Hurt Cobra Motor...What should I do??

[03mgtermi]

I recently had posted a thread outlining some strange engine behavior and started troubleshooting.

To make a long story short, after trying a ton of different things without any positive outcome, I put it in a trusted shop.

After my mechanic looked at it (briefly) he stated I have a problem with one or more valves and would have to take it to a performance shop. (He doesn't do major engine work)

Assuming he is right (even though he didn't perform any conclusive test, this was also my first and now current fear), what should I do to fix it?

I plan on locating the problem with a compression test then pulling the heads. Should I just get new heads, have these heads reworked, or try to just replace the damaged valve(s)??

Any suggestions are appreciated, thanks!

-Brandon

 

[bubblehead93]

without searching for your other thread and reading it... it seems to me that this assessment might be premature without performance of a compression test and a leakdown test (based on compression test results). there is so much troubleshooting to be done before you get to "the which route should i go?" stage.

jmo.

 

[lgonz051]

+1

 

[03mgtermi]

ok. i guess i will post up the results of that when i get it done.

troubleshooting i have done so far is to do a vacuum test (passed), fuel pressure test (passed), installed new FRPS, cleaned MAF, replaced fuel filter, inspect plugs and injectors (all are good), coils all appear to be functioning properly, also recently installed a new catalytic converter, and it has a brand new alternator, battery, and terminals on it. oil and filter is brand new and at the proper level, coolant and other fluids are all good. i also went over the entire car to inspect all electrical connections and everything checked out. gas in the tank is fresh 93 octane from a trusted gas station. filled my other vehicle at this same station on the same day so i know the fuel is good. oh and it has a new belt as well. what else is there to troubleshoot before i conclude it's a valve problem? other than the compression test that is...


here is a link to my other thread: http://www.svtperformance.com/forums/terminator-talk-229/713594-need-some-help-diagnosing.html

 

[92stanglx]

ok. i guess i will post up the results of that when i get it done.

troubleshooting i have done so far is to do a vacuum test (passed), fuel pressure test (passed), installed new FRPS, cleaned MAF, replaced fuel filter, inspect plugs and injectors (all are good), coils all appear to be functioning properly, also recently installed a new catalytic converter, and it has a brand new alternator, battery, and terminals on it. oil and filter is brand new and at the proper level, coolant and other fluids are all good. i also went over the entire car to inspect all electrical connections and everything checked out. gas in the tank is fresh 93 octane from a trusted gas station. filled my other vehicle at this same station on the same day so i know the fuel is good. oh and it has a new belt as well. what else is there to troubleshoot before i conclude it's a valve problem? other than the compression test that is...


here is a link to my other thread: http://www.svtperformance.com/forums/terminator-talk-229/713594-need-some-help-diagnosing.html

Sounds like the next step is to do a compression test and see what you've got

 

[03mgtermi]

started to do the compression test and here's the #6 plug, not good.

Curious where that chunk of ceramic went. Or what it damaged on the way out. Putting the fiber optic scope to it now, then running the comp test. More later.

 

[Avispa]

You may want to check that #6 coil pack after you do the compression test. That plug is a dead short circuit. That can't do the coil pack a whole lot of good. There's no quench area in Cobra heads to smash up the little piece of plug insulator, so the whole thing had to go through or get partuially stuck in a valve. About the only reason for a plug insulator to do that is bad detonation.

 

[03mgtermi]

OK, compression test is done. Everything checks out. All cylinders are within 10% of each other and average about 145 psi.

My dad is in the medical field and had him bring his fiber optic scopes over and all the cylinders look clear of debris. The tops of my pistons are, for the most part, pretty clean. BUT some of them have black carbon deposits. they also appear to be very slightly pitted in some respects.

Don't really know what that all means or indicates but the cylinder walls look good, no gouges and I can still see the honing marks.

You may want to check that #6 coil pack after you do the compression test. That plug is a dead short circuit. That can't do the coil pack a whole lot of good. There's no quench area in Cobra heads to smash up the little piece of plug insulator, so the whole thing had to go through or get partuially stuck in a valve. About the only reason for a plug insulator to do that is bad detonation.

Thanks for the info. How do I check the coil?

Also, the plug insulator is gone so it must have blown through if it is true that it couldn't have smashed up. I guess it could have made it out the exhaust manifold and down the x pipe where it would have been stopped by the cat??

Going to put the new plugs in now and see how it runs at least...