Timing chain repair

JOEPARROTT

MEMBER
CHEVROLET IMPALA

I recntly purchased a 2001 Saturn SL2 with 46,000 miles.
the car was was in very good condition.
I had my regular mechanic check it over - no problems found.

three days later the timing chain broke.
The repair shop installed the entire timing chain repair kit.
Now they are telling me there is no pressure in 3 out of 4 cylanders.
And the engine head must be sent to a milling shop for a "head job".
Now, after finding this problem they inform me that this head problem is very common when the timing chain has broken.
My questions are: DO you know what this problem actually is?
Does the head need to be repaired?
Does a timing chain normally break after only 46,000 miles?

1 Reply

BADJERJIM

MEMBER
3 POSTS

Tough break on the timing chain (sorry, couldn't resist).

If the compression went to zero on a few cylinders after your "incident" - that means the Saturn head is an "interference" design. That means that when the chain breaks, all the valves "freeze" in their current position - some open, some closed.

The valves that are open are now in the way of the pistons as they come to the top of their stroke - which means they get smacked by the pistons, and bent so they won't close properly.

A good mechanic should have checked this and informed you before installing a "timing chain repair kit." Meaning: the likliehood of valve damage was very high.

The "head job" he's talking about is replacing some or all of the valves, and machine work to seat them. And perhaps touch up the surface of the head while they're there. YES - it must be done.

Next question: common at 46K miles? Noway. I drive a 96 Saturn SL-1 with 182,000 miles. Timing chain replaced at 100K. Car still runs great, and still returns 30-40 mpg.