D7F opinions

[ironage]

Hi everyone. Im considering buying a D7F dozer to do some work around the farm and would like to know what im getting into before going any further with it. I have read some information on them and got conflicting opinions as to the reliability of these machines. I don't have a lot of information on this machine as of yet but I do know it has the 6 cylinder engine and is a 1977. It has a semi u blade and 3 shank ripper. The under carriage im told is about 60% and total hours are unknown. It was bought at an auction 3 years ago and the owner has since passed away so his daughter is selling it now. She said he used it for about a week to clean up an old yard site and that was all. What sort of things should I be looking for on this series of machine and are there any real problem areas that I should watch for? My plan is to clear some brush and burry rock piles with it as well as cut down some high ridges and push the dirt into the low spots beside them. Will I be able to dig down decent for burying rock piles or will I be having to make a long trench to get a big enough hole? I will be going to look at it on the weekend and hopefully be able to run it and get some pictures and more information.

Thanks.

 

[lowbed driver]

D7F made in 1977?? I think this may be a typo. By 1977 Cat was well into making D7G's. Could be a real late F made in 77 I guess. I ran a 72 or 74 D7F and they are good machines. Pics are always nice. Good luck with it.

Lowbed Driver

 

[D6 Merv]

yep the D7G came out in 74. The early Fs were a problem but the last of them were ok; all depends on what serial number.

 

[Cam85]

Hey mate if that dozer has been sitting that long b careful this could turn into a can of worms if it were me if I could afford it afford it I would try n find a G ur getting away from pilot motors ( cantankerous pigs at the best of times ) and get in to a 3306.
The G is more common easier to get parts and info 4.better injection and stuff.
That's my 2 cense worth any way.

 

[ironage]

I have a serial number!!!! 94n5775. I talked to the daughter again and she gave me her neighbours number who knows a little about the machine. He said as far as the year he thinks its more like an early 70s machine and from what he remembers it should have the newer smaller transmission, it does have the 3306 engine and injectors and turbo were supposed to have been changed just be for it was sold at the auction. He figures there might be a leaking or cracked valve body for the ripper control or bad cylinders because the ripper creeps down and has to be chained up. Other than that he didn't know to much more other than it was working good when the former owner was using it. I guess now if someone could tell if that machine does have the good transmission from the serial number and actual year of the machine then I could get a better idea of what to offer for it.
Thanks.

 

[lowbed driver]

Cat updated the transmission at serial # 94N 5192 and above so looks like you are good to go. If I remember correctly the early D7F had the transmission from the D7E and the F had more horsepower and that transmission was the weak link , so to speak, in the drive train. I have heard (but do not quote me) that the early D7F's with the weak transmissions are still a good machine for the hobby equipment owner or someone who is going to be easy on the machine. I think the problems would arise from heavy dozing, pushing a scraper, pulling a scraper etc. Contractors were starting to shy away from the F model so Cat updated the transmission.

Cheers Lowbed Driver

 

[lowbed driver]

Oh yeah ...I forgot...post some pictures for us to see..... grin...cheers again L.D.

 

[Old Magnet]

s/n 94N5775 is a 1973 machine.

 

[D6 Merv]

yep 94N5775 has both 3306; earlier was D333C; and the later smaller transmission; problem with the earlier D7E trans was it went from 1200rpm with the D339 to 2000rpm with the D333C and it didn't like it should be a reasonable tractor. Check the magnetic screen and filter, and id also drop the final drive oils to check for sadness. If alls good buy her

 

[FinnTech]

Ran a 1973 94N for many years pulling scraper and clearing brush, it was a great machine. Over the course of 15 years or so replaced one transmission and 3 or final drives. I always found the final drives to be the weak point on all the low drive dozers.

 

[Chum Duffy]

I put several thousand hours on a D7F and found it to be one of the most reliably tractors we have ever owned and we have owned over 100 or so!! I would'nt hesitate one bit buying one that was in good shape to do land clearing on the farm. The 3306 cat engines were used in many application and are as bullet proof as any engine ever built. they are also very reliable and low maintenance. You will burn 5-6 gallons of fuel per hour if your working it steady. BTW I have never herd of a D7F with a pony motor for a starting system. They came from the factory with a 24 volt direct electric starting system. On another note the later model D7E's with a D333 turbocharge engine was rated at 180 horsepower the same as the D7F's with a D333 or a 3306 engine at the same R.P.M, and everyone will agree the later D7E's were wonderful tough machines with no weak links!! Yet the early D7F's that weighed nearly the same and had the same engine with the same horsepower and same transmission yet the every one claims the early D7F's had a very weak transmission and stay away from them!! Go figure! The fact is they started using the newer designed smaller lighter cheaper to build D6C transmissions in the D7F's. Frankly I don't see how it had anything to do with higher failure rates of the time tested D7E transmission, we've own and operated them both!! Yet my guess is there will be those who come and say -"No no those trannys were weak such and such told me so!!! Chum..

