Interference in play of timing. - Performance Forum
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Well, the chain just failed in my '94 dime's Double-deuce (LN2 2.2L) and the local shop did a cranking compression test (Something I could have done) that says the valves are bent. And they wanted a small fortune to repair it, which I didn't have. Now the truck is back & still awaiting repairs. But before I turn wrench one just to deal with the timing chain, I have one question about something I can't seem to get any clarity on: Is the LN2 an "interference" or "Non-interference" engine? I ask because this will decide if I do repairs or just replacement.
Go beyond the "bolt-on".
If your valves are bent and you don't have compression you've got yourself an interference engine. Most any timing chain failure will result in valve piston marriage.
-Chris
yeah, but I would not take a shops word for it having bent valves....I do not know off hand if the older 2.2L's are interference or not.
Obviously you arent going to get compression if the valves arent opening and closing (unless they happen to be closed when the chain breaks).
Okay, that's two so far. Anyone who actually knows? I could really use a clear answer here, ASAP. MadJack? Notec? Slowolej? C'mon...
Go beyond the "bolt-on".
Not according to MadJack's post in that other thread...
Guys, please... Can we have some final clarity on this? I'll follow Funky & Jack if I must but let's try to put this to bed, huh?
Go beyond the "bolt-on".
well now i'm confused too
i could've swore the ln2 was an interference engine...i retract my previous statement until the truth comes out.
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why don't you just try putting on a new chain/belt set timing and then compression test it again. If all is well then you don't have a problem and the ln2 is most likely not an interference engine.
An easy way to finish this argument once and for all is to put the engine at TDC and measure if there is any the cap between the top of the head and the piston. Next turn the head upside down and get one of the cam lobes at full extension, if the valve protrudes beyond the bottom of the head or no further then the top of the piston if it doesn't come to level with the block you have your answer.
-Chris
Did anyone come up with THE correct answer on this one???
Also, I think we are all assuming this is a completely stock motor, with stock dished pistons, stock cam, pushrods and lifters...right??
You are correct, sir!
Go beyond the "bolt-on".
if the chain failed, it's either broken and not doing anything or it just skipped and bent up the valves...either way, you need to check the timing chain..if its not broken and you still have no compression, you have bent valves, aka 'interference.' if it's broken then some of the valves could just be open and not bent thus also giving no compression. so if you replace it if it's broken and you have good compression after that you'll should know if it's interference or not. if the valves ARE bent up and you are just gonna replace (i'm assuming you meant 'replace the motor') then you'll have a nice new timing set to put on the replacement motor.
and...my 97 2.2 is an interference type..not sure on how different the motors are.
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Okay... But what if the chain didn't break (Don't know yet) and just skip one or more teeth? Seriously guys, I need some definite clarity on this before I even spend money on parts. Anyone?
Go beyond the "bolt-on".
Well if you are really trying to figure it out, take all your plugs out, take off your valve cover, and remove all the rockers and pushrods, following Mitchell, Haynes, whatever. This will put all the valves into the fully closed position. Then do a quick compression check.
this way even if the cam is WAY out of time, that would result in a false "no compression" reading....you are taking that part out of the system. just make sure you have the plugs out of the other holes....
That should give you a more precise answer to if you have internal damage, and doesn't involve TO much time/labor.
I'm pretty sure the 97- is, and the 98+ isn't......
John Benham wrote:with stock dished pistons
They are dished, but unfortunately there's no valve relief.
fortune cookie say: better a delay than a disaster
Well, look's like Benham has a pretty sharp idea as how to tell if the valves are bent. That would work especially well if you had a leakdown tester (Which I don't). Still good, though. Okay, back to the original question.
And Notec: Not to be dumb, but when you say "is" & "isn't", do you mean interference or non-interference? I ask because there have been so may responses so far that I lost track which we were referring too.
Go beyond the "bolt-on".
97- should be interference.
98+ should NOT be interference.
fortune cookie say: better a delay than a disaster
Okay then... Well I guess I'll just hafta try the method Benham suggested, although one must admit: It's alotta work just to see if a cam timing set replacement is justifiable. But at this point, what choice do I have? I'll be keepin' tabs on this thread to see if anyone can finalize a solid answer to this question, so if anyone knows (For certain), please let it be known here!
Go beyond the "bolt-on".
Well, I just tried Benham's method. Did it twice on each cylinder. Here's the results:
Cyl. 1.): 90psi on the first try. Purged pressure in line to gauge. 40-45psi on second try.
Cyl. 2.): Same results as Cyl. 1. Also tried temporarily disconnecting gauge from line to allow air to enter cylinder to see if it made a difference. It didn't.
Cyl. 3.): 40psi on first try, 45 on second with gauge temporarily disconnected from line between trys to allow cylinder to refill with air to see if it made a difference.
Cyl. 4.): Same method & results as Cyl. 3.
Keep in mind as you read this that I had no idea at what height in the bore the pistons were when I did this test, so it can't be said that the results are from a full compression stroke. But if what I got is any indication (Short of doing a leak-down test. Don't have that tool, remember?) all is well & I can go ahead and install the timing set when I get it. I'll just hafta go back and loose the rockers again to insure no problems as I bring the cam back into time, and run the test once more with the rockers torqued properly after that. Wish me luck, and I'll be lookin' for feedback now!
Go beyond the "bolt-on".
Although your compression is not consistant.....given the circ's, at least there IS compression, which means your valves are most likely fine....
I would redo a proper compression test when done though....
Might be a while before I can do that, but I'll do it! Please stand by for further details when it's done.
Go beyond the "bolt-on".
It's running!!! Thank goodness of skills, senses & knowledge (That's where you guys come in. Thank you!) that I was able to theorize & diagnosis what the problem was, and fix it easily in just a few hours. Shame how I had to run to the hardware store just for a T-30 Torx & a few metric bolts and washers (Just to use the puller I just got back from a friend), but it's running just as smooth as I remember it runnin' when I first put a crank in it (Minus contaminated lifter tick!).
Just thought I'd give an update & thanks... Again!
Go beyond the "bolt-on".
Glad to hear it is up & running....
Nickelin Dimer wrote:It's running!!! Thank goodness of skills, senses & knowledge (That's where you guys come in. Thank you!) that I was able to theorize & diagnosis what the problem was, and fix it easily in just a few hours. Shame how I had to run to the hardware store just for a T-30 Torx & a few metric bolts and washers (Just to use the puller I just got back from a friend), but it's running just as smooth as I remember it runnin' when I first put a crank in it (Minus contaminated lifter tick!).
Just thought I'd give an update & thanks... Again!
So what exactly did you do to fix it? Is it an interferance engine?
Edited 1 time(s). Last edited Tuesday, May 27, 2008 7:11 AM
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