Ford 6700 motor rebuild

[parts man]

I had a customer aproach me recently to rebuild the engine in his 6700 Ford diesel. He said that the tractor had about 8000 hours on it. I asked a few questions about why he felt it needed rebuilt to get a bit of a feel for what I was in for. The symptoms he described were;
1: Hard starting
2:loss of power
3: excessive exhaust smoke
4: increased oil consumption

Any one of these symptoms could be caused by any number of things, but when combined are usually a good sign of a tired engine. The one thing I found confusing was that he said that a few times when he tried to start it after it had not been running a few days it was kind of binding up, not rolling over freely. I found that rather confusing because from the other symptoms he described it should be low on compression, but I figured when I got into the engine I would find the cause.
He had the tractor dropped off at our place, and I got the loader off out of the road, and got down to business. Once the tin-work and fuel tank were off I started taking off wiring, alternater, PS pump and so forth. The starter binding binding became a little clearer when I took off the intake manifold and it had a lot of fuel in it! I asked a former Ford dealer where this fuel woiuld have came from, and he explained that these tractors have a manifold heater with a fuel line going to it. The manifold heater has a valve that only allows the fuel to enter the manifold when the heater element is at temperature. The valve in this heater had failed and was allowing fuel to enter the manifold while the tractor was not running, going through any open valves, and sitting on top of the pistons, causing the hard starting. It would also seep down by the rings and dilute the engine oil.
I then took the head off and fastened a chain to the top of the block to lift the engine with. Finnished removing the bolts and put the short block in our engine stand to complete dis-assembly of the engine.
When I removed pistons number 1 and 4 there was a shower of bits all over the floor! The deisel on top of the pistons caused excessive pressure and broke some piston rings. The broken rings wore ridges into the cyinder walls in those cylinders too.
The block was sent to the local engine machine shop to be bored, and the crank to be checked and ground as needed, along with the cam to machine the new cam bearings in the block. My job was done until I could order parts and get started at re-assembly.
Being somewhat forgetful, I never thought to get any pictures until this point! :fing20:

http://www.chowntractorparts.com/posts/repairs/ford6700.JPG

[parts man]

The machine shop bored the block and found that cylinder walls were rusted quite thin ( a common problem with this series of engines, 4000, 5000, 6700 and possibly a few others), so it had to be bored out to to accept sleeves, putting it back to standard bore. The good news was that the crank was in good shape and only had to be polished.

http://www.chowntractorparts.com/posts/repairs/fblock.JPG

http://www.chowntractorparts.com/posts/repairs/fmains.JPG

When I got the block back and the rebuild kit arrived, back into the engine stand. Next was the new standard main bearings.

http://www.chowntractorparts.com/posts/repairs/inserts.JPG

[parts man]

When installing the inserts, you locate the locking tab in the recess, and roll it down in, makling sure that the stand-out is equall at both ends, about .002-.005" (the bearing insert is slightly longer than the space to give the proper "bearing crush" when the cap is tightened.).

http://www.chowntractorparts.com/posts/repairs/inserts2.JPG

Next I liberally oiled the bearings with the same kind of oil that will be used in the engine, and the crank was lowered into place very carefully so as not to damage the polished journals. Any nicks, dents, or scratches would damage the bearings and shorten the service life, and with a 60 -75 LB crank, you have to take great care, another set of hands would be a real plus! ;)

http://www.chowntractorparts.com/posts/repairs/fcrank.JPG

Then the insert was placed into the rear main cap, and the seals placed into there ridges to be slid down into the rear of the block, much easier said than done!! I had to use a pair of 6" C-clamps to hold the seals in place while I very carefully slid the cap into the block making sure that the seals stayed in place.
The rest of the main caps went much faster using the same method of inserting the bearings as the block.

http://www.chowntractorparts.com/posts/repairs/mcap.JPG

http://www.chowntractorparts.com/posts/repairs/maincap.JPG

In the bottom picture you can makeout the bearing standout if you look closely. The bottom picture is also the rear main cap that gave me the trouble. :duh:

I guess that's enough for one night, more to come! ;)

[Ohioplowboy]

so thats what the inside of one of those pieces of sh!t looks like. We used to have a 6700 that we sprayed with and did odd jobs that didnt take much power, because it didnt have any to spare.

In fact it didnt even have enough power to run the sprayer as fast as I like, especially in a soft spot. But to its credit it would always start in the winter time....

[parts man]

Nobody interested???

[Argee]

Nobody interested???

Yes...by all means..I read through it yesterday and am anxiously awaiting todays installment. :fing32:

[Edward]

Nobody interested???
I am even tho I haven't the slightest clue how these things are assembled, never messed with one so it's an education. I have worked on internal combustion engines, just not the type of tractors you have here. It's interesting. Kind of looks like an AT-ST (http://www.starstore.com/acatalog/AT-ST-model-kit-star-wars.jpg)!

Carry on!

