Hello, and help!! Cam Belt Problem

[RedSurf]

Hi everyone, found this site while searching for answers. Can't find the answers by searching, so i'm throwing it out to you all.

Today, i have mostly been snapping the cam belt on my '93 3.0.

First question is;

Am i likely to have bent any valves and/or damaged any pistons?

Second question is;

From what i can see the stud holding the cam belt tensioner on the head has snapped off, is this normal, and can it be repaired safely?

Or am i better off just scrapping it?

[stormforce]

I would say there would be some form of damage and probably to the cam in the head or the valves may be bent.I've no idea how to get the broken stud out unless it can be tapped out

[TonyN]

If its just been over tightened and snapped, the bit left shouldnt be tight, try turning it with a scriber or small chisel and tapping gently. I depends how far down the hole hte bit thats left is.

Otherwise you need an extractor, but this mean you need to make enough room in front to get a drill in to make a hole.

In my experiance you'll have bent a couple of valves, unless you where just starting it.

Its not the end of the world, but head will have to come off to fix.

A compression test will tell, otherwise fix the belt and see how it runs.

If it has bent a valve, check the valve guide isnt cracked where it sticks through the head, I've seen bent valve stems, that have broken the guides when the piston pushes the valve back up, and then the bits of guide get mashed between the piston top and head.

It's very fixable, just labour intensive, unless you were really giving it some stick when it went!

[RedSurf]

Wasn't giving it any stick at all really, going up a short steep hill, about 20mph, cut out and coasted to a stop in about a cars length!

Once i've got it apart, will i be able to tell by rotating the cam shaft if any valves are bent? Or will i have to take the head off and inspect it?

Sorry for all the questions, Surf's aren't my specialist subject.

[stormforce]

me personally i would take the head off and get it checked proper if you don't know what your looking for

[BUSHWHACKER]

Early (1990-1996) Lexus V8s have non interference heads. If the timing belt should snap, no damage is done.





Just thought I'd mention it.




As you were.

[TonyN]

Once i've got it apart, will i be able to tell by rotating the cam shaft if any valves are bent? Or will i have to take the head off and inspect it?

sometimes, look for big valve clearances on the bent valves, as they can't go all the way up.

you can start by checking there, but there is very little clearance between piston tops and valves, and the pistons can ram the valve back up so your valve clearances look ok. (this can break the guides if the stem is bent higher up like I mentioned earlier)

compression test is best, but its not so easy on a diesel, i'd have a look at the cam and clearances, then feel how it turns over by hand with the belt back on, then carefully start it up and see how it runs.

odds on you'll have to have the head off though.

Early (1990-1996) Lexus V8s have non interference heads. If the timing belt should snap, no damage is done.

Just thought I'd mention it.

As you were.

I'm sure that'll cheer him up no end...