Did you do a compression test on this? Does it have a compression release feature?

"Easy spin" starting which works off the intake valve. Compression is 78 psi cold and 173 hot

Big swing from 78 psi to 173 psi...

78 psi cold... are you holding the throttle wide open while testing? Is that 78 psi cold dry or with an oil squirt in the plug hole?

That seems kinda low and low compression would contribute to hard starting.

Throttle wide open with the air filter on. Dry cylinder

78 psi sure seems low and the huge difference between the cold and hot numbers screams out top end problem or would that be side end problem ;-)

If it were my engine that's the direction I'd go...

I've had the tractor sitting in the basement for 2-3 hours now. 70 degrees and I can pull it over faster since it's warmed up. I redid the compression test with the air filter off. and throttle wide open And now it shows 98 psi cold. I pushed it outside to see what it would do and it fired up on 2 pulls with no choke.

Sorry, but but there is still too big a difference in compression between cold and hot... your hot reading is almost twice the 98 psi you are now getting cold.

An internal combustion engine needs three things to start... fuel (with air), spark, and COMPRESSION. The big difference between the cold and hot compression readings indicates a piston, rings, bore or valve (train) problem. Could be a problem with the Easy Spin.

The way to solve these problems is Diagnostic Commandment #1... start at square one.

What weight oil is in that engine?

Have you adjusted the valves?

Have you verified that you have the correct valve lift to eliminate a bad cam lobe?

Oil is 5W-30 full syn.

Valves clearences are intake: .006 and exhaust .010. which is within specs

How long have you been running synthetic in that old engine?

Its a shortblock. 2.5 years old. Still has hone marks visible on the cylinder. I've been running synthetic for 2 years and only in winter. SAE 30 or 10W-40 is what I use in summer

I would revisit the carb. and points and condenser if it was me.

RC, nothing in the the carb can cause low cold compression if he's holding the throttle wide open during the test and then there's the almost 90% increase in compression when hot. That right there is a top end problem giveaway IF the valve train is adjusted and operating properly

A-C, IMO it's not a good idea to be switching between synthetic and dino oil in any engine, but especially in that old an engine design. Pick one type and stay with it. With that old an engine design I'd use dino oil.

As I already said "the way to solve these problems is Diagnostic Commandment #1... start at square one"

My bad, I assumed you rechecked all the basic stuff like points, condenser, timing, valve clearance, and plugs before you posted.

When you're absolutely sure all that is correct then with the engine cold, squirt a couple squirts of dino oil into the plug hole, crank the engine a few revs with your finger covering the plug hole, replace the plug, and check the compression.

If the compression comes up above the 98 psi cold you have now then top end is where you go.

This is really a simple problem to diagnose if you don't jump around from idea to idea and proceed from square one in a logical order. You may not like the diagnosis but it is what it is.

The book that came with the short block said for oil that 5W-30 or 10W-30 full syn can be used from -20F to 120F. Air filter cover says

Summer: SAE 30, 10W-30, 10W-40
Winter: SAE 5W-30, 10W-30

Regardless of who or how the short block was built or rebuilt that is an old engine design with a lubrication system and seals designed back when dino oil was being used.

I agree that 5w-30 in cooler climates and 10w30 for moderate climates is a good choice.

As far as synthetic oil from new as in a new engine or short block generally that is only done when the engine is designed to use synthetic and synthetic is the FACTORY FILL.

Unless my engine (in anything) comes with synthetic as a factory fill I use dino oil till break-in is accomplished and then consider switching.

I've discussed this at length with a Kohler engineer regarding Command twins and singles and their position is that synthetic is ok after 100 hours.

Seems I'm beating my fingers up trying to help you so I'll just watch till you stumble on the problem and let us know how you resolved it.

As i read this, I wonder how this engine will start onna fresh cold start - with the air filter off. If it does, that may indicate the filter is vapor frozen or dirt plugged. Last post, I din't realize the engine was in a tractor and had an air filter- just assumed it was a thrower w/ an air box. Let us know what happens w/ the next cold start.

8hp Briggs I/C. IMO he's luckly to have 98 Cold. 80 PSI is well within the range to start and compress gas to fire.

Individual Cylinder Chart: Engine % Variation Chart: (if 2 or more cyl.)
0- 24 p.s.i. = Bad valve OR bad head gasket 0-5 % = Great
25 - 54 p.s.i. = Poor (worn rings) 6-10 % = Good
55 - 64 p.s.i. = OK 11-25 % = OK
65 - 79 p.s.i. = Good 26% = Poor
80 + p.s.i. = Race or too high compression

All the experts say 80 in the minimum?

Ref:
http://staff.edmonds.wednet.edu/users/carlsons/0_esd_auto/images/1B&S_Compression_Test_Job_Sheet.pdf

Truth is, I barely put a compression gauge on anything. Useful to do a ring /comparision test tho. Briggs didn't use to pubish a rating on these -rather use a leak down tester. About the only time I do see compression that high is a twin that lost a pushrod. Doesn't the high reading seem high for an L head to begin with? Lurker talked about valve lift, which could maybe create a similar situation. Supossedly it runs and starts well warm? Though when I've seen that on OHVs, the lash has increased as well.
"When the engine is cold I still have to take off the air filter to start it." Does that not sound as though the filter isn't allowing enough air through? Compression then goes up 20 points? Why else would that be unless it can't get enough air? Just thinking aloud here....

