Dam-I think I just blew a head gasket

[madkaw]

:mad: Well I was all excited about the cooler weather and how well the car was running and then she started running kind of different. I pulled the plugs and #3 was about carbon fouled, but 1&2 weren't bad. So I whipped out the compression guage and all 6 were hovering around 180-looked good. So I'm thinking why would just one cylinder be rich when the other two on the manifold were decent. I had a spare set of bosch wires so I put them on and figured I would get some new plugs eventually. I swapped the #3 plug around to #1 so I could hopefully see if #3 would do that again. I also changed around by O2 sensor to the other bank of cylinders to see if I had them running fairly close.

I took the car for a long drive and she sounded a little better , but still not right. I get home and pull the plugs again and see no carbon fouling, but a green tint on the foward 3 cylinders-dam. I take the radiator cap off and start it up and see a few bubbles, but I thought it might be from the thermostat just opening. I walk around the back of the car and there is water spitting out the exhaust.

I guess the perplexing part for me will be WHY?? Has my engine been detonating all this time? I know I ran it lean for a considerable amount of time because I didn't realize it was that lean. I guess when i pull the head off ,I will see rest of the story

[JLPurcell]

Steve,

I don't get blown head gasket from your description of the problem??? Good compression, the plug does not usually carbon up when you are getting water in the cylinder just the opposite, and the condensation from the exhaust with our weather lately is not abnormal. It will be interesting to see what is causing your problem. jlp

[madkaw]

I know the description doesn't spell out blown gasket exactly, but the green tint on the plugs worries me. I've never seen my car put out that much condensation either. Maybe it's not fully blown? Not sure what else I can do to troubleshoot. I need to let the engine run again with the radiator cap off and watch it closely I guess.

[Arne]

Leakdown test.

[madkaw]

Not equipped for that test, but good idea

[240260280z]

Are you losing coolant? (Level in rad dropping?)

Pull plugs in morning then have a friend crank car and watch to see if drops of water come out of plug holes.

Edited September 24, 2011 by Blue

[LeonV]

FWIW, when I changed my plugs recently, they all had green tint. I was using straight water for coolant, no glycol. I'd never seen it before, but didn't think much of it as the car runs strong. What, exactly, are the symptoms you're experiencing Steve?

[madkaw]

The engine just didn't sound or feel the same, maybe a bit lethargic would be a way to decribe it . It's one of those deals that I worked on the car to fix a couple of things and suddenly it seems different. One thing I worked on was mooring down my weak trans mount. My method of fixing caused more noise to transmit into the car(semi solid mount), so I experiencing unusual noises for the first time. The car ran decent, but didn't seem to have the POP it had previous.

I will state from my earlier post that I haven't done another compression test since finding the "green tint". The level in the radiator was down a little-but so little it has me second guessing. I guess I was expecting something more defining from a blown head gasket.

No overheating-not even close

No detonation-that I could here

No laboring from the starter-like my timing was too far advanced

Always run premium

[madkaw]

WOW, just priced a Nissan headgasket from Courtesy-150$$

I don't think I will consider anything else.

I would love to find out that this problem is tied to my persistant oil leak at the rear main. I have changed everything and she is still pushing out oil. Could a leaky headgasket around the oil passage be pressurizing the oil??

I think in the end I will have concluded that I ran this engine too lean for too long with too much timing and compression-Compression detonation-

hopefully I didn't do any damage

Edited September 24, 2011 by madkaw

[cygnusx1]

Head gasket leak pushing oil out the main seal is a long shot at best. By the time the oil gets to the rear main seal, it has already dropped down to crankcase pressure, which is much, much, lower than oil pressure. Make sure all your crankcase breather systems are, well, breathing.

Changing a head gasket in a Z is relatively easy. It's one of those jobs that seem like a big deal, until you have done it. Looking back at it, you will say, "That was easy".

Don't pull the head though until you have totally proven that the head gasket has failed. So far you don't have proof.

Sometimes you just have to drive it until it gets worse. My car had three shattered pistons and a severely breached coolant passage in the head gasket with gallons of water out the tail pipe...and it still started and ran!

Edited September 25, 2011 by cygnusx1

[madkaw]

I knew it was a long shot-but I've been fustrated over this issue.

Don't know if I want to drive it till it get's worse-especially a fairly new motor. Like you said it's not a huge job to change the gasket. When I get back into town Im going to look at it some more. I guess I will do another compression test now that I have green plugs. I have never seen fluid out my pipes like this before-I'm betting the gasket gave out.

My Z hasn't given me a lot of fun this year:(

[hr369]

see if some of those symptoms go away. also could try

block test kit

http://www.blockchek.com/index.htm

Edited September 25, 2011 by hr369