 

[D6 Merv]

your all up the creek chum. ALL D7E had the 4 cylinder D339 that did 1200rpm at full load. That transmission was quite happy at that rpm. early D7F came out with the 6 cylinder D333C at 180hp at 2000rpm. The F used the same D7E transmission BUT with different transfer gears to slow it down. Trouble was the big heavier planetarys didn't like the higher rpm and they failed. Also the D333C was a lot lighter than the D339 which led to everyone complaining about Fs being lighter in the nose. Cat changed the trans to the lighter D6C style trans; but with more plates and stronger transfer gears at 94N5660. the D333C changed into the 3306, with its own 3N engine serial number and was fitted at 94N5192. a lot of people think the change occurred together but it didn't.
But as chum rightly does say all later ones after that are good tractors the problems were fixed; but the reputation stuck so cat introduced the D7g in 74

 

[ironage]

Lots of good info and advice guys, thanks. Still haven't had a chance to go run the machine yet being minus 35 and wind pushing the temp down to minus 50ish I don't think the old girl would like the idea of trying to run and neither do I lol. I had a chat with a fellow who ran an early 7f and he said it was a great machine. Then they traded to a newer one with the 3306 and he said it dang near put them out of business with tranny issues so when cat put the smaller tranny in the last 7fs they traded to one of those and have been running it ever since and very little problems. He did mention that there was an issue with the transmission heating up if you worked up and down a steep slope for a long time but it was fine running on a side hill. Any thoughts on that? What about oil types, what does cat run for tranny and hyd oil in those machines?

Thanks.

 

[D6 Merv]

oil is a to4 spec 30 grade. hyd are 10w grade engine oil. D7F and Gs can get into trouble on slopes, if the oil level is low, especially climbing the trans can suck air; and there will be no go, no steering and not a lot of whoa either :eek more so on G, F is mechanical only brakes:. Cat recommend a 5 gallon overfill of the transmission when doing hillside work

 

[td25c]

Never been around or operated a Cat D7F... My uncle has. He started on the early 7E's then was impressed buy the "high horse" D7E that came in around 1970. His only complaint about the D7F that he ran was it did not have the snap & crack power of the older High Horse D7E . I'm guessing he would have been running an early model D7F. Then the 7G came along and he loved that model.

 

[D6 Merv]

Hi TD25C any thoughts on how your uncles D7s compared to your HD16B; nosey people us crawler guys :drinkup

 

[td25c]

That's funny you ask that D6 Merv. My uncle had only ran Cat dozers his whole life working in the union. He calls me one morning and wants some clearing done. We dropped off the 16B and He climbed up on it and the first thing he said was..... " it's a little bigger than a Cat D7" . He ran it the 16 on the job while I ran the excavator. My uncle really enjoyed the tractor. Later he ended up finding a nice high horse Cat 7E that he still uses today. I'm still running the 16 .

 

[Chum Duffy]

I still have a pretty good 16B and no low track D7 of that era can compete with it, and I have had 3T, 17A E, F, and G's!! By the way D6 Merv, the 7F & G had way better balance than the than the old 7E's. The early E's were flat out nose heavy with there hyd pump in the front, always stuck!! and the later ones were still bad enough on soft ground or trying to back up hill. The 7 F was way a better overall balanced machine. Chum..

 

[td25c]

That's cool Chum Duffy , another 16B owner operator . Uncle & I were guessing the 16B was about a ton heavier than a Cat D7F or G . Is that pretty close ?

 

[Chum Duffy]

TD25, Yeah I think closer to two tons difference the 16B weights over the 7F or G!! And even though the book says not. The 16B has way more wallop than the cats, and I like the cats but it is what it is, that ole' 16B is a heck of a tractor!!! Chum..