I bought this 1641...

RumbleFish · #1 01-01-2017, 10:27 PM

Late this past summer I stumbled across a 1641 on that facebook marketplace thingy and since Ive gone from mowing one yard to three I decided I should buy a rider. My first choice was a Cub of course since I've had a nicely repainted O for like 20 years. Anyway, the thing ran ok (or so I thought) but had the somewhat common oil blowing out of the carb problem I've read about several times and had a bad miss with the pto engaged. The PO got it when it came with the house he bought, and said it hadnt really ran right for the last 2 or 3 years so he bought a newer mower and was tired of looking at this one. So I roll the dice and buy this thing for what I feel was a pretty reasonable price and stash it in the garage until I have time to mess with it. I thought it ran good with the pto disengaged. Turns out one of the plugs was solid black goo and it was only running on one cylinder. New plugs got it running on both cylinders which I assume has now fixed the miss when under load although I havent tried to mow with it in the snow. Now the carb issue-
seems the general consensus is that it probably needs a new carb due to the needle not seating well and filling the crankcase with gas (the oil was overfull when I got it and reeked of fuel). Is this really likely the case? The overfilling explanation makes sense but in my (automotive) experience my instinct is telling i have bigger problems like rings or a hole in the piston. Id appreciate any suggestions.

Jeff

Mike McKown · #2 01-02-2017, 04:39 AM

Quote:

Originally Posted by RumbleFish

Anyway, the thing ran ok (or so I thought) but had the somewhat common oil blowing out of the carb problem

Now the carb issue-
seems the general consensus is that it probably needs a new carb due to the needle not seating well and filling the crankcase with gas (the oil was overfull when I got it and reeked of fuel). Is this really likely the case? The overfilling explanation makes sense but in my (automotive) experience my instinct is telling i have bigger problems like rings or a hole in the piston. Id appreciate any suggestions.

Jeff

Oil blowing out in the air cleaner can be caused by a blown head gasket blowing compression into the crankcase through the push rod cavity. It can be caused by a dirty air cleaner.

I doubt your carb needs replacing. On a 1641, if the float doesn't seal, it'll overfill the float bowl and gasoline will run out the small 90* pipe at the back of the float bowl. A blown head gasket can cause a plug to foul. If the plug doesn't fire, some of that unburned gasoline will go past the rings and into the crankcase.

Jumper · #3 01-02-2017, 09:46 AM

Jeff, I'm not real familiar with the 1641, but if it has a mechanical fuel pump, the diaphragm could have a leak. In most cases the leaked fuel drains back into the crank case.

RumbleFish · #4 01-02-2017, 11:59 AM

Oh yeah, I remember reading that the head gasket is a weakpoint on these vanguards now that you mention it. That would make sense as well. I did a compression test a while ago and i think they came in at 90 and 95 psi but Ive slept since then. Maybe a leakdown test would tell me more.

Mike McKown · #5 01-02-2017, 02:14 PM

If you find a blown head gasket, pull the tin off the engine and clean out mouse nests, grass, dirt, oil packed around the cooling fins. Also check the rear crank seal for leaking while you have it apart.

I've had 3-4 Vanguards with blown head gaskets. All had gotten hot because of debris packed on the cooling fins.

It's not uncommon to find a mess like this.