[NITRO-BTU]

YES, I did, and found Absolutely NO-MOISTURE from fuel, or anything on the spark plug. The plug was dry as if it were sandblasted. Secondly, manually activated the throttle several times, and then cranked 8 times, and still nothing... IT'S BONE DRY! Yes, of course, the engine was fully choked both times.

[KISS]

OK.

1. Ignition - It doesn't exibit classic ignition problems - rule out ignition

2. Engine - No smoke, running rough etc. So except for compression release (do bounce back test) that would seem OK

3) Fuel (yep a fuel problem)
1. Compression - probably not (do bounce back test hot and cold engine)

2. Carb - The carb has various "systems". Loosely. Start, idle, run and power. They seem to run OK, not great. Carbs usually flood or no fuel or run very rough at some or all speeds.

2b. Fuel pump. In an older or even newer automobile, I'd measure the fuel rail pressure.

2c. Bowl vent/fuel cut solenoid if so equipped. Ususlly this is an on/off thing. It works or it doesn't.

Look at the fuel pump.

[NITRO-BTU]

Hello, 2b, and 2c Don't apply.
The Briggs fuel pump on this 5hp. Pulsa-jet carb is internal, requiring only a diaphram, spring, and metal ring... for the spring.
When I talked about cranking it 8 times, I meant Manually pulling the starter rope that many times. No electric starter. Regards, Jim.

[KISS]

OK, so do the hat and cols bounce back test.

Cold engine:
Remove blower housing and turn flywheel backwards. It should find some resistance during compression and then let go. The flywheel should "bounce-back".

Hot engine:
Do the same.

[NITRO-BTU]

Hello there, NOT to be Disrespectful, but this "Ballpark Test" is just that, and is used to determine whether a cold engine has enough compression to start.. . NO-MORE / NO-LESS. I am trying to determine the available power still left in the engine. Example: The Higher the compression readings, the Greater the power output. This Briggs Test is worthless when it comes to determining the available power output.
What-say-you, Of this ? Regards, Jim.

[NITRO-BTU]

Clarke, Are you still with me ? I finally got through to a Service Tech, to discuss their "bounce back Procedure." Mark (the tech) himself told me the procedure was only intended to get you started, and that I should run a compression test. For my engine, he said after a couple pulls, the PSI. should be between 70, and 90. So, I did the test, and here are the results.
DRY CYL. BORE: 1pull.. 30 / 2pulls.. 40 / 3pulls.. 50 , and 4pulls 57. With a few more pulls MAX. IS 58
PSI. Then I shot 2 squirts of oil into the dry cyl, and tried it again.
WET CYL. BORE: 1pull.. 40 / 2pulls.. 50 / 3pulls.. 60 PSI, and this was MAX. THEN TO MAKE SURE THE RINGS WERE OIL SOAKED, I added two more squirts of oil, and rotated the engine a few times before taking the last set of readings. This reading Really surprised me... 1 PULL = 80 PSI. and the following 2 pulls DID NOT INCREASE THE 80 PSI.
ALL OF THESE READINGS WERE TAKEN WITH A "COLD ENGINE."
I believe, had the engine been warmed up first, the first set of readings probably would not have been so low. However, had it been hot would the last reading be Even Highier? You tell me, I don't know.
I asked Mark what could/would prevent the engine from starting cold, (without external priming) with the choke on. He mentioned two things: the fuel pump diaphram, and the crankcase breather tube. Either one, or Both could be at Fault. The latter is food for thought.
Well, That's the latest... PLEASE GIVE ME YOU THOUGHTS on this stuff. Again, Thanks, Jim.

[KISS]

Well, that's the classic test for bad rings. Compression improves dramatically when oil is used.

The test seems difinitive. Without compression there is no fuel.

I doubt a clogged oil breather applies here. You could always remove it for another compression test.

If this engine has overhead valves, you could try a valve adjustment.

[KISS]

What I'm implicitly implying is that the compression will be worse when the engine is hot.

The rings will be weaker.
The Cylinder walls may expand but not at the same rate as the piston. This would contribute to the near impossible starting when warm and the loss of power when warm.

Engines aren't hard to rebuild. Did my first when I was about 10 YO.

[NITRO-BTU]

KISS, Can you Explain why there is NO-BLUE, or WHITE SMOKE coming out of the Exhaust, IF in-fact the Problem is Rings?

[KISS]

White is going to be coolant which you don't have.

Blue in a car, for instance usually comes at start up when the valve seals fail. You get a puff of blue.

When the rings fail, you burn oil.

You may not be at that stage yet. That's why I'm suggesting a compression test when warm.

