i just had this happen to me. broke the chain on the passenger side bank.

it didn't break the piston tho but bent every valve in the head. had a valve job done on both heads, and a complete head job. also all new timing chains, gears, and guides.

parts and labor i had around 1300. 700.00 of it was the head job w/head gasket kit (almost 300.00 for the gasket kit) :P

and i had like 250.00 in the complete timing kit from advance so 950.00 in parts and 400 in labor.

but my truck runs like new now.

kyle

 

The timing chain broke on my 4.6 in my Mustang, I'll never forget the sound it made. It happened at idle at a red light. I would junk the shortblock, who knows what damage the pistons, rods, rod bearings took with the shock. I put a new shortblock in the mustang and got the head fixed. That's probably the most cost effective way to do it or find a decent used longblock.

This is what the shortblock looked like and all the valves that hit were obviously bent, but no other damage to the head.

 

The timing chains are extremely durable. I have seen many off of 200,000 mile engines and higher that are like new. However usually the main reason a timing chain will break is because a cam started to seize in the cam bore from lack of oil. With that said I suspect if you were to remove the cam caps on the failed cyl head you will see over heated bearing surfaces and or heavy galling of the aluminum in the cam bore. This condition puts too much strain on the chain ( acts like a brake) and the chain fails. The pistons will hit the valves if chain timing is lost. Breaking a chain is very rare on these engines if sufficent lubrication is available. If I was you I would follow some of the others advice here and just get a reman or a long block. We used to dyno test Jasper remans at Romeo. They are a very good replacement engine with decent warranty. Good luck.

 

do you have an example.
because overhead valves and the size of the combustion chamber ther is no othe place for the valves to be.

 

A valve locked up which caused it to shatter. When that shattered it smashed the spark plug next to it. So there wasn't any timing chain issue because both of them where on and fine.

I decided to go with a jasper engine and I get the truck back tomorrow.
Thanks!

 

1985 Isuzu Imark 1.47 4cyl engine. non interference. Break the timing belt, dead in the water. Put new timing belt on, time the cam and back in business. Happened 2 times on my dads car when I was in high school. Broke every 62k miles or so. Since I am off on a tangent anyway. Had to pull the motor to get the timing belt off. Frame was in the way of the crank pulley and bolt. Couldnt get it off withouth pulling the engine. Repair maunal had 3 steps. 1) Pull engine and transaxle. 2) Change timing belt. 3) Replace engine and transaxle.

 

is this an overhead valve engine

 

i couldn't find an image of that engine on yahoo.
i'm just curiuos about "non interference"
sounds like an advertising gimic.

 

The old 2.0L & 2.3L I-4 engines in the 80's Rangers were non-interference engines.

Several of my friends and myself had the pleasure of replacing a failed timing belt and breathing the sigh of relief when you realize that no valve damage had occurred.

A non-interference engine WILL NOT make valve to piston contact, no matter where the cam / piston timing may be.

 

as was said... the 2.3 OHC pinto motor and many other motors are not interferance engines. I do believe most all 302/351 engines are non interferance engines. You brake a timing belt or chain on one of these engines, and you won't get any damage from the valve/piston hitting each other. interferance engines on the other hand will cause damage.

 

Whats the mileage on this disaster??

 

does anyone here have a cross section or other diagram?

i would like to see how the valves are possitioned above the piston

thanks

 

Every engine sold in every car in the united states today is an OHV engine with the exception of the wankel engine (RX8). The isuzu is an OHV and an over head cam. 2v, so only one cam with 8 lobes.
The 4.6, 5.4 is an OVH and OHC. The 4.2v6 is a pushrod motor (cam in the block). The 4.0 current in the explorers and mustangs is OHV and OHC.

The 302, and 351 (5.0 and 5.8) are OHV pushrod engines. A flathead is not an OHV motor. The valves are in the block and run more or less in parrallel with the cylinder bores. Your lawnmower engine could be a flathead or and OHV design. Just depends on what you purchased.

See below for the differences. In a non-interference engine, as the piston moves up and down in the bore, cannot contact an open valve if it were to get stuck open for any reason including a cam timing belt or chain breaking.

 

bad day!

 

My intention was not to patronize you. I simply thought that you didn't understand the relationship and wanted to change that into comprehension of what was happening.

See, I have already risen of above my patronizm but not my patriotism.