td42 Crankshaft Keyway Issues

[GeneralFubashi]

I have a GU with td42-t, just came back from the cape and managed in the last few weeks to somehow break the key in the crankshaft connecting the main pulley. Took it to nissan dealer and they have helpfully suggested one of their new crate engines for only $8k + fitting. Though, they did show me the damage to the crank with the pulley off etc. From what i can see there is pitting and slight scoring on the crank a mil or so in front of the timing cover/pulley oil seal, but the actual keyway is in perfect condition and where the pulley has been contacting the crank is worn smooth, but without visible damage.

Mechanic didnt seem to have a lot of answers or solutions, apart from pulling the crankshaft or full engine replacement. My question is: If the only damage is the slight pitting behind the pulley contact area, would that affect balance of the crank etc. if i instruct them just to re-install a new pully/harmonic balancer assembly?

The mechanic couldnt lay his hands on the broken pulley while i was there, so i cant see what the damage to it was, but he did say it was "moving around a lot". Would rather not fork out for a new 4.2td at 160,000k, so any advice appreciated.

Cheers
Sam

[madrolla68]

I have a GU with td42-t, just came back from the cape and managed in the last few weeks to somehow break the key in the crankshaft connecting the main pulley. Took it to nissan dealer and they have helpfully suggested one of their new crate engines for only $8k + fitting. Though, they did show me the damage to the crank with the pulley off etc. From what i can see there is pitting and slight scoring on the crank a mil or so in front of the timing cover/pulley oil seal, but the actual keyway is in perfect condition and where the pulley has been contacting the crank is worn smooth, but without visible damage.

Mechanic didnt seem to have a lot of answers or solutions, apart from pulling the crankshaft or full engine replacement. My question is: If the only damage is the slight pitting behind the pulley contact area, would that affect balance of the crank etc. if i instruct them just to re-install a new pully/harmonic balancer assembly?

The mechanic couldnt lay his hands on the broken pulley while i was there, so i cant see what the damage to it was, but he did say it was "moving around a lot". Would rather not fork out for a new 4.2td at 160,000k, so any advice appreciated.

Cheers
Sam

I would suggest that if the keyway is not damaged then supply a new front pulley and see how it fits onto the crank,if its still a decent slip on fit and not real loose then fit a new key and a light smear of locktite on the shaft re-install the bolt and tension.

This is only if the snout of the crank is not worn too much,otherwise pull the engine,repair the nose of the crank and refit it.

Matt

[turps]

And Blackburn Nissan had TD42 (turbo spec) crate motors for $6800 a couple of months back

[its aford not a nissan]

5500 for a crate motor when i looked yesterday

[GeneralFubashi]

Just got a call with the quotes for their 2 options.

$13,500 to fit a nice new engine that just happens to be lying around the workshop and they might even throw in a free baseball cap.

or

$1,600 to fit a new pulley, belts etc. But they couldnt possible warrant anything if they do it this way.

Im not fussed on 14g, so im going with the new pulley (which i had to suggest)(now at double the original suggested price). And given they cant warrant it, i might have to insist on putting the final turn on half the bolts myself, cause i just cant see some 18yo apprentice getting it right, especially when they arent willing to give me any guarantee its even going to be put back together correctly.

[brad-chevlux]

when they arent willing to give me any guarantee its even going to be put back together correctly.

how did you come up with that?


they are telling you they will not warrent the thing if something goes wrong that can be traced back the damaged crank.

IF it were at my shop i'd be telling you the same thing.


though i'd have given you the option to just replace the crank.

[GeneralFubashi]

maybe im being dramatic, but i got it from "we cant warrant anything if we do it that way" like anything, im sure there would be a bit of give and take if something did happen, but it would be up to me to put up a fight. Could have just been their way of trying to convince me to buy their new engine too.

[nastytroll]

Have you priced getting the crank snout spray welded and re-ground? Ring around some engine re-conditioning shops.

[Dzltec]

No one will warrant a worn crank snout and a new balancer. It will work, but for how long.

You have 3 options.

New parts where necessary without doing the crank. No warranty if it comes loose.
New parts and new crank, with warranty on work done.
New engine, full warranty.


Time to make a decision.

Don't blame apprentices, we all have to learn sometime. If you don't like the the idea of it find a workshop that will guarantee a mechanic will work on it.


Also best to find out why it happened so it doesn't happen again.


Andy

[brad-chevlux]

maybe im being dramatic, but i got it from "we cant warrant anything if we do it that way" like anything, im sure there would be a bit of give and take if something did happen, but it would be up to me to put up a fight. Could have just been their way of trying to convince me to buy their new engine too.

honestly, how do you get "they can't even garranty it will be put together properly" from that.

did you honestly expect them to warrant a damaged part? or further problems caused by that damaged part?

[GeneralFubashi]

Good advice,

not trying to blame apprentices, chances are they know what they are doing, and do their work much better than i could do it, but being a bit of a control freak always makes it hard. I dont know for sure why it happened, but can guess i overstressed the pulley key when air-con threw a belt, might have been pre-stressed from something else. Key has snapped and part of it has worked its way back to where it had some movement and gouged the crank behind pulley contact area. I do not believe there was enough movement of the pulley on the crank to wear it to a point where torque will be transferred through the key instead of the cone washer, but this is where i cant be sure.

Choice is 1. Im willing to put up with the chance the engine will go bang for the initial saving. Ill tell you how much of an idiot i am if or when i backed the wrong horse. Im not unrealistic in my expectations, just have bad experiences elsewhere which have made me pessimistic.

Thanks all for the advice and prices, its much appreciated.
Cheers
Sam

[GeneralFubashi]

sorry Brad, not trying to cause trouble, but i wouldnt expect them to either warrant a damaged part or sell me one in the first place. If me being a cheapskate means the parts break again, I'll take that. If the radiator hose falls off cause its missing a clip, i dont see how the crank being worn could possibly be the cause. Im not being unrealistic in my expectations.

Cheers
Sam

[tailpipes]

i had the same thing happen to my 4.2 diesel, still carnt work out what caused the key to break out of the key way, the key way was opened up a bit and the crank was scoured with only 180000km on it i wasnt getten anther engine, eneyway i got a second hand pullely from the wreckers bought a genuine key from nissan i think it was $30 and some welding glue, glued it up put it back together and the clock is reading over 300000km now no problems touch wood.

[brad-chevlux]

sorry Brad, not trying to cause trouble, but i wouldnt expect them to either warrant a damaged part or sell me one in the first place. If me being a cheapskate means the parts break again, I'll take that. If the radiator hose falls off cause its missing a clip, i dont see how the crank being worn could possibly be the cause. Im not being unrealistic in my expectations.

Cheers
Sam

I don't beleive that when they said they "can't warrant anything", they are in any way implying the whole job is void of warranty. if poor workmanship caused a problem in any other area, you be quite within your rights to have it fixed.

[PGS 4WD]

The keyway breaks when the crank pulley comes loose, it is a common missconception that the keyway is there to stop rotation of the pulley on the crank, this is not the case, the keyway is to line up the TDC marker, the tension on the bolt and the interference fit on the crank are what do the securing of the balancer.

Joel