[NITRO-BTU]

KISS, There's no point in running a Hot compression test. The reason being, is that all readings would be relative to each other... Just Higher, or Lower. The only way the engine could burn oil is if both top compression rings are bad, or worn. After all, the oil has to pass through these 2 rings before exiting the exhaust valve. THEREFORE, Because there is NO BLUE SMOKE the two compression rings must be Good ! I don't believe the piston rings to be bad.
Now, possibly the valves may be the problem. At times the engine will backfire upon Rapid deceleration.
LASTLY, How do you account for the Power at times the engine puts out, to remove 6" to 8" of snow... Then all of a sudden for No apparent Reason the engine dies, as if it ran out of gas ? PISTON RINGS aren't Good one minute, and then bad the next, going from one extreme to the other. Rings simply Don't self-correct, So, I discard the rings as being the culprit. Rather, I focus on either the valves, or the carb. Possibly, the carb is so screwed-up, that it tends to over richen, or over lean the A/F mixture. A Long-shot, might be a condition called "Vapor Lock." Sometimes found in High performance vehicles. Regards, Jim.

[KISS]

The hot compression test is easy, so why not do it? Rings can not seal as the engine heats up which you said was a problem.

Backfires can be carb, timing or valve related. To rich of a mixture or messed up flywheel key. If they are overhead valves, check the valve clearance. Usually they are checked when the piston is at 1/4" below TDC on the compression stroke.

Check the flywheel key.


Carbs have internal passages and I had to rebuild one on one of my Toyota's that I owned because a piece of the aux fuel pump diaphram got stuck in it. Carb cleaner wouldn't touch it. It had to be soaked in the stuff that eats at the carb. And the passages blown out.

Do the easy stuff. You have a test that fails. A compression test with oil. No amount of oil will fix a valve that won't seat.

Poor compression means the fuel pump won't work right.

It's not the rings per say, but the ring seals over the temperature range.

Ahhh! I was trying to think about what the effect of a bad oil breather might be. It would increase the pressure in the crankcase which would impinge on the ability for the oil pump to do it's job resulting with poor piston ring sealing and lower compression especially after the engine warms up.

Again relatively easy, but not that easy.

Vapor lock should never be a problem with that carb. Poor tank venting could be.

[NITRO-BTU]

KISS, The reason I mention valves, is because several years back when I didn't use this blower every year this became a problem. THEN... When I did need it, it wouldn't start. Well one of the guys at work had mentioned these engines, 5hp Briggs are natorious for "sticking intake valves." Sure enough he was correct. So, I removed the head, and took care of the stuck valve. First soaked the area thoroughly with liquid wrench, and then worked it free very carefully. Cleaned everything up, and reassembled. It seemed to run good as new; then a few years later the same problem. Corrected it again, and that's been it.
There is no oil pump, it's the splash system with a pointer attached to the bottom of the connecting rod to splash the oil.
Lastly, Briggs claims that a leaky exhaust valve will cause a lean fuel mixture, most notable at start, and idle, it dilutes the fuel mixture. So now both valves have become a potential problem.
WHAT SAY YOU - NOW ? Regards, Jim.

[KISS]

Well, then maybe it's your intermittant and fuel problem wrapped into one.

[NITRO-BTU]

KISS, What do you Recommend ?
Scrap the engine, or try to lap the valves. Where can I get a Good used Carb for a reasonable price ?
Regards, Jim.

[KISS]

My initial thoughts (no order. Just thoughts):

1. Replace engine

2. Replace valves and seats. See http://aee.ag.uidaho.edu/default.aspx?pid=96166

3. Carb is going to cost about $80-$100 probably.

4. I's hate to put $ into a bad design unless I could improve it.

One can only hope that if this is a systemic problem that Briggs could have changed the design. It happened onec, so it may happen again with just replacing parts.

Taking things apart is more labor intensive, so it's possible to find a machine shop that will do it if the engine is stripped to the block.

It was a whole lot easier to drop off the heads of my car (to a neighbor who had a business) when I was 15 YO than to pay someone to do it. While they were being done, I ported the intakes.

[NITRO-BTU]

TO WHOM IT MAY CONCERN:
Has anyone out there heard of Harbor Freight ?
Well, They have a replacement engine called the "Greyhound," and I'm trying to find out who makes it, probably a major company. It's a 6.5 hp. OHV design, Priced for about $100 bucks.
If any of you have this engine, Please give me your Feedback, whether Good, or Bad. Thank-You, Jim.

[DG]

I have used a few of those engines on some of my customers equipment.
But I'll tell you like I tell them.
YOU GET WHAT YOU PAY FOR..

[NITRO-BTU]

I have used a few of those engines on some of my customers equipment.
But I'll tell you like I tell them.
YOU GET WHAT YOU PAY FOR ..

SO, YOUR TELLING ME THEY ARE "TRASH?" Regards, Jim.

[DG]

No what I'm saying is that they probably will not last as long as the factory one did.