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HELP! 14 hp B&G Vanguard engine smokes sometimes and oil in Intake manifold alwa


Mark Dunwoody's Avatar
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09-14-12, 06:17 PM   #1  
HELP! 14 hp B&G Vanguard engine smokes sometimes and oil in Intake manifold alwa

My question is can anyone help me sort out what the problem with this engine is and is it worth fooling with? THANKS! I just bought a used Simplicty lawn tractor with a Vanguard 14 hp motor. Model # 28P777 Type 0641-A1 Code 970116ZE. The Problems are:
Mower smokes like there is no tomorrow with air cleaner on and making (slight)downhill hard right hand turns and for next 20 seconds or so. Can hardly see the mower.
Left hand turns don't smoke, even when headed down hill
Crankcase was about 25% low (about 1/2 qt low out of about 2 qts or just below bottom "add" mark on dip stick)
Intake manifold is dripping with oil. Really dripping.
When mowing with air filter off, little if no smoke ever. OK power, nothing to get excited about but does a pretty good job. Does bog down in tall grass, but it is not an Exmark, so I may be spoiled.

When mowing without an air filter, oil is blown out the carb area big time. To the tune of probably about a cup of oil in 20 minutes of running. Completly covers underside of hood and carb side of engine.
The breather line into the air filter base puffs pretty good. Although if you hold your finger over it your finger does not get particularly oily.
The compression gets up to about 90psi. No change when oil is squirted into cylinder and rechecked.
Hard starting when hot (hard as in engine would not turn over which is an indication of valves out of adjustment?)of last week seems resolved by buying new battery. Mower is starting fairly easily all of the time now, probably because I replaced the fouled out plug and bought new battery.
Grounding spark plug and cranking show good spark while cranking.
Throttle lever controls engine speed fairly well now, whereas before adding fuel filter and new plug I could get smooth change in engine rpm.
At idle with air filter off, every 5-20 seconds a backpuff comes out of breather tube in base of air filter and almost causes engine to die.
Yesterday, I filled the crankcase to exactly the perfect "fill" level. Mowed the front yard 4-6 times (30 minutes) with heavy smoke 25% of the time. Today oil level was exactly at the bottom of the "add",. i.e. it needed about 1/4 - 1/2 qt. I mowed the back yard for about 20 minutes, trying to make it smoke or not etc and now the level is back up to the "full" mark. You go figure.
The fuel filter just shows gas in the bottom with air above, although it runs wide open and is not starved for fuel so this doesn't mean anything except that I don't understand how a filter could not be full of fuel all the time.
The clown I bought it from said he adjusted the valves and put on a new coil. Also said it had sat for a few years before he got it, When it wouldn't run for me, he changed his coil story and said that he actually put on a used coil. His worthless opinion is that it need a new head gasket and "maybe" a coil.
My question again, is this engine worth worrying with or is there some likely causes of this?

 
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09-14-12, 08:43 PM   #2  
Sounds like your engine could have a blown head gasket or ring problems. Pull the cylinder head off and look at gasket and or cylinder head mounting surface. If nothing unusual there look at cylinder and check to see if there is a ridge at the top of cylinder bore. If block is worn badly, then I would say engine needs major overhaul or new block, if there is not a lot of wear there may be a broken ring or rings may be full of dirt. Check cylinder bore for heavy scoring or gouging where a ring may have broken and scorn the cylinder. Good luck

 
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09-14-12, 11:07 PM   #3  
Yep, sounds like a head gasket problem.


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09-15-12, 06:48 AM   #4  
What might cause blown head gaskets?

 
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09-15-12, 07:05 AM   #5  
More than likely the head bolts have come loose.

 
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09-15-12, 09:51 AM   #6  
OK, I pulled the head off. The one bolt nearest the spark plug was loose, but none of the others. I could not see anything that looked like it had been leaking....but don't know if you can see a blown head gasket or not. I also can't understand how a blown head gasket (especially on the opposite side from the valves could be allowing pressure to build up inside crankcase and back through breather(?) and push oil into intake manifold. But, I'm a mechanical engineer and learned a long time ago that I don't understand most mechanical problems..... hohum.....

Cylinder walls look smooth and the way my dad's 56 Cadillac looked when I saw him rebuild that engine 40 years ago. Top of piston is shiny, pushrods look OK, valves look like they are sealing/seated well, I don't know what else to look for. Should I just put new gaskets in and give it a try? Should I replace the breather thing-a-ma-gig that has the vacuum for the fuel pump and breather line to the air filter housing coming out of it? Any other thoughts would greatly be appreciated.
Thanks

 
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09-15-12, 10:27 AM   #7  
Normally when a head gasket is leaking, you can see where it's leaking from. What happens often is the head gasket will blow across the partition between the cylinder and the area where the pushrods pass through. This causes combustion gasses to pressurize the crankcase, blowing oil out the breather and other places. It happens very commonly on that style engine you have. Make sure you properly torque the head bolts in the correct pattern.

Does you oil smell like gas? Does the engine run at higher rpms than it used to? You could check the breather and clean it, but I have only seen one breather go bad that I recall, ever.


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09-15-12, 12:02 PM   #8  
Thanks. I will order new head gasket and put it back together and see what happens. From how good the cylinder looks to me and the fact that it does not smoke when air filter is off, I can't imagine rings being the problem - therefore it seems that head gasket most likely is/was the problem.
I can't seem to find on internet a free copy of B&S manual that would give me the torque sequence and amount as well as how to adjust the valves. Is there a site or do you have the time to respond, or should I just break down and buy a manual?
Thanks again, you are a life saver...
Mark

Also, if the intake push rod has very small <1/16" flat spots on each end, is this OK? exhaust is perfectly round.

 
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09-15-12, 03:19 PM   #9  
Try this link Mark,, Choose torque by model number.
http://www.briggsandstratton.com/sup...B5DCA17EF.ashx

 
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09-15-12, 05:29 PM   #10  
The push rods sound like they're okay. Set the valves to .005" clearance with the engine just after TDC with the piston 1/4" down from TDC.


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09-16-12, 08:39 AM   #11  
Would using premium fuel cause a head gasket to blow? I just remembered that the guy I bought this from said he put premium in gas tank because he felt ethanol in regular gas messed up the carb. I know premium has ethanol as well but am just wondering if maybe it didn't have a blown head gasket until I brought it home and put it under load mowing thick grass - which maybe he had not done. So maybe he was being honest, just made an honest mistake...that I'm having to pay for.

 
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09-16-12, 10:02 AM   #12  
No. the gas didn't cause it. Heat, age, and fatigue and sometimes a loose bolt or two causes it.


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09-16-12, 10:58 PM   #13  
As pointed head gasket failure on those is common due to the design. Note the gap between bolts on the intake side. Gasket blows out between cylinder and midway of the push rod galley.

 
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