2008 Tundra Limited 5.7 Broken Valve Spring help

Hey guys, first time posting. Been reading through the forums a lot since I got this truck. Never had an issue with it. Started it up one morning instantly had a misfire. Did several testing (im a novice) finally narrowed it down to likely a broken valve spring. Pulled the valve cover and sure enough found the broken spring sitting there. Just one broken spring on cylinder 1. This is honestly my first time working on a dohc engine this in depth.
I could use some advice on what exactly my next step is. Ive got the spring on order. Ive got an oh cam spring compressor. Do i have to remove the entire cam arm? Do i need to pressurize the cylinder or anything? Right now its closed. I appreciate any help and will answer any questions as best I can.

 

Best bet is to look up the maintenance manual for the 3urfe. Not sure if it's on this site, but I'm sure you can probably find it online. Looks like a clean snap.

 

Did you confirm that the valve isn't bent? Typically when a spring fails, the valve drops and it gets bent when the piston comes up. Not always, but often. Typically the only way to get a new spring on is to add pressue to the chamber. Never did valves on this engine, but most overhead cams must me removed to get the rocker in or out. Some mechanics will use something to lever the rocker down to get it out, but this often creates damage.

 

How do I check to ensure the valve is not bent? I have a borescope but when I put it down the spark plug cylinder I believe it is closed so not really anything to see, as you can see in one of the pictures

 

is the piston damaged? Image is not the best quality.

 

lift valve stem up and use borescope to see if the valve seats fully against the seat. Usually helpfull if you can shine a light in the chamber and use scope to look for the light shinning through.

 

@Ruggybuggy - can you help him out?

@Mkoger7 - how many miles on the engine?

 

Once it’s together a compression test will confirm if it’s bent or not. A leak down test could also determine if the valve is sealing.

 

Ok will give that a shot asap.
About 160k on engine, never an issue.
So am I correct in understanding I have to remove that rocker and rocker arm assembly to put the new spring on? The old one was broken in half and so it just slid right off.
Also, are any of the bolts torque to yield and need replaced?

 

Yes it’s possible but you’re going to need a valve spring tool that will allow you to compress the spring in place and while compressed slide the keepers in and then the rocker. You going to have to use compressed air in the cylinder to keep the valve from falling in. It’s not an easy job and should be left to a professional if you’re not confident in your abilities. If you drop the valve it will fall in the cylinder and your taking the cylinder head off.
Here a video of the tool that is used. It’s a universal tool.
https://youtu.be/0Sr74Pd0VYI?si=00ID7mU7GN6XCRv7

 

Hello,

Check out this video. The carcarenut is very detailed on the tear down of this engine and what all should be replaced to properly fix it. It’s an hour long but I think it’s well worth it. https://m.youtube.com/watch?v=2bsULQcMxlg

 

This might be helpful as well.
https://www.tundras.com/threads/2007-tundra-4x2-crew-max-limited-valve-spring-issues.131851/

 

I was able to get the spring replaced without removing the cam shaft finally. But that valve will not come up. I assume the only reason would be bent valve, correct?

 

Yes, that would be a reason the valve won’t come up. It’s bent and not allowing it to seat. That sucks.

 

Yes, it does suck. So now i will beed to remove timing cover, chains, cam tower and then the driver side head, correct? Is it doable with the engine in the truck?

 

You can do it in the truck but it’s difficult. It’s hard on the back and awkward to be bending over the truck. If you have the time, it’s easier to pull the engine and makes assembly much easier. Better yet, if you have a hoist, lift the cab up out of the way.

 

I have a driveway and thats it lol. No hoist. I can get an engine lift if its necessary

 

If the valve is bent it might be time to look for a replacement engine. Before going any further it would be wise to get a decent bore scope and inspect the piston and cylinder walls.

 

Im admittedly inexperienced at this depth of a repair. But lack of funds forces me to learn, which i am pretty good at. Why do you suggest a new engine over pulling the head and replacing the one valve?
I do have a borescope, i can not see any noticeable damage when i put it down the spark plug tube. I didn't think about it before but i guess i could pull the intake cover and view the bent/broken valve from there, correct?

 

BTW, I appreciate all of you taking the time to give me some advice/tips. Thank you.

 

it just may be cheaper in the long run if you can find a good used motor. It’s just not going to be one valve. Complete gasket set, time spent, stuff you find such as coolant leaks from the valley plate, stuff breaking and stuff you break. Also you said that you are inexperience in this type of repair. This job does require skill and knowledge. A complete engine replacement is much quicker and easier but make sure you honestly access the Tundra’s condition to make sure it’s worth the investment.

 

Im not seeing any motors under $4500. Shouldnt my costs be just gasket sets, the valve, coolant, oil, sealants? Unless like you said, i break something. I understand the time may be less swapping an engine but I dont have $4500 to drop on an engine right now anyway.
Not trying to argue, just want to make sure im not missing something big.
The truck itself up to this point has been absolutely flawless and meticulously maintained.
Just this freak broken spring.

 

I am not sure that I would pull the engine and replace in a case like this if limited on funds. I suppose it really depends upon the cost of an engine. Getting everytjing off is a lot of work, but like anything, you have the time/$ equation. Some have more money than time and others the opposite. seen several posts here where folks have to replace blown head gaskets. Same levle of work. Watch the poted video. It is a good overview of the effort.

Need to research the head bolts. Believe that toyota typically uses TTY head bolts and those cannot be re-used. Also need to look for valve guide damage. They can sometimes be destroyed from the bending forces. If the heads are thin castings, you can even get cracks in the head around the guide. Machine shop can put a new one in. Don't forget to lap the new valve and check for proper face/seat fit. Paint valve face with sharpie and spin with lapping tool. Need 360* where marker is removed, otherwise it needs a valve or seat grind. Can get away with less than perfect on intake, but not exhaust, otherwise will burn the new valve.

Personally, I would go in deeper with borescope to insure a bent valve is the issuie first. That is most likely the issue, but there is a chance it is something easier to remedy.

 

Keep looking. Find a Tundra that someone is parting out privately.

My fear is that you are over your capabilities in doing a job like this. If you get the timing wrong when you reassemble you’re going to need a motor. Also you may find other components that were damaged. The bent valve could have damaged the cylinder head. There are also other areas that you should consider while it’s apart. The drivers side oil tensioner Is known to fail so it should be changed. Cylinder head should be check for straightness and if it’s out you could end up changing the cylinder head. I use to own a repair shop for 13 years and when a higher mileage vehicle came with engine damage it was always more cost effective to replace the engine with a good used motor. The customer ended up spending less and got their vehicle back quicker. I realize your labour is free because your doing the work but your inexperience in this type of repair and doing it outside in the driveway would make it a very challenging endeavour.

 

So this is my general consensus as well. It takes considerably less time to swap an engine than to rebuild one. In addition there’s always things that break along the way and you just won’t have a full picture of those costs until you’re in there. It will surprise you how your budget will balloon along the way.