RC,

Your link is a classroom exercise and does not deal in specific with that engine. It does not take into account the compression ratio or altitude

The giveaway to the problem is the difference between the cold and hot results. If you peruse tech info I'm confident you'll find that the differences in this guy's readings from cold to hot are far greater than usual... with your experience common sense would tell you that. Something in the top end is sealing dramatically better at working temp to register that much higher a reading and frankly, IMO that hot reading is way too high for that one lunger.

I'm not up on that engine but if you can link to the service manual let's see the specs and exactly what we're looking at in compression raatio.

I have never seen that great a difference in all my experience.

The really telling test would be a leakdown test. That would tell us volumes.

Of course, all out figuring is based on what the OP sees and tells us and whether or not he's accurately relaying that info and whether he has the knowledge or skill to really see what's in front of him.

That was just one example, it deals with Briggs engines, Last time I check they still make small gas engines? there was more that refered to 80 PSI when I goggled Minimum compression in small engines. I paste that one cause it had a chart. IMO if he kept oil in it with minimum run time there's probably nothing wrong with the bottom end.

JL: A/C has posted this Hard Starting issue on another "Previous Thread" . We all have started(Including Mownie) with the basics of Hard (Cold) Starting 101 . The New Spark Plug , Points & Condenser , Ignition Module , Fuel Filter , Fresh Gas , fuel conditioner , Compression Test vs Leak Down Test to validate Valves vs Rings issue Scenerio's . Initially when the Original Compression Spec's came back from the OP we all felt ( I believe) that perhaps they were marginal and that a tired engine may be require a Cold Starting Ritual ( Starting Fluid or Carb Cleaner assist). I do not recall the extreme swing from Cold to Hot reading previously ? The Multi Grade Oil transition recommendation came from me but I don't recall advising Full Syn in an Older Engine , normally Dino 5w-30 or 40 dependant on coldest temps reached during his season . Hope you can further assist with his ongoing problem Bro !

Diagnosing problems like these is difficult to do long distance. Sometimes the symptoms are so clear and the problem is common enough we are able to help a poster but more times than not we just spin our wheels.

I'd never try to diagnose a problem over the phone for a customer but we type and type trying to help a stranger. Now, if the OP could move it closer to his monitor so we could see it that would be a big help...

The OP has a 2.5 year old short block... a new short block or rebuilt? Who rebuilt it? Who installed it? Who tuned it? What has it's life been in the last 2.5 years? Low hours? If so, perhaps this problem was introduced by the replacement short block?

If I had that puppy on my bench I'd diagnose it in less than an hour but on the forum no, so I'll bow out out of this thread cause it will be a matter of blind luck if anyone figures it out.

If the engine here is the same one in the link below, your piston ring tension may have been compromised by what the mice did.
Regardless of crosshatch marks still visible on the cylinder walls, the rings may have contracted enough to keep them from inflating as quickly as they need to when stone cold.
You might want to revisit a set of piston rings here.
Piston rings would be my suspect here, now that I reread the older thread.

Here is a link that might be useful: Overheated

Yes Mownie. Its that same engine. I believe with the cold compression test I wasn't able to pull it fast enough so the "Easy Spin" was kicking in at the slower speed like it is suppose to. After I let it warm up in the basement I was able to pull it over alot faster then before so the "Easy Spin" didn't affect it as much. I called my dealer and talked to the mechanic this morning and he said for the hot reading, when hot I should be able to pull it over fast enough so the compression release doesn't stay open as long. 110-180 psi when hot is what he said is good and that the I/C series usually have a bit high compression then the standard aluminum bore because the I/C uses a different piston and rings than the aluminum (I knew that before) and the ring seal is better against the cast iron bore then the aluminum bore.

As usual... there's more to the story and this time from another thread.

It doesn't take a lot to overheat a thumper.

Cross hatch means little... the rings are everything. The rings may have lost their tension as Mownie said or they may be sticking in the rings lands of the piston (burned oil in the land) or the rings may have polished themselves and aren't sealing when cold. The ring gap may not have been fitted correctly when the short block was assembled or rebuilt.

All very apparent to the eye of a professional but not so obvious to an amateur or hobbyist or DIYer.

This is obviously another wild mouse chase...

I put some SeaFoam in the oil when I changed to help free them if they were sticking. I've had great luck with it for freeing up stuck/sticky rings. I had an Allis-Chalmers 6hp Homesteader tractor with a 6hp Briggs on it. And the rings were stuck and the compression was only 50 pis cold and it smoked really bad when first started and burned alot of oil. After 3 oil changes with the SeaFoam in the oil the compression went up to 70 psi and it didn't smoke as bad and the oil use pretty much stopped

OK, Seafoam or other solvent additives can certainly help free up rings if they are sticky from hardened carbon/oil/varnish deposits.
But neither Seafoam nor any other type of oil additive can bend a contracted ring back to its original elastic value.

