Rod and Main Bearing Surfaces

[ddoan]

Well, I'm really into it, now.

Initially, I wasn't going to rebuild my Dexta's motor, but decided that since I had a complete seal and gasket kit, I might as well bite the bullet and go for it.

Since I am not a mechanic by trade, I was troubled by what appeared to be "rusty" rod bearing surfaces. I contacted a mechanic friend of mine, and he mentioned that often softer metals (tin/copper) are used on bearing surfaces so that the bearing wears, but the crankshaft doesn't. Here's a photo of a main bearing (silver color), and a rod bearing (copper color):



In showing this photo to some of my Ford N-Tractor friends, a comment was made to the effect that the "babbit" (a silver colored material) had worn off the rod bearings, exposing the copper - and that's not good.

So, the question is, were Dexta rod bearings manufactured with copper-colored linings? Should mine be replaced?

Here is a shot of my crankshaft:



It really looks good to me, but at this point, I'm second-guessing myself quite a lot.

Don

[pjjms]

Your Ford N friends are correct in that the babbitt has worn off. The bearing shells will need replacing. Check the back of the shells for any size markings. If the crank has already been ground the number of thou undersize will be marked on the back.

For the crank there are a couple of things that need to be checked. The journals need to be round, not worn oval, and in good condition. You will need a micrometer to check this. I suggest you have it checked by your local engine shop.

I would think that the oil pressure would have been very poor at hot idle with the bearings in that condition.

[russelm]

Yep, the soft metal has worn off the bearings.

The crank in the photo looks ok.....but clean it up well and polish it before measuring the journals to check they are round (I suspect they will be as when they ware oval its often pretty obvious from the marks).

You have certainly been lucky as its worn to the copper base metal and not yet hit the hard backing which would damaged the crank or worse!.

I would be paying close attention to the oil ways and oil pump to in order to try to ascertain the cause..

[YorkshireDextaMan]

One thing i did notice on my engine was ,with the shells been worn they had become a loose fit in the Con rod & cap. and had worn the Con rod itself, it's quiet easy to see if this has happened (hope fully not) as in my case had to fit a new Con rod.
And i recon most would agree a new oil pump is important.
Also some Dexta engines have a half moon locating tab on the crank thrust washers, i could'nt find any new one's ,so with a little bit of filing on the rear main you can make the washers with the square tabs fit,

[ddoan]

Thanks, Guys!

I have a friend who restores engines and heads. He's going to stop by and give me a primer on how to use a micrometer.

I did check the crankshaft journals and they appear to be perfectly round. Not oval. I also checked the OD of the rod journals against the ID of the rod big ends with liners in place, and they fit nicely. No slop.

I will polish the journals. Would you suggest something like 2000 grit, wet/dry sandpaper? Also, I note the holes in the crankshaft journals. Where do they go? Are those the oil ports you are all indicating must be cleaned. Do I just blow compressed air into them?

Should the thrust washers also be silvery in color? Mine are copper.

I did not see any markings on the back of the main or rod bearings that would indicate that the crankshaft has ever been turned. Matter of fact, it would seem that if the liners were any thicker, they would be too tight - so if there were any babbit still on them, they would be too thick.

Thanks again for the input.

Don

[pjjms]

The babbitt coating would be very thin. If you measured the clearance with plastigauge it will be out of limits, even if you don't feel a lot of play.

2000 grit would be far to coarse for polishing I would think. Your friend will be able to advise you on what to use. I just used metal polish liquid (braso if I recall) on my race bike crank applied on a strip of think demin. Takes a while using that but comes up good. I bet there is a more effective modern alternative given that was 25 years ago.

Yes, oil holes, give the crank a good wash when finished and blow out with air. You may want to use a drill bit held in your fingers to make sure there is no sludge in the holes.

No markings on the shells may indicate the crank has not been ground. Check the crank diameters against the manual. Sounds like the crank is in good condition.

[russelm]

I use a fine garnet paper to do mine as this is constructed from crushed rock (pummice often) so is softish unlike wet and dry which has silicon carbide on it so if any remnents remain in the ystem they dont do any major harm.

When doing an engine re-build (on any engine) I try to work very clean and minimise the use of very aggressive compounds.

If they are not to bad then a paint cutting agent like G3 or T-Cut on a rag will work quite well......remember that you will be trying to remove any muck and varnish without removng any of the metal on the crank

The small holes you describe are the crank to bearing face oil feeds, these do need to be clear (pipe cleaners work well dipped in diesel) as do the other oil ways in the block (compressed air is about all you can use for these sadly)

[Mark]

I use emery cloth on all my polishing needs, it works real good.
You might do well with taking your block to a machinist and have it boiled out. This will clean it all down to bare metal, always a good start when you are rebuilding your engine. Be sure and remember how everything came apart, eg. thrust washers, and con rod numbering, oil pump and the like, and always be CLEAN, CLEAN, CLEAN when you go back with everything using plenty of oil on everything. I used white lithium grease on all my journals, but they make a regular grease for this as well.
You will have plenty of help from the people on this board so don't be afraid to ask questions, it's what were here for.

