Do careful research. Years ago a Sigma engine of that era was bored out as part of recon. It ran horribly until it was finally resleeved to std and std pistons fitted again! And yes, the o/sized pistons were supplied by the agent!
tygertung,
Feb 9, 7:16pm
What was the cause of the bad running? .5mm oversize isn't a great deal bigger.
franc123,
Feb 9, 10:45pm
Some fool probably didnt time the oil pump and the balance shaft correctly when fitting the timing belt the first time more like. The engine will vibrate if they are mistimed, particularly under hard acceleration in the lower gears. I recall doing a head change on a late 80's 4G63 Galant that had been bored out 1mm and there was nothing wrong with how it ran.
tygertung,
Feb 9, 10:49pm
Yes, it is easy to get the balance shaft 180 degrees out on those.
elect70,
Feb 11, 12:01am
Iwas never a fan of exchange short blocks as didnt know how far the regrinds /rebores were or state of the block heard a few horror stories back in the 80s i prefered to get my own engines reconned & know. first make sure they can find new pistons & bearings shells . Those sigmas were quite a good car i had a wagon as work van for 5 years & had a hard life but was reliable
gunna-1,
Feb 11, 2:54am
There was some chinese ute that used the same block as a sigma motor, or very similar, it might be worth looking at just incase, there will probably be one or two at the wreckers now, most of the noise problems i,ve had were worn camshafts, rocker gear making racket, i had a hillman hunter with seriously worn piston skirting and it just blew oil, after what looked like new rings were put in it at some stage, and didnt rattle, are you sure it isnt something like a worn camshaft? because if the bore is that loose for a fourstroke engine to do that it must be down on compression by now, you could try some heavy duty oil stabilizer that will shut it up if it is the pistons, the motors must be getting rare now so i would say bar some stroke of luck you would likely have to take your one out and get it re bored.
gunna-1,
Feb 11, 3:19am
"Greatwall v240 engine" thats the one, i was told they were the same as a sigma motor, there might be some differences if they are so make sure your older stuff like heads and manifolds will bolt onto it.
weeoneswoolies,
Mar 31, 9:58am
the rwd blocks were wide in turbo and cyclone only, anything non turbo or pre cyclone will fit your vehicle .If you get a fwd block from a 86 or older Mitsubishi you should be fine The conversion from front to rwd is easy if you have both engines present.
gmphil,
Mar 31, 7:41pm
mounts on fwd are on the gearbox
kazbanz,
Mar 31, 7:48pm
hey team. My brain is currently in a bit of a fog. But wasn't the 81 sigma a chain drive motor.--with a big long slappy cam chain? My memory was that when it got a few miles on it the chain got pretty darn noisy. I wouldn't bank on me being right but given its running and not smoking etc.
tygertung,
Mar 31, 9:49pm
The OP reckoned it was a 4G63, which are belt drive.
I was reading yesterday that it is only the turbo RWD versions which are wide block, the non turbo RWD versions are narrow block, same as FWD.
I've rebuilt one of these engines before, it was real easy.
Those 4G63 are really strong, they have been using them for years. They are good for 600+ HP.
Must be pretty reliable if it has done 429 000 km.
What I'd like to know is how has it lasted for so long on the west coast without rusting out?! 80s cars were usually pretty bad for rust.
Surely it is good engineering to have the minimum of parts? More efficient material use?
hotelcarpet,
Apr 1, 2:13am
Ya dreamin thing would be snappin rods at that kind of psi.
franc123,
Apr 1, 3:10am
No that was the previous model with the quad rectangular headlights that was sold up to 1980. The engine you're referring to was the 4G52, not the 4G63. Both were 2000cc.
kazbanz,
Apr 1, 10:45pm
Thanks mon I knew it was about that period just not sure exactly
jmma,
Apr 1, 10:50pm
Need phillip.weston for this one.
