Outer Limits 4x4 Board

i recently bought a 89 mav td42 with under 200 000 on it. i thought it would last me a long time but 1000ks later one of the pistons cracked. so now im trying to find the cheapest and best way to get her back on the road. my local diesel mechanic quoted me $5500 for a full rebuild or east coast 4wd will do an exchange motor for $3700 im also looking into a low ks import motor but apparently they are getting rare now i havent found one yet. im thinking about rebuilding it myself i have never worked on a diesel and have limited tools but i should be able to do most of it myself and save some $$$ rebuild kit from repco $1400. are there any other options and what do u think is the best option.

Drop the sump and crank in the car pull the piston that is cracked buy a new piston then bolt it all back up it will cost you sweet f all

how to you propose he will compress the rings to put new piston back in?

I'm no engine builder but if you only replace 1 piston doesn't the whole engine need to be balanced!?

Would be an idea to find out why the piston cracked first - overfuelling (pump injectors, run dry, overheated etc), as 200,000 isnt very far at all for a TD42.
Then if you decide on a rebuild, this will ensure you are not putting new parts in which may suffer from the same fate


If the bore is ok then It is possible to replace the one piston without any ill effects, however I would get the head tidied up while it off as well. You are supposed to use new head bolts once removed.
The Genuine Nissan gaskets are far superior to the aftermarket stuff, so I would consider using them in the build
I have the prices of most of the stuff you would need, as I did some major work on my engine recently, and this could give you an idea of what you are up against.

Yeah mate have a lookaround first plenty old gq wagons laying in backyards recently missed out on a deisel wagon for $500 drive away!! Even possibly find a good motor for $1500 just ask around and you will find one. If you were going to rebuild best to drop the sump and lift the head put another piston in through the top. Only that to drop the crank like afore mentioned you would have to drop the gearbox to get the clutch off. Bit rough doing one piston but we did this trick to a cruiser ute on a property that was overheated and used a second hand piston and rings!!!!!! It still goes 5 years later and runs ok.

Clanky wrote:Would be an idea to find out why the piston cracked first - overfuelling (pump injectors, run dry, overheated etc), as 200,000 isnt very far at all for a TD42.
Then if you decide on a rebuild, this will ensure you are not putting new parts in which may suffer from the same fate


If the bore is ok then It is possible to replace the one piston without any ill effects, however I would get the head tidied up while it off as well. You are supposed to use new head bolts once removed.
The Genuine Nissan gaskets are far superior to the aftermarket stuff, so I would consider using them in the build
I have the prices of most of the stuff you would need, as I did some major work on my engine recently, and this could give you an idea of what you are up against.

i still dont know why it done a piston it always stays cool never heats up. any suggestions on how to check the pump and injectors. it has an after market turbo running 10 psi i was told that was safe boost. i think the mav had a hard life befor i got it.
any prices u could give me would be much appreciated or any tips on the rebuild

How does the rod look? It could be possible that water has managed to make its way in it only takes the smallest amount and it will bend rods and crack pistons.

hey mate did you have an EGT gauge on it ?
it is very easy to get a diesel hot enough (with the fuel turned up) to melt or crack a piston if it hasn't been tuned to a sustain egt leave even with out the coolent teams moving

i pulled the motor out and started to pull it down and found it had dropped a push rod. i had myself convinced it was one of the pistons but maybe it was just the push rod.
the symptoms were- the motor was missing on one cylinder, blowing smoke, knocking, breathing heavy and pushing oil up into the air filter.
could these symptoms all be caused by the push rod or should i still pull the head off and have a look?

I would guess the pushrod bent when the cracked piston allowed it to hit the valve.??

I am selling this at the moment - http://www.ebay.com.au/itm/330647174820 ... 1586.l2649" onclick="window.open(this.href);return false;

Contact me if you want more info. I have it listed as pick up only, but for an outers member, I will put it on a pallet if you organise a courier (if you're not local).

ok so i put the push rod back in put the motor back in and put it all back together started it up and it runs ruff and blows lots of smoke same as before. so i pulled the head off and had a look. all the pistons look good from the top and what i can see of the liners look good aswell the head and valves all look good except one of the precombs has a small crack. i cant see anything wrong.
what should i check next??? still trying to work out if its worth fixing this motor or just buy another one.