LT1/LT4 Tech 1993-1997

Hesitation, engine stutter, idle problems...

  #71  
Old 10-13-2011, 10:40 PM
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Originally Posted by JGuy07
The anti-freeze is fine, I haven't seen any problems with the oil yet and this problem has been going on for quite some time. Even if I haven't noticed the fluids mixing would it still be possible for them to be bringing in air? I'm getting air from someplace and nobody could pinpoint or find it.

They told me I could be sure I was getting air from another source by taking off the intake exposing the TB, then taking a towel and blocking the passage of the TB to close it off from getting air and seeing how it reacts. They said it should die almost instantly, if not then I have a leak of some sort elsewhere.

Also, I still haven't done a compression test. And I know I've read up on it but can't recall right now. What exactly would the compression test show? Depending on the reading could mean exactly what, bad valve seals and stuff? Not quite sure, and if it does show low compression could that also be related to a leak of some sort which could be effecting the pressure within the block or heads that would be relating to my vacuum/high idle problem?
Well, when I had a bad head, it skipped real bad.
Just a thought, but have ya checked you throttle body gasket? Also check you throttle arm- where you gas cable is on the throttle body, see if you can wiggle it. I know on a holley carb that cause headaches.

Compression check, check the compression of the cylinder. So if you have a blown head gasket or bad ring...ect you'll see it. Last one I did one was on my sbc 400 in my s10.
 

Last edited by numskull223; 10-13-2011 at 10:42 PM.
  #72  
Old 10-13-2011, 10:58 PM
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The TB gasket is new as of 3 weeks ago or so when I also did the intake manifold. I'll be pretty ****ty if I have to remove it to do the head gaskets or to have head work done, I won't be able to do any work like that for awhile for money reasons. I can use a vacuum gauge and also do a compression test to locate any leaks like that. It would narrow it down for me to see if it has a leak and then I know that would be the cause of my problem since it would be pulling in extra air.

I think I could deal with it for awhile, it would be drivable until I can manage to have it fixed it need be. As long as I can get a new cap and rotor in soon to get rid of the shudder and shake so it's drivable I'll be happy for now.
 
  #73  
Old 10-13-2011, 11:26 PM
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Ok, I think I may have been overlooking some signs of the head leak. Now I feel stupid. When I take the rad cap off I get subtle drips of brownish tented coolant from the cap, but only a few drops and the rest of the coolant looks fine normally. Also, when leaving the cap off when flushing the coolant system earlier this summer I came across a problem. Left the cap off so I could watch the coolant circulate and slowly add more if needed. After a minute or so the coolant began to overflow, so I turned the engine off and the coolant sky rocketed out and almost hit the hood it got so high, basically emptied all coolant when it did that. This is why I feel like an idiot, I was told it was "natural system pressure" that caused that and I just left the cap off too long. So which is it, "natural system pressure" or the exhaust gases built up from the head leak? With the brownish tented coolant and the overflowing it sort of has me rethinking the things I did, and I feel ridiculous for overlooking these things.
 
  #74  
Old 10-14-2011, 12:28 AM
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Originally Posted by JGuy07
Ok, I think I may have been overlooking some signs of the head leak. Now I feel stupid. When I take the rad cap off I get subtle drips of brownish tented coolant from the cap, but only a few drops and the rest of the coolant looks fine normally. Also, when leaving the cap off when flushing the coolant system earlier this summer I came across a problem. Left the cap off so I could watch the coolant circulate and slowly add more if needed. After a minute or so the coolant began to overflow, so I turned the engine off and the coolant sky rocketed out and almost hit the hood it got so high, basically emptied all coolant when it did that. This is why I feel like an idiot, I was told it was "natural system pressure" that caused that and I just left the cap off too long. So which is it, "natural system pressure" or the exhaust gases built up from the head leak? With the brownish tented coolant and the overflowing it sort of has me rethinking the things I did, and I feel ridiculous for overlooking these things.
Well I can tell you, 2 weeks ago I ran my Z with rad cap off for about 5-10 mins, just adding some antifreeze and bleeding the air. it would run over alittle as I was filling but nothing like that.....sound like you got some pressure there, if it wasnt running hot. I saw a set of ported heads on ebay ready to install for 150.00 today. If that the prob.
 
  #75  
Old 10-14-2011, 12:49 AM
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Well I'm just trying to get a general diagnoses haha but it is a bummer that I've overlooked this somehow and would have to go back in again for a lot more work. I had plans (future) to put some LE2 heads and intake work into it, but no way I could do that right now. So once I get the opti either replaced or just cap and rotor to fix the shudder and miss problem I'll start working towards getting the head gaskets done. I'll have to find a place to check them for me and mill if needed, which would be a pretty penny I'm assuming. When I did the intake it was nice and straight though, and the mating surface with the heads looked fine as well. I might be able to get away with just replacing the gaskets until I want to do the other work; pp heads and intake and put a cam in...like I said, future plans.
 

Last edited by JGuy07; 10-14-2011 at 01:17 AM.
  #76  
Old 10-14-2011, 02:02 PM
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did you bleed the air out uning the bleeders?
 
  #77  
Old 10-14-2011, 02:43 PM
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Yea, I've done that every time I add coolant. Read up on how head gaskets can also cause misses(which I have) and I also have the slight brown tent in my coolant at the rad cap so assuming it's oil but not much. I still have the built up fluids behind the engine from the intake leak and I'll clean that and see if there's any outer leakage from the heads going on.
 
  #78  
Old 10-14-2011, 04:59 PM
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yep sounds like headgasket and would not surprise me if a valve or two are not happy. could always do a compression test. cometic gaskets are the way to go if you can afford em.
 
  #79  
Old 10-14-2011, 05:13 PM
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Yea, every sign I have is subtle. Like I said; misfiring, brown tented fluid by rad cap, no smoke from exhaust yet subtle sweet smells at times. I have never had a problem with overheating since I replaced the relays earlier this year so it's not overheating my engine now, and I don't have coolant loss that I've noticed since replacing intake gaskets, however I've always had a good amount of oil loss. Not sure on how much was just intake and how much were heads but I'll find out now :/

And just to be clear, you can have a bad head gasket(s) without having the smoke out of the exhaust correct? It would also create vacuum problems by pulling in outside air? I am getting excess air from somewhere, which made me take a look at identifying head gasket problems to begin with.
 
  #80  
Old 10-14-2011, 05:49 PM
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just replaced the head gasket in the netter, gm 350 and it did not leak water or oil but was shootin coolant when ever i reved the motor up and we had blow by with steam in the pvc system that did finally show as condensation but never turned the oil milky. i fought with that sob for a month tryin to figure it out before i did a compression test. man i felt stupid when the numbers come up with two dead holes next to each other. it was suckin and blowin back and forth between the two. also had two burnt valves to boot
 

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