1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Found vacuum leak

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Old Dec 18, 2007 | 07:06 PM
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From: Austin
Found vacuum leak

Well it ended up being the intake manifold gasket after all. So I replaced it and its still steaming like a biotch, and yes I cleaned it really well. I was hoping with rotaries that you let the enging warm up the gasket and let it cool and that would stop the leak. Coolant is going into my intake runners I believe.
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Old Dec 18, 2007 | 07:15 PM
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I don't know if there was an original thread that I missed but...

There are two parts - the intake manifold gasket and the rubber o-rings which go around the coolant holes between the intake manifold and the engine.

Personally, I hate the rubber O-rings, so I replace them with 20mm Frost Plugs (you can get these from any place that rebuilds engines, or some parts stores can order them. I got a box of 10 for like $4). Those can be used to carefully plug the holes in the block, so that you only have to worry about the gasket and not the coolant. Plus it makes your gasket last longer.

If you want to use the stock o-rings, use high-temp silicon to hold them in place. If they were to get pinched on reassembly that would cause a leak.

Another thing that can cause a leak is old gasket material. The first time I removed my intake manifold my gasket was on there so tough that after I went over it with a wire wheel, it *looked* like metal. I actually reassembled my intake half a dozen times before I realized that parts of the mating area were flat and parts were raised. It took a lot of time, patience, "gasket remover" (a spray can of stuff that eats through gasket) and lots of wire wheel, but it all came off and then there were no leaks (vacuum or coolant).

Jon
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Old Dec 18, 2007 | 07:22 PM
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From: Austin
I assume the steel is where the intake ports are going in? I couldn't tell if it was rubber or the steel, it was slightly raised but I couldn't remove it for anything. Really irritating but I really want this PITA to run. I'll try what you said. Thank you. I've taken the damn thing apart so many times the rat's nest doesn't confuse me.
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Old Dec 18, 2007 | 08:18 PM
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Keep at it, i know it can be frustrating, but dont give up
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Old Dec 23, 2007 | 09:02 PM
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From: Austin
Alright I did the 20 mm freeze plugs, but I still had steam coming out. I am hoping its just what poured onto the exhaust. We will see in a few days. Thanks.
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Old Dec 23, 2007 | 09:08 PM
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yikes, where exactly is the steam coming from?
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Old Dec 23, 2007 | 10:03 PM
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From: Austin
Thats the hard part to figure out, since the fan is blowing. It seems to be above the exhaust manifold, from where I can't figure out. Could it be the Tstat isn't functioning and the pressure is building too much?
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Old Dec 23, 2007 | 10:40 PM
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From: Ottawa, Soviet Canuckistan
Aah... are you sure it's steam?

Marc's car had a similar situation going on, it ended up being the exhaust manifold gasket making the "steam"

So your idle problem might be something entirely unrelated to the smoke.

Jon
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Old Dec 24, 2007 | 02:00 PM
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From: Austin
The darkside is twisted.

The smell is a bit sweet, yet when it hit my tongue it was kinda bitter; probably death knocking on my door. :P

I really hope you are kidding about the vacuum leak. I haven't run it long enough to find out since I'm afraid of over heating the engine.
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Old Dec 24, 2007 | 10:06 PM
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From: Ottawa, Soviet Canuckistan
I made a pretty good post here about tracking down vac leaks:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/nikki-idle-problems-714426/

So if you really want to troubleshoot your intake to its fullest extent, read that and run with it.

But yeah, as for overheating, start it, run it and WATCH the gauge. If it moves enough that the needle covers the C, turn it off and you'll have caught it before it heated up to do any damage. If it just covers the little degree sign before the C you're fine, that's proper running range.

Jon

Edit : I just realized that my gauge cluster might look different from yours.
Here's mine. Note the "C" and the degree sign I was talking about on the temp gauge.

Attached Thumbnails Found vacuum leak-dcp03942-medium-.jpg  

Last edited by vipernicus42; Dec 24, 2007 at 10:14 PM.
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Old Dec 24, 2007 | 10:45 PM
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From: Ottawa, Soviet Canuckistan
Found a better pic

Here's where my temp gauge stays at operating temp. I took this partway through a 5hr drive to Toronto I believe, when I clicked over a cool-looking number on the highway I pulled off, topped up the gas and snapped a pic.

Remember: Happiness is a full tank!



Jon
Attached Thumbnails Found vacuum leak-gauges.jpg  
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Old Dec 25, 2007 | 05:05 PM
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From: Austin
Well I went back out there and started it up. It smelled of coolant, but it wasn't steaming. Rather it also smelled like burning rubber. (?)

Must be the new gasket. Anyways, thanks for the write up, I'll have to try that out.
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Old Dec 25, 2007 | 08:48 PM
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OMG those gauges are so WEIRD!!! Where can I get some of those fancy gauges??? I need some of that right there...
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