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[jnaut]

Wow, can we get a straight-up answer on this interference engine thing? My understanding (which means a man I've never met before on an internet forum told me) is that the 3.7l IS an interference engine.

Yes, interference?
No, not interference?

If my timing chain(s) breaks, will my engine get all blowed up? If we can't agree, then I'll be forced to start a poll thread.

 

[ThunderbirdJunkie]

It shouldn't matter, because your timing chain will make noise before it breaks.

So, just don't let it get to that point, and you don't have to worry about it

 

[jnaut]

It shouldn't matter, because your timing chain will make noise before it breaks.

So, just don't let it get to that point, and you don't have to worry about it

But... how long before it breaks will it make noise? protest.gif

 

[ThunderbirdJunkie]

Who cares? Just fix it when it starts making noise.

 

[Powerslave]

jnaut: That's what I was told here as well, that it was an Interference engine, then just recently that it was not. I had said before, I just searched for it, and I did say it was NOT an interference engine.
http://www.jeepkj.com/forum/showthread.php?t=39245&highlight=interference+engine

The engine was making a bad knocking noise, it was from the piston hitting the valve. Since the valve is bent, that means these engines are interference engines.

He quoted me saying I thought they were NOT, then I was told by him there, they WERE, so which is it? I want to know as well...

 

[ThunderbirdJunkie]

If something that restricts valve travel (IE valve spring or keeper) breaks causing the piston to hit the valve, that does not mean it is an interference engine, because it was obviously not DESIGNED for the valve spring to break.

 

[Powerslave]

Interference motor or NOT? Anyone?

 

[ThunderbirdJunkie]

Again, it shouldn't matter, because the only way you'll really care is if you let that timing chain make noise long enough to lose ALL tension OR allow the cams to get THAT out of sync with the engine.

 

[tjkj2002]

Interference motor or NOT? Anyone?

The 3.7 is not a interference engine.On any engine if the valve spring breaks the valve can contact the piston only from the valve being able to travel beyond it's intended travel.Most timing chain engines are not interference engines that still only run 2 valves per cylinder heads.

 

[Powerslave]

The 3.7 is not a interference engine.On any engine if the valve spring breaks the valve can contact the piston only from the valve being able to travel beyond it's intended travel.Most timing chain engines are not interference engines that still only run 2 valves per cylinder heads.

Right... IF the valve comes loose from retainer clip at the TOP of the spring, or it breaks, then it slides down too far into the cylinder....

That's what I thought, if you have a timing CHAIN, they are usually not interference motors.

What the POINT is, if the chain slips, the piston won't come in contact with any valve at TDC on any stroke, no matter HOW out bad the chain slips, or even if it breaks. So, if the chain breaks while any valve is open FULL, the piston won't hit it, no matter how OUT OF SYNC the cam is with the crank.

 

[ThunderbirdJunkie]

The chain won't slip unless you've got bad tensioners/excessive chain stretch

And that won't happen without the aforementioned noise...

 

[tjkj2002]

The chain won't slip unless you've got bad tensioners/excessive chain stretch

And that won't happen without the aforementioned noise...

X2..................

Plus normally takes about 150,000+ miles at least for that to happen,not uncommon for timing chains to last well over 200,000+ miles.

 

[ThunderbirdJunkie]

Unless you have an SOHC Ford 4.0.


MMMMMMM....14 hour job....

 

[ThunderbirdJunkie]

Unless you have an SOHC Ford 4.0.


MMMMMMM....14 hour job....

 

[jnaut]

Hey, I feel like I've got a good answer. And thanks. Y'see, I was told some time ago that the 3.7 was an interference engine and if your timing chain ever broke, you were in a rebuild situation.

However, I also read somewhere that the KJ's timing chain was "designed to last the life of the vehicle". So... now I'm not so paranoid since I'm at 77k miles...

 

[Powerslave]

Hey, I feel like I've got a good answer. And thanks. Y'see, I was told some time ago that the 3.7 was an interference engine and if your timing chain ever broke, you were in a rebuild situation.

However, I also read somewhere that the KJ's timing chain was "designed to last the life of the vehicle". So... now I'm not so paranoid since I'm at 77k miles...

They never are, really... IF well kept and not beat, it can. My Avenger never had the timing belt changed, and that has 150+K miles on it when traded. No oil on it, which is what does THEM in. I got a whole timing belt kit for a 2.5 or 3.0 Mitsubishi engine too, never had to use it.