davidimurray
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| posted on 6/9/14 at 07:17 PM |
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Engine Rebuild Advice (Duratec)
After a crazy 6 weeks at work I am hoping to finally get back to my Duratec conversion.
After some advice, I decided to take the opportunity to change the piston rings before the engine goes in. While looking for rings, I found an engine
an engine builder selling brand new rods, pistons and rings taken straight from a crate engine, for less than a set of rings. So instead I am going to
change the whole lot.
I've never done a bottom end before, but I am planning to leave the crank untouched. I have been advised to give the bores a quick deglaze
first. Am I right in thinking that when I out the pistons back in I just need to use standard engine oil to lube the bores. Is engine oil ok for the
big ends or do I need an assembly lube?
Second question is I've got the head gasket set here, complete with new bolts and valve stem seals etc. It seems like a good opportunity to give
the head a refresh at the same time. The plan is to strip and clean and replace the bits. Is it worthwhile lapping the valves in or am I going to get
into a big mess having to change buckets?
Cheers
Dave
Gallery 1 http://www.facebook.com/media/set/?set=a.116893465324.130778.601005324
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Gallery 6 http://www.facebook.com/media/set/?set=a.10150550640070325.430417.601005324&type=3&l=fe779b358c
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Mr C
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| posted on 6/9/14 at 08:17 PM |
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When I rebuilt mine I lapped the valves in which is vital. though the gaps still stayed within tolerences. With regard to the pistons and rings I
replaced mine with forged and gapped the rings accodringly. If you are using "standard pistons, rings etc, you may want to check to see if they
are matched to the bores. In other words there are very slightly different sizes of pistons available and are usually labelled a , b, etc which are
matched to the bores at the factory to take up differences in machining tolerences
If you have to match pistons to bores I would stick to the original pistons putting them back in the same bores and put new rings on gapped
accordingly.
The other thing with these engines is they are built for ease of assembly in the factory and don't have any keyways on the crank or cams if you
remove sprockets etc I would strongly recommend getting new diamond encrusted washers for reassembley or even better getting a keyway machined into
the crank, available from a few specialists. I presume also you have the correct tools (vital) for retiming the engine on assembly if not readily
available on ebay for not a lot
SALE! FORD MAZDA 1.25 2.0 16V DURATEC ENGINE TIMING CRANK LOCKING TOOL
Lastly you can use engine oil to reassemble the pistons in the bores, you also need to use engine assembly paste on the bearing etc. to protect them
on initial startup whilt the oil pump primes and the pressure sorts itself out.
Engine Building Graphogen Lube For Crankshafts Bearings Cams Valves
All the above is my view, based on my own experience, I sure others may be along to add correct dispute etc.
All the best with the build.
Girl walks into a bar and asks for a double entendre, so the barman gave her one
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Smoking Frog
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| posted on 6/9/14 at 08:32 PM |
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I've always used engine oil but the last engine I rebuilt was over 30 years ago. Best advice I could give, if you've never rebuilt one
before is to make sure all the components match with the block i.e. if pistons are standard size make sure the block hasn't been re-bored. Same
with the crank if it's had a regrind you want bearings to match. However being the engine is quite new non of the things I've said may
not apply but I would still check. I know it's obvious but ensure you can turn the engine over OK by hand.
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snapper
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| posted on 7/9/14 at 06:52 AM |
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Good advice, Ford/Mazda will have several standard size pistons available and many oversize to match bores
HOWEVER, it is never a simple matter of dropping standard pistons into a standard bore
The pistons must have a clearance to the bore wall as specified by the piston manufacturer or they will seize if to tight or you will get low
compression and blow by if to loose.
Piston rings must be gapped by putting the bare rings in the bore and using a feeler gauge to the correct gap, if not the rings can expand and the
ends touch, broken rings and/or scored bore. Filing ring ends is also critical you don't want an angle, the ring gap ends need to be
parallel.
Cranks are also used by manufacturers with different big end and main bearing sizes, so you would need to check big end bearing clearance or they can
seize or if loose you can loose oil pressure.
Your easiest route is to deglaze the bores ( some call this honing but in reality the home builder with drill mounted hone tool only deglazed) and fit
new rings.
Cover the crank and bearings or remove crank from block.
A tip, cleaning the bore out of metal filings and hone stone dust means a lot of washing out and I finished off by using a lint roller many times per
bore until it was clear of fine dust then further washing out with thinners
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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beaver34
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| posted on 7/9/14 at 09:12 AM |
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I would fit new rings to what you know already works
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The Black Flash
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| posted on 7/9/14 at 09:26 PM |
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I used assembly lube for my rebuild - its main benefit is that it's very sticky so it doesn't run off like engine oil will.
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Paul Turner
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| posted on 8/9/14 at 08:23 AM |
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In my experience over 25 years with 7's and 40 years with cars in general if an engine needs new rings its almost certain that one or more bores
are worn at the top and even with new rings you will never get a good seal. In truth the original rings will seal just as well or possibly even
better. That has applied not only to ancient x-flows but 2 Zetecs one of which had only done 60,000 miles. When I have built myself an engine simply
bought a set of oversized pistons, little more expensive than a set of rings but you do need a rebore. You get a slightly higher capacity engine which
does tend to improve torque as well. Better still get a set of forged pistons, normally give a useful compression increase and some even come with
valve cut outs to suit high lift cams.
For years I used Graphogen paste from Burton on the bores and bearings etc and never had an issue other than the fact that the oil looks likes it been
in a diesel for 20,000 until its been changed 10 times, its the graphite in it I guess. But the last time I built an engine (which was for a mate) the
machinist supplied a bottle of Torco assemply lube. Just like treacle and really stuck to the bore etc. Would use it again.
