Loose Valves 2004 450 Foreman - Honda Foreman Forums : Rubicon, Rincon, Rancher and Recon Forum
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post #1 of 27 (permalink) Old 03-28-2011, 08:45 PM Thread Starter
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Loose Valves 2004 450 Foreman

Hello, I was hoping to get some help? I have a 450s it started smoking after 3500 miles. We rebuilt the top end. The engine sounded fine when we cranked it and then it started tapping in the valve train. I pulled the valve cover and put on topdead center and the exhaust valve had at least .040 loose play in it. I adjusted it and ran the engine again and all of a sudden the engine shut off and you could hear exhaust huffing thru the exhaust. I pulled the cover again and the exhaust valve was as over tight as it was loose before. So I readjusted the valves again, ran it then it started tapping again. I pulled the front cover off to inspect the timing chain and tensioner. The chain was not loose but the tensioner was all the way extended. I changed the timing chain but the tensioner would screw up and down like it should and would tighten the new chain up when turned loose. I put my crank on top dead center and had my cam gear timing mark lined up and set my valvelash a .006, then put everything back together and ran the engine for 5 minutes and heard a pop and the engine shut down and was huffing thru the exhaust again. Has anyone ever saw a bad compression release on the camshaft cause this? Cam bearing maybe? Valve Seat? I would hope to get some ideas on this problem? Thanks in Advance, Robert
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post #2 of 27 (permalink) Old 03-29-2011, 02:27 AM
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Welcome to the forum. Hopefully someone will be able to chime in with some more info.

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post #3 of 27 (permalink) Old 03-29-2011, 09:46 AM
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welcome to the forum, did u adjust ur valves when the motor was cold? did u check the valves after u tightened them up. when u tighten the lock nut it will tighten them up. if its been ran like that for to long u may have a flat spot in ur cam or even a flat pushrod.

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post #4 of 27 (permalink) Old 03-29-2011, 09:53 AM
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i think he bent a valve when he overtightend them .....tare it apart again dude

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post #5 of 27 (permalink) Old 03-29-2011, 10:29 AM
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that's a hard way to learn a lesson on valves!!!My nephew learned that way also ,because he couldn't wait for me to come over an show him right the first time !!! he learned after that !!
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post #6 of 27 (permalink) Old 03-29-2011, 10:34 AM
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Welcome to the forum rebel. When you replaced the cam chain did the adjuster spring itself into position (tighten chain) or did you have to manually adjust it. It is possible for the auto decompression to mess up but a not common problem at all.

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post #7 of 27 (permalink) Old 03-29-2011, 07:58 PM Thread Starter
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Hi Too Deep, the tensioner will screw down by itself and tighten the chain. I never heard of a decompression assy. going bad but i'm thinking this might be the case. I talked to my son and he said this last time it was ran, he was the one that ran and it ran fine until he shut it off and pulled the pull rope to crank it. Thats when the pop began and the huffing out of the exhaust began and would not crank after that. I am going to tear it back down and inspect everything very close before its put back together. Thanks.

Last edited by rebelraddaddy; 03-29-2011 at 08:00 PM.
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post #8 of 27 (permalink) Old 03-29-2011, 08:12 PM Thread Starter
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Hi sspeckerwood, the valves were adjusted with the engine cold .006 at assy, engine ran fine and sounded good for 10 minutes. Then when the tapping started we shut it down and adjust to get the slack out of the valve train .006 engine hot. Engine runs fine until the exhaust valve tightens up the engine shuts down and you hear the huffing in the exhaust. Adjust again to .006 hot engine and the engine sound good and runs fine again until you hear the tapping loose exhaust valve. Thanks
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post #9 of 27 (permalink) Old 03-29-2011, 08:48 PM Thread Starter
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Hi rich450es, Anything is possible with me. I could have bent a valve but all the bent valves Iv seen in 35 years of being a diesel mechanic, once the valve is bent, there is no way to adjust the huffing out of the exhaust or intake manifold. The only fix is to remove head and replace, grind valve and reassemble engine. On my engine when the huffing starts , you can readjust the valve clearance to .006 and the huffing goes away. Then when the tapping starts , you can readjust the valves to .006 and the tapping goes away until the valve tightens up again. Thanks for your input. Robert
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post #10 of 27 (permalink) Old 04-06-2011, 02:32 AM
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we are having close to the same problem. Our 450fm was runnunig just fine and just up and died. No compression. Camehome and checked the valves one had tightened right up. ajusted it and then it fired right up. Ran for about 15 min and just died again. tore into it and the same valve tightened up again. thought maybe the cam so we changed it and put it all back together and it fired up. let it run for about 5 min. shut it off to finish puting in fenders and went to start it, it back fired and yup, no compression. Not sure what to try next. we did put in new valve springs too. Any thoughts?
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