112 grader

How old is it? Look on the engine block just above the pony pinion clutch and just below the head gasket. Tag should be about 1.5 x 3" wide held on by 2 rivets. If tag is gone, look between the rivet holes for the numbers stamped in the block.

The 40's 112 grader could have had a D4400 with the big tall high pressure injectors that Bill rebuilds or after 1947 the D315 engine with the capsule type low pressure injectors that are not serviceable.

D315 engine then...if it is a 112. Quick check for a 212 with D311 four cylinder engine is the moldboard will be 10' long vs 12' on the 112. Also the rear wheels on the 212 stick out past the rear of the grader frame. I don't think they do on a 112. The D315 and D311 look very much alike.

You might have a problem other than the injector. Best way to diagnose is to swap the injector with another cylinder and see if the miss moves with the injector (bad capsule or CAT called them an injector "valve")

If the misfire stays in the same cylinder with the good injector from another cylinder.....Then you could have a pump problem or a cylinder/valve problem. The pump can be checked pretty easily by installing an injector line pointing out toward the wheels and screwing an injector extension piece and a good capsule onto it. Then turn engine over using the pony motor with decompression pulled so it cannot start when you open the throttle. The spray pattern should be fine and even. This setup can also be used to check any number of capsule injector nozzles, the capsules will not leak if you screw them on the extension hand tight as long as there is no trash in the joint. The thread holding the capsule on the extension is not a tight fit and will not stand tightening much more than finger tight.

Be careful not to get close enough to get fuel injected through your skin. This is a true emergency, get proper treatment immediately if that happens to avoid infection.

Problems with the cylinder could be valves (usually would hear it) or rings/piston/cylinder. The old style pistons used in the engines of that era were two pieces screwed together and the tops came off fairly often. Operators frequently reported bits of hot piston would be blown out the exhaust when that happened.

Permanent install the injector with a new set of dust seals to keep debris from getting in around the injector and under the line nut. The hold down nut is torqued to 100 pound-foot. Can do without the dust seals for temporary installation.

[quote="ccjersey"]D315 engine then...if it is a 112. Quick check for a 212 with D311 four cylinder engine is the moldboard will be 10' long vs 12' on the 112. Also the rear wheels on the 212 stick out past the rear of the grader frame. I don't think they do on a 112. The D315 and D311 look very much alike.

You might have a problem other than the injector. Best way to diagnose is to swap the injector with another cylinder and see if the miss moves with the injector (bad capsule or CAT called them an injector "valve"😉

If the misfire stays in the same cylinder with the good injector from another cylinder.....Then you could have a pump problem or a cylinder/valve problem. The pump can be checked pretty easily by installing an injector line pointing out toward the wheels and screwing an injector extension piece and a good capsule onto it. Then turn engine over using the pony motor with decompression pulled so it cannot start when you open the throttle. The spray pattern should be fine and even. This setup can also be used to check any number of capsule injector nozzles, the capsules will not leak if you screw them on the extension hand tight as long as there is no trash in the joint. The thread holding the capsule on the extension is not a tight fit and will not stand tightening much more than finger tight.

Be careful not to get close enough to get fuel injected through your skin. This is a true emergency, get proper treatment immediately if that happens to avoid infection.

Problems with the cylinder could be valves (usually would hear it) or rings/piston/cylinder. The old style pistons used in the engines of that era were two pieces screwed together and the tops came off fairly often. Operators frequently reported bits of hot piston would be blown out the exhaust when that happened.

Permanent install the injector with a new set of dust seals to keep debris from getting in around the injector and under the line nut. The hold down nut is torqued to 100 pound-foot. Can do without the dust seals for temporary installation.[/quote]

It is a 10 ft moldboard. With it running I can loosen the back injector line and the smoke clears up and quits missing. Still could be the valve? Do you know where I can get parts? We have over 2 feet of snow so It will be a couple weeks before I work on it again.

Wow! 2 feet! I guess it will melt off pretty fast this time of year?

You are right, probably the injector is the problem, but it doesn't take long to confirm it by swapping things around. Almost sounds like the pump on that cylinder might be mistimed with the rack.

Usually loosening the line makes a definite DEAD miss and you look for the one that DOESN'T affect the running of the engine. I get what you are saying about the smoke going away though. Maybe the injector on that one is going bad, nearly there but still getting an abnormal burn in that cylinder. What color is the smoke? Seen one with mistimed pumps that made some strange noises and lots of black smoke!

I have never seen a 112 in the flesh. Had a 1953 212 and now a 12E, so I am not sure on the moldboard length on the 112. I always heard the 112 was basically a 12 sized frame with a D4 sized engine. You probably can use the casting numbers in the side of the block to confirm what engine you have. The block of a 112 should be the same as the D4 that was made at the same time. The engine in the tractor will have different oil pump and pan from the grader and may have different injectors. The graders typically have a higher HP rating than a tractor but some of that may be done with governor setting to increase the rpm.

Serial number will be on the grader frame somewhere along the sides in front of the cab. I have seen them just in front of the cab and up front by the front axle. If engine is original to the frame, serial numbers will match. I have seen some engines that had the serial number stamped along the side of the lower edge of the block below the transfer pump just above the oil pan gasket. This was in addition to the tag above the pony motor pinion controls.

Get a serial number and someone will be able to give you a part number for the injectors. With a part number you can search online and see what's available. The capsule injectors are relatively cheap, but there will be quite a difference between CAT dealer and aftermarket sources.

In the parts book there will be a number listed for a set of injectors but the individual capsules have a different part number from that set number. You probably will want to replace them all while you're at it. They will frequently still spray when they open at pressure below 400 psi, but new/good ones will crack at over 500 psi and give better power etc. The one you have sounds like it might be stuck and letting compression back through into the fuel line. Probably it's just streaming fuel into the cylinder instead of spraying.

[quote="ccjersey"]Get a serial number and someone will be able to give you a part number for the injectors. With a part number you can search online and see what's available. The capsule injectors are relatively cheap, but there will be quite a difference between CAT dealer and aftermarket sources.

In the parts book there will be a number listed for a set of injectors but the individual capsules have a different part number from that set number. You probably will want to replace them all while you're at it. They will frequently still spray when they open at pressure below 400 psi, but new/good ones will crack at over 500 psi and give better power etc. The one you have sounds like it might be stuck and letting compression back through into the fuel line. Probably it's just streaming fuel into the cylinder instead of spraying.[/quote]


Thank you again for all your help. It will be a while before I get a chance to work on it.