|
|
|
I am reassembling an engine for my Suzuki Samurai, I had it bored to match a new set of pistons and rings and the crank ground to suit new bearings.
I put the crank back in and put the rear and front covers on no problem, all rotating nice and smooth. Next came the pistons and connecting rods. all ok until I got to the last one (number 1) the assembly seems much too tight and will only rotate if I lever on the flywheel with a spanner. I took number 1 out again and it seems to rotate easier, I'm pretty sure the problem is with number 1.
I don't have any precision measuring equipment and have ASSumed the machine shop has got it right (they have a good reputation) but it seems the bearing on number 1 is the problem (too tight)
This is only my second engine build and I got help with the first.
So my options seem to be...
1. I take a gamble and continue the build.
2. Take it all apart again go and buy some expensive measuring kit and double check everything and eventually throw it all in the garden in a rage.
Taking it back to the MS whining about it is not an option, they (as all MS shops do) have a disclaimer saying about its not their fault if it all goes tits up
|
|
Last Edit: Jun 5, 2010 12:14:48 GMT by suterman
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|
|
|
|
I've twice had engines machined at reputable places where they made a mess of it. Once they ground the mains 20 thou under and installed the crank with 10 thou bearings. It was a little loose Never assume they have got it right! Check the bearing sizes are all the same in the big ends and if they are then borrow a mic and check they crank journals. It binding up tight could also be caused by a slightly bent rod or the rod big end being slightly out of round. Try dropping that piston and rod into a different bore and see if it binds up then. if it doesn't then the problem is probably to do with No1 crank journal. If it does then look at the rod and bearing.
|
|
1962 Datsun Bluebird Estate - 1971 Datsun 510 SSS - 1976 Datsun 710 SSS - 1981 Dodge van - 1985 Nissan Cherry Europe GTi - 1988 Nissan Prairie - 1990 Hyundai Pony Pickup - 1992 Mazda MX5
|
|
|
|
|
Check the ring gaps. If the crank is free but the pistons are tight then this may be what's causing it. Measure the bore (accurately with a vernier or a bore mic) and decide from there which one of the two is wrong.
|
|
|
|
kv77
Part of things
Posts: 62
|
|
|
A vernier, plastigauge and a set of feeler gauges arent' t that expensive, and are all you need to double check the measurements and make sure your new engine is within spec.
|
|
<a href="http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=81096&page=1"> My 1975 Mazda 616</a>
|
|
|
|
|
bent crankshaft could do it as well. some people say you should store crankshafts carefully as they can flex over time and end up bent just from incorrect storage - although I'm not sure how much I believe that?
I've had an engine snarl up once during a build and thought there was something terribly wrong with the engine (I had left it sat for several years before comming back to it) - all I had done in the meantime was change the flywheel from lightened stock steel flywheel to modified aluminum flywheel. It turned out that the replacement flywheel was catching on the aluminum block end plate. Luckily it wasn't a part that needed keeping so I just chopped it off with the angle grinder and the engine turned over fine after that.
So check there is nothing else on the crank which could be catching. If there is no cylinderhead on the engine then ideally it will turn fairly eaisly, should be no sweat to turn by hand.
|
|
|
|
|
|
|
i had an engine that was supposedly 'seized'. took it apart and the previous owner had put the big end bearing carrier, (bottom of the con rod) 180 degrees out. this just made it overly tight. make sure all of the big ends are on the right way round first.
|
|
|
|
|
|
|
That is extreemely good advice. The big end bearing caps need to go the right way around and the cap and rod should be kept as a pair forever. They are machined as one part.
|
|
|
|
|
|
|
Thanks for the tips.
All the rods are in right way round and the caps too, they're all arrowed during manufacture which helps.
However, during the 6 months or so since I stripped the engine and now things have got a bit jumbled up. I'm not certain the caps are on their original rods.
On a lighter note, I went back to the engine this morning after my first post and took the sump off to check it over, it seems to turn easier than yesterday, I pumped some more oil into it I asked my neighbor and another mate and they think its seems alright seeing as its all new parts and not run at all.
|
|
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|
|
|
The caps do need to be on their original rods. They are machined as an assembly so the tiny variances between each rod assembly will be enough to cause the problem you describe.
|
|
1962 Datsun Bluebird Estate - 1971 Datsun 510 SSS - 1976 Datsun 710 SSS - 1981 Dodge van - 1985 Nissan Cherry Europe GTi - 1988 Nissan Prairie - 1990 Hyundai Pony Pickup - 1992 Mazda MX5
|
|
|
|
|
ok I'll have another look, cheers.
|
|
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|
kv77
Part of things
Posts: 62
|
|
|
Weren't they marked? like this engine for example:
|
|
<a href="http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=81096&page=1"> My 1975 Mazda 616</a>
|
|
|
|
|
The caps and rods are marked with numbers. in this case the caps are marked from 1 to 4....... .53 .51 .53 .51
EDIT, the sides are all marked with a 2, the 2 being half on the cap and half on the rod.
