Small Engine Repair/Troubleshooting

[warpedskydiver 0]

Thanks once again, I found a small amount of what appears to be carbon in the pushrod galley @ the gasket area.(both cylinders)

It is not much, but is probably the culprit.

[DeNReN 0]

Sorry for not getting back sooner...from your description the problem deff seems to be a case of the crankcase being over pressurized....ie: excessive blowby of the rings or another problem (head gasket) allowing the cylinder compression into the crankcase...

1969912 sais that engine is know for head gasket problems so that sounds like the place to start....once you have the heads off inspect the gaskets ....if there is a obvious passageway from the cylinder to a crankcase opening(pushrod hole) then do a head gasket job and go from there...if there is no obvious signs...the I would suggest going farther and removing the pistons to inspect the rings...

And it would not hurt to call a small engine shop familiar with the vanguard and asking about common problems.

[marks 0]

Quote

The oil is coming through the top end via the crankcase vent (PCV)

I cleaned it using non clorinated brakleen, made sure it moves (about 2mm?) and put it back on.

Same thing, oil coming through it and so it goes down the carb and gets burned, thus smoking like a mosquito abatement truck.

WTF?

replace the valve?

or what else is causing this?

that could be because it is over full of oil, or that for some reason the crankcase is being pressurized.

[jm951 0]

one other thing to consider, it is possible to get good cylinder pressure readings, but leak down tests will tell whether the rings really are shot. At the moment, I'm thinking it's most likely a headgasket. I'd suggest easy stuff first.

[warpedskydiver 0]

I got the cylinder heads off, and found no carbon marks indicating blow by on the gaskets.

I found the cylinder walls in beautiful shape, and the valves and piston tops absolutley caked with carbon from burning the oil.

I am certain it had to be either the rings, or valve stem seals...or both. (302 hours running time )

This has turned to a real pain in the ass.

I will be taking the heads to the shop tommorrow and ask how much for the valve lapping etc.(dealer shop which will probably try and rip me off)

I guess I could clean the chamber up by lightly glass beading it, and try lapping the valves and seats myself, or have my machinist friend do it.


Again any suggestions?

[jm951 0]

We used to decarbon gunked valves by locking the stem in a drill press, set it to medium speed and touched the bottom of the spinning valve with sandpaper. Grit used varied with amount of buildup, but we never used anything coarser than 100. The key is to let the paper do the work. This is ONLY for the bottom of the valve, the side that faces the chamber. We then took the valve out of the press and hand lapped them. Hand lapping is very easy. Get some compound, follow the instructions, don't overdo it. Put in new valve stem seals.

Glass bead the chamber to clean it up. Put in old spark plugs to protect the threads. It is possible that you have a broken oil ring. Unfortunately, you're at the miserable point of doing stuff "while you're in there". May as well take care of other stuff too.

[1969912 0]

Well that sucks. Might as well clean the heads and grind/lap the valves while the heads are off. There is a section on cleaning the heads on the B&S site.

How did the plugs look? Any evidence of oil?

If it were rings or valve guides, it seems that the problem would have developed over at least a few months. It started suddenly, right?

The breather was not clogged. Did you blow air through it or anything? Most of those breathers have some kind of check valve built in. Did you see anything like that in the breather? Here is a page on checking breathers, but your engine uses a different type. Bring the breatherwhen you go to get teh gaskets and mayby they will look at it.

http://faqs.custhelp.com/cgi-bin/faqs.cfg/php/enduser/std_adp.php?p_faqid=3433&p_created=1098905985&p_sid=nnmZywHi&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9NyZwX3Byb2RzPSZwX2NhdHM9MCZwX3B2PSZwX2N2PSZwX3BhZ2U9MSZwX3NlYXJjaF90ZXh0PWJyZWF0aGVy&p_li=&p_topview=1


I think some Vanguards had a problem with improperly drilled oil drainback holes in the heads, but it didn't happen on your model. Since the pushrod boxes on your engine are on the inside of the "V", they are on the "uphill" side of the head, so there should be hole(s) on the opposite side for oil drainback so the rocker arm area doesn't fill with oil. If there are holes, make sure they are clear.

Supposedly, any gasket leak that allows air to get sucked into the crankcase can cause oil misting. About the only way to check for leaks is to put a pressure gauge on the case.

"Once we got to the point where twenty/something's needed a place on the corner that changed the oil in their cars we were doomed . . ."
-NickDG

[warpedskydiver 0]

Both pistons and heads were gunked up.

I will post pics brb

[warpedskydiver 0]

I found the check valve to be fine, I can easily blow through it.

[1969912 0]

Quote

I found the check valve to be fine, I can easily blow through it.

Did the valve close if you blew in the other direction?

How does the rocker box look? Is there a lot of oily sludge and stuff?

Can you see how oil is drained out of the rocker box, and back into the case?

And just to clarify, did it start smoking pretty suddenly?

