I bought a 97 4runner with a bad cylinder. Pulled it out and Bought a used motor out of a 2001 3.4l to swap in. Yes the motor is under warranty but they dont warranty my work of course.... So i put the motor in and it was dumping white smoke out (Like a bad head gasket) Went back in. And changed my injectors from the 97 to new engine. Still same problem. No access to leak down test so i only did regular compression test. 150-155 PSI in every cylinder. Seemed great. Now i bought a lower intake manifold gasket and have her takin apart. Upon taking off the lower intake. The Gasket seemed fine. (No apparent leaks or through that gasket) I am assuming they are not re usable so im trying to find more places to look before i put the new Lower intake gasket on. I cant imagine my head gaskets bad. But idk what else could be leaking coolant into my exhaust. Any suggestions are greatly appreciated.
Also might i add. All the spark plugs look fine. None out of ordinary look steam cleaned or fouled. They all looked the same. Thanks in advance.

 

By chance get a coolant and vacuum mixed ??

Dumping coolant into the intake.

Coolant Pressure test before pulling things apart would have been a big help

 

I did not do a coolant pressure test =/ Could have helped a ton. I'm pretty positive no lines were mixed though. I have 2 other 3.4l's so pretty simple for me to find reference.
i was maybe pondering about the oil cooler? Don't know if that could cause the coolant out of the exhaust but that part was not swapped from my 97.
Also. I did have one of my heater hoses leaking before i swapped my injectors. When i pulled my lower intake there was quite a bit of coolant floating on top of the block, But i assume its just from that heater hose dripping down the metal bypass pipe under the intake. And i couldnt see that excess coolant left over made it into my exhaust but maybe it could be that easy? hah
New hoses have been installed on the firewall now so no more leaking back there. Never over heated either.

 

Dont know if these really mean anything but the heater hose that connects to this metal bypass pipe (whatever its called) was the hose that was cracked and leaking. It was replaced though when i swapped injectors. Still blew the smoke. Obviously theres still a puddle of coolant ill clean that ip before she goes back together.

 

How long did you let the motor run? Is it possible there was residual coolant in the intake that now has to be burned?

Recyclers arent always the cleanest when they are stripping carcasses.

 

Thanks for the reply.
I would say its had at least an hour of idle time. Of course off and on while messing with my wiring. (I had some cut wires on the harness between my drivers kick panel to rear door that took me a bit to find)
While idling though, It doesn't show much smoke so i could barely tell until i test drove it. I drove her around the block twice so i would assume anything that's been soaking in there should have burnt out by now. Plenty of power but it's got quite the cloud of smoke once you put some pressure on the motor, and coolant leaking out of the tail pipe.

This happened on my old motor as well but no cylinder 5 and when i pulled that head it was steam cleaned from the coolant on cylinder 5.

 

Thinking with my old motor (Although cylinder 5 was bad) It had the coolant smoke coming out just as bad and dripping coolant from the tail pipe same as new motor...
I used my 1997 (original motor) Upper intakes, exhaust manifolds. Pretty much everything. Aside from lower intake manifold, and timing belt/water pump. I wonder if its possible my upper intake manifold has a crack in it somewhere? I have the intakes from the 2001 (donor motor) Just felt better running my 1997 parts as i know some things were different.
hmmmmmm

 

You are seeing a significant coolant loss ??

Your positive it is coolant not condensation coming out the exhaust

I gave the oil cooler a thought if it failed it would mix coolant and oil .almost impossible to get in the exhaust system.

Head, Intake Manifold or cracked cylinder wall

 

not too much coolant loss. In the time I burped the system drove around the block twice and idled it over and over. Maybe took 1/3 of my overflow. So not really much, also having new motor and it taking time to cycle in. It seemed pretty normal to me. It's pretty sweet smelling. When i rev it up. It damn near is spraying my driveway and has the anitfreeze feel. I think I'll throw it together tomorrow with new intake gaskets and see how she does. If it's still spitting smoke I'll probably just pull it for warranty. Maybe try to idle her for a bit longer and watch a little closer on coolant level. I wouldn't mind doing head gasket in reality but the kits are a bit pricey and I know I'll need a new timing belt tensioner as well. Just adds to the bill.

 

A good compression doesnt mean a good head gasket unfortunately.
also plugs dont necesarily get cleaned by coolant leaking into the cylinder, but did u check all 6 for any visible differences?
ive had a pajero 3L v6 with a suspected intake gasket leak like urs and as i ripped it all apart, i found the same tube damaged that u talked about as well as a visible leak from the coolant passage through the gasket. maybe one leads to the other.

 

I got a few cans of carb clean. Im gonna clean her up real good, inspect and try putting back together. Thus far i haven't seen anything out of the ordinary that's visible. I'll give an update here in a bit when i got her put back together. I think im going to put on the intake from the donor motor as well. Cant hurt

 

=( Must be the head gasket... Shes still pooring smoke.. Thanks for the help everyone. Appreciate your time. I'll get her done =D

 

bugger haha.
rip into it and please show us pics of the head and gasket when u get to it!

 

 

Might as well check that the donor head isn't warped since you're replacing the gasket. Just another suggestion so you don't have to wonder once its put back together in that aspect. I know you said it hasn't overheated, but that's really the only way to verify. The compression test was only a dry one, so who knows what a leakdown would reveal.