New user, maybe old problem?

Howdy!

I have a 2002 Tacoma 3.6L with 96k original miles. All belts and hoses replaced at 91k. It sat in my garage for a few months with the negative lead disconnected to save the battery. Right before I parked it, it was running flawlessly.

When I tried to start it, I could tell there was a mis-fire. Being a newbie, I started throwing parts at it (spark plugs, OEM coil packs, wires). I did compression test and all cylinders came up to 180psi after 4 seconds of cranking besides #4. #4 cylinder has ZERO psi, didn't even move the needle.

Bought a end scope and took some pictures. One of the two exhaust valves is stuck open!

I am hoping there is a non-invasive way to dislodge the stuck valve. A co-worker suggested shoving rope through the spark plug hole and hand crank so the piston presses the valve shut, but my concern is that compressed rope might not come out easily unless I hand-crank a bit counter-clockwise to relieve pressure.

I was also wondering if I stuffed a thick balloon or air bladder in the cylinder, and then inflate/deflate.

I read about using Marvel Mystery Oil, but I don't understand how it should be applied (dump in cylinder and hand crank? Poor into engine and hand crank a few times?)

My plan is to run treated oil and/or gas through the engine once the valve is back in operation.

Anyone have experience with this? Any recommendations? Are the ideas above good or silly?

 

Is it just me or does that valve look "too" open, almost like it has a broken valve stem?

 

Thanks for the response HAVOC. Here's a picture with both open. To me, especially while viewing from slightly different angles, they looked pretty equal.

Any thoughts about the solution ideas? Is it okay to manually rotate crank CCW?

 

It's stuck so I think that leads to a possible bent valve. With OHV (over head valve) engines (think Chevrolet V8), you can tap on the of the valve stem after moving the rocker arm out of the way which would normally loosed them up.

With you engine, i don;t think it's possible. It may be but you will have to remove the valve cover and have a look.

 

Welcome to TacomaWorld

 

I would pull the valve cover and see whats going on on the other end

 

Definitely pull valve cover first

 

Probably a broken valve spring.

 

Thanks for all the advice.

How bad is it on the engine to manually rotate crank counter clock wise a few degrees?

 

Welcome to TW!

 

Rotate it around all you please, either direction... They all say never rotate it backwards but I've never had a problem. Its not like it is running backwards.

 

Maybe the concern is compromising the 19mm nut or bolt torque? Will most certainly remove all spark plugs before I stuff rope down the spark plug hole to press upward hopefully freeing the stuck valve.

Not 100% committed to trying the rope method, but I can’t imagine how a engine went from running very well to this state by just sitting in the garage for several months. While the oil was about 8 months old, there was less than 500 miles since last oil/filter change. Do valves bent or break while sitting in a garage? Springs for that matter, or shim getting wedged in a bucket?

I am open to removing the drivers side valve cover, my concern is about the coolant that’s going to be spilled out when I remove the intake manifold/throttle body. I imagine it’s not good to leave coolant passages with air pockets.

If there is more than just old oil/residue causing the exhaust valve to stick open, using piston to force the valve closed with rope sounds sketchy. Maybe I’ll study the assembly of the valve train before any action.

Really appreciate the feedback. I am not a mechanic by trade.

 

Nobody really knows what is wrong yet or why it happened, but it seems like you are past the "quick and easy" fix. Things will get involved to remove the valve cover but nothing about it will be too difficult. You are correct that the coolant system will need to be bled but if you are capable of taking the valve cover off you can bleed the cooling system of air. I would take the valve cover off first so you can determine for a fact what is holding that valve open before you try using force.

 

Thanks for the advice. The engine has to be running well enough to get it hot to properly bleed the coolant system of air, right?

 

Yes, you could look into renting a coolant vacuum filler from somewhere. It uses compressed air to draw a vacuum on the system and then you reverse the flow and it sucks in your jug of coolant. That does not need the engine to be on. I would worry about that later though.

 

Welcome to tw