The dreaded exhaust leak

[Pomorza]

Ladies and gents

About two weeks ago my car developed a rather nasty exhuast leak (pretty bad actually, nice TICK noise when you start it and pretty much there the whole time). At first it would go away on its on when the motor got warm but now its just there, all the time. Today I tightened everybolt on the manifold, other then the last two (going towards the engine) they were all pretty tight. I also tightened the manifold to pipe bolts. Leak is till there without avail. I've come to the conclusion that I may have blown my gasket out and no amount of tightening will help.

So here's a couple of questions. First off, would driving on a bad gasket cause any major damage. I won't have time until after Christmas - 26th or so - to do this. I won't be driving it for more then a few days (I leave to see family on the 20th and I'm renting a car (see previous message(s) about this)? I've heard (and seen) burnt and broken valves from bad gaskets but these were from years of neglect. Secondly, do you guys agree with my theory on the blown (or bad, burnt etc.) gasket? Thirdly, is there anything I can do so this doesn't happen again. This gasket itsn't more then a year old (I replaced it along with the exhaust June of 2011 (so last year roughly, which was a pain in the arse as the bolt under the tstat was broken and we had to drill/tap it) and it now is bad. Finally, do these things need to be torqued to the specs given in the FSM (which I think is like 22 lb/ft) or can I just tighten the crap out of them until they are overly snug.

Thanks for the read.

Jan

[CW240Z]

Have you tried the soapy water test to verify that it is the gasket leaking? Get a spray bottle of soapy water and shoot it on anything that could be a possible source to leak.

I'm sure there's a reason why Nissan has specific specs on torquing the exhaust bolts down. Having them too tight can lead to crushing gaskets and/or snapping a stud off.

Chase

[Zed Head]

I've heard that blown head gaskets make that noise also, along with cracked exhaust manifolds. I've also read that Seafom is a good way to find an exhaust leak from all of the smoke it produces. A leakdown test should confirm the head gasket.

You might also check your spark plugs, one could be loose and on its way out.

[jfa.series1]

You really don't want to crank down on the intake or exhaust manifold nuts. The studs are mounted in the aluminum head and will pull right out if too much torque is applied.

[Pomorza]

I've heard that blown head gaskets make that noise also, along with cracked exhaust manifolds. I've also read that Seafom is a good way to find an exhaust leak from all of the smoke it produces. A leakdown test should confirm the head gasket.

You might also check your spark plugs, one could be loose and on its way out.

Wouldn't there be other signs of a head gasket failure? Poor performance, coolant burning etc?

I'll pull the plugs next weekend and take a look.

Thanks

Jan

[Oiluj]

If it is your ehaust gasket, welcome to the club! I have the manifolds off and will be putting them back on over the holiday...

The bad news:

You can re-torque the manifold nuts to spec without worry, but it's unlikely to solve the problem. In my experience, once an exhaust gasket is breached, they don't usually re-seal.

The good news:

If you gather all the parts in advance, it only takes a few hours to ghange-out the the manifolds.

Let us know how it works out.

[siteunseen]

A vacuum gauge reading could help out too with the blown head gasket. http://atlanticz.ca/zclub/techtips/vacuum/

[Oiluj]

Ladies and gents

About two weeks ago my car developed a rather nasty exhuast leak (pretty bad actually, nice TICK noise when you start it and pretty much there the whole time). At first it would go away on its on when the motor got warm but now its just there, all the time. Jan

FWIW, mine had the "exact" symtoms you describe. Took off the manifolds and the leak path was obvious, a dark line on the block from the exhaust port up beyond the gasket edge line on the head.

[Pomorza]

FWIW, mine had the "exact" symtoms you describe. Took off the manifolds and the leak path was obvious, a dark line on the block from the exhaust port up beyond the gasket edge line on the head.

I poured some seafoam into the Z's engine to see if I can find the exhuast leak. There is a very very small leak coming from the front of the manifold. I can clearly hear the "tick" coming from this area (the #1 exhaust). I don't know why everyone here keeps suggesting a head gasket. While I agree they do make said sound I can't see it being this. I don't have oil in the coolant or coolant int he oil. I don't have any smoke at all neither at start up or accel/decel. I pulled the plugs today (as I replaced them after running the seafoam). All were pretty consistent, #5 and #6 were a bit on the lean side. #1 was a bit hot (reddish hue).

Thanks for the info

Jan

[Zed Head]

I was the only one that suggested head gasket. Because you said "may have blown my gasket out", not "certainly blown the manifold gasket". Heads warp and head gaskets leak, it happens, more so with aluminum heads. It seemed worth checking while the engine was together, rather than after the manifolds are off. And you didn't mention the state of the water and oil in your first post. siteunseen just suggested a way to check it. Even so, that's just two people.

Just being thorough in my response. I try not to waste people's time, although this post might contradict that.

Did smoke come from the leak in front or are you still working from noise? A piece of heater hose to your ear works well to find noise from a small area. And, sometimes, you can actually feel the hot gas leaking with a hand or finger, if you can shield the air from the fan.

[Pomorza]

I was the only one that suggested head gasket. Because you said "may have blown my gasket out", not "certainly blown the manifold gasket". Heads warp and head gaskets leak, it happens, more so with aluminum heads. It seemed worth checking while the engine was together, rather than after the manifolds are off. And you didn't mention the state of the water and oil in your first post. siteunseen just suggested a way to check it. Even so, that's just two people.

Just being thorough in my response. I try not to waste people's time, although this post might contradict that.

Did smoke come from the leak in front or are you still working from noise? A piece of heater hose to your ear works well to find noise from a small area. And, sometimes, you can actually feel the hot gas leaking with a hand or finger, if you can shield the air from the fan.

Zed head,

I reread my orginial post and did indeed realize that the answer you guys gave were quite good. Thanks for that. As for the leaks. I did see white smoke (from the seafoam) creep out of the number #1 exhaust until the fan turn on at which point it was pretty hard to tell anything. Secondly, I have isolated the sound (using a screwdriver) and that's where the ticking noise is coming from. I'm going to check again with an actual stethescope a bit later this week.

I expected this to happen. When I was replacing the gasket (about a year ago) the #1 stud (the one under the thermostat housing) snapped and broke off in the head. I drilled it out (using a smaller bit) and retapped the whole with a M12 (or m10 whichever the studs are) and it worked well. I replaced all the studs (all of which came out fine - minus the first as explained). When retightening them I figured that I shouldn't tighten it too tight as it may break again. I will do the vacuum test when I return from my trip.

Thanks for all the help

Jan

[Zed Head]

No problem, I've had the exhaust leak frustration, and the broken studs that had to be drilled out (thermostat housing) frustration, and paid a shop good money to remove a stud (one of the three for the flange to the pipe) and resurface the sealing surface (before I knew that undamaged manifolds are relatively easy to find). Did you check the manifold for straightness, across all of the ports, and good sealing surfaces on each one?

Good to know that the Seafoam showed something, another trick for the tool box. Good luck.