[ddoan]

Well, I unzipped my cranium, removed my brain, put it on a high shelf, and started polishing my crankshaft. I also blew the boogers out of the oil ways. It's not perfect - still has a little oil stain on the journals, but they are smoothe and shiney.



I'll call a local machine shop on Monday to find out how much it will cost to have the block boiled out. It it's more than I want to spend, I'll keep my brain nice and safe on it's shelf, and start scrubbing my motor's innards.

I also am working on my hydraulic lift cover, which you may want to follow in a new thread.

Thanks, for the great input.

Don

[russelm]

I use paint stripper to clean many of my engine parts, its also worth covering them with traffic film remover followed by a pressure wash before hand.

[russelm]

I should add, the journals look good with no marks so top job!

[Mark]

Don,
Everything looks good, if you could mike all the journals it would let you know exactly how much they are worn. Good start!

[ddoan]

"if you could mike all the journals"

Hi Mark,

Yes, we mic'd all the journals and found that they were well within spec. Frankly, the bearings showed about .001 of wear, but since they are out, I ordered a new set of standard rod and main bearings - and thrust washers - from Yesterday's Tractors. I hope to see them within the next few days. I also ordered new gaskets and O-rings for my hydraulic lift cover. Now, if only I could find a source for one of the torsion springs for my double clutch!!

I'll be putting together photo journals of a step-by-step motor rebuild and the hydraulic lift cylinder reassembly once all the parts come in.

Don

[Mark]

Don,
I'd like to see your journal on these projects. On the springs, let me know if you find them, I need one to. I've got my tractor in my garage at this time getting ready to put a new pto clutch in her. It will be a few weeks before I start though.

[pjjms]

I have used paino wire from the local radio control model shop to wind new spreings in the past when they are not available. Being spring wire it will break if bent around sharp corners though bending around a drill shank works ok.

[ddoan]

PJ & Mark,

Here is a link to some photos of my Dexta clutch renewal project, with specific shots of the torsion spring that needs replacing: http://s133.photobucket.com/albums/q59/ ... 20Renewal/

You can buy the entire clutch assembly from a number of suppliers - anywhere from $400 - $600. I just need the spring, and no one seems to want to reveal who makes them. So, I may just have to make some, myself.

As it happens, there is a spring manufacturer near to where I live, but they will only make up a minimum order of 25 springs, for a total charge of $325. I am going to find out if they will sell me the correct spring material. Then, I think I can make a jig to bend them myself.

If any of you want to muck around and try and find the source for these springs (which are used in a lot of Ford/Fordson tractors), at least you have the photos to work with.

Don

[Bensdexta]

Don,
Would a 2nd hand spring do?
If so, try a breaker near you.
Failing that email malcolmhipperson@aol.com
All the best,

[terry274]

Some information I collected when I was looking to replace my clutch:


These people can supply clutch PARTS
You should install New spring retainers (duplex)
They have Them
John Andreotti
Director of Information
Ott's Friction Supply
Portland, OR
(503) 283-4165
andreotti@ottsfrictionsupply.com

I did not call upon these people so I don't know anything about them, I found a rebuilt clutch for my Super Dexta locally. If you can find a place that rebuild large truck clutches, they might be able to help you.
Terry

[Erik B]

Hello folks, have been looking around in my garage, and in there i found a double clutch (complete) which came here bolted on my second Dexta engine (F3-144). However, my Dexta has singel clutch so this is a piece of junk for me. Will come back with pics when the camera is charged.

Pics

[ddoan]

Erik,

This is exciting! Are you saying that you might be able to send along the torsion springs from your junk clutch. If so, I would be happy to receive them. You can send a personal reply with details and we can go from there.

The springs themselves are relatively easy to remove. Let me know if you need any instruction about getting them out.

Don

[ddoan]

As much as I enjoy working on old tractors, I also have enjoyed the friendship and comaradarie of our little community. Especially the willingness of everyone to share and help.

I was most appreciative of Erik's offer to provide to me a very-hard-to-procure torsion spring for my Dexta's double-clutch. One of my springs was broken, and it seems that no supplier is interested in selling such a small, but integral part. They all want to sell the entire clutch assembly for $400-600, plus shipping and tax.

So, to my delight, I found a package from Norway in today's mail:



Erik, your spring made it all the way to California in fine shape.

Straight away, I pulled out my clutch, and put the spring into it's new home:



And, here it is, back in the clutch:



I am relieved to get the clutch along this far. It would appear that I am going to have to fabricate a device to reattach it to the flywheel and engine - so that it's centered. But, I think I can do that.

For more photos of my clutch renewal project, here's the link:

http://s133.photobucket.com/albums/q59/ ... 20Renewal/

Don