• Advertisement

Craftsman Tractor Won't Start.

Use this forum to discuss small engines, and the equipment or machinery that they power. This is the main section for any technical help posts and related questions.

Re: Craftsman Tractor Won't Start.

Postby lefty » Sat Apr 20, 2019 1:28 pm

I'm about to pull this head. Just letting some penetrating oil work on the exterior head bolts, or nuts in this case, for a bit as the last head I took off, I broke a bolt. While that simmers...I had a couple of questions.

Is there anything I should be careful about with this? I've only removed one head on a hydraulic machine in the past and it was more for exploratory reasons. During that procedure, one of the lifters came out. It was kind of stuck at the end of the push rod . I just popped it back in but the machine was not to be used again. While this head is off, should I be inspecting the lifters as well? Or should I do everything in my power to not disturb them?

Also, not sure if anyone had any thoughts on my question regarding the strange behavior during my leak down test. How the pressure jumped on the cylinder side when I went from about 50-60lbs on the compressor side. Just wondering if that's normal or strange. Or an indication of how I may be doing it incorrectly?
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby bgsengine » Sat Apr 20, 2019 7:24 pm

lefty wrote: While this head is off, should I be inspecting the lifters as well? Or should I do everything in my power to not disturb them?

Generally as a rule of thumb you will loosen (don't need to remove at this point) the rockers, before removing head , then note the push rod location (intake / exhaust) while removing push rods only, and leave the lifters in place - only reason you might pull lifters is if they are bottoming out (you'd have excessive valve clearance then, rather than zero clearance, in which case you also need new lifters, they are not serviceable, and you don't really wanna remove them, if you do, you wanna note which hole they went into so you can put them back in the same location)

Also, not sure if anyone had any thoughts on my question regarding the strange behavior during my leak down test. How the pressure jumped on the cylinder side when I went from about 50-60lbs on the compressor side. Just wondering if that's normal or strange. Or an indication of how I may be doing it incorrectly?
One possibility I can think of is a broken piston ring that pops back out under increased pressure, so if you do not find suspected cylinder damage , you might want to think on that possibility.. if you do find the cylinder damage you gonna have to pull piston anyways for rebuild, (or just short block 'er, in which case you ain't gonna be worrying about push rods/rockers/lifters anyway) But I'm betting you will find something not right when you get the head off..
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)
bgsengine
Briggs MST
Briggs MST
 
Posts: 3296
Joined: Sun Nov 03, 2013 10:07 pm
Location: Northcentral P.A.

Re: Craftsman Tractor Won't Start.

Postby lefty » Sun Apr 21, 2019 7:19 pm

Sounds good. I'm getting my hands on a scope tomorrow so I'll see if I can't spy something in the piston before pulling the head. Thank you.
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby lefty » Mon Apr 22, 2019 3:00 pm

I know I've been a pain in the butt on this one but I have some new information, I think. So I took a look with a scope. Of what I could see, there wasn't anything that jumped out at me. So before I pulled off the head, I wanted to just do another quick leak down. Call it just being chicken or OCD. Not knowing much about these hydraulic lifters, I wasn't sure if the air pressure would cause them to shoot out from crankcase pressure so I figured I'd put the rockers and push rods back on to hold them in just in case. During this process, I noticed that when I tightened the exhaust rocker, it actuated the exhaust valve. Thinking I had moved the piston into the range of the compression released, I realigned top dead center...same result. It seems, now anyway, the position of the lifter when the engine is at TDC is such that it is leaving the exhaust valve open.

Can I do a leak down with the pushrods and rockers removed? Will the lifters stay in place or will they shoot out during this procedure.

If this is not normal, is this information helpful?
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby lefty » Tue Apr 23, 2019 11:34 am

Leak down with valves out of the equation gave the same results. So I pulled the head and attached a picture. Although the cylinder wall doesn't look bad, I noticed that the piston clearance is not uniform. The piston is right up against the cylinder on one side and there's an enormous amount of space on the other side. This is relatively consistent throughout the stroke. I've attached a picture so you can see it. Is this normal or do we think this is the problem? Worn rings? Something out of round?

Image
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby lefty » Tue Apr 23, 2019 4:45 pm

Could this be the problem? Looks like the gasket got pushed and compression may be escaping into the crankcase through here? Might explain why it sealed off during the leak down. Maybe a piece of gasket flaps up during high pressure?

The exposed silver area all the way over on the right is just some of the gasket came apart during disassembly.

It definitely does look good.

Image
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby bgsengine » Tue Apr 23, 2019 9:16 pm

lefty wrote:Could this be the problem? Looks like the gasket got pushed and compression may be escaping into the crankcase through here? Might explain why it sealed off during the leak down. Maybe a piece of gasket flaps up during high pressure?

The exposed silver area all the way over on the right is just some of the gasket came apart during disassembly.

It definitely does look good.


definitely a blown head gasket which would push air into crankcase, yes, but you should check head for flatness before just popping in a new gasket, looks like you may find warpage in the head itself... may need to put a new head on 'er.. hard to tell really just from photos..
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)
bgsengine
Briggs MST
Briggs MST
 
Posts: 3296
Joined: Sun Nov 03, 2013 10:07 pm
Location: Northcentral P.A.

Re: Craftsman Tractor Won't Start.

Postby lefty » Tue Apr 23, 2019 9:49 pm

Thank you. I have some Starrett squares laying around. Could I use the metal ruler from one of those? And what is my tolerance as far as what sized feeler gauge should I be using.
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby lefty » Wed Apr 24, 2019 1:14 pm

Didn't find any warpage in the head so I reassembled. I'm getting the same results with the leak down.

When the head was off, I noticed that the piston could be rocked back and forth by hand. I read that the piston does rock back and forth just a bit during normal operation. I guess when it gets bad they call it "slap"?

Anyway, I thought that maybe that's what I'm hearing during the test. Maybe when the pressure builds to a certain point in the cylinder, the piston centers itself up and creates a good seal which causes the pressure to shoot up from horrible to more normal readings during the leak down? Then once deflated, the piston rocks back to one side. Rinse and repeats. Really worn rings maybe? I know I really can't tell without pulling it apart but I feel like I need to know what is causing this weird behavior during the leakdown.
lefty
Forum Pro
 
Posts: 967
Joined: Sun Jun 08, 2014 10:12 am
Location: Massachusetts

Re: Craftsman Tractor Won't Start.

Postby KE4AVB » Wed Apr 24, 2019 2:03 pm

Why not just measure the cylinder diameter? It should be 90mm with max diameter of +.12mm (.005 in.). This at top, middle, and bottom of the stroke. Done twice at each level 90 degree apart.

Ring end gap should be 0.77 mm (0.030 in.) max. in a used cylinder bore and 0.3/0.5 mm (0.012/0.020 in.) in a new cylinder bore. Should be able to eyeball the top ring ends with as much side movement you have.
The truest measure of society is the how it treats its elderly, its pets, and its prisoners.
User avatar
KE4AVB
Forum Pro
 
Posts: 5999
Joined: Mon Nov 04, 2013 11:23 am
Location: TorLand

PreviousNext

Return to Technical Discussion Forum

Who is online

Users browsing this forum: No registered users and 7 guests