Hey guys. I am new to owning a CAT 977 although I have operated other heavy equipment for many years. I recently purchased what I believe to be a 977L model (Serial # 70J1348) and found that during a production run in 1971, they started making the L-model but kept the K-model serial prefix 70J. Specifically, I’ve read in 3 different places now that the L-model production that started in 1971 began with 70J1303. Is there anyone that could help me find an absolute answer to this? I’d also like to see if there’s anyone who might be able to help me determine whether or not I have a 3306 vs D333 engine. This machine has direct injection. Machine is in outstanding working order, starts and runs perfectly, operation is fully functional, and has a brand new undercarriage. Only 1 issue that I have noticed is that something is causing a lot of aeration in the hydraulic system. I might post at another time about that to try and find where air is getting in. Has new lift and bucket seals. Any help would be greatly appreciated!
The 70J prefix indoicates that you have a Japanese-built 977. The US-built equivalent model carries an 11K S/N prefix. The fact that the engine carries a plate with the same Serial Number as that of the tractor indicates that it is a D333C model. When the 3306 was introduced engines started to carry their own individual Serial Numbers. A 3306 engine in a later 977 of 70J S/N prefix would carry a Serial Number plate stamped 44Vxxxxx. The 70J-prefix changed models from 977K to 977L from machine Serial Number 70J1303, along with an increase in engine power from 170 to 190 FWHP. The 3306 engine was not introduced into the 70J machine until Serial Number 70J2223. So what you have is a very early 977L model fitted with a 190 FWHP D333C engine. There is very little information in the Cat online systems for this particular model, so the best advice would be to get hold of a Parts Manual. The Caterpillar Publication reference is UMX00191 which covers all 70J machines from first built up to 70J2222. It is available for download from the Cat Pubs web site for $124 if you can't find one available on places such as eBay.
Nige correct me if I'm wrong. The OP mentioned that it has a direct injected engine. If that is correct wouldn't it be a transplanted 3306?
Good point. It could potentially be somewhat of a Frankenmotor with a direct injection head mounted (and I assume the FIP, etc to go with it) on top of the original cylinder block, which by the S/N plate on it was originally built as a D333C. It sounds as though photos are required, especially of the cylinder head & injection pump. If the Frankenmotor theory is confirmed it might require more than one Parts Manual to cover the engine, because even the early 3306 engines in 977 machines were not direct injection.
After zooming in on a couple of the photos I would be hesitant to call that a brand new undercarriage. Just my $.02
^^ Agree The bolt heads are about even with the grousers
The RH rear carrier roller is looking distinctly second hand.
I am so pleased with these responses, thank you very much everyone for being so kind and offering your help! * Please see attached photos of the fuel system. I could be wrong as I’m still learning. * As for the undercarriage, yes you are correct. I didn’t share any details, sorry about that! The final drives were rebuilt, steering clutches, new chain, sprockets were swapped from one side to another and not replaced, and the track plates were not replaced but have grouser tabs welded on in a staggered pattern. * My brother is working on this machine with me and has been a great help doing a lot of research. He is still firmly believing that we have a 3306 but I don’t know how to tell the difference. In either case, it’s a monster machine and runs EXCELLENT and will meet our needs. It’s possible that we might not reach a definite answer for the engine but I’m patient and this has been a true joy working on learning this machine. * This machine was purchased new in 1971 and was owned, maintained, and operated by the city of Tonasket way up north in the WA state mountains. It worked in a rock quarry its whole life, the undercarriage work was done in May of 1993, and then the machine sat for roughly 20 years. It was sold to a local resident of Tonasket but he was unable to operate it. He had an injury that became worse and he wasn’t able to get in and out of it. I believe he said he put less than 20 hours on it and he had replaced the upper lift cylinder seals before selling it to us. * We have all of the original service manuals purchased by the city including notes, part numbers, and greasy fingerprints in all the sections where they worked on it It’s pretty cool. I’m not at my house at the moment but I’ll take some photos of the manuals and send them this evening. I do not have the parts manual that was suggested in this thread though. All of the service manuals are for the 977K and 977L with greasy fingerprints and notes on the pages for the 3306 engine. Also the sections of the manuals are for the 70J serial number. Again though, I could certainly be wrong here! Just because the pages are dirty in those specific sections doesn’t mean that it’s a 3306. Nige, your information is extremely similar to what I had found and posted originally in this thread: the main difference being that the other post said that the serial number starting with the 3306 was 70J1303. You have much more detailed information and judging from your help with others on this site, I trust your wisdom and judgement. I know the ROPS cage on our machine is from a D7 dozer (according to my brother’s findings) and that’s why they modified and made brackets and a shroud around the diesel and hydraulic tank. Here is a link where I found this information: https://tractors.fandom.com/wiki/Caterpillar_977K Again, thank you everyone for being such a great help to me. I hope you know that you are greatly appreciated.
