leaf blower blues (Briggs 8HP I/C)

[hazmat]

Since it seams customary to post small engine repair questions here, I've got one to add.

I've got a hand me down Little wonder walk behind leaf blower. It has an 8HP briggs Industial/commercial horizontal shaft engine. I estimate the unit is between 10 & 20 years old.

I couldn't find a serial number on the engine. Of course I was trying to find it quickly this morning while trying to get to work on time. Where should I look? I want to buy a service manual to walk me thru troubleshooting & repair.

Sometimes it is hard to start. Once it gets warmed up, the engine frequently loses power. The choke needs to be set about halfway on (in line with air intake tube vs 45 degree up for "ON" or 45 deg down for "OFF") for it to run correctly.

So far I've changed the oil, sparkplug, fuel filter & air filter (all the basics). I've also tried playing around with the carb adjustment screws, but I don't really know what I am doing & it didn't seem to make much of a difference. Any tips while I try to track down serial number & manual?

I suspect a blown head gasket as I think I saw some blow out as I was trying to start it. Plus it is really loud even with a new muffler. I don't have a compression tester. Is it a worthwhile investment? Or should I just pop the head off & inspect the gasket?

hmm, maybe this is a blessing in disquise, If the motor self destructs, I just might have to convert the blower to a three point hitch version for the tractor. Probably cost more than replacing the motor/w3tcompact/icons/frown.gif

 

[heehaw]

my guess would be fuel problems, maybe trash in the carb bowl and/or tank. good luck
heehaw

 

[kubmech]

It's a leaf blower, so it does alot of sitting around not running. The fuel in the carb gets old and allows varnish deposits to build up and gum up the needles and seats and orifices in the carb. Sometimes you can get away with removing the adjustment needles and the float bowl and spraying 2+2 carb clean (with the little red hose attached) through all the orifices and clean out the bowl and this will get you going again. When re-installing the needles, gently (with your fingers) screw them in till they bottom out. Then back them off about one and a half turns. This should be pretty close to get it running. Then run at full throttle, adjust the needle that goes into the bottom of the carb till it runs smooth. Then at idle adjust the other needle till that smoothes out. That should get you pretty close. The model/serial number should be located on the engine shroud, it's stamped in. Unless you have a newer engine then there will be an id plate/sticker. Another problem you will see with equipment that sits around alot is "critters" love to build homes in the cooling fins under the shroud which will cause the engine to overheat and blow the head gasket. Both of these likely problems are very common. The manual you want is part#270962 if you have the good old fashion L head engine.

 

[hazmat]

Thanks guys, I looked again tonight. Armed with the knowledge that the ser. number was on the shroud. wouldn't you know, right there on top staring me in the face. Amazing how much more open my eyes are at 10pm vs. 6am!

For those interested
Model 195432 type 0297-01 code 84011710 per the briggs and stratton web page That dates it as a 1984 model.

I'll order up a manual & get myself a compression tester to check the gasket. I'll Also try some carb cleaner on it & pop the shroud to check for critter damage. Might not have a chance to spend too much time on it before turkey day.

 

[hazmat]

Well, ordered the manual & while I was at it got the gasket set for $13 and the carb rebuild for $17. all from jacks small engines. Figured that the kits were cheap insurance: I'll be up and running & the leaves removed before old man winter settles in.

I'm going to pick up the compression tester & carb cleaner tonight & open the old girl up.

 

[justractors]

Most, but not all, small engines have a compression release system of one type or another that make them easier to start.
Your engine does have the compression release built into the camshaft. Point is that the engines will not show the proper compression reading with the compression gauge unless you can spin it fast enough to override the compression realease feature. Best way to check the rings and valves on your engine would be by performing a leakdown test which any good small engine repair shop should be able to for a small charge.

Just my humble but well thought out opinion.
Bill

 

[hazmat]

<font color=blue>Your engine does have the compression release built into the camshaft. Point is that the engines will not show the proper compression reading with the compression gauge unless you can spin it fast enough to override the compression realease feature. </font color=blue>

Hmmm,

I got 80 psi for a reading. What is the compression ratio for the briggs? If it's 7:1 I should have read 90psi, if its 6&change:1 I'd get the 80.

Edit here:
Should mention that this test was on a cold engine contrary to the compression tester's instructions.

 

[kubmech]

Hazmat, Bill is correct. They do have a compression release. However, when I first started out, I didn't know about the leak down/differential pressure tester (not even sure if they had them) and I use to use a good old fashion compression gauge. On most of the small engines I tested, I found that an engine with an electric starter was in pretty good shape if I got 90 psi. If it was a pull start, I would be satisfied with 80 psi. After checking compression on light aircraft with a leak down tester for a few years I was pretty happy to see that Briggs came out with one and immediately purchased it. Granted, it is a better test. But the compression gauge will still tell you what's going on if you have used one for any length of time on small engines. At 80 psi (never saw a little wonder blower with electric start, besides the "2" at the end of your model# indicates a pull start if I remember correctly) I would venture to say that the cyl. piston, rings and valves are in pretty good shape. Just keep in mind that this is not "the most effective test" for a leaking head gasket due to the fact that cyl. pressure under running conditions will be much higher. You said you ordered a gasket kit and that you were going to pull the shroud. It only makes sense to pop the head off at this point to have a look at the gasket and clean the carbon out of the combustion chamber. It's good PM to clean out the carbon anyway. As an added bonus it gives you a great excuse to buy (or use if you already have one) a torque wrench./w3tcompact/icons/wink.gif

 

[hazmat]

<font color=blue>As an added bonus it gives you a great excuse to buy (or use if you already have one) a torque wrench. </font color=blue>

Already got 4 of those. From screwdriver size all the way up to 1/2". I have been looking for an excuse to upgrade the 3/8 & 1/2" ones. They are the "old school" beam type. Kind of inconvenient to use if you're in a position where you can't see the gauge. Also the ratchet comes in handy. But the price was right & I can recalibrate them myself.

 

[hazmat]

Well after a little mix up (they shipped me the wrong order) I got the manual & parts yesterday. Just in time for 6" of snow!.

Pulled the shroud off, only found 2 leaves, so the fins weren't clogged up. Pulled the head off. Gasket looks OK. LOTs of carbon on the head & piston. What's the best way to clean it? Wire brush? Solvent?

Took apart the carburater. It doesn't look gummed up, but does have a slight tint to it. Since I've got it apart I will soak it in carb cleaner. Only ran into one snag. The "Inlet seat" is pressed in, the replacement that came with the kit is a threaded one. Should I worry about it?

If the ground stays covered in white stuff, I've got 5 months to figure this out.....