Hi guys. I've got a 2004 mondeo with the 1.8 duratec engine. There's a slight knocking from the big ends and I'm thinking about changing the bearings but a couple of things are bothering me. According to the haynes manual, Ford say that due to the tolerances of the crank assembly, no work is possible on the bottom end of the petrol engine and the whole thing must be replaced as a unit yet its possible to change them on a diesel engine?. The big end bearings can be replaced on just about every other make of car and the bearings are readily available from motor factors so surely they can be replaced. Also, ford don't list any torque settings for the big end bearing caps (presumably for the above reason). Basically, I have two questions. Has anybody else successfully replaced the big end bearings in a duratec engine and does anyone know what the correct torque settings are for the end caps?
mike67
You can't. 
This is exactly why they want you to buy a block or get a crate-engine. :biggrin:
What you do is the following. You buy a set of standard size bearings (in case you don't plan to regrind the crank) and when you install them, you do plastigage measurement on all journals. After measuring you switch around the bearings so they give the most even clearance possible.
Clearance tolerance for big ends is: 0.026 - 0.052mm. You obviously want to be as close to middle as possible.
So if you get to the high end on piston 4 but on the low end on piston 1, you simply swap them and they should both be around middle.
Conrod journal diameter min-max: 46.979 - 47.000 mm. If journal is thinner, you might need undersize.
Main bearings are even tighter. They have 7 color codes instead of 4.
This is exactly why they want you to buy a block or get a crate-engine. :biggrin:
What you do is the following. You buy a set of standard size bearings (in case you don't plan to regrind the crank) and when you install them, you do plastigage measurement on all journals. After measuring you switch around the bearings so they give the most even clearance possible.
Clearance tolerance for big ends is: 0.026 - 0.052mm. You obviously want to be as close to middle as possible.
So if you get to the high end on piston 4 but on the low end on piston 1, you simply swap them and they should both be around middle.
Conrod journal diameter min-max: 46.979 - 47.000 mm. If journal is thinner, you might need undersize.
Main bearings are even tighter. They have 7 color codes instead of 4.
Maybe I'm missing something and this is a stupid question but, if Ford don't give out the technical data regarding what the tolerances should be, after I measure it, how will I even know if it's within spec and therefore what size bearings to put in. Without the data to refer back to any measurements will surely be meaningless.
Like I said, maybe I'm missing something and someone on here will be able to put me straight.
Like I said, maybe I'm missing something and someone on here will be able to put me straight.
No. For some reason, when it comes to big ends, the smaller the journal the larger undersize you take. There is no oversize.
Yes, I just linked the undersize above.
Here is the standard size: http://www.burtonpower.com/hd-con-rod-bearing-set-2-0-ford-duratec-he-i4-std-size-fd140-std.html
Or even Mahle standard size: http://www.burtonpower.com/mahle-con-rod-bearing-set-1-8-2-0-ford-duratec-std-kk3480.html
Yes, but the bearings are much softer than the crank so usually, if the bearings are simply worn, you can get away with just replacing with new standard size, and you are in clearance again. However if the bearing spun, then regrind is inevitable. Ofc, anything can happen, and when you dig this deep into an engine, you can't assume anything before you actually measure. So, measure first, then take the appropriate action.
Yes, undersize is available in several sizes in fact, usually from sportscar companies, like Burtonpower: http://www.burtonpower.com/hd-con-rod-bearing-set-2-0-ford-duratec-he-i4-0-25mm-undersize-fd140-25.html
The reason is indeed, the tolerances. However it's not about tightness, but rather the clearances are evened out on all big ends. Ford has 4 different thicknesses (4 colors) for big end bearings and after measuring the crankjournal, they make a pair from these colors that gives the closest value to the factory clearance. This way, all the clearances are exactly the same. This is why duratecs are so reliable.
When you buy aftermarket bearings, they are not colorcoded, they have a general, estimated thickness, and you hope that all your clearances will be the same in the end. Also, since there are no locating notches in the bearings, positioning is a nightmare.
Anyway, however, yes, it has been done, and it is doable. Take a look at this: http://duratecfury.blogspot.se/p/duratec-engine-reconditioning.html
The link by Stripe is correct. Here are the exact values:
Big Ends: 29 ± 3 Nm, then 90° ± 10° (Note: do not reuse conbolt if length is over 46mm)
Mains: 45 ± 2 Nm, then 90°± 2.5°, 90° ± 2.5° (Can be reused max 3 times, however ppl usually change them to ARP studs)
When you buy aftermarket bearings, they are not colorcoded, they have a general, estimated thickness, and you hope that all your clearances will be the same in the end. Also, since there are no locating notches in the bearings, positioning is a nightmare.
Anyway, however, yes, it has been done, and it is doable. Take a look at this: http://duratecfury.blogspot.se/p/duratec-engine-reconditioning.html
The link by Stripe is correct. Here are the exact values:
Big Ends: 29 ± 3 Nm, then 90° ± 10° (Note: do not reuse conbolt if length is over 46mm)
Mains: 45 ± 2 Nm, then 90°± 2.5°, 90° ± 2.5° (Can be reused max 3 times, however ppl usually change them to ARP studs)
know some have done it, can only find this http://www.talkford.com/community/topic/148035-big-end-bearing-torque-settings/
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