Leak down test & compression test...

[TownsendsFJR1300]

Just posting for S&G's for those not familiar with a leak down test.

Now these pic's are from a TWO STROKE, OLD, Mcculloch chain saw
(that came in for repair):

Compression is 70 PSI:


Leak down was from 90PSI (at TDC), to 38 PSI, a massive drop (major wear/damage internally) with lots of air coming out the carb (piston port-no reeds):

[boscoe99]

How does the chain saw motor run?

One aircraft motor maker (Teledyne Continental) allows for up to maybe a 40% pressure loss from an input pressure of 80 psi.

Instead of working with a constant minimum value they have the mechanic install a calibrated orifice on the test equipment. This will bleed X amount of air pressure at 80 psi input pressure. The input gauge is set to 80 psi. Pressure is applied to the calibrated orifice. Input pressure is reset, if necessary, to 80 psi. What ever the output gauge indicates at that particular moment in time (it varies with the equipment and the atmospheric conditions) will be the standard that is used to measure a cylinder against.

[99yam40]

I put together one PM 610 from 2 that my oldest son brought to me.
one had bad compression and the other was no spark(plus missing clutch and a few other parts) including oil feed tube problems.
had to take both apart to get it going right.

bet that the piston,rings, and cylinder walls have a problem from running lean

guy from church borrowed a Husky pressure washer for clean up after his house/property flooded
and it dumped all of the oil when he tried to use it.
he will being it to me friday so I can look for where it is coming out from.
Have you dealt with Koler XT 7 oil leaks before?

[scofflaw]

What are the leak down numbers on that canal wall ?

[TownsendsFJR1300]

Ok, lot's of questions..

For the chain saw, it does not run, won't even try. Rebuilt /cleaned carb, plenty of spark. Starting fluid (of course you shouldn't on a two stroke), NOTHING, not even a cough... There's so much air coming out of the carburetor it is funny(with leak down test), again, at TDC. The head and cylinder are one piece (no head gasket, plus the leakage thru to the carb...
http://www.mcculloch.com/ddoc/MCCI/M...a_pspm610_.pdf


As for the Kohler oil leak, no I haven't worked on that specifically. But simply fill it back up with oil and crank her up. There should be a vent line from the crankcase into JUST BEFORE the air filter... Blow by, compression past the rings, will pressurize the crankcase and blow oil out that vent line. Oil spurting out is tell tale of worn rings. Rarely they break, wear yes. A leak down test would tell you alot w/o even cranking. You'd hear air coming out the oil filler tube(passing the rings). Most of those engines have a "low oil" shut down feature... I'd FIRST, (if they didn't add oil), see if the oil is low. If so, sounds like they toasted that engine... Might get by with new rings, if the cylinder walls aren't scraped up (usually aren't)..




Sea wall leak down #'s,

R&R all 80' of wall, cap, davit bases (removed-NOT being re-installed), remove concrete cantilever dock, back fill.

NO sod, no 5' dock to the boat lift, I do all sprinklers, both water lines to the lift, electric, I R&R both sides (20') of my 4' chain link fence. $46.125.00

Small boat dock (with the plastic wood), 5' x approx 18' (waiting for exact #but roughly $1,800.00

No idea on sod #'s, won't know till it's graded out and what's needed. Boat LIFT CANOPY R&Rd by them included. Boat lift/posts stay in place.

My boat cannot be on the lift during this time (liability should they drop something). That'll be two doors down on a lift under canopy cover.

3-4 month wait, one months time construction (wall, cap, fill dirt).

Latest pic, (davits removed, tree cut down, stump is NOW ground down, $225), trying to shore up future erosion:



Rotted re-bar inside slabs:

[99yam40]

he said he added oil and it left in 30 seconds once started, saying it is seal between motor and pump.
do not believe that
will see for myself tomorrow what is going on

just wondered how you put the metal sheets down into the ground

[boscoe99]

99yam, remember the other day we were discussing carburetor inlet valves and how they might or might not seat given a different level of pressure on the valve due to the change in float height? It got me to thinking about intake and exhaust valves.

The springs exert X force on the valve trying to make it seat. In a leak down test about 80 ~ 100 psi is used in the test which should help to force the seat further onto the valve seat. In an F40 the intake valve has a diameter of 1.77". If 100 psi is used during the leak down test then there is a force of 177 pounds pushing on the valve, trying to seat it.

But let's say that the valve does not completely seat even with the added force from the leak down pressure and with the force of the valve spring combined. It loses a bit of air across the face of the valve. Is it possible that during combustion, when the combustion chamber pressures rise to ~ 1000 psi, that the extra pressure on the valve may cause it to seat better? The valve will now have 1770 pounds pushing on the valve. If my math is correct.

[cleddau1]

Replaced cylinder and piston on small McCulloch chain saw last winter. Never done this before and surprised how easy it was. The new cylinder was cone shaped at the bottom thus squeezing the rings in so no need to fiddle with a ring clamp.

