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B without compression

T

Tylerpresser14

Member
So I got a John Deere b drive it to where it sits went
to start it and there is no compression with the
petcocks closed set the valves figuring I had one
stuck no such luck they all are set and move nice
looking for information something g tells me my
pistons are not moving but wanted to know if there
is a shear pin or something of the affect that would
have sheard
 
Fill in the blanks as in what year and how long it has sat.

If it has sat for say a month to a year or more it could well have stuck rings and a simple jack it up in the front and then fill the cylinders with ATF and let it sit a few days may fix it.

Or you could have a valve while they move are not seating down all the way and that too will cause that and a ATF treatment with a s much as you can pour down the exhaust plus in the cylinder may fix it also
 
No shear pins,,,,,I seriously doubt there's a major crankshaft or connecting rod problem. Remove the plugs and look inside the hole and use a piece of wire in there and you can tell if the pistons are going up n down with flywheel rotation which I bet they are.

If the valves aren't stuck and are opening and fully closing but no compression, the air intake pipe or cleaner being fully closed off and full of gunk can cause low/no compression, but it would have to be like badly clogged up.

Often if a tractor sets a long time the rings can be stuck but it should still have at least some albeit low compression.

Try to remove the plugs and squirt oil in the cylinders as that can increase compression.

If its sat a long time you might remove the plugs and fill the cylinders with a mix of brake fluid and diesel fuel and auto tranny fluid and let her soak to free things up then drain and change oil and see if she has compression.

John T
 
The info you gave would lead a reasonable person to think that #1. Less than a week has passed since you drove it and parked it and tried to start it again. # 2 That there now is zero compression in either cylinder. #3 It's an older "B" since has comp reliefs. #4 In order to check compression you would have had to turn it over either by hand or elect. start. #5 that while cranking it over with reliefs closed or open you not only don't hear hissing through reliefs but also don't feel any resistance as if it had compression. #6 that you verified that all valves were operating correctly. This is what your post said. NO there isn't any "shear pin". So now if you care to make any additions , deletions or changes I'm sure we can help you. I'm sure it didn't break both rods when you parked it.
 
It is about a 47 I believe hand start only and no puff or anything from exhaust or petcocks usually I know there is at least some sort of pressure even if it is only 10 psi but I have absolutely nothing and it ran to its parked spot that's why I was asking if it could have a shear pin I know that even with bad rings it should have something for compression
 
Again how long has it sat with out running??? One like that I would probably try pull starting it. I have a 1935 JD-B that I have not started in a couple of years but when I do start it I clean the points and then once I know I have a good spark I pull it and so far it has never made it out of the building it is parked in with out starting. It sits in the back of a 16X16 machine shed so i starts in less then 16 feet
 
Has not sat been used for raking and a #5 mower up to the day I got it do I need to open the petcocks to pull start it will try that if that doesn't work it will have to come apart I can hear something tumbling in the threshing belt pully any idea on what that would be
 
Nothing "wears out" overnight. It has to be older than '47 because they did not have compression reliefs and all were elect start. If you do not hear hissing out comp. reliefs and hear noise in clutch housing then NO I would NOT try to pull start it until you find/fix the "rattle". May be related or maybe not to why it has no comp. Are you sure the flywheel is actually turning the crank? Splines good and tight and nothing broken there? Stick something inside spark plug holes and see if pistons are coming up and back when turned. Since you have something "rattling" in clutch, I would make SURE that you ALWAYS have both brakes set and locked tight BEFORE doing anymore with it. Easy way to get ran over if it starts and you don't know what's going on inside the drive line. Only two things that would do exactly what you are describing...2 rods broken at same time or a crankshaft broken at flywheel end. Both unlikely but never know until you check. That is the only scenario that would let you crank flywheel around freely with absolutely zero resistance with valves operating correctly like you say and spark plugs in place.
 
Should be able to pull start ti with or with out the petcocks open. The belt pulley area is also the clutch so you could have a broken spring or other such thing in there and you need to check that
 
"It has to be older than '47 because they did not have compression reliefs and all were elect start."

Randy, both early styled and late styled B's were built during the '47 model year.
 
The B had petcocks up until serial number B289376 which was a 1951 model.
Part number AB1898R. My book shows that at serial number B201000 they used the block that had the petcocks on the bottom of the block. Block number B2500R. I know a couple of people who had never discovered the petcocks on the bottom. I never use them anyway on a B.
 
Pappy,
The B2500R block on serial # B201000 and later tractors had plugs on the bottom of the block which could be removed and petcocks installed. Don't think they came from the factory with petcocks already installed.
 
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