I checked and they correspond with the rods so I swapped the number 1 and number 3 caps, it seems to turn better now but still binds a little at TDC and BTDC but I'm guessing that is normal.
|
|
Last Edit: Jun 1, 2010 14:12:39 GMT by suterman
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|
|
|
hmm shouldnt bind at all. should be able to spiun the lot and it to a couple of revolutions.
edit::
unless you have the head on?
|
|
|
|
|
|
|
The head is not on yet.
|
|
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|
|
|
On a fresh rebuild, unless it's got a very heavy flywheel, I wouldn't expect it to carry on spinning for a couple of turns.
I would, however, expect a roughly constant resistance to motion, perhaps with a slight reduction at TDC and BDC, when the pistons aren't moving as fast.
Not sure what to suggest - measuring all the clearances (ring gaps in particular) is probably the best place to start.
|
|
|
|
|
|
|
I'd check the piston isn't tight in the bore- lift the crank out, you should be able to push the piston from TDC position down the bore fairly easily with your fingers. Compare it to the other bores doing the same. If they all move about the same with the same amount of push your culprit is somewhere south of the piston CROWN- be it a siezed gudgeon pin (did you oil them up thoroughly and does the conrod move freely back and forth in the piston?) or the rod's slightly bent out of true, or the crank hasn't been ground right.
You mentioning that it's harder to turn at TDC and BTDC is the opposite of what I'd expect, suggests something's not quite round on the bottom end.
Get a decent vernier or micrometer and measure the crank journal all the way round, it should match the machine shop's paperwork, and be exactly the same all the way round.
Don't build it up if it's binding, that'll chew up the money you spent on having it machined real quick.
I got a good digital vernier from a local machine supplies shop for forty quid, and a set of feeler gauges from Halfords for a tenner- they pay for themselves and the digital ones, although more expensive, are less of a headache to read over and over.
--Phil
|
|
Last Edit: Jun 1, 2010 16:22:01 GMT by PhilA
|
|
|
|
|
On a fresh rebuild, unless it's got a very heavy flywheel, I wouldn't expect it to carry on spinning for a couple of turns. I would, however, expect a roughly constant resistance to motion, perhaps with a slight reduction at TDC and BDC, when the pistons aren't moving as fast. Not sure what to suggest - measuring all the clearances (ring gaps in particular) is probably the best place to start. Thats what I was thinking. I just measured it with my torque wrench on the front pulley bolt and it clicks below 25 ft/lb is that too much?
|
|
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|
|
|
On a fresh rebuild, unless it's got a very heavy flywheel, I wouldn't expect it to carry on spinning for a couple of turns. I would, however, expect a roughly constant resistance to motion, perhaps with a slight reduction at TDC and BDC, when the pistons aren't moving as fast. Not sure what to suggest - measuring all the clearances (ring gaps in particular) is probably the best place to start. Thats what I was thinking. I just measured it with my torque wrench on the front pulley bolt and it clicks below 25 ft/lb is that too much? Yes, too much. To give you an idea, I'm rebuilding a 2.0 four-pot right now- haven't had anything reground, but I have new bearings and new rings- with the crank in on its own I put two of the flywheel bolts in at the end and can rotate the crank with finger and thumb without making my fingers bruise. With all four pistons attached I can turn it over with an 8" ratchet using three fingers as there's a bit more resistance as the pistons move up and down, with it being easier at TDC and BTDC where the rings aren't dragging in the bores. It feels nice and even in the force required to turn it. One thing to see would be if you crack the rods off and look at the bearing shells. New ones usually have a bit of a haze to them from being in the packaging- this will rub off and show up tight spots as shiny areas. There shouldn't be any specifically shiny spots on any of the bearings turning it over by hand. Oh, and their disclaimer is for you putting things together wrong and it all going boom; if you measure up where they ground the crank and it's not right or to spec, their warranty should cover that as that's their foul-up, not yours. --Phil
|
|
|
|
|
|
|
^WHS. On the Imp engine I'm building at the moment you can turn it over with fingers on the crank throws - with all 4 pistons in.
|
|
|
|
|
|
|
ok chaps.
Cheers for the advice.
I'll get some decent equipment and take it apart and do some measurements.
|
|
1985 Bedford CF2 camper 1991 Volvo 240 Turbo
|
|
|