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| Won't idle down and got worse https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=9152 |
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| Author: | wkearney99 [ Fri Apr 27, 2012 2:34 pm ] |
| Post subject: | Won't idle down and got worse |
Had a bit of a scare on re-commissioning this Spring. Starboard engine (6.0L Crusader V8 inboards) wouldn't settle down after starting, kept idling at 2000 (instead of the usual 6-700). Port was fine. Thought it might be a simple matter of being cold so I took it out for a run. Wouldn't sync with the other engine, stayed about 1k RPM higher. But it would go faster. After about 10 minutes I throttled down and it wouldn't come below 3k. Did a bit of debugging out on the water and removed the throttle linkage and it still wouldn't come down (simple to pop loose). In fact, it was getting worse (now stuck at 3700). Way too fast to use it, as that would wreck the transmission. So I limped back in on just the port engine to the open T-dock. Then had some friends help pull it by lines into it's slip. There was too much wind to be able to make the hard left needed to get down my fairway. Did a bit of debugging and couldn't find something obvious. Did find a small fuel leak from where someone else replaced my filter last season. Damned if you do, damned if you pay someone else... grrrr... Started thinking more and realized it seemed like an air flow issue. So I pulled off the plastic top cover to get a closer look at the engine. The cover screws into two posts molded into the intake body. Lo and behold, one of the posts wouldn't loosen. Turns out the post was cracked off of the intake! This left a massive vacuum leak into the manifold. About a 1" circle. When I jammed the post back onto the hole and taped it down the engine returned to behaving normally. I'll be using a bit of epoxy on it to fix it, and possible a bit of stainless wire to hold it physically too. Otherwise it looks like I'd have to replace the entire intake runner. No idea how the post came to be cracked that way. But it does seem like a bit of a design deficiency as any excessive torque on the cover bolt would risk cracking out the post. So if anyone else runs into the same sort of problem, be sure to go over the intake thoroughly checking for leaks. Meanwhile it's been 6 years and I may be due for new exhaust risers. Seeing a slight leak on the port side and a bit of a rust line on both engines where the risers meet the exhaust manifolds. Fortunately that's not a complex job, just heavy. |
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| Author: | Cap'n Morgan [ Fri Apr 27, 2012 2:51 pm ] |
| Post subject: | Re: Won't idle down and got worse |
wkearney99 wrote: No idea how the post came to be cracked that way. Probably the same "someone" who replaced your fuel filter..... |
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| Author: | ric [ Fri Apr 27, 2012 2:55 pm ] |
| Post subject: | Re: Won't idle down and got worse |
Cap'n Morgan wrote: wkearney99 wrote: No idea how the post came to be cracked that way. Probably the same "someone" who replaced your fuel filter..... Same mechanic who blamed E10 and charged some poor guy for two fuel pumps on a 2010 boat? |
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| Author: | wkearney99 [ Fri Apr 27, 2012 3:10 pm ] |
| Post subject: | Re: Won't idle down and got worse |
Yeah, hard to say. Not like he would've had to remove the cover as it's nowhere near the fuel filters, nor would it give a better view of them. I had to remove it myself to get better access when doing the sparkplugs. So it could just as easily have been my own mistake. As for blaming ethanol, go find another thread for that nonsense. Either way. That said, I did think about potential fuel issues when this happened. But figured I'd have trouble with NOT gaining RPMs had it actually been a fuel quality problem. Turned out not to be the fuel at all, but, essentially, an excessive air mix. Makes me wonder about how the engine system decided to 'auto-correct' for it. But these are 2005-era engines, just before Crusader went with full CANBUS engine systems. So it's not like I can hook up an OBD monitor to examine flow rates and such. I've got a $20 eBay bluetooth-OBD module and the Torque app on my Android phone. Works great at showing all sorts of engine data. When hooked up to my Jeep it revealed a marginal set of O2 sensors well before it would've thrown a DTC code (and probably have allowed an excessive mix to fry the catalytic converters). In fairness they are a 60k miles suggested service part and I've got 68k on it. |
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| Author: | aguyindallas [ Fri Apr 27, 2012 5:53 pm ] |
| Post subject: | Re: Won't idle down and got worse |
Is it something that perhaps somebody stepped on top of the cover or leaned on it while servicing it, causing it to break under stress? It almost HAS to be something like that as it doesnt seem possible for it to break any other way. Yes, I too am done hearing about E10 plus and minus. |
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| Author: | wkearney99 [ Fri Apr 27, 2012 7:49 pm ] |
| Post subject: | Re: Won't idle down and got worse |
The hatch tilts up above the cover, but there's nowhere near enough room for anyone to step on it. I suppose someone laying on it to reach the belt (rearward) end of the engines might be a problem, but there are other plastic stand-offs under it to handle that. No, I'm guessing it was either me or the filter mechanic that torqued the bolt enough to twist out the post. I can't quite describe it properly, it's not just a chunk of plastic that broke out. It's almost like some sort of fitted plug that popped out. The cover screws down into this post and the post somehow attached to the intake runner. I'm guessing with a sonic plastic weld as there's no clear type of plug or other attachment point. The parts diagram for the engine doesn't show it as being a separable piece. As for fuel issues, way too many of these folks fail to understand that gasoline itself is a SOLVENT and ABSOLUTELY WILL EAT THROUGH HOSES and non-metallic tanks, eventually. This also includes diaphragms and floats inside of carburetors and pumps. Some sooner than others, but eventually all of them will have issues. Even without additives. It's pretty naive to think 10+ year old hoses or tanks that have never seen maintenance won't require repair/replacement. Yes, in a few unique situations ethanol can exacerbate that condition. But the ones susceptible to this have long since had this problem and had to deal with it. The rest are just ones succumbing from long term exposure to the gasoline, additives or otherwise. No surprise here, that's just what happens to material soaked in solvents for all that time. |
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