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nick205
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| posted on 8/9/14 at 01:02 PM |
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Does it actually need rebuilding?
If it's smoking, rattling etc then it will likely be worn out throughout and better replaced with a good 2nd hand engine.
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davidimurray
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| posted on 8/9/14 at 08:05 PM |
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Aaaarrggghhhhh
Now I really don't know what to do.
Two members who have fitted duratecs have advised me that they have had issues with gummed up rings causing smokey running. They have both had to
remove their engines and fit new rings which has caused the smokiness. I was hoping to avoid the same problem by being proactive.
My engine has done 80k and came from a running car that failed MOT on brake lines although I never saw it running myself. The oil and water all looked
lovely and clean and even had Iridium spark plugs in it, but I will say the inlet looked quite oily/gummed up but I assume that is EGR related.
I did a cold compression test on the floor and found the following figures -
Cyl 1 - 185psi
Cyl 2 - 190psi
Cyl 3 - 240psi
Cyl 4 - 180psi
Looking around, there doesn't seem to be any published figures for compression figures, and obviously my test is not a tru representation as it
is cold. I also noted at the weekend when I turned the engine over to remove the sump, the remaining oil dropped around the pistons and on turning
the engine over by hand you could see and hear air bubbling through the oil around number 3 cylinder.
So the question is what do I do???
1) Do nothing
2) Strip, examine, if intact clean piston and oil control rings and reassemble
3) Strip, examine and fit new conrods/pistons/rings that I have to hand (only cost £39)
4) Strip, examine and remove piston rings from new pistons and fit to old?
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Gallery 2 http://www.facebook.com/media/set/?set=a.245243755324.181913.601005324&l=a9831a9319
Gallery 3 http://www.facebook.com/media/set/?set=a.440671625324.232627.601005324&l=3f0d42c523
Gallery 4 http://www.facebook.com/media/set/?set=a.490098255324.297598.601005324&l=efb083b7df
Gallery 5 http://www.facebook.com/media/set/?set=a.10150244028550325.366987.601005324&l=583fd5cd3a
Gallery 6 http://www.facebook.com/media/set/?set=a.10150550640070325.430417.601005324&type=3&l=fe779b358c
Duratec Engine Swap https://www.facebook.com/media/set/?set=a.10152527759580325.1073741828.601005324&type=1&l=40aae5e72f " target="_blank"> https://www.facebook.com/media/set/?set=a.10152527759580325.1073741828.601005324&type=1&l=40aae5e72f
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Mr C
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| posted on 8/9/14 at 10:32 PM |
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Decisions, decisions..... I'd probably go for 4) in the first instance and pop the rings in the bores to measure the gaps. What I do is use one
bore and measure each ring in that, then you can work out which ring has the biggest/smallest gap. Then get one ring and measure the gap when placing
it in each bore. That will tell you the biggest to smallest bore size. use a piston to push the rings in square to get a more accurate measurement.
You can them place the rings in each bore and measure the gaps moving them around to get the best gaps.
If you can't get them within tolerences then bin the lot and start again with some high compression pocketed pistons, a set of H beam rods and
some race bearings  or as a last resort put the old pistons/rings back in. I would also replace the mains/big end shell bearings and oil seals
whilst the block is in a state of disassembly
Ideally you should use a bore gauge and check at a number of points up and down and round the bore for size wear etc.
[Edited on 8/9/14 by Mr C]
Girl walks into a bar and asks for a double entendre, so the barman gave her one
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snakebelly
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| posted on 9/9/14 at 03:54 PM |
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If they are any good to you I will soon have available a set of Duratec rods and pistons out of an ST150 engine that has only covered 60k,
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nick205
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| posted on 10/9/14 at 11:32 AM |
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Option 1 - leave it alone and get it in the car and running, fresh oil and filter of course.
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haz87
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| posted on 10/9/14 at 12:01 PM |
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As above, option 1
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davidimurray
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| posted on 10/9/14 at 08:16 PM |
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All thanks for the advice.
Mr C I agree with you in principle - the problem is I can't find any ring gap spec for standard pistons. There are 3 piston sizes for 3 bore
clearances and they arrive at ford all pre-assembled with rings so there is no spec for ring gap etc.
Snakebelly -thanks for the offer but I have a set of new rods, pistons and rings sat here from a new engine.
Nick and Haz - that was my original plan, but the horror stories of stuck oil rings and having to remove engines after installing have scared me! In
particular the massive variation in the values I got doing a cold compression test - does anyone have any opinions on these values?
I've got all the bits to strip the engine and put it back together so a strip, check, clean and rebuild is a possibility. I also have bore
gauges so can check the condition.
Cheers
Dave
Gallery 1 http://www.facebook.com/media/set/?set=a.116893465324.130778.601005324
Gallery 2 http://www.facebook.com/media/set/?set=a.245243755324.181913.601005324&l=a9831a9319
Gallery 3 http://www.facebook.com/media/set/?set=a.440671625324.232627.601005324&l=3f0d42c523
Gallery 4 http://www.facebook.com/media/set/?set=a.490098255324.297598.601005324&l=efb083b7df
Gallery 5 http://www.facebook.com/media/set/?set=a.10150244028550325.366987.601005324&l=583fd5cd3a
Gallery 6 http://www.facebook.com/media/set/?set=a.10150550640070325.430417.601005324&type=3&l=fe779b358c
Duratec Engine Swap https://www.facebook.com/media/set/?set=a.10152527759580325.1073741828.601005324&type=1&l=40aae5e72f " target="_blank"> https://www.facebook.com/media/set/?set=a.10152527759580325.1073741828.601005324&type=1&l=40aae5e72f
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