22r boom knock knock knock

[beaver_scott]

my cousin has a 4runner with a 22r. he just had the cluch replaced and two days later goes to start it in the morning and it idles rough. he revs it and it makes a boom noise, then a clunking noise and a rough idle. the mechanic says its a bad valve and he needs a new motor (the motor has not been taken apart yet). any opinions? do you think he could get away with just a top end replacement or do you think there could be piston damage?

[jetwhine]

beaver_scott,

That all depends on what other damage has been done. If the valve broke then I would assume that it went into the cylinder and caused more damage. Maybe you can find someone that has a borescope and look into the cylinders and see if there is any other damage. Then at that point you can determine if a engine replacement is needed. It might be just a head replacement. Or, if no damage, just a head overhaul.

[fourwd1]

Definitely have it checked out further. Saying you need a new engine right off the bat is really jumping to conclusions.

[sam333]

A compression test will tell you alot.

[jetwhine]

sam333,

If that valve is broken off inside of the cylinder the compression check would not be a good idea.

[sam333]

You have to start testing somewhere and givin the description , sounds like he has some major mechanical problems. Turning the engine over with the starter 5-10 times isnt going to do any worse damage than he did running it with dropped valve or valve head). You really have to use common sense in anything, if he thinks its dropped a valve, then he needs to pull a plug and look or pull his valve cover to see whats happend , no bore scope needed. You can always do a leak down test( that only requires you rotate the engine by hand).