[parts man]

Edward, I didn't think my pictures were THAT bad! :ROF

http://www.chowntractorparts.com/posts/repairs/fsleeve.JPG

This is a picture of the installed sleeves (forgot to show this before :duh: ). They are a dry sleeve and not very thick. I never asked if they could be bored OS, but I expect it's a matter of pressing them out and replacing them if the rest of the tractor lasts that long. At the left you can also make out the shiny new cam bearings too, purty. :)

http://www.chowntractorparts.com/posts/repairs/mtorque.JPG

IIRC the manual said to torque the mains to 100-105 FT/LBs, so I split it at 102. We have a micrometer style torque wrench which I like very much! No holding your head over a dial to make sure you get the proper reading, it's got a trip release that breaks away at the preset reading. It only gives about 1/8" at the end of the handle, so you have to apply slow steady pressure, but you can pull from a comfortable position and feel for the click. Well worth the $$ if your in the market for a torque wrench. ;) Just make sure you set it back to 0 when your done or the tension goes out of the spring and it's jujst a pricey ratchet. :00000060:

http://www.chowntractorparts.com/posts/repairs/cam.JPG

Next came the cam. I lubed it up good with engine oil and it slid nicely into place.

[Edward]

do you use a break-in fluid on the cam lobes?

[parts man]

http://www.chowntractorparts.com/posts/repairs/plate.JPG

Then came the front engine plate. It was seriously grimey and the gaskets were stuck hard, so took some time to clean up.

http://www.chowntractorparts.com/posts/repairs/pad.JPG

I have a resurfacing tool for my die-grinder that is a kind of plastic fibre pad. I think in the US you guys may call them a "scotch-brite" pad. They are the greatest for cleaning gasket surfaces!

http://www.chowntractorparts.com/posts/repairs/platedun.JPG

The finished product.

[parts man]

do you use a break-in fluid on the cam lobes?


I didn't, no. The cam was not reground, nor the lifters, and they all went back from wence they came, so just the same oil that will be used for the engine oil.

[Carl]

The gear in the middle of the crank is for starting?
That surprised me to not using a special assembly lubricant.
Were the original sleeves that thin? Must be designed for replacing the sleeves each time a rebuild.
So the failure of the valve in the fuel line caused the breakdown of the engine? That is too bad. A rotten little part causing all that damage!

Good show!

[parts man]

With the front engine plate all shiney, it was time to install, that's when I figured out that the cam went 1 step early! :fing20: Back out with the cam, on went the plate, re-lube cam and install. :banghead3 That's why pencils have erasers, right. :hide:

http://www.chowntractorparts.com/posts/repairs/bottomset.JPG

Nice clean bits to put everything right.

http://www.chowntractorparts.com/posts/repairs/ipump.JPG

This engine has an idler gear between the crank and cam that drives both the cam and the injector pump. It was next, then the injector pump and drive gear.

http://www.chowntractorparts.com/posts/repairs/geartrain.JPG

All meshed up pretty like.

[jodyand]

Good job with everything Parts. :thThumbsU But be careful with those scotch-brite pads. Even though they aren't sand paper they will still remove metal if you stay in one place to long.

[Edward]

I didn't, no. The cam was not reground, nor the lifters, and they all went back from wence they came, so just the same oil that will be used for the engine oil.
ah, okay. I was just wondering what you do.

[parts man]

Carl, the crank gear bacame clearer in the post after yours (timing gear). I have had good luck using regular engine oil, I have concerns of blocking small oil passages with a heavier lube, I also have a plan for before starting the engine, but that comes later.
The engine was not sleeved originally but was bored out to accept sleeves due to a rusting problem with these engines.
$25 valve/heater caused the whole thing!

[parts man]

Jody, maybe these aren't scotch-brite pads then? They are kind of a woven half melted plastic. 10-4 on careful use though, they will gouge, especially with softer metals like aluminum. 1 more post for tonight.

[jodyand]

My bad Parts i had put they are sand paper when it should have said they aren't sand paper :duh: But i fixed it in my post.

[parts man]

http://www.chowntractorparts.com/posts/repairs/pumptime.JPG

The gears all have dots to time them properly with their coresponding gears(sorry for the blurry picture there). Some on the tooth, some on valley so that the idler with 3 dots, can only go one way for all the dots to line up at once. With all the dots lined up, the engine is at #1 TDC on compression.

HMMM, seems it's time to resize and upload some more pics, so I guess that's all I've got for tonight, oh well, always leave 'em wanting more right! :D

[parts man]

My bad Parts i had put they are sand paper when it should have said they aren't sand paper :duh: But i fixed it in my post.


Sure make me look like I just fell off the turnip truck! :ROF

K, so they are like scotch-brite pads?

[Ingersoll444]

Yes...by all means..I read through it yesterday and am anxiously awaiting todays installment. :fing32:



Ditto. we are just waiting for more!!!!!!!! :wwp: :wwp: :wwp:

[Ingersoll444]

Sure make me look like I just fell off the turnip truck! :ROF

K, so they are like scotch-brite pads?

Ya they look like the scotchbright pads. I use them also and they are AWSOME!!!

