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Last night I went out to Seafoam my 280zx and when I pulled the PCV hose to the brake booster off, the engine died.

I plugged the hose with my thumb and started it back up, went to add seafoam and it died before I could. I decided to see if I could get it to stay running by holding down the throttle a bit, which worked. I let go and the engine died. I only have so many hands, so I put the Seafoam away and made a video to get some feedback

1. ) checked the distributer cap for cracks, it looks ok.
2.) I replaced the plugs and wires a week or two ago.
3.) I siphoned out 10 gallons of old gas and replaced it with fresh 91 octane gasoline.

I have a new fuel filter I'm going to put in today. I don't have a compression tester, fuel pressure tester so I don't know what the numbers are.

In the video, the PCV hose is removed, and I'm keeping the engine running by playing with the throttle. When the hose is connected, it pops less frequently in the intake manifold. My dad is lazy and says "Just take it to a mechanic and throw money at it" but where's the fun in that?

I'd like to fix it myself, or at least know if this is beyond a weekend of work. Thanks for your input

I can't link the video or else it rejects my post...

NismoPick

The line to the brake booster is not a PCV valve... it's a direct line to the intake. The PCV is on the bottom middle of the intake. Your motor won't stay running w/ the brake booster line disconnected because it's a huge vacuum leak. Reconnect that line and use a smaller one.

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Oh... lol. I'll see if I can force-feed the seafoam tonight, also without getting the fire dept. or 5-0 called. Thanks for the tip!

Now to fix the mysterious popping :/ ....


Video: http://smg.photobucket.com/albums/v6...chine280zx.mp4

snwbrderphat540

The popping sounds like the AFM flapper/intake backfires. Which could be from the brake booster line being of. Put that back on, take off a vac line more from the center of the intake manifold and that is SMALL place the hoes into the can of seafoam, and start it, it should idle fine since it will still hold intake Vac but also suck in the seafoam, you can rev it up a little if you want, the car will smoke like a bitch, do about half the can then throuh the other half into the gas tank and you'll be good.

Make sure all Vac line are re-connected and start, and drive around till the smoking stop with any kind of driving you like.

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I ran 1 can through a much smaller line in the middle of the intake manifold, waited 30 minutes, did another half can and poured the other 1/2 into the gas tank. I can't drive right now, I have class but I might do it when I get home.

The popping happens when the brake booster is on, just not as often. when I seafoamed the engine, smoke came from the valve cover and from under the intake manifold, presumably the exhaust manifold. Which would mean my PCV valve is NFG and my exhaust manifold probably leaks

snwbrderphat540

THe PCV on these cars don't involve the valve cover. it goes from a hole in the side of the block to under the intake manifold.

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My dad said the PCV vavle might be clogged, which would have caused the valve cover gasket to blow. He explained when the PCV valve cannot regulate pressure, it puts strain on the gaskets. I'm not sure how accurate this hypothesis is, I'm just repeating what he said. he suggested;

- replacing the PCV valve
- replacing the valve cover gasket

I think I need to replace the exhaust manifold gasket, or perhaps the headers have a leak. I'm not sure what causes the AFM/intake backfire. I also think my dad can make mis-informed hypotheses at times.

snwbrderphat540

nah... the PCV on these are so primitive, but the valve itself I hardly ever see clogged... its something I don't pay much atention to. and these cars just have crappy made intake/exhaust mani gaskets since they are the same... So they just blow sometimes... they need to make an MLS one. sell it for 50 bucks a pop and someone would be rich haha.

WildmaN

Hey if you have an actual header on your car. Get the header gasket from MSA, for about $12. Well worth it, and also you can't put a regular gasket with a header. And I never had had the PCV valve plug on me. On any of my engine's.

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Sorry Wildman, I don't have headers I have a stock exhaust configuration. I'm pretty sure they're made of iron, which means my manifold has rusted and the gasket is NFG. I don't get my tax return for a while so I think I'll just buy the stock gasket and a blowtorch to get those pesky rusted bolts loose.

Just to confirm, you have to take off the intake manifold as well to change the exhaust manifold gasket, because it's all once piece, right?

I figure I can either take it to a mechanic, or do it myself and use the money I would have spent on the mechanic anyway and get some sweet performance headers

thoughts? comments?

snwbrderphat540

you can buy my pacesetter headers for cheap. lol. and Yes you have to remove the intake manifold and then the exhaust manifold. It isn't hard though.

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You got me interested, How much + shipping to 95054, California? (Although I'm not sure if my N/A 1979 zx has square or round exhaust ports on the block.)

Also, Do I have to drain the coolant too? Or is it just unplug wires, fuel lines, unbolt intake, unbolt exhaust, clean/prepare mating surfaces, replace old bolts with new, and reconnect everything?

One more thing, I read this from another forum...

" replacing the manifold if and when you do this you want to replace the 8mm studs with 10mm studs,, see they lie,,, BIGGER IS BETTER!!
you will at that point have MUCH ( THEIR ARE THOSE CAPS AGAIN) life and less problem with either a stock or an aftermarket part.
the reason behind this is the length of the manifold causes it to BANANA ( NO JOKES PLEASE) and it breaks off the outside studs hence the need to replace them
need more info ASK TONY DDDDDDDDDDDDDDD" - Tony D. - Some other Zcar forum

snwbrderphat540

You can do that, but if you don't break any studs taking them off, I say just clean em up and put anti-sieze on them. The headers, pffft, 40 bucks + shipping. They are round port. And I think (though not positive) all the S130's had round port other than the turbo head. What is you head cast number? That is the easiest way to find out.

you don't HAVE to drain the coolant, but there are coolant lines in the throttle body that if you disconnect, will leak. So you can just pinch the lines with clamps and undo them and have a little splashing, or drain the coolant just a bit.

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$40, nice. I'll check my head casting number when I get home. Where is it stamped at?

I called a mechanic and he said $85/hour for at least 3 hours if none of the studs break. There are 10 studs and if they break they have to be drilled out which takes longer. Then he gave me the classic mechanic line, "Bring it in and I'll take a look at it."

So at least $255 to $510 for this job to be done by this guy, and I'm still not sure if it would pass smog. At lunch today, my dad suggested driving the car to the mechanic and just saying, "I want you to make this car run well enough to pass smog." But his solution for everything is to throw money away.

WildmaN

Your dad sounds like he is not too bright. No offense. Just get yourself a Haynes or FSM on your Z. You can get the FSM free here. Ask for the link, I don't know what it is. These cars are relatively easy to work on. Oh, and you should have round ports on your head. And that is a steal for the headers.

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I have the FSM and the Haynes manual already.

My dad is a total moron when it comes to cars. It's another story when it comes to the network programming stuff he gets paid to do. @_@

I think I'm going to have the mechanic diagnose the issues for $85, and then fix them myself to save some coin. $85 is a night at the bar, or a trip out to dinner. so I just wont go next week, lol. We'll see how it goes, hopefully better than my experience with seafoam :/

snwbrderphat540

most checkups on cars are done for free... lol. What a tool mechanic. And you can swap the manifolds yourself, it'll take you a little while being your first time, but it's pretty hard to screw up.