# leaking valves?



## Ariens1976 (Jan 1, 2013)

What is the best and easiest way to diagnose a leaking exhaust valve on a tecumseh 8hp? I do believe that might be the problem with my engine since i can see glowing red inside of the muffler with occasional spitting out of bluish flames out of the muffler while using machine at night.


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## motorhead64 (Dec 15, 2013)

I'd say you've already diagnosed it. The valve hanging open is allowing still combusting hot gases to leak into your muffler and to burn there.You need to check your valve clearance soon. MH


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## Ariens1976 (Jan 1, 2013)

That's what I was affraid the answer was going to be...


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## classiccat (Mar 1, 2014)

I just did 2 of my engines (HM80)...much easier than I anticipated. If your head bolts come out, then this job should be pretty straightforward. Order a new head gasket, breather gaskets and hit the auto store for a lapping tool, lapping compound and a feeler gauge. Seafoam + a nylon brush makes short work of the piles of carbon that you'll likely find!


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## Ariens1976 (Jan 1, 2013)

Debating if this wouldn't be the way to go... depending on how much the valve lapping way would cost :/

7 HP 208cc OHV Winter Gas Engine | Princess Auto


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## classiccat (Mar 1, 2014)

Ariens1976 said:


> Debating if this wouldn't be the way to go... depending on how much the valve lapping way would cost :/
> 
> 7 HP 208cc OHV Winter Gas Engine | Princess Auto


 Reseating the valves might not be entirely necessary. You could try a seafoam decarb and see if the problem improves....I've always used the Tashasdaddy method. Wait for spring for a more extensive cleaning.


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## Ariens1976 (Jan 1, 2013)

Only problem with waiting for spring, is this is my only machine. I might just soak up the head bolts over x-mas time and tackle that after the holidays.


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## classiccat (Mar 1, 2014)

Ariens1976 said:


> Only problem with waiting for spring, is this is my only machine. I might just soak up the head bolts over x-mas time and tackle that after the holidays.


 I'm with ya! What I'm saying is that you may be able to correct the gross problem by doing a simple seafoam decarb (_you don't have to pull the head_).

One warning, it smokes like CRAZY from all of that crud burning off!


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## Ariens1976 (Jan 1, 2013)

Yeah, read the link you posted... can just see the curious bitter neighbors bitchin' hahaha. Thanks for the info, will mull on it and see what I do. My other neighbor offered me his honda in case of emergency. I huess it's Christmas after all hahaha.


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## classiccat (Mar 1, 2014)

Ariens1976 said:


> Yeah, read the link you posted... can just see the curious bitter neighbors bitchin' hahaha. Thanks for the info, will mull on it and see what I do. My other neighbor offered me his honda in case of emergency. I huess it's Christmas after all hahaha.


 Oh yes...'Tis the season of giving...and receiving!


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## SteelyTim (Nov 14, 2014)

Check out my thread here: http://www.snowblowerforum.com/foru...3353-easy-way-remove-tecumseh-head-bolts.html

Before you go any further though, pop the rectangular cover off the side of the head and make sure you don't have a weak or broken valve spring, or a spring keeper that's loose. I've had both happen.


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## Ariens1976 (Jan 1, 2013)

Thanks Tim, I was thinking the same thing... after all, no use to do all that work when springs are the culprits...


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## CarlB (Jan 2, 2011)

in many cases the cause of the problem is the valve reseeding into the valve seat causing a lose of clearance or lash between the lifter and the valve stem. The lash on that engine should be between .008 and .012 if i remember correctly. Check the clearance on the exhaust valve with the intake valve slightly open to insure the exhaust should be closed. If you have too little clearance you will need to remove the valve file or grind the stem down to get the correct clearance. 

here is a youtube link


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## Ariens1976 (Jan 1, 2013)

Got everything apart... now time to get the feeler gauge going. Up to now, springs are intact and no visible looseness noticed. Some carbon build up on top of valves and piston but everything looks good, even cylinder wall is smooth. What would be next step if everything is specs?


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## scrappy (Dec 7, 2014)

Does this engine have points/condenser? If so I would check ignition timing. Late timing would cause the exhaust to be hotter than normal. Or possibly a lean condition.


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## Sblg43 (Jan 18, 2014)

You may still want to lap the valves. The valve lapping tool and valve grinding compound are not expensive. If you decide to do this, get the tool that is just a dowel with suction cups on the ends.

The tool in this video is overkill unless you do it a lot. 
http://youtu.be/vbRMZ1vF2Os?list=PLHhi09gGkzy4x3mloG92Hg-en0byqwUxT


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## Shryp (Jan 1, 2011)




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## Ariens1976 (Jan 1, 2013)

Valves are lapped and gaped, de-carbed with seafoam, only waiting on my valve spring compressor to put it all together. Anxious to see the end results.


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## db9938 (Nov 17, 2013)

In a pinch, I've used a 7/16 open ended wrench, with holding the valve down with my thumb. I just slide the wrench, retainer and spring, into the breather opening. Coaxed it into position, slide the valve down, and carefully compress the spring by prying up. Call me cheap , and follow the safety suggestions above.


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## Grunt (Nov 11, 2013)

I have compressed the valve springs in a vise and used two small nylon ty-raps 180 degrees apart to hold the spring compressed. After inserting on the valve stem, cut the ty-raps and pull them out with pliers. As Stated, use eye protection, just in case.


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## nt40lanman (Dec 31, 2012)

Good for you Ariens76!! I hope it all works out well.


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## Ariens1976 (Jan 1, 2013)

Everything back together... just need to start it. Fingers crossed.


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## Ariens1976 (Jan 1, 2013)

Fired right up on the first crank and sounds so much smoother. Not bad for the first time i play around with the valves. Thanks guys for all the input.


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## classiccat (Mar 1, 2014)

Awesome! Bringing-in 2015 with a WIN!!!!


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## Ariens1976 (Jan 1, 2013)

Little update... everything done and just came in from cleaning 6-8 inches of wonderful white stuff. Purrs like a kitten and spits it out to the neighbor's. Didn't think the ole st824 had it in her.

Thank you guys for all the input offered.


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## classiccat (Mar 1, 2014)

Congrats!!!! That's what it's all about!!!


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