Pat McPherson

Yesterday my engine shut down at about 4000rpm. Long story short; the engine cranks but the distributor does not turn. I pull the distributor and it looks fine. I'm thinking the timing chain snapped.
How ugly does it get if that happened?
Do the pistons hit the valves that remain open?
What else could it be?
I plan on tearing into it tonight. Can I get the timing cover off without dropping the pan?
The engine is a 1999 7.4MPI...
Thanks for the help,
Patrick

Rookie

iTrader: (4)

Had this happen once, it was a broken cam

steve stanko

Ditto, on the broken cam, several bent valves though, and cam and lifters.

Pat McPherson

Can't imagine a steel roller cam breaking, but I guess anything is possible...
So, the pistons did probably hit the open valves too then?
Anyone got a Gen 6 7.4 long-block or base engine?

z.zuperboat

Sound Like A Total To Me.your Insurance Companys Going To Love You This Year.im Afraid To Put Mine In The Water Any More This Year With All The Bad Luck Going Around.what Brand Of Cam Was It?pm Me With What Your Looking For And What U Want To Spend And Ill Make Some Call On The Island.

BOBALOO

I had the same thing happen when my oil pump siezed up and broke the gears off the distributor gear. Pull the dist out and check the gear.
Good news is that most internals were fine .

Bad news is that the motor was pulled and disassembled to flush out the metal. The cam was still ok. New pump, gear and gaskets and all was good for the year I had it.

Pat McPherson

Hey ZZ,
Don't think the insurance company will cover this one...
If the engines is gone, I will be looking for a replacement Gen 6 (1996+) 7.4 or 454mag.

Bobaloo, The distributor is fine... Either the chain or cam must have broken???

Lmarth

Patrick-- Sounds like you're getting pretty good advice. You may want to pull the valve covers and spin her over. Obviously if you snapped the cam there won't be a lot of rockers going up or down. If none of the rockers move, you're right and the chain broke. If it did, crank the starter and listen for a constant rpm. If the sound varies, you've probably got some bent valves because of uneven compression. Look for evidence that the valves are seating. A compression test and leakdown test should confirm what you've seen and heard. Unfortunately, even top shelf cams break. Let us know what you find.

Pat McPherson

Thanks Lmarth,
I'll pull the valve covers first, got to do it anyway...

Pat McPherson

I hear you Tempest, but I have cranked it over may times already.
If the pistons hit the valves, the damage is already done...