Just swapped motors, very rough 3.4.. No CEL

[schmauster]

Our family 4runner has been rock solid except a few things over the years.. Its got 300k on it and it has been through a lot.

Mother in law was driving it with a slightly leaking head gasket... It got hot and blew the radiator. Got a used motor and a new radiator...

Got the new motor hooked up and its running really rough like its on 3 or 4 cylinders. I have gotten codes for multiple misfires on cylinders 2,3,4 and 5 at different times, but it wont post a CEL often at all. O2 trims are pegged out rich when this is happening. You have to give it gas to start it up, it will idle on its own but very badly.

Theres also some kind of weird acrid burning smell I cant put my finger on when its running. Its been down for about 3 or 4 months at least. The fuel smells ok but I wouldnt rule it out.

Heres what i have done so far.

Checked codes - No codes except for a missfire code every so often

Checked and cleaned grounds - Intake manifold, big ground under oil filter, firewall to engine block ground

Swapped intake manifold,injectors, spark plugs and coil packs (had these from the other motor)


Just got done cleaning the grounds and the battery died, so its on a charger. I need to get a volt meter today.


Ill post a video later when the battery is charged and I can get it running.



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[LittleCaesar]

So you know that the “new” motor had zero problems before installing it? Verified timing? I would double check that all grounds are good and tight.

 

[schmauster]

No clue on the 'new' motor. Came with a 100 day warranty from a wrecker we have had good luck with in the past. I would assume this isnt a compression issue.
Already cleaned the grounds, ill verify the continuity later when i get a cheap volt meter.


It does run similar to a vehicle with cam timing off. Its got an old OEM timing belt, didnt look damaged. Are these motors known for slipping timing?


Verified the timing. Looks good, put a plastic card across the timing marks to the timing cover.. Lines up perfectly


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[schmauster]

I do have the VAC line going to the EVAP stuff disconnected. I dont know if this is where it gets its MAP reading from and if its messing with it

 

[LittleCaesar]

Looks good to me. Rarely do they jump time, like very rare.

I would make sure the plug wires are in the correct firing order. How do the plugs look btw?

 

[LittleCaesar]

I would also take off a valve cover to see what the top end looks like, regardless of reputation.

 

[schmauster]

The plugs that came out of it looked like what i'd expect from a 180k unmaintained 3.4... A little melted aluminum on one or two of the plugs from what looks like light knock.

I think the previous owner got their money out of the old plugs :wtf:

The completely clean parts are weird, but i did toss them aside in the gravel in no order whatsoever.

Didnt think i'd get good pics of the plugs did ya?

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[BrianSD_42]

Just curious but how much did this donor engine cost in parts?

If you do the plugs I'd also suggest replacing the wires. Both should be replaced with OEM, not AutoZone knock offs. There are a lot, and I mean a lot of threads where non-oem plugs and wires performed very badly.

 

[schmauster]

A little strange that a few of the electrodes in the middle have maintained shape. Maybe these were changed previously

 

[schmauster]

Paid 800 for the motor from a place in Sacramento..

The wires I have off the old motor are almost new NGKs but maybe not OEM. They have worked great for me in the 10k miles ive had them. I swapped them over with the coils from the other engine and am still having the same issue.

 

[schmauster]

I would also take off a valve cover to see what the top end looks like, regardless of reputation.

What would I be looking for?


Ill be doing a compression test when the battery charges... If i have bad compression in one cylinder it could be my issue and a moot point as ill be getting another motor. Plugs dont look pristine

 

[LittleCaesar]

More than one member has pulled off the valve cover from a yard motor to find sludge.

A compression test or leak down test wouldn’t hurt.

Yard motors are a craps shoot IMHO.

 

[schmauster]

I just may have found something of importance...


Cylinder number 2 has absolutely no compression. Doesnt even move the needle... other cylinders have right around 200psi which is about what i was hoping for.

Im going to take the intake off and see if something made its way to the intake valves and are holding them open... otherwise it might be a broken valve spring, thrown rod or ?

Im doing some poking around, i should have more info later

 

[schmauster]

Yep stuck exhaust valves

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I tried to hammer on them a little bit with the end of a screwdriver but they werent budging... Looks like ill be sending the motor back. Too bad because it looks like they actually changed their oil.


Is it common to have both valves stuck open on one cylinder or is there a chance that theres just a big dead rat or something in the #2 exhaust port? Im guessing not a rat...

 

[LittleCaesar]

For all that work I would be inclined to just pull the head and go from there. That isn't the cleanest one I have even seen but the oil was indeed changed regularly

 

[schmauster]

Considering its under warranty im not sure what to do about it. Im tempted to get the head repaired or replace it with one from the old motor.

Could be going down the rabbit hole of engine repair or not. I feel like the shop would work with me considering we were trying to convince them to come pick the engine up 4 hours away...

 

[LittleCaesar]

Good luck. With the rest of the engine that healthy I would keep it as long as a little head work suits you.

Have you spun the motor by hand, to see if the valve can move at all? Maybe squirt some lube down into the valve. Usually yard motors don't turn, for the folks I have been with, due to rust. But it doesn't look like the case here.

 

[TheRandyMan]

I do have the VAC line going to the EVAP stuff disconnected. I dont know if this is where it gets its MAP reading from and if its messing with it

Try getting this hooked up. I had a line going from the EVAP system to the intake slip off had misfires on 3 cylinders and was running lean. Hopefully that's your issue.

 

[schmauster]

Thanks TheRandyMan.. Good to know that it'll cause problems.. I need to get some fuel rated hose and change a lot of those little evap lines


Ive got it figured out, ive got two exhaust valves stuck open on cylinder number 2. It was obvious after I did a compression test.


Im going to get the head from the other motor cleaned up and swap the drivers side head.



Hoping the piston isnt too damaged from valve contact. Ill be removing the head tonight and ill get some pics.

 

[schmauster]

Good luck. With the rest of the engine that healthy I would keep it as long as a little head work suits you.

Have you spun the motor by hand, to see if the valve can move at all? Maybe squirt some lube down into the valve. Usually yard motors don't turn, for the folks I have been with, due to rust. But it doesn't look like the case here.

I could see it moving the valve at full lift around 1mm. I hammered on the valves without the lifters with a screwdriver handle and they didnt budge.

I figure since both valves are stuck chances of piston contact are good. We'll find out soon enough. Ive got some other projects going on so it'll be another few hours at least till i can get to work on it