Originally Posted by ecp (Post 637006)

They said the pistons looked good. hoping for busted valve spring or a stuck lifter but i’ve already got a used head and cams priced out. just gotta get the car back and tear into it on a weekend

Originally Posted by Stl-986 (Post 637308)

did you have plastic bits in the oil pan?

Leak down test would have helped before as that will show a valve issue usually.

snap some pictures of the head, maybe it will be obvious if it's a spring.

You did lock the cams right? Both of them?

Originally Posted by ecp (Post 637343)

i pulled the exhaust cam, a definitive broken valve spring broken on cylinder two, need to pull the intake cam to look at the intake springs on cylinder two or one.

Do you guys think i need to pull the head? i’d definitely like to avoid that if i could. I’ll probably end up replacing all the valve springs if two simultaneously broke to be safe.

also any tips on reassembling? i marked the chain and sprocket with a marker and have the lock tool from my Ims kit. it’s a variocam 3 chain motor

Originally Posted by blue62 (Post 637361)

These are interference engines.

If you have broken valve springs then there is a very good chance that the piston has contacted those valves.
So the valve stems on those valves could be bent or there could be damage to the valve guides, and or damage to the valve seats.

The only way you are going to know if there is damage is to remove the head and have it checked out by a good machine shop.

You may have dodged a bullet and can save that engine.
Pull the head and have a automotive machine shop examine the head and check specs.
That is the prudent thing to do.

Originally Posted by ecp (Post 637363)

I did another borescope (at home). no contact with the piston, no seat damage. i was able to wiggle it around just enough to get a good look at the seat and it looked good.

Honestly at 124k miles, i’d rather start saving for a new or upgraded motor. I thought about pulling the head, but the borescope answered questions i had. The spring broke in such a way that it wouldn’t return fully, but it wouldn’t go in far enough to hit anything either. No damage to any piston.

I think that cylinder one was “dead” because the ecu went into some kind of mode or just couldn’t compensate for the one cylinder with zero compression.

I’m trying to decide now if i should replace all 24 springs, just the springs on bank one, or just the one spring. they look okay, but if one broke, others might soon follow. replacing all the springs and getting it back on the road is worth it to me. Any thoughts on that or good while you’re in there’s are welcome

I do love this car so spending the money for a new engine down the road doesn’t bother me. i just don’t have that kind of cash right now:D

Originally Posted by Stl-986 (Post 637369)

Usually there is a reason why it broke. I wouldn't do them all right now if it were me, I would just do bank 1.

Now, with that said....the plastic you have been getting in your oil and that you have noticed....is a problem. Should have addressed that when you saw it the 1st time. I suspect this was the 1st problem and then started to get worse. Shouldn't cause a broken spring, but, if there is something in in the oil that shouldn't be there, it is only a matter of time before that plastic gets somewhere that will cause bigger issues.

Originally Posted by blue62 (Post 637373)

You can do what ever you like it's your car.:D
I gave you my opinion and I stand by it.;)
Keep us posted.

Originally Posted by ike84 (Post 637388)

Not to derail this victory (good job finding the broken spring!) But what is going on with cylinder 1? There's no "limp mode" that will cause total loss of compression.

You said the dealer did a leak down test - what did they find on cylinder 1?

If you have no compression in cylinder 1 and a leak down supports that finding, I think you still have more trouble ahead.

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Originally Posted by ecp (Post 637463)

I did my own sort of test. i modified my compression test hose so it can put air into the cylinders, and then when i unplugged the compressor line, i’d feel for air coming back out of the hose that’s screwed into the head. cylinders two and three had good pressure when i undid the line, but cylinder one had nothing. keep in mind all valves are closed, but cylinder one is at TDC.



My question is:

Is the reason that i felt no air coming back out of cylinder one because there’s no space for it to go (TDC, very small space vs the other two pistons which are further inward etc)

or because there’s also a problem with cylinder one and the broken valve spring on cyl two isn’t all that went wrong.

Cylinder one was not firing, i’d like to think it’s just the ecu not being able to compensate for cylinder two which had zero compression, but this is having me re think my approach. I don’t want to pull the head, but if i have to, i have to.



i only put in about 25 psi. Should i try closer to 100 like what people do when they perform leakdown tests?

Originally Posted by ike84 (Post 637466)

So you pressurized the cylinders (with the head cover off I'm assuming?) And cyls 2-3 returned pressure when the supply line was vented but cyl 1 returned nothing?

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Originally Posted by ecp (Post 637467)

yup i have the head cover off, and removed the broken spring. was just trying to get my parts list together and wanted to make sure i didn’t need to add a bunch of things to it. Cyl one returned very little after doing the test again with more pressure put into it. I think it’s due to the fact that there’s a much smaller space for air to go since the piston is at tdc. starting at zero and firing up the compressor it builds pressure nearly as quickly as when an air tool is attached to the line.

there’s a slight hiss coming from back near the crankshaft area which i assume is just air seeping past the rings. it did it on all cylinders



after putting more pressure in and confirming air returned on cylinder one numerous times i think it’s worth a shot putting new springs in and trying to fire it up, and maybe it was just an ecu error causing cylinder one to not fire. I could be wrong, but i could be right. Only one way to find out.



The fact that the dealership only mentioned a valve being stuck open on one cylinder also leaves me to believe that they didn’t really find any other issues, but i’m gonna give them a call tomorrow and ask just to double check.

Originally Posted by ike84 (Post 637468)

At tdc, both intake and exhaust valves should be closed. Hence, whatever pressure you put in should stay there. Even in a small space, 25psi is a lot of air. If you aren't getting it back there is a problem. You are effectively doing a poor man's leak down test, but I don't think you're gonna get any kind of good diagnostic data with the way you're doing it. You said the dealership did a leak down - what did it show?

The bottom line here is that if a cylinder won't pressurize, or won't hold pressure, you have a serious problem.

One caveat there - we have low pressure piston rings. So, in the absence of a crank case vacuum, expect some leak down. Not complete loss though.



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