[parts man]

:ditto: I used them at a friends place once and went right out and got the set-up for my die-grinder, best way to clean a gasket surface I've ever seen! Not only will they clean off the old gasket, they give a nice ridged surface for the new gaskets to grab onto. ;)

[parts man]

Next came getting the new pistons ready. Since the engine was set at TDC on #1, I started with number 2 and 3 pistons, because you want to have the rod journals at BDC so there is no chance of scoring the journal.

http://www.chowntractorparts.com/posts/repairs/lockring.JPG

The pistons have lock-rings on each side to keep the piston pin from coming out and scoring the cylinder. I removed both lock rings,

http://www.chowntractorparts.com/posts/repairs/pinout.JPG

and pressed out the pin.

http://www.chowntractorparts.com/posts/repairs/piston.JPG

The new pistons came with the rings already installed, so just had to press the pin out, locate the rod on the pin, and press the pin back in.

[Edward]

They get used allot in aviation for removing pitting and corrosion in aluminum and steel on the airframe. You might see if you can get some HERE (http://www.boeing.com/assocproducts/surplus/retail/), I used to buy my tools there when I lived in the area in early 90s. I didn't really think of this place again until this thread so they might have internet sales by now.

Browsing that website I see they have used laptops for sale....hmm....

Sorry, I hope I am not hijacking the thread

[Edward]

The new pistons came with the rings already installed, so just had to press the pin out, locate the rod on the pin, and press the pin back in.
So 4 rings? Do you stagger them and I didnt notice; does the gap for the oil or wiper ring matter where it goes?
Or is that even a concern on these motors? Thanks for the play by play. Except for the coffee and smell of fuel, I feel like I'm there!

[parts man]

http://www.chowntractorparts.com/posts/repairs/piston-2.JPG

Next the rod bearings were installed in the rods using the same method as teh main bearings.
I staggered the ring grooves and put the pistons in a ring compressor for installation,making sure that the ring compressor coved all the rings but left as much as the piston as possible exposed to align it in the cylinder. I then prelubed the cylinder and rod bearing with oil and slid the piston into place.

http://www.chowntractorparts.com/posts/repairs/piston-3.JPG

I used a piece of broken sledge hammer handle to push the piston out of the ring compressor into the cylinder. One thing to check carefully is that the ring compressor is tight so that the rings won't catch on the top of the block. The piston should push in by hand, or with only light taps of a hammer against the handle to be sure that nothing binds and breaks the new rings or piston. Also, just slide the piston in until the ring compressor drops off so you don't risk damaging the crank.

http://www.chowntractorparts.com/posts/repairs/rodin.JPG

Then from the botton side, use both hands, one on each side of the crank journal, and pull the rod down tight against the crank.

[parts man]

Sorry, I hope I am not hijacking the thread

No way Edward, discussion is what we're here for! :)

In Canada we have Princess Auto (http://www.princessauto.com/PAcountry.cfm?CTRY=CAN&INF=home), a lot like Harbour Freight, I think. They are a good low-cost tool source. The toy store for big boys. :D

[Glad2bHere]

Excellent posts. I have rebuilt gas engines, never even seen the guts of a diesel. Thanks for sharing!!

[parts man]

So 4 rings? Do you stagger them and I didnt notice; does the gap for the oil or wiper ring matter where it goes?
Or is that even a concern on these motors? Thanks for the play by play. Except for the coffee and smell of fuel, I feel like I'm there!





I hope you're warmer though,, unheated garage! :duh:

Yuppers, 3 compression rings, one oil ring. On diesel engines it's not unusual to have 2 oil rings either.

To stagger the rings I put the top ring gap over one end of the piston pin because there is less pressure against the cyinder there. I figure less chance of scoring the cylinder. The next ring goes about 180 degrees and so on.

[parts man]

Todd, thank you very much! The internals aren't that much different, usually a little sturdier though. The main difference is in the periferals.


I got tied up on the phone, guess the next installment will have to wait for tomorrow night, or maybe later tonight.

[Ingersoll444]

So the pins are pressed AND clipped in the piston??? Never seen that before.

[parts man]

Paul, the piston pins aren't really a press fit, just a friction fit. I used the press to make sure I didn't damage the piston. ;) One of the old pins pushed out by hand!

[parts man]

Once the pistons were in and the rod caps torqued,

http://www.chowntractorparts.com/posts/repairs/balancer.JPG

I moved on to the dynamic balancer. This engine employs a seperate balancer gear set that consists of 2 counter weights timed to each other to minimize engine vibration.

http://www.chowntractorparts.com/posts/repairs/btimed.JPG


The balancer is then timed to the gear in the center of the crank. I marked the timing marks with a paint marker show they would show up well.

http://www.chowntractorparts.com/posts/repairs/opump.JPG

Next comes the oil pump.

[parts man]

http://www.chowntractorparts.com/posts/repairs/cover.JPG

The timing gear cover went on next with another one of those nice new gaskets.

http://www.chowntractorparts.com/posts/repairs/opan.JPG


Then the heavy cast oil pan. That thing weighs around 50-75 LBs!! Watch yer fingers with that one!

There were a few tidbits to put on the engine (front pulley and such),

http://www.chowntractorparts.com/posts/repairs/painted.JPG

Then I shot a couple coats of engine paint on to give the job a little more finished look.