I'm trying to gather info on this old cat, any input would be appreciated. Best I can tell the SN # is 3T26663. What year is it? The only site I found here doesn't list anything for the 3T but based on the other numbers it looks like a 64 model. Does that sound right? Most of the tractor looks to be complete and in decent shape, but the limited info I have on it says its been sitting 15-20 years and the engine is toast. What does everyone think about swapping a more modern engine in there? Which leads me to my next series of questions. What type of bell-housing are we looking at? How were the gearboxes in these, stout? Thanks guys
I have NO IDEA of what it would take to make it fit or if its practial,but later d7's used a 3306 engine and those are fairly easy to come by
The D7-3T series was built from 1947 to 1955 of which your serial number is a 1954 model. Engine is a D8800 4-cylinder. Extremely rugged and popular machine in its day, some 28,058 units built. Can't help you with conversion engines though, don't recall anyone wanting to.
The D7 motor is a great piece of iron, its best described as 4 cylinders of a D8 6 cylinder engine, they are built to the best standard I think CAT ever managed (in my mind), they make the new C series engines look what they are???, the best part about the D8800 is when it takes up a load, the cylinder firing can be counted in your mind as the engine just seems to nearly stop, it can lug down to 1rpm it would seem but just keeps on working, A 3T with anything other than the 4 pot motor, would destroy the best bit of the tractor, the D7 in the U.K. is fast becoming the tractor to have, I will admit that in seat starting is a good option, but they are good on fuel, the parts are easy to find, they are not to heavy to transport, plus the noise they make is what a CAT should sound like, I would buy the tractor and fix or swap the motor from another D7, if the running gear is good and all the bits are on it including the return springs underneath its belly, its worth tackling.
What do you mean the engine is toast? Just frose up or a big hole in the block?If the block is good rebuild it.
Why in God's name would you want to try and improve on perfection. I don't know if a D339 would be an option or not. That is the four cylinder version of the D342. I am not sure when the D339's started but know they are in the D7E 48A series. That is also one h--- of an engine. Run one here on a routine and regular basis. Again, you can count the cylinders firing in your mind. Top speed on the D339's is about 1,300 RPM. Leave it alone and fix it right.
Ah, yes, the sound they make well up on the governor is music to this old man's ears......who in their right mind would wanna change that sound?
The D339 came out with the next model, the 17A series.....basically the same great engine with the valve push rods now inside the block, same displacement....later models got turbo. I don't know if the D339 will fit up in place of the D8800 but it's got to be close. The D8800 go's back to the 9G series of the 30's, then the 7M series of WWII fame then the 3T's. lots of parts interchange range including the D13000 same 5-3/4 x 8 in. stroke.
There is some Lanchester style ballance shafts stuffed under the crank as well on the last of the 4 pot D7's, the turbo just adds to the music, the D7 model tractor was also the common tractor to be used through out WW2, the history is well stacked in favour of the D7 being the VIP of the track type tractors.
First of all thank you everyone for the help. I expected most everyone to say it was built perfect the way it came from the factory, and that may be true. But I'm looking at it purely from a production standpoint, I want it to push dirt efficiently and cost effectively. It's not that I don't appreciate the classic tractor the way it is, it's just a very distant 2nd priority. A 3306 did come to mind mainly because I have a friend with a rebuilt one that could very well cost me less than a stock rebuild. Any idea what it would take to bolt it to the transmission? Another thing I'm considering is especially out where I live diesel engines this old are on borrowed time before the green police shut them down. So rebuilding the 4cyl may only allow me a short amount of time to actually work and push dirt, which again is the primary goal. As far as the condition of the current engine goes I don't really have any idea what shape its in. The owner died a few years back and I've only talked to his grandson who was fairly young the last time the dozer moved. He told me that he thinks it lost a oil pump, but he's not really sure. But at the time everyone agreed it wasn't worth it to them to fix. So I would assume if it was ran with no oil pressure it would need at least some heavy machine work, possibly a rotating assembly and block depending how long it was run. I was thinking if I was to purchase it I would expect the worst and investigate the bottom end first thing.
Well LT, this is just my thoughts on the tractor, the 8800 is about as clean running if not better than the 3306 turbo or no turbo, both engines would not comply with any Euro4/5 clean air thing, I know in the U.S. this scale is called some other marvel of mistery??,the 8800 is a slow speed high torque engine the 3306 is running at near twice the speed of the fitted unit, so you would be sort of going back before you get there if you understand, plus the balance and appeal of the tractor would be s##?, I think you would be far better off with a D6R-11(2)this has the C series engine fitted that would sort your smoke issue and would be a fine thing on production work, the 3306 is in itself a real old banger, its early name was 333A-B-C, so it was churning out the coal well through the 1960's, so nothings new, it only smells new, Buy a High drive and leave the D7 for someone else to " gather up "
+2 It makes no sense to modify and push a 1954 tractor into production. Please keep it "as is" for an appreciative collector or fix it up and keep her around as a putt putt. That would be like telling grandpa he has to go back out and start working again.
If your going to run production in Ca. forget it. The greenies will never let it happen. As a personal collector piece....with a little production on the side.....it would be something to enjoy. If that doesn't do it for you it would be nice if you'd get the word out to other perspective owners or at least a donner to one being refurbished.
Well "production" may have not been the best choice of words. I would be extremely happy to put 300-400 hours a year on a machine like this at this point in time. My point was, I don't want to collect it, I want to put it to work. There are several contractors in my area still running cable dozers, (this particular 7 is hydro) and several more running iron from the 70's. Or they are for now, until the greenies string them up.... I know the 3306 wouldn't be any better for emissions, the emissions problem is just one of the problems that had me thinking of a engine swap. For now it seems the current owners are not sure they want sell. I think the old cat has some sentimental value.
No doubt i'd be much better off with a 6R! Have you seen the price tag on one of those? Any way you slice it I could have this old 7 pushing dirt for 1/8th of the price!
There's alot of cat wrecking yards around to find parts, I haven't had any issues finding parts for my 17a so it shouldn't be a problem finding the correct engine. I personally am not a fan of the 3306, the ones I've been around don't have the grunt that the big 4 or 6 cylinders do and don't seem to last as long as well. Sent from my DROIDX using Tapatalk
Getting the 3306 into this machine and getting it to mary up to the transmission would also be a problem. I am not sure what the difference in length between a 3306 and the stock engine is. I am assuming that this one is still a direct drive. I know that there were lots of problems with the D7F series when they put a 3306 into the same power shift transmission that the D7E series had coupled to the 339 series engine. There were lots of problems with the early D7F series with 3306 engines. Took until they got the D7G series out to correct everything which is one of the best tractors Caterpillar ever produced.
Not really encouraging a swap but coupling might be the least of the problems. That late a serial number 3T had the oil clutch with "U" joint output shaft arrangement.
Guy I’m needing help also I have a D7 3t the tag reads 3t99sp? Im trying to find the year of this thing.
Here’s my tag
Same on back unit