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Briggs & Stratton Intek 18.5 Oil Blowback Thru Oil Fill Tube


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06-05-13, 01:10 PM   #1  
Briggs & Stratton Intek 18.5 Oil Blowback Thru Oil Fill Tube

Need an expert on this one. Tried B&S Support -- no help. Problem is:
When engine starts it runs rough and after 'bout two minutes oil blows out of the oil refill tube in a steady stream. MORE: This engine has a fuel pump that is operated by a hose running from the oil fill tube to the fuel pump. When the hose is connected the oil blowback enteres the fuel pump, mixes with the gasoline, and enters the combustion chamber via the carburator.

What I have done: adjusted the valves, new air filters, compression check 140The good compression indicates that the rings/valves are within tolerance.

I have the hose coming from the the oil fill tube to the fuel pump disconnected and directed to a container. The engine runs, but rough and the container will fill about one ounce of oil in a five minute engine run. There must be pressure building in the crankcase and therefore creating the oil blowback. I believe there is a compression doo hickey on the camshaft, but don't want to go into the crankcase--yet.

Suggestions?

Its all fun.
REBEL

 
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06-05-13, 02:20 PM   #2  
Is the oil over filled?? Also check crancase vent which I think is under the flywheel but I could be wrong. If oil is over full does is smell of Gas? I'm sure Cheese will chime in here and he may be able to help more. Good Luck

 
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06-05-13, 03:27 PM   #3  
First check was the oil and checked the carb needle--just to be safe installed a fuel cutoff switch. Changed and reinstalled exactly 48 ounces. The vent assembly under the flywheel may be the culprit, but I think that the flywheel has to be removed to inspect/replace. Might have to remove the flywheel to check the vent, but still looking for the magic bullet.

Thanks for the reply.

It all fun.

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06-05-13, 07:46 PM   #4  
Ok, so the oil is not thin and does not smell like gas?

If not, the likely culprit is a blown head gasket. I assume this engine is smoking heavily when it runs? Did it start by blowing a huge cloud of smoke, settling down, then blowing a huge cloud of smoke again? I wouldn't worry with the crankcase vent, it has never caused a problem on any of those engines I have ever worked on (I make my living working on them, so that's a lot of 'em). The head gasket often blows between the cylinder and the chamber for the push rods, pressurizing the crankcase with combustion gasses which need a place to escape.


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06-05-13, 08:25 PM   #5  
Head gasket totally slipped my mind,,,but yes indeed a strong culprit.

 
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06-06-13, 06:36 AM   #6  
Cheese & Mowerdude

You caught me. When I adjusted the valves I pulled the head just to clean away the carbon, which was a bunch. I looked hard at the gasket and it did have a little separation in spots, but I took the gamble and reused it. Then after reassembly I checked the compression and got 140. Soooo, I will bite the bullet and install a new head gasket as soon as it sops raining.

I'll keep in touch.
Thanks
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06-06-13, 03:10 PM   #7  
Ya win some ya loose some,,,,,, for some reason the BS engines are failing in the head gasket area. Poor design??

 
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06-06-13, 09:57 PM   #8  
Mowerdude

I agree on the B&S quality. I now lean to Kohler for dependable and repairable engines. Still not sure the head gasket will fix my problem because the compression checks within spec. I plan to start it up and squirt some carb cleaner on area around the head gasket to see if it reduces the rough run. If it smooths out, it will be a bad gasket. If it shows no improvement, its gotta be sompin' else.

Thanks for the interest.

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06-07-13, 04:47 AM   #9  
You can also do this, release the rocker arms and pressurize the crankcase by putting air into cylinder. I found a Kohler that way and it was blown also in the lifter area. It too had good compression and ran well.

 
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06-07-13, 08:47 AM   #10  
I hate to hijack the thread but have you noticed a difference in quality with the B&S Vanguard V twins? Aren't they still made in Japan? I'm wondering if they are better than their other models.

 
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06-07-13, 10:11 AM   #11  
Compression testing and spraying carb cleaner won't reveal a blown head gasket.

Pilot Dane, I haven't noticed any decrease in quality on the vanguards I've worked on lately, but come to think of it, I haven't worked on many newer ones lately. They aren't real common. I know the older ones were as good as any engine out there and better than most.


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06-07-13, 02:51 PM   #12  
Did with me,,,,I saw the air bubbling in the Oil in the passage where the pushrods go on the Kohler,,but may be different on BS.

 
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06-07-13, 03:30 PM   #13  
Sprayed the head gasket

OK, so I sprayed the area around the head gasket with carb cleaner and got no improvement in engine running. I have used that trick on intake manifolds and around carbs with good results. Engine pumped about four ounces of oil out of the oil fill tube while doing the test. I put a finger over the hose coming from the oil fill tube to the fuel pump, there is LOTS of air and oil exiting the hose. Lots of pressure in the crankcase. I will install a new head gasket.

Will advise.

Thanks for all the replies.

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06-07-13, 06:40 PM   #14  
Good Idea,,,,,,,,,,,,,,,,,

 
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06-11-13, 01:54 PM   #15  
Guilty -- me bad

Soooo, I checked the head gasket and It looked fine and I did not buy a new one//cost $10.00. Cheese suggested a new head gasket. Sooooo, I installed a new head gasket, readjusted the valves, torked the bolts, started the engine and it went----PURRR. Lesson learned, don't reuse a head gasket.

Thanks to all who responded. PROBLEM SOLVED.

iTS ALL FUN

REBEL

 
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06-11-13, 03:52 PM   #16  
Good job,,,success!!!!!!!!!!!!!!!!!!

 
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06-11-13, 04:15 PM   #17  
Thanks/mowerdude

Mowerdude:

Appreciate your acvice.. Great follow up on your part. See you on the next "malfunction".

Thanks

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06-11-13, 04:57 PM   #18  
Glad it worked! Thanks for the update.


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God bless!

 
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06-11-13, 07:13 PM   #19  
You are welcome rebel. There is always something to learn on these mowers and small engines. Iam learning a lot from this site and it helps me to help my customers.

 
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