LC 200 broken valve spring

[TexasHusker]

Well well! Several weeks ago I wrote about a potential "burnt valve" diagnosis on my 2010 LC 200. But!! The mechanic just let me know that it's probably a broken valve spring. He said the book says you have to pull the head to replace it, but he's mastered a technique where he shouldn't have to do that.

He's not for certain on the broken valve spring but will be tomorrow. All of this is $$$$ good news!

 

[Moby]

One way that I've seen is to put the piston in bottom dead center and then pressurize the cylinder with compressed air through the spark plug hole. This keeps the valve from dropping while the spring retainer is removed from the valve stem.

How did the spring break without causing internal damage from a dropped valve? I'm sure happy you don't have to deal with that nightmare, just curious what happened?

 

[bloc]

One way that I've seen is to put the piston in bottom dead center and then pressurize the cylinder with compressed air through the spark plug hole. This keeps the valve from dropping while the spring retainer is removed from the valve stem.

How did the spring break without causing internal damage from a dropped valve? I'm sure happy you don't have to deal with that nightmare, just curious what happened?

Many people report periods of misfire codes before things go boom, so it seems some of these operate for a while before there is significant contact. I suspect the problem spot in the spring can get weak leading to reduced spring rate before it actually breaks.

Also I’ve heard of feeding small diameter rope into the cylinder via the spark plug hole and turning the crank to push it up against the valves as another method..

Hopefully I don’t have to try either one.

 

[TexasHusker]

One way that I've seen is to put the piston in bottom dead center and then pressurize the cylinder with compressed air through the spark plug hole. This keeps the valve from dropping while the spring retainer is removed from the valve stem.

How did the spring break without causing internal damage from a dropped valve? I'm sure happy you don't have to deal with that nightmare, just curious what happened?

We don't know that there isn't internal damage just yet.

 

[TexasHusker]

Many people report periods of misfire codes before things go boom, so it seems some of these operate for a while before there is significant contact. I suspect the problem spot in the spring can get weak leading to reduced spring rate before it actually breaks.

Also I’ve heard of feeding small diameter rope into the cylinder via the spark plug hole and turning the crank to push it up against the valves as another method..

Hopefully I don’t have to try either one.

This is the method.

 

[jfz80]

We’ve had 2 local club members suffer the same issue. AFAIK two different mechanics used the compressed air trick and only replaced the affected spring and keeper

Glad (hope) it wasn’t any worse off
A couple have ended up with new motors.

Thread 'Death of a 3UR'

Aug 25, 2022

Initial info:
2014 and 15xxxx miles. Oil level good and just hit 5k oci and was set to be changed.

Drove fine on mix of interstate and secondary roads until parked. Wife reports that as she parked it developed a rough idle just before turning off. Will not start after.

Several jump attempts later and we chalk it up to the starter issue. Replace starter and no improvement. Engine appears seized. Throw in the towel and have it towed to shop.

Cylinder 2 is done

Borescope pictures confirm the carnage inside. Can’t see the whole cylinder yet but turning the...

• Bryanseye
• Replies: 187
• Forum: 200-Series Cruisers

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