is the 3.1 MPFI an interferance motor?

[TurboSedan]

does anyone here know for 100% certainty weather the GEN-II pushrod 660 IS or IS NOT an interferance motor? someone here has to know for sure lol.

apparantly my timing chain and/or camshaft broke on my turbocharged VIN 'T' '91 3.1 MPFI engine. while i was revving it to ~5000 RPM Neutral (i just installed the turbo and was checking things). it sounded great but the engine just completely died and wouldn't start back up. no bad noises or anything it just died. i found out later after pulling the front valve cover that the valvetrain was not moving while cranking the engine (still no bad noises while cranking the engine....the starter just sounded like it had less load on it).

also - the engine has 227,000 miles...is the problem more than likely a broken camshaft or the timing chain?

thanks in advance for any help!

[geoffinbc]

Yes it is.

[Doubt_Incarnate]

pretty much got to takt the motor out/aprt to see for sure,

[geoffinbc]

Yup sometimes you will get away with no damage or bent valves.

[TurboSedan]

well i have some people telling me it is and some people telling me it isn't. if i don't hear any bad noises while cranking the engine (camshaft NOT turning but crank IS) than i should be OK right? i pulled all 6 pushrods out of the front bank and they were all perfectly straight. i haven't had time to check the rear pushrods (i've been told that usually the pushrods bend before a valve will) and i still need to pull the timing cover. not to doubt you, but so far i'm really thinking this is a non-interferance engine. or maybe that's just what i want to believe lol.

[TurboSedan]

so no one on the 60* V6 forum knows if the GEN-2 MPFI pushrod 660 is an interferance motor or not? hmmmm...ok...

so far only one person is telling me it's an interferance engine.....

[bszopi]

Amazing what a search brings up...

http://www.60degreev6.com/index.php?name=PNphpBB2&file=viewtopic&t=2658&highlight=interference+engine

http://www.60degreev6.com/index.php?name=PNphpBB2&file=viewtopic&t=472&highlight=interference+engine

[TurboSedan]

thank you Brad, i was getting so many conflicting answers i wasn't sure what to think so i just made my own new thread. btw i have to admit i just blow off search functions on forums because i never seem to use the right keywords....or something...lol.

i should have the motor out of the car next week sometime, we'll see what's up....

[TurboSedan]

either i got really lucky, or the 3.1 is indeed a non-interference engine. it's hard to believe it is an interferance engine, ecspecially considering it broke while the engine was turning 5000 RPM.

i pulled both valve covers, and all 12 pushrods are straight as can be (i even rolled them across the 3/8" thick glass 55 gallon aquarium. then i had my brother turn the camshaft while i inspected each valve and spring....all of them moved like they were supposed to so none of the valves seemed to be bent either. although, only a compression test will tell me for sure i suppose.

oh yeah here are some pics of the damage:

http://www.turbosedan.com/cutlass/engine/DSC01965.JPG

http://www.turbosedan.com/cutlass/engine/DSC01968.JPG

i bought a new timing chain and all of the gaskets i need yesterday, so hopefully i can get the Turbo Cutlass running again today or tomarrow.

[geoffinbc]

See sometimes you get lucky. I guess it just depends where the cam stopped turning.

[oleman]

I believe all overhead valve engines are interference motors. I know all of the Chrysler engines are. Some are just more interference than others.
If cam gets out of sink the valves will hit the pistons.
I once had an ISUZU 1.8 ltr diesel that broke a cam belt. Everyone knows that diesels are interference, so does ISUZU. The valves were pushed out past the rocker arms breaking a rocker shaft hold down bolt. The engine suffered no damage and went on for another 100,000 miles after the belt change. The saving factor was that the valves were directly inline with the pistons and were pushed straight up.

[SS_EURO]

i have a 92' 3.1 euro sedan and I floated two valves still driving car home for 15 mins and didn't do any damage to the valves or push rods, I have a friend who says no it isn,t interfearance motor and i have to believe it is not!

[geoffinbc]

Wrong. It is. We have had several people bash valves and pistons.

[SS_EURO]

guess i got lucky.

[torq455]

umm, just wondering why you would put a turbo on an engine with 227,000 miles on it....