[TownsendsFJR1300]

he said he added oil and it left in 30 seconds once started, saying it is seal between motor and pump.
do not believe that
will see for myself tomorrow what is going on

just wondered how you put the metal sheets down into the ground

There will be a crankshaft seal (Obviously) on both ends of the crank.

The pump should have 4 bolts holding it on, maybe an allan key access hole as they'll be a key way
in the crank/pump shaft. Both should easily separate once the bolts are out.

Then you can see if oil (may see it W/O pulling the pump) IS coming from that seal.

If leaking the pump must come off. The seal, if bad, is usually easier to remove by pulling off the side cover
(pretty easy, just pick up a side cover gasket as well), and smack the seal out.

*I wonder HOW MUCH OIL HE ADDED..IE How LOW was the oil level.



The metal in the pic's shoring up erosion.

My neighbor was throwing a BUNCH of those aluminum hurricane panels out. I garbage picked them, took some of the short ones,
set them in place, then beat into the ground with a block of wood (to spread the load) and a 40 oz hammer..
Their probably 6" deep into the ground (for now).


Re the chain saw:
This thing is a beast. I believe it weighs 28lbs, twice that of engines now a-days.
He ordered a chain oil "cap" and got the wrong one. I seriously doubt he could get
rings for this thing if he wanted. It's easily 30 years old.. I have to heave it up
just to get it on the work bench...

It was made from 1981-88 so about 30 years old: https://www.napaonline.com/en/farm-t...aw/pro-mac_610
*Between my fence and the neighbors fence is about an 7" space. I stored those and other crap there where it's out of sight...

You can see the size of this machine, (yellow on the end), compared to the newer machines:

[99yam40]

oh, I thought those panels were a lot longer.

The PM610 I got running has a 20" bar and chain.
and it does not seem to scream like the Stil the other guy was using when we were cutting up a good size pecan tree the fell during Harvey in our pastors yard.
But it was steady ripping and never bogged down.

Guess I should see what RPM it runs

[99yam40]

99yam, remember the other day we were discussing carburetor inlet valves and how they might or might not seat given a different level of pressure on the valve due to the change in float height? It got me to thinking about intake and exhaust valves.

The springs exert X force on the valve trying to make it seat. In a leak down test about 80 ~ 100 psi is used in the test which should help to force the seat further onto the valve seat. In an F40 the intake valve has a diameter of 1.77". If 100 psi is used during the leak down test then there is a force of 177 pounds pushing on the valve, trying to seat it.

But let's say that the valve does not completely seat even with the added force from the leak down pressure and with the force of the valve spring combined. It loses a bit of air across the face of the valve. Is it possible that during combustion, when the combustion chamber pressures rise to ~ 1000 psi, that the extra pressure on the valve may cause it to seat better? The valve will now have 1770 pounds pushing on the valve. If my math is correct.

I have a feeling if a valve does not seat well more pressure is not going to help.
every valve I have ever found not seating/sealing was burnt and had to be ground along with the seats.
Even if it was a carbon build up, that carbon is hard enough that more pressure is not going to push it out of the way.

But you are correct, combustion in the cylinder should exert forces on the valves.
the springs should have enough pressure to seat the valves if the surfaces are what they should be.
the extra pressure from combustion should help keep the valve seated/sealed

[TownsendsFJR1300]

oh, I thought those panels were a lot longer.

The PM610 I got running has a 20" bar and chain.
and it does not seem to scream like the Stil the other guy was using when we were cutting up a good size pecan tree the fell during Harvey in our pastors yard.
But it was steady ripping and never bogged down.

Guess I should see what RPM it runs

Wish I could have gotten it running. It is so frigging heavy and their isn't any plastic on it, maybe just the pull starter... Made in the USA too!!

I have some long one's but I used one's just long enough to penetrate about 8" into the ground.

The 3 chain saw's, all Poulans, are running about 9k RPM's, WOT.

Dug up the electric line to the dock today along with water lines I wanted re-routed, about 100' of trench, jesh-too old for this crap... Just have to move the boat and 20' of fence once I get the two week notice call their coming...

BTW, just started seeing some fish IN MY BACK YARD. A bunch of small Mangrove Snapper inside the cap and the grass...

Lake Okeechobee (very large lake in the middle of the state), dumps all this murky "fresh" water into the river. The tides been so high as they release so much water...

The water does NOT taste salty at all, maybe 6" visibility. But it stains the side of your fiberglass boat!

[TownsendsFJR1300]

Yam, did you find the oil leak to the pressure washer?

[pstephens46]

Ahh yes. The ole tea stain. There is a nice big marina nearby with a restaurant and everybody hangs out there. It is on a big river that travels a long way inland. I despise it because of the stains I get from just a few hours of being there. Current is nasty too...

[99yam40]

Yam, did you find the oil leak to the pressure washer?

nope he just dropped it off, but may be the pan gasket. will need to check bolts for tightness before anything.

oh I would not be tasting for salt after all of that water coming from who knows where