Seafoam will do nothing to remove the polish from an overheated ring and, in agreement with Mownie, will do nothing to repair a damaged ring.

You've got pros here trying to help you and you have an excuse for everything without a single answer. Are you telling us not to try to help you?

Engine overhaul in a can... always the easy way rather than doing the work and learning.

Sorry A-C, the mark of an amateur... again.

Best of luck to you.

Update: It is still hard to start but I have ran 3 tanks of gas with a heavy dose of SeaFoam and half a can down the intake. Changed the oil to Mobil 1 5W-30 with 1oz of SeaFoam to control the condensation. Compression is a bit stronger since switching to Mobil 1. It runs alot better since. I did notice the crankcase breather tube is ripped where it goes into the carb...could this cause excess air leakage and cause the hard starting?

Follow-up's by 'Justalurker" will be ignored

No, the tube won't cause hard starting in itself. It could leave an opportunity for dirt to be ingested tho. Is it starting markedly better yet w/o the filter installed?

Yes it is a little bit better. Still can't start it cold with the filter on

A/C: JL knows his Stuff ! The air filter removal requirement points to a lack of proper fuel to air ratio which of course will lend to a overly rich fuel charge , when the filter is installed and insufficient air is being introduced to the cylinder. I think as I previously stated and voiced also by JL and other contributors that your engine is tired. There are numerous conditions that must be met for constant cold starting performance . Any one or combination of other deficiencies can and will cause your condition. As JL and I think most members would concur if your engine was on our workbench the diagnostic solution would be much easier to determine. All the Best Dude , keep a can of quick start available if cold storage is only available , just the thoughts of a retired former Diesel Mechanic lol :)

A-C, ignore this...

Before your next try at a cold start remove the spark plug and give a quick squirt of your engine oil of choice into the combustion chamber. Not a lot of oil just a quick squirtlet(?).

Turn the engine over by hand a few turns to distribute the oil and then replace the spark plug.

If it starts easier then...

I had this issue posted on Simpletractors.com also, and from what they told me it's a vacuum leak that is caused by the crankcase breather tube being torn and letting more air into the carb. As a test I unhooked the tube from the carb and plugged it and it fired up on 3 pulls with the filter on. I will be heading to the dealer today to buy a new tube.

JL: I do use this tractor year round for mowing, tilling, hauling gravel, firewood, plowing snow, etc. I mow mine and my neighbors yard with it so she does rack up some hours on her...that's why I went with the I/C (Industrial/Commercial) 8hp shortblock.

Can't be a vaccuum leak caused by a breather tube. A tube that feeds from the breather to a carb or airbox is an emissions item only. Remeber the days that the breather tubes fed out into the open air? The breather itself is a one way valve allowing venting when the pressure would other wise build. It closes and allows a vaccuum to form. That's not to say that the tube shouldn't be replaced. You may want to call ahead as it may not be a stocked item.

With respect to those posting on any other forum... it doesn't matter whether the air cleaner box is on the carb or there is or isn't an air cleaner element in the air box or the carb is exposed to the open air... mixture and choke is done in the carb and that air fuel mixture is critical from the carb throat (venturi) towards the intake manifold and into the combustion chamber.

If the breather tube connects to the intake before the carb and if you do have an air leak it is elsewhere than the breather tube.

If the breather hose connects to the intake on the cylinder head side of the carb that is an entirely different story.

A caveat to the first paragraph in my previous post...

If the air cleaner box or air cleaner element is grossly restricting the air flow to the carb (sopping wet with oil or dead bird or rodent... the possibility of which I believe has been eliminated by the OP) the engine will be hard to start... hot or cold.

JL: I got the new tube this afternoon and the problem is solved. I can start it with the filter on and it starts on 3 pulls

Where does the tube connect from and to the intake tract?

It goes from the crankcase breather to the right side of the air intake below the air filter

A question I've been trying to get you to answer for quite a while...

On the air filter side of the carb or the cylinder head side of the carb... in other words before the carb or after the carb?

Before

Air starvation is what I was indicating from your description of starts easier with the air filter off allowing adequate air to fuel mixture. As JL has advised dirty or loaded filter medium will cause this extreme condition. However as JL has requested (orientation) if the hose connects to the venturi area of the carb it will have a direct effect on air entrainment into the fuel air mixture. As we have stated previously , not having you engine at arms length make diagnosis rather difficult (hit & miss) . A torn or cracked or loose impulse line is something any technician inspects and replaces as a matter of fact. This from a former diesel mechanic who has chased numerous vacuum / return to tank fuel line issues causing air entrainment hard or no start diesel applications . Anyhow for what ever reason glad you have solved your hard starting dilemma :)

AC, how has the starting been?

It's been great. Full choke and 2-3 pulls and away it starts

Amen lol .

That's great news! It is real gratifying for you I'm sure to not have to mess around with it just to get it cranked up. At your next service interval, you may want to give the breather a good servicing as well. Thanks for reporting back.