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Author Topic: tvt691 oil in air filter  (Read 2360 times)
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Flaming Mow
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« on: April 08, 2013, 05:11:48 AM »

G'Day,

I am racing in australia using a stock tecumseh tvt691.

On rough tracks where the front end bounces a fair bit I am getting oil from the crankcase breather into the air filter housing.
This happens to the degree that it runs out of the bottom of the air filter.

I have fitted a catch can and this has solved the problem to a degree until the can is about quarter full.

Is this a common prob for tvt691? As no one else has this prob with other breeds of engine - the only other tvt691 i know of experiences the same issue.

Any help appreciated.
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« Reply #1 on: April 08, 2013, 06:22:19 AM »

Is the engine completely stock? The ring's are probably worn.
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Ed King

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« Reply #2 on: April 08, 2013, 08:49:44 AM »

I run one modified and no catch can, never been an issue.
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L Curt Hodges
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« Reply #2 on: April 08, 2013, 08:49:44 AM »

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Flaming Mow
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« Reply #3 on: April 09, 2013, 03:31:21 AM »

Yes motor is stock.
Has only ran 5 race meetings.
Oil change every second meet
Has been an issue since second race.
If I drive a bit more conservative and smoother when racing and avoid front end bounce it doesn't seem to be an issue.

I run iridium plugs and 95 octane with "Flashlube" upper cyclinder lubricant.(only for last two race meets - oil problem was pre-existing)
Motor does not seem to be overly hot after each heat.
Going by plug color it appears to a bit rich.


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George Herrin
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« Reply #4 on: April 09, 2013, 05:05:34 AM »

run only 1.5 quarts of oil. remove the hose from filter and silicone the hole in filter plate closed run the breather hose directly to the catch can. your rprolly making right hand turns this and the bouncing is causing the problem. run the lesser oil as stated above and make the breather hose mods it should fix the issue.
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George Herrin #6
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Flaming Mow
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« Reply #5 on: April 09, 2013, 05:35:03 AM »

George,

Your on the money with your deductions mate.
Most tracks here run clock wise and bar a few left handers thrown in here and there right hand turns are more numerous, usually faster and gradually deteriorate in condition as the race meet progresses- hence the front end bounce.

I had thought of this as my next option.

When you say run there breather pipe to the catch can, i assume i should still have some means of pressure equalization to the crank case,
ie: breather on catch can?

Thanks.
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George Herrin
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« Reply #6 on: April 09, 2013, 05:48:00 AM »

being your making mostly all right hand turns your gonna fight this issue alot. There is an internal pvc valve in the case behind the suare plate on the left side of block it works ok as long as the oil isint thrown on it. Take the rubber hose off the breather and run it to another catch can it going to the breather is simply an epa thing and has nothing to do with crank case ventilation. YOU can however add another pvc to thos hose which also helps. I will take some pictures of how I did mine. I have run my motor backwards and this is why I know what your going thru. YOU can turn your motor around in your case with mostly right rough turns this would also all but solve the issue.
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George Herrin #6
Indian Power.. You gotta Go big to beat em or Go HOME
8 time ARMA National Champion
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Retired from BP
www.herrinmowersports.yolasite.com
www.allamericanmowerchampionships.yolasite.com
My other racer is a 1/5th scale Dirt Late Model!!!!
Flaming Mow
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« Reply #7 on: April 09, 2013, 05:55:00 AM »

George,
Some photos would be great.

It took me 3 minutes for me to understand what you meant by running motor backwards.

However now i see what you mean- a wierd idea to me at first but really simple and brilliant logic!

A bit of wiring change and fuel line modification - but a great out of the box solution.

Thanks again.
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« Reply #8 on: April 09, 2013, 06:45:42 PM »

Don't want to be a party pooper here, but I would not recommend running a full quart low on oil. I realize that running clockwise will keep oil near the oil pump pick-up, but will it always? Best to just run the separate breather line.

You will also be running into trouble with your fuel pump. As the pulse is taken off the left side of the block, the pulse line more likely than not will someday fill with oil, thus killing the pulse signal to the fuel pump. I would suggest plugging the pipe-tapped hole on the left and move the whole system to the right side of the block.

Another issue may be that racing "Down Under" means that the mower is actually upside down, in which case, the engine should immediately be shut off while you grab several beers to aid in thinking the problem over. Foster's, anyone?

Bert
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« Reply #9 on: April 09, 2013, 07:19:47 PM »

Bert didnt say a quart less I said 1.5 quarts total as thats only a half quart. My motors only hold 2 quarts eve with new filter.
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George Herrin #6
Indian Power.. You gotta Go big to beat em or Go HOME
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« Reply #10 on: April 10, 2013, 01:42:54 AM »

Bert,

Thanks for the heads up on the fuel pulse scenario  -i will investigate further.

FYI - Fosters is an export only beer these days as it tastes like stale wine. We just send it around the world so everyone else can drink it now and again and pretend they are an Aussie for a brief moment.

Real aussie beer gives us powers that make upside down mower racing possible.
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« Reply #11 on: April 10, 2013, 06:06:28 AM »

This is the part where Bert asks to be sent some real Aussie beer for sampling......
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Ed King

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« Reply #12 on: April 10, 2013, 06:33:35 PM »

Can I have some real Aussie beer for sampling??

Bert

PS. G, every Tec I've ever owned holds 2.5 quarts.
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Flaming Mow
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« Reply #13 on: April 11, 2013, 04:54:18 AM »

If you can get it where you live try ''Coopers"
Great aussie beer.
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Flaming Mow
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« Reply #14 on: April 17, 2013, 03:04:33 PM »

George,

Will the 17 hp ohv carbys (640072a/640330A) fit on to the tvt 691 stock manifold?
Is there any modification s required?

Thanks.
Nigel
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