Troubles w/ our 312B

[ernie]

I'm very impressed with the experience, pics, & international flavor of this site. We're pretty small compared to some of you fellas so when we have any mechanical probs. we try to work on them ourselves. Our 312 exc. has developed a travel motor prob. When oil is hot one track looses power in one direction, the other looses power in the other. Problem isn't consistant, though. All hyd. filters were changed about 130 hrs. ago. Fuel filter, too. All power isn't lost, one or the other track will slow and eventually stall when climbing even a small incline and you can hear oil bypassing. All other hyd functions seem to be full power. We've ordered a repair manual. Until it arrives we thought we'd ask if anyone has had similar probs w/ similar models.
Also, we're considering rebuilding or replacing the engine as it has some blowby. We have 3 machines total: 312, JCB 212 loader, Cat 420E. The only one that meets tier 3 air quality requirements is 420 so we wonder if it's better to rebuild engine or try to find a replacement that meets new standards. Afraid to ask Cat dealer for a quote on that one!!!!
Any ideas.

 

[John C.]

It sounds like your swivel is leaking by. The clue is the problem swaps sides when you change direction. It's probably an eight hour job to remove and repack the thing. I don't think the seals are that expensive.

The engine issue might be a thornier problem. So far in my experience rebuilding those Cat motors is very expensive just for the parts. As I recall you also need some special tools to set up the fuel system when you put the thing back together. Most people trade the machine in on another one rather than go through the expense.

You might check on the price for an exchange rebuild from your Cat dealer. A few years ago those were pretty cheap. You couldn't rebuild it for the cost of the exchange, plus you got a warranty.

Good Luck!

 

[d4c24a]

perkins

i may be wrong but the uk spec 312 has a perkins engine ,these are quite cheap to rebuild and special tools are not required,it may pay you to source the parts in the uk
thanks graham

 

[DirtHauler]

I agree that it is the swivel leaking by. We had an Hitachi start doing that and we paniced and traded it in rather than figure out how to fix it. I guess its not as bad of a fix as you think. As for engine blow by, I would not worry about it until you start loosing oil out of tube. REMEMBER: DO NOT ADD OIL to CAT engines until the oil level is BELOW the ADD mark. We found this out the hard way with our truck engines. Everyday one of our new trucks as down to the add mark, and everyday we added a gallon of oil. After spending a ton of money on oil we took it to CAT power systems to find out WTF is going on with our oil. :beatsme They said that every engine has a personality and likes a certain amount of oil in it and will simply blow off any more oil than it wants. The service manager said the full mark is for changing the oil only and that the ADD mark is the only one that people should look at between oil changes. Guess what.... we stopped topping it off to the full mark every morning and now the oil level stays exactly the same... just about to the ADD mark. :Banghead

 

[bobcat ron]

Same here with my 247's hydraulic tank.

 

[freedom digger]

ERNIE
I am in the same boat I do all my own repairs on my 311B. I had the same problem .I also bought a service manual couldn't belive you could spend $600 on a book.
What I will say is that it payed for itself in just a few repairs.
As for the swivel manifold it is recommended that if you have over 4000hrs it should be rebuilt.I wasn't sure if this was my problem but the seals were only around $200.
The removal and rebuild wasn't to bad I did build a puller to put it back together.(nothing fancy)
One thing I found out the hard way is when the swivel was pulled out we caught around 4 gallons of oil then it stopped thinking that was all we were going to get and because it was late we did the important thing (we had a few beers :drinkup)and left the shop for the night.what we didn't know was that the reason the oil stopped was that it had drawn a vacumn in the tank once it caught air all of the oil drained onto the floor :Banghead
One other thing to look at closley is the rubber seal around the swivel.Before I bought my machine the retaining bolt got broken and replaced but not before it rippied the rubber letting the house fill with water which turned to ice and ripped out the seal on the house drive.That is what I bought the manual for.
As for the swivel it didn't help my travel problem.Turned out that the pedals were out of adjustment easy fix.
Hope some of this helps Also if your manual doesn't come soon I might be able to scan and send you the pages you need :usa

 

[ernie]

Thanks for some direction on travel motors problem. :notworthy We picked up the 312 out of upper Washington state a few years ago. It had about 3000 hrs on it then yet it showed excessive track pin & bushing wear. Everything else appeared in good condition & we figured tracks would hold for awhile. It was a rental & evidently was walked alot. Pads are like new but we replaced the chains & sprockets at 4500 plus hrs. It's got a little more than 5000 hrs now.
The oil blowby does spit out the fill cap & now that you mention it, seems I did add some oil just before the problem! The machine is Japan built & it appears that the engine may be Cat. I think we will call dealer about an exchange. Has anybody had good results with engine exchanges from other markets besides dealers?:beatsme When we bought the 420E we figured a thumb factory installed would be the least expensive than an after addition from an other vender. Turns out we ended up buying some t-1 steel, pins, & had a cylinder made & made one ourselves for half the cost!! So we are hesitant to quickly buy from the Cat dealer. Also, thanks for the heads up on oil drainage when changing the swivel seals.
Repair manual should be here in a day or two but thanks for the offer of scanning pages. It's raining now & we have time for repairs.

