the top end check.

if these tests are good i would do the regular timing belt etc and get your rig running and save for the rebuild.

3.4's are known to go a long way. i read about these engines going as far as 750k miles with only timing belts and water pumps/ regular stuff.