yoshi_w Posted January 31, 2011 Share #1 Posted January 31, 2011 Hi, so sometimes when I turn off the engine in my 1973 240z, it rattles and hisses for a few seconds after I remove the key and all around doesn't sound good. It doesn't do it all the time, but its starting to worry me. Does anybody know whats wrong? Thanks! Oh, and its a 1973 240z runnning an l28 with flattop carbs. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/ Share on other sites More sharing options...
LeonV Posted January 31, 2011 Share #2 Posted January 31, 2011 Research engine dieseling or run-on. Could be a few things like excessive carbon deposits or engine overheating, for example. I'd check your coolant first and flush it if it hasn't been done in a long time. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344015 Share on other sites More sharing options...
Dobber Posted January 31, 2011 Share #3 Posted January 31, 2011 I think you will find that those flattop emission carbs are the least desirable carb you can run. Replace with round top S.U.s from a 72 and burn premium fuel. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344056 Share on other sites More sharing options...
Jennys280Z Posted January 31, 2011 Share #4 Posted January 31, 2011 Here's a video of a 260Z with a horrible case of run-on. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344058 Share on other sites More sharing options...
Diseazd Posted January 31, 2011 Share #5 Posted January 31, 2011 Yoshi.......An L28 with flat-tops? That's a first......very rare! Bruce Palmer where are you? I agree with Dobber. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344064 Share on other sites More sharing options...
sblake01 Posted January 31, 2011 Share #6 Posted January 31, 2011 (edited) It's a 73 with a 280Z engine but has the stock 73 intake setup....When I bought my car it came with an l28 but retained the flattop carbs from the 1973 year my car was made (1973 240z). Edited February 2, 2011 by sblake01 Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344066 Share on other sites More sharing options...
Diseazd Posted January 31, 2011 Share #7 Posted January 31, 2011 I've heard that run-on can be caused by too much advance......try retarding your timing. See if that helps. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344067 Share on other sites More sharing options...
yoshi_w Posted February 1, 2011 Author Share #8 Posted February 1, 2011 Thanks guys for all the help so far! and I am pretty sure it kept the flattops due to the carbs being the stock intake setup. I would like to replace them eventually, but I doubt thats the problem, beyond the butterfly valve not closing all the way. I will try to adjust the timing as soon as I can get a hold of a timing gun. New development though, as I was driving today the engine just started to cut out and when the engine did cut back in, there was no power at all. Are these two problems related, like would this new problem also be caused by bad timing? Thank you everyone so much so far! Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344101 Share on other sites More sharing options...
Jennys280Z Posted February 1, 2011 Share #9 Posted February 1, 2011 Yoshi.......An L28 with flat-tops? That's a first......very rare! Bruce Palmer where are you? I agree with Dobber.OT: Wow your dad's cars are wonderful! Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344103 Share on other sites More sharing options...
Reverend Posted February 1, 2011 Share #10 Posted February 1, 2011 Related to this topic: I have 72 240z and its having the same symptoms. Banging, rattling and hissing after shutdown. In my case the engine is overheating..There is either air in the system or bad head gasket? Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344128 Share on other sites More sharing options...
Diseazd Posted February 1, 2011 Share #11 Posted February 1, 2011 Yoshi......Just loosen the 10 mm nut on the base of the distributor.....start the car then twist the distributor counter clockwise a small amount.....see if that helps.Timing can be set by listening to the engine to find it" s smoothest idle.Make sure the engine is fully warmed up when doing this.Good Luck. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344138 Share on other sites More sharing options...
Walter Moore Posted February 1, 2011 Share #12 Posted February 1, 2011 Engine run-on can be a symptom of overheating, at least cars that are running way to hot will run-on. Link to comment https://www.classiczcars.com/topic/38428-rattling-and-hissing-when-engine-turned-off/#findComment-344165 Share on other sites More sharing options...
Yarb
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