 

[tctractors]

Dont Forget THIS,

Ernie, before you start undoing a load of pipes etc, you must first set the hydraulic system and oil tank free of any pressure, to release the system of all energy, place the arm/bucket on the ground then stop the engine ,then turn on the ignition key to position 1, have the safety lever in the work position then work the hand control as if to lower the arm for about a min' or work it lower/rase about 10 times, then turn the key off, go to the top of the hydraulic tank with a good breaker bar fitted with a 1 3/16" (30mm) socket and undo the big plug in the tank top, undo it slowly about 3 full turns, you will here the air pressure escaping when it stops slowly remove this plug to check for all tank pressure to be released, re-fit the plug leaving loose untill your repair is completed, when you remove the top oil lines from the rotary coupling, fit blanks or caps to minimize any oil spillage or cover with rag held with a cable tie after lifting them up as high as possible and securing them with cord what-ever, I would only expect to loose 1-2 gallons of oil in total doing this sort of repair, its also worth checking around the foot controls for dirt/stones restricting the full movement of the valves,
blowing it on, tctractors

 

[Backhoe310SG]

My dad and I have a 96 model 312. Its a gray market machine, 7DK series serial number and this spring we had to replace our motor. I heard a real bad knocking one afteroon and after my cousin dropped the pan, he could see the crank was broken. If I remember right, I think the 312's do have the perkins engine. My cousin and uncle help us with our mechanic work and my cousin did all the dealings with our dealer. Our machine had around 6200 hours on it and with the cost of parts and machining, we were better off to just buy a new motor. If I remeber right we had around 13000 in the engine and parts alone. I don't know if with the emissions controls you guys have would drive up the cost much or not, but thats roughly what we had.

 

[wrench2556]

I to have rebuilt the perkins engine or the perkapillar as they call it. It was an expensive repair.it was a 3054. The other thing with perkins, if you have not rebuilt one before there are a lot of different specs to the pistons and rods. You will want to be sure to replace the pistons that will be marked with a letter with the same letter and the rods can be a fractured rod or a tang rod. this can be very confusing if you have no experience with perkins. Also piston clearance and liner protrusion are critical. As for dealer exchange, The experience I have had with dealer engines has been good and you can not beat the warranty. But I also guess that depends on your dealer. Good luck. Billy:Banghead

 

[T_S_S]

how many hours are on your 312

 

[ernie]

how many hours are on your 312

5000 plus a few. We got a estimate from the dealer yesterday for about 11,500 new-they told us they don't have re-mans. We don't have a lot of experience in rebuilding engines ourselves so replacement looks safer for us.

 

[ernie]

I to have rebuilt the perkins engine or the perkapillar as they call it. It was an expensive repair.it was a 3054. The other thing with perkins, if you have not rebuilt one before there are a lot of different specs to the pistons and rods. You will want to be sure to replace the pistons that will be marked with a letter with the same letter and the rods can be a fractured rod or a tang rod. this can be very confusing if you have no experience with perkins. Also piston clearance and liner protrusion are critical. As for dealer exchange, The experience I have had with dealer engines has been good and you can not beat the warranty. But I also guess that depends on your dealer. Good luck. Billy:Banghead

Thanks, Wrench. We haven't got enough experience or tools to do that kind of major surgery. We will probably do a replacement from the dealer. Can't believe the costs per part ratios-we're still trying to locate travel motor probs & have been doing pressure & drain case tests. I thought I would just check to see what a replacement for travel motor complete would be. Turns out that motor & finals are all one unit (about 12,600 ea)!!!! But we can replace eng w/ new for 11,500. Got to do more testing before buying.

 

[tctractors]

Somethings Odd,

I cannot understand how the engine is a knacker,with only 5'000 hrs put against it???? this engine is good to stand (with moderate servicing) 15'000hrs of hard work, all that poking about with pressure gauges your doing should take you 1/2 hour tops, the first thing to test is the pilot pressure you cannot go wrong as all the test points are in the same door area, the main pump is fitted with a test point for both sections (1 might be removed if a Q/hitch is fitted) it is not to hard to stall out the motors, the track pressure is often the highest set pressure on most excavators, make sure you are reading the gauge hooked into the pump, dont bother with any other tests untill you have checked these, also double check the thottle linkage to make sure when the throttle is turned full bore you are getting all the beans.
tctractors

 

[tctractors]

Somebody sent the same message as me????
tctractors

 

[RonG]

I haven't laughed that hard in a long time.Thanks Tony.......Ron G

 

[wrench2556]

T.C. It is pretty commmon problem with these 4 cylinder perkins in the usa. This year alone I have rebuilt 3 of them, 1 spun a main bearing and 2 of them actually melted number 4 piston down and it galled itself to the head damaging the head. You are right about being tough! They both ran with the piston seperated from the rod although it made one heck of a noise, these are the 3054 caterpillar engines also known as perkapillars as it has some cat componants on it, but the internals are perkins. Since I have rebuilt these they have run fine with no problems. Could have been an assembly issue at the factory. All the engines had less than 4000 hours on them. Most of the cat dealers in our area will not even try to rebuild them, just replace with new.:drinkup

 

[Countryboy]

Somebody sent the same message as me????
tctractors

Pretty funny .....I fixed it for ya.

 

[tctractors]

Wrench, in the U.K. this engine has a good name for taking plenty of stick, it was fitted to the Komatsu excavators (in a Komma spec) for years, it is thought to be one of the simplest engines to re-build and also very cheep to do so in the U.K. in CAT speck they do suffer with water leaks from bits of plastic bolted on the front of the head, also like a new water pump now and again, but 15'000 hrs is what is expected around here .
tctractors

 

[drewtam]

The machines originally sold into the EU used the 3054, the machines sold into North America used the 3064. The only thing these engines share are that they are both 4-cyl turbo diesels.