"Once we got to the point where twenty/something's needed a place on the corner that changed the oil in their cars we were doomed . . ."
-NickDG

[skydemon2 0]

I pulled a motorcycle engine apart that was burning oil?? Well what it was was the crank case was over pressurized and it was pushing oil onto the air box and right down the carbs..... Turned out the gaps in the rings somehow got aligned? the compression was going right past them and into the crankcase. I dont know if the guy before me did this or what, I set them up properly and reassambled, ran great and no pressure problem or oil loss. My engine looked a lot like the pictures you posted.

Beauty is only skin deep, but ugly goes clean to the bone!

I like to start my day off with a little Ray of Soulshine™!!

[warpedskydiver 0]

yes it was sudden, the rocker galley was clean as can be, no pooled oil.

[warpedskydiver 0]

WTF?

I have heard of it happening on rebuilds, but from the factory?

I guess anything can be possible.

[1969912 0]

Quote

yes it was sudden, the rocker galley was clean as can be, no pooled oil.

From your pics it looks like the oil in the rocker box drains back through the pushrod box, so it's not a clogged drain passage trapping oil up there.

It's still hard to believe that your rings could either suddenly wear out or break bad enough to make the engine smoke unless the rings rusted onto the cyl walls during the off-season, and then broke the next time you started the thing. Did the problem start right after winter?

I'll try to ask ask a couple people about it today.

"Once we got to the point where twenty/something's needed a place on the corner that changed the oil in their cars we were doomed . . ."
-NickDG

[warpedskydiver 0]

Does anyone have a diagram of how the linkages connect up on this motor? (carb, choke, and etc.)

I should have taken a photo, I cannot find a diagram.

Grrrrrrrrrr I can figure it out by trial and error/POE but would rather just be done with it.

[DeNReN 0]

your putting it back together??

what did you find??

[warpedskydiver 0]

Well I found that the crankcase valve may have malfunctioned.

I had already cleaned the old one, but the new one was far easier to blow through.

The only other thing it can be is the rings (mind you there is only 302hrs on the engine)

So I did the gaskets and valve stem seals, plus glass beaded the chamber on the heads and cleaned the ports well.

It all looks brand new now.

I can do a leakdown test once it is reassembled, either by borrowing the tool or taking it to the dealer for a test.

I should be able to borrow whatever I need.

After having this apart the rings would be an easy job, but according to the dealer the compression I was getting was more than sufficient and it was equal in both cylinders.

[warpedskydiver 0]

Finally got back to this, I have to pull the motor and pull the pistons and inspect/replace the rings.

I had it all back together and now the motor ran smooth as hell, BUT there was an awful lot of crankcase presssure now.

RINGS it has to be, whether lined up gaps or bad rings.

Damn

[1969912 0]

Quote

Finally got back to this, I have to pull the motor and pull the pistons and inspect/replace the rings.

I had it all back together and now the motor ran smooth as hell, BUT there was an awful lot of crankcase presssure now.

RINGS it has to be, whether lined up gaps or bad rings.

Damn

Still smoking?

"Once we got to the point where twenty/something's needed a place on the corner that changed the oil in their cars we were doomed . . ."
-NickDG

[warpedskydiver 0]

was great until the crankcase pressure came up.

It is like a small air compressor,like for an airbrush.

Tearing it back down now, a few more bolts and the motor is out, then break down the heads and crankcase, pull the pistons.

I am getting to be like an indy pit crew on this thing.

Oh well when it is done I will probably habve a very sweet running tractor.

It did not actually burn oil today, rather it was ingesting it, had I not circumvented it.

I will update after seeing the pistons and going to get skunk-off shampoo for my dogs, and mowing the half acre with a push mower, and repairing a board on my deck (the hard way, as it is in the middle of the deck.

Other than that and fighting with AT&T over an overbilling of $318 and getting my ass chewed by Karen my SO, I have been having a great day.


I mean otherwise I would have been forced to go to summerfest and do nothing at all

[warpedskydiver 0]

The engine is finished being rebuilt, new rings, new gasket set, and some tweaking on the throttle/govenor.


All seems well, started on the first try.

It was making some valve noise, so I adjusted them, and now it really runs well.

No smoking at all, and it runs around 3800rpm.

So the conclusion is yes, the rings can be worthless at only 302hrs on an engine!

The good thing is, I spent only 160 bucks in parts, and some time.

Now on to sharpen the blades once I get them off the deck and reinstall the deck, and mow the living shit out of my yard.

The push mower was working fine, but my knees won't hurt so much after speed mowing a half acre with ditches, and a steep slope on a third of it

[DeNReN 0]

oopsy...missed the last couple of posts to this thread

Glad you finally got it all sorted out...However I do recall saying that if you didn't see a obvious problem with the head gaskets to pull the pistons out for inspection while it was apart............

Now mow like you have never mowed before!!!!

Mow MOW Mow Mow moW mow and mow some more
come do my yard while your at it please...its very long and I'm quite lazy.........

[1969912 0]

Glad it's OK now. Definitely was an unusual problem, especially with low hours.

"Once we got to the point where twenty/something's needed a place on the corner that changed the oil in their cars we were doomed . . ."
-NickDG