Spun a bearing or not spun a bearing, that was the question.

[evolutionary]

As in a previous post thought of spinning a bearing was apparent, however diagnosed problem to be faulty flywheel bolts.

Now new problem has arrived, Jon and I were installing another flywheel yesterday when he noticed there was play in the crank :cry: , we grabbed the engine crane removed motor and stripped it down to find that it didnt actually SPIN A BEARING but had completely worn out the thrust bearing on the clutch side, so back to square one. Have to source another crank and cradle (anyone know of a spare 7 bolt crank and cradle please dont hesitate to let me know, either ring jon or pm me) so it looks like im another victim of Mitsubishis infamous crankwalk fault as outlined in link below
http://www.magnusmotorsports.com/crankwalktheory.htm
its was ironic though that all main and rod bearings were fine and dandu and had worn in evenly just that dam thrust bearing which by what Jon tells me doesnt appear in the the VR4 motors.

So im just another statistic, but im just glad it was diagnosed now and not later i acn still salvage this engine. :cry: :cry: :cry: :cry: :cry:

 

[Sloth]

Yeah, Jon rang...

Is your crank that bad??? Can't be repaired???

 

[bazeng]

can u use a vr4 block / sump / crank ???

machine the rods to suit? if thats possible.. do that
save u hassles in the future..

 

[evolutionary]

In a perfect world Baz id love to do that, i dont really wanna be having to buy new rods and pistons, but ill look in the main diff between 6 bolt and 7 bolt motors.

Its probably gonna be alot easier to chase a 6 bolt crank than the 7 bolt. I just cant believe as motor development went on at mitsubishi reliabilty got worse.

I mean this was comical/interested site ive found in my travels on the net http://www.mitsubishisucks.com/

Well see how we go im not in a super rush i just want this roblem not to happen again (fingers crossed) plus im more occupied with Jons car which will take my mind of my car for a few weeks

 

[JSTYLE]

hyundai 4G63 blocks are 7 bolts... ill chase one up for ya.

Jon

 

[Andrewv]

I have a 7 bolt crank and a block with a crank girdle. (no oil squirters). E mail me if you want more info.

 

[evolutionary]

im just waiting for jon to get back to me, but ill keep you in mind Andrew thanks matey, still gotta get it to the guy who assembed bottom end to find out if it was anything he might have done wrong. Jon thinks it may have been wrong sized bearings, however Reliable Rebore in coburg who done the machining on the bottom end supplied the bearings to suit.


Possibly cause flywheel bolts came loose the inertia from the wobblying may have caused it too but im doubting that was the problem because i turned car off straight away and got it towed home and this doesnt coincide with whats left of the thrust bearing..........one side(pulley side) is like new) and the flywheel side has worn away to almost nothing.

 

[Sloth]

Re CRANKWALK

Relates to 2G blocks & 7-bolt cranks.

The cause seems to be two-fold, one of which is the main problem, the other would just make the situation worse.

1 - Mitsubishi f#%@*d up on a couple of batches of crankshafts. One of the bearing journals (the one that takes the bearings with the thrust face) is the incorrect size. If you get the "usual correct" bearings, but have the crank from the crook batch, the tolerances on the thrust face are wrong. Add the extra force of a heavy-duty cluch to help shove the crank around...

2 - The oil squirters for the pistons are fed by the same gallery as the main bearings. Which would affect the oil flow to the journal....


Remember, that the oil is there to keep the metal from touching metal. If the gaps at the thrust face of the bearing are too large, the oil would "flow out" of the space quicker than it should. Lower oil pressure at the bearing faces - more likelihood for metal to metal contact....

The crankshafts are identified by number, and by a coloured mark. Once you have the block number & crank number & colour, you look up the correct bearing in the Mitsi manual. There are bearings with different thrust face thicknesses available - the dimensions are listed in the manual.


Hope this short explanation helps.


PS: being EVO2, a 6-bolt crank & 1G block should accept all the other parts you have without too much hassle........

 

[CamZR4]

if you are buying a second hand 7 bolt crank, make sure it is inspected and crack tested before you part with any money.

A large proportion of used 7 bolt cranks will be in similar condition to yours, and a lot of the others will be cracked.

 

[Andrewv]

The crank I have is from an engine that had 34000 km on it but the block was broken in a pass side accident.