Cub Cadet RZT 42 won't start

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  #1  
Old 06-15-16, 06:28 AM
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Cub Cadet RZT 42 won't start

I have a 2010 Cub Cadet RZT 42. It has a Kohler SV600 engine. Last summer it was harder and harder to start with every passing week. It would crank for 10 or 15 seconds before it would slowly sort of puck, puck, puck until it built up enough momentum to start. I was thinking I should check the fuel system, maybe clean the carb. But I didnít. I did replace the battery though.
This season it did the same thing only it took longer to start. Iíve only been able to start it three or four times. Until last week it wouldnít start at all. It would still half heartedly fire a couple of times, but no start.
So, I checked the spark plug. Grounded it to the crank case, turned her over and got what looks like a good spark. I removed the fuel lines and made sure they were clear. I replaced the fuel filter. I tested the fuel pump by removing the line from the carb and cranking the engine. I got a good fuel flow. I took the carb off, cleaned it (it really wasnít that dirty) replaced all the replaceable pieces with one of those handy dandy repair kits.
AndÖ.the engine still wonít start.
One other thing that happened last summer, the muffler fell off. It appears to have gotten so hot that the metal expanded and warped around the screws that were holding it to the mounting plate. It just fell of the screws.
Iím beginning to suspect I have a timing problem. But frankly, Iím reaching the end of my experience rope. Any help you guys could give would be greatly appreciated.
 
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  #2  
Old 06-15-16, 08:20 AM
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I believe I would start by adjusting the valve lash.
 
  #3  
Old 06-15-16, 10:38 AM
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Thanks marbobj. I'll give that a try. Won't be til next week though. The grandkids are coming in town tomorrow and will be here all weekend. I need to round up some feeler gauges too. I'll post back and let you know what happens!
 
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Old 06-15-16, 11:32 AM
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Will it start with a shot of gas or starter fluid in the carb?
How does it run once it starts?

Might check your choke adjustment and use....I notice on those engines that when the air temp is warm, they start a bit easier starting with full choke then go to half after a couple of revs, (Assuming you have a seperate manual choke lever)

Checking the valve clearance is a good idea as well, if you do, I would have a new gasket or permatex on hand. Those are some type of cork gaskets and the heat really hardens them, most start leaking by the age of your.
 

Last edited by BFHFixit; 06-15-16 at 11:48 AM.
  #5  
Old 06-15-16, 05:24 PM
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I agree with adjusting the valves and if you old gasket doesn't break when you take it off (probably won't), I prefer to use the old hard gasket and coat it with peratex and re-use it instead of putting a new one on. The outdated cork gasket will only harden and leak again soon after replacing it.
 
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Old 06-16-16, 05:42 AM
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A shot of gas in the carb won't do it. I even tried a little gas in the spark plug well. It will halfheartedly fire a couple of times, but no start. And the last time it ran it seemed ok. That is to say it didn't run rough, it idled fine and no back fire. I don't have a separate choke.
Thanks for the heads up on the gasket!
 
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Old 06-22-16, 08:09 AM
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Hey marbobj! I adjusted the valve lash on my cub cadet yesterday and it started up like it was brand new! Big big thanks for the advice! The intake valve was really loose and the exhaust valve was tight as a drum. Just curious as to how they could have moved so far out of tolerance. Is this indicative of some other problem? Thanks also to Mr. Cheese and BFHFixit!
 
  #8  
Old 06-22-16, 09:21 AM
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Not really. It comes up here a lot on an engine with adjustable valves that haven't been adjusted. Usually it's the first thing the regular shop guys bring up.

The loose valve would be pretty normal, but the tight one sounds like you may be adjusting it on the wrong part of the cam. What position are you putting the flywheel at for adjusting the valves. It should be about 1/4 inch past TDC.
 
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Old 06-22-16, 11:10 AM
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I agree, valves don't get tighter on OHV engines so something wasn't right during the adjustment procedure.
 
  #10  
Old 06-22-16, 12:54 PM
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Hmmmm. I have a manual for the engine. It said to do the adjustment at TDC of the compression stroke. I rotated the flywheel 2 or 3 times through all 4 strokes to make sure I was at TDC of the comp stroke. Having said that however, I'm pretty sure there was no clearance between the rocker arm and the valve stem no matter where I was at in the cycle. I remember thinking that was kind of strange. Do you think I should readjust?
 
  #11  
Old 06-22-16, 01:42 PM
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The 1/4 inch past TDC is for an engine with a compression release. If yours doesn't have one the TDC setting would work. I think I would double check the lash. Something may have slipped a little when you were inserting the feeler gauge or you may have had it on the exhaust stroke.
 
  #12  
Old 06-22-16, 04:19 PM
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I believe it does have a compression release. So 1/4 inch past TDC....in other words reach TDC then advance just a little further so that the piston head recedes back down into the cylinder by 1/4 inch?
 
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Old 06-22-16, 04:51 PM
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Yup, that gets you past the compression release. The compression release holds the exhaust valve slightly open on starting for that small rotation of the cam. Once it starts that release goes out of play.

With all that in mind that could be why the exhaust valve didn't have a lash to it at TDC.
 

Last edited by marbobj; 06-22-16 at 05:15 PM.
  #14  
Old 07-03-16, 01:03 PM
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Hey Marbobj! Sorry it took so long to get back. Made the readjustment. Running really fine now! Thanks again!
 
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