I’m actually heading back outside for a while to finish working on changing out hydraulic fluid and picking away at some other things. If you need better or different pictures, please let me know!
You have a pre-cumbustion engine as the glow plugs are visible in your pictures. Simon C
Thank you, Simon! Attached are the photos of the service manuals that came with our machine.
Those photos confirm that it is not a direct injection engine. Therefore bearing in mind that the cylinder block carries the same Serial Number as the tractor and the head is a PC type it is my humble opinion that you have a D333C engine, most likely the original one that was installed in the tractor when it was built. The clue is on the cover of the Parts Manuals for the 70J machine. UMX00191 simply says “977 track type loader 70J1-2222.” XMBP9580 for machines 70J2223-Up is titled “977 track-type loader powered by 3306 engine”. It also includes information regarding the engine Serial Number “44V00001-44V15266”. All my sources carry the same information; that the 977K (Japanese or US built) was originally built with a D333C engine. At a certain Serial Number the model changed from K to L and the engine power was increased from 170 to 190 BHP but the engine model remained as a D333C. At a later point the engine was changed to a 3306 and generally what happened was that a new Parts Manual was created that contains the text “powered by 33xx engine”. This in my experience is always the clue relating to what machine Serial Number the engine changed from a D-Series to a 3300 model.
Just to be clear machine S/N 70J1303 was the point at which the engine power was increased by 20BHP and at which the model suffix changed from K to L. The engine model did not change to a 3306 until much later.
The track looks too tight as well.
Gentlemen, I can’t thank you enough for your help. I’m sure I will have something pop up here and there that I might need help with. Thank you for being so kind helpful to me.
Good luck with it, that is indeed a real beast! If it proves worthy, then on your list should be a cutting edge, adapters/teeth etc. Note the scalloping on the unprotected bucket edge.
I don’t think that’s what it actually says. Copied from your linked article……. “Caterpillar replaced the 977K with 977L in 1971, but retained the 977K serial number prefixes. The 977L featured increased horsepower to 190 hp (140 kW) FWHP, beginning with 70J01303, 48J00586, and 11K03919.” So that was the time at which the machine model reference changed and the engine power was increased, but it doesn’t mention anything about a change in engine model because there wasn’t one at that time.
I have an interesting update I believe. I finally got another chance to do some cleaning on the engine block and found the block serial number. I got everything cleaned up and it is very easily visible. Attached is the picture of the markings as you see them on the right hand side of the engine underneath the fuel system. Sorry for my terrible napkin CAD I can’t find anything specific, but it seems to possibly point to a 3306 engine? Could that be possible?
A lot of people labour under the misapprehension that a D333C block and a 3306 block are different. In fact they were both originally produced from the same casting number. There are differences between the two engine models but they are mostly in relation to minor components such as the water pump and the way it is driven. Post a couple of good photos of the water pump please. What you see on the block is a code indicating when the casting was manufactured and the Part Number of the block casting itself.
The x on the end of casting number only means it was made in japan
All the more reason to believe that the block is original and belongs to the same motor the tractor was built with. I just checked and the 5S6777 Part Number is discontinued with no listed replacement.
I would guess some where it would go to a spacer plate block
In the Parts Manual the block is listed as 5S6778. It's shown as being used in the 11K US-built 977L from S/N 11K3919 to 11K4257, all of which were equipped with a D333C engine. In the 11K machine the 3306 engine, still with pre-combustion chambers, didn't arrive until 11K5083.
Casting numbers are usually one number off part number
My info on casting numbers for the block show the 5S6777 used on both the D333C and 3306 along with a whole string of other interchange casting numbers.
The spread between casting and part numbers depends on the number of machining operations
Check the water pump....
It's been a BUSY month but I've been able to do fluid and filter changes, get about 4 hours of heavy run time on this.......it's a BEAST. This engine runs extremely well, shifts smooth, steers smooth, and I am very pleased with the condition this machine is in. Such a huge blessing to my family and our needs. I wanted to say a huge THANK YOU to everyone who posted on here to help me. Your wisdom and knowledge are invaluable. I do have one issue where I'm getting coolant in the hydraulic fluid but I will start a different post for this. I downloaded and purchased the parts manual for this machine but I don't see where coolant ties in with the hydraulic system.
Is there an oil cooler on the bottom of the rad?