bill1451,
Apr 2, 6:19am
45 years or so back I had a short block from Mace engineering for my Morry thou, they have moved from central chch to 2/16 Sir James Wattie drive Hornby on Shands Road, So yea Mace engineering is it for you, rip your motor out and ship it to them.
bill1451,
Apr 2, 6:21am
Mace Enginneering 2/16 Sir James Wattie drive Hornby just of Shands Road ChCh, just south of Heinz Wattie.
mannix51,
Apr 2, 9:56pm
Thank you for all the interest. As I speak, an engine recon dude right here in Gmouth is doing my engine. The last day before I removed it from the car, it literally blew up! Laying in the sump was a mangled balance shaft bearing that somehow exited its rightful home . Shopping online has got me a set of std pistons for $120 with gudgeons and rings, Repco supplied the shells for $34 big ends, $23 for mains. It looks like it will be a fairly cheap rebuild. The gasket set is a worry at $139 from China. fairly expensive for rubber and cardboard bits and bobs. Bores are fine, crank journals are fine, these engines are fairly agricultural, and strong obviously. Even the clutch plate will do another turn, flywheel not scored either. The noise was piston slap, I could actually see the pistons "tilting" slightly in the cylinder as they went over TDC. Seems they wear the piston skirts and not the bore, a new one on me. However, I expect to have it together in a week or two, and enjoy another lifetime of happy motoring.
franc123,
Apr 2, 10:58pm
I suspected that a balance shaft bearing failing was likely. I'm very surprised about the bore wear, I would have looked very closely at the taper and ovality of it. But hey if the reconditioner is prepared to guarantee it like that.
mannix51,
Apr 3, 2:29am
I just assumed the bores are fine, there is no lip, no scoring, in fact, mid way and down there is still evidence of the factory honing marks from 1981. I did wonder if I could save a few $$ by knurling the old pistons to tighten them up. I remember doing this in my karting days to improve 2 stroke cylinder lubrication. But then, there is a limit to saving on vehicle costs I suppose. The engine dude will likely measure them properly, but even the way it is, will outlast me I guess. On a related note, I found the Pakistani truck channel very enlightening, simple tools, and lots of enthusiasm. https://www.youtube.com/watch?v=u_kWZgOZFHE
morrisman1,
Apr 3, 8:49am
good option to rebuild, and good to hear no bore wear so you can stay 85mm. I run mine at 85.5mm, a little bit of boost and around 650hp. They are bulletproof engines, but like anything are going to wear over that time on some components, thankfully those that can just be replaced.
Obviously you are committed to the car, especially considering we used to get weekly mileage updates! The cost of the engine rebuild will be worth the money to you. Im pretty impressed that the bore is not worn and you can stay 85mm, kudos to mitsubishi. I presume the oil pump has been dismantled and inspected. hopefully not worn and can be reused.
mannix51,
Apr 3, 9:03am
And I see someone expressed suprise that it hasnt rusted out. It gets oiled. Instead of polishing it, it gets wiped over with a dripping oily rag periodically. The oil gets into the overlapped seams, behind the windscreen rubbers where most cars rot eventually. Rubber seals are made from silicon now, so oil doesnt rot them.Every few years, I take out the plastic bungs, and a few well chosen screws and pump in a deisel/oil mix into the cavities, diesel is more like kerosens these days and creeps all around in places where you cant get paint. The odd oily mist underneath the car keeps the underseal soft and protective too, with the added benefit of making a mess that WOF inspectors prefer not to linger under there too long. These cars were known for rust, mine has NONE. If you do a wee experiment , find a rusty piece of panel steel and put a drop of oil and diesel on it and wait. After a few hours, the spot will cover a big area, and once the diesel dries, the oil will remain. If you use Vege oil will eventually skin over and be impervious to moisture. Most people dont keep their car long enough to worry about doing this.
mannix51,
Apr 3, 9:08am
Im not sure about the oil pump as its part of the front alloy cover, can this assembly be sourced, i have never seen any for sale? I have trouble with choosing parts because of all the variants of this engine.
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