pain in the @$$ buick need help

natehead · 11-17-2008, 05:30 PM

98 century, dtc cyl 6 misfire, thats it. cyl 4 and 6 balance out at 52-55 lbs comp. no water in oil, no oil in water. no vacuum leaks, new plugs, good wires. misses at idle and a little off idle , pretty smooth at speed. is there any other way of seeing wtf is going on short of tearing it down? and what do you guys think it is? I beleive head gasket.

RedZMonte · 11-17-2008, 05:41 PM

What kind of plugs/wires are you running? have you pulled plug #6 to see if there is any crud/corrosion on the plug? did you try replacing that 1 plug/wire to see if the problem goes away? try swapping a couple of the coil packs around and see if the miss moves to another cylinder, if so most likely a bad coil. then you can also suspect the ignition control module or maybe a plugged/leaky injector. have you ran FI cleaner (BG44K)?

If the plug come out clean after running then i would not suspect head gaskets. usually you will have oil/water mixing, smoke out the tail pipe or corrosion on the plug if the head gasket is failing...

Hope this helps,
S

natehead · 11-17-2008, 05:46 PM

delco plugs and wires(new). didn't swap around coils, will try when i get home (doesn't explain the really low comp between cylinders tho)plug was nice and tan-ish. no smoke or abnormal steam for this time of year or antifreeze smell. is it likely that the HG blew between the cylinders without getting to oil or water jackets?

RedZMonte · 11-18-2008, 08:14 PM

i wouldnt think HG if its not smoking. i would suspect maybe something in the head.. but again im just guessing. i didn't read the compression in your 1st post... well i did but didn't think about it.. my guess is you will have to pull the head really dianose the problem..

S

95Grand-Am · 11-18-2008, 11:35 PM

I have heard of head gasket blowing between cylinders. Turn the engine so that either 4 or 6 has the valves closed, put pressurized air into that cylinder, and check the other cylinder to see if air is crossing over to it. You should be able to get an adapter at any parts store, that wil screw into thew spark plug hole and hook to an air line.

Superdave · 11-19-2008, 07:56 AM

check your injectors

natehead · 11-19-2008, 01:34 PM

definite head gasket...really bad head gasket. Just crapped out on me last night......then the smoking, corrosion on plugs, and all of the other tell tale signs. The gaskets bad enough that all of the compresion is bleading across the whole front bank and choking it out, pulled 4 or 6(either or) plug completely out and it ran enough to pull it into the trailer and get it to our shop. so its motor pulling time gonna put a 3400 in.

natehead · 11-25-2008, 12:33 PM

IT was all caused by a plugged cat. put in new head gaskets and u-lim gaskets.. still didn't run, so i unbolted it at the mani and it ran fine. thanks for the help .