TB42 Head Decisions

[blkmav]

It looks as though my TB42 has done its head. I am still to pressure test it however the signs are there.

It's using water but no bubbles coming out of the radiator neck, oil looks ok and oil level isn't rising. The overflow bottle level is rising and I need to add between 200-400ml of water each time I drive it. I’ve just fitted a new Nissan radiator cap. I also fitted a new Nissan thermostat as the gauge went to 3/4 the other day just after I started it. The gauge normally sits on 1/3 and never moves. It hasn’t gone above 1/3 since the new thermostat.

It’s never been on gas and is 200,000 klms old.

If the pressure test doesn’t show anything and I rip the head of, is it worth doing anything else other than fixing the head whilst it’s off?

[MyGQ]

Mine did the same

Loosing water yet the oil stayed normal.

Tried new cap, new hoses and seals. Still lost water

1 week later the results in the oil showed up, while oil

Head had cracked at the no. 6 cylinder allt he way through the spark plug hole.

Had it fixed up at Central Coast engineering. they had to remove the 6th cylinder all together and put on a new one (very good job with what has been done) this happened at 250,000K's yet a friends GQ did it at 201,000

I would put money on the head being cracked somewhere

[bogged]

get it ported, different cam grind, not that the last few to do that have gained much, but new valve seals, and usual shit

or put a 350 in there...

[MyGQ]

I wish i had done that when i got mine done

When i got mine re-done i knew sweet FA about LPG.

However, i did get new seats, stems and springs put in designed for LPG that should last longer than the original ones.

I have been given the name and number of a guy down my way to get a Gas Cam for my engine and also been told to get 40 thou taken out my head for LPG

now correct me if i am wrong (as i think i am) but aren't you supposed to increase compression for LPG rather than reduce it?? taking 40 Thou out would lower the compression rate wouldn't it???

[MKPatrolGuy]

I wish i had done that when i got mine done

When i got mine re-done i knew sweet FA about LPG.

However, i did get new seats, stems and springs put in designed for LPG that should last longer than the original ones.

I have been given the name and number of a guy down my way to get a Gas Cam for my engine and also been told to get 40 thou taken out my head for LPG

now correct me if i am wrong (as i think i am) but aren't you supposed to increase compression for LPG rather than reduce it?? taking 40 Thou out would lower the compression rate wouldn't it???

Taking 40 thou off the face of the head will reduce the size of the combustion chamber and increase the compression ratio. This is because the same amount of fuel/air is getting squished into a smaller area.

[Rainbow Warrior]

It looks as though my TB42 has done its head. I am still to pressure test it however the signs are there.

It's using water but no bubbles coming out of the radiator neck, oil looks ok and oil level isn't rising. The overflow bottle level is rising and I need to add between 200-400ml of water each time I drive it. I’ve just fitted a new Nissan radiator cap. I also fitted a new Nissan thermostat as the gauge went to 3/4 the other day just after I started it. The gauge normally sits on 1/3 and never moves. It hasn’t gone above 1/3 since the new thermostat.

It’s never been on gas and is 200,000 klms old.

If the pressure test doesn’t show anything and I rip the head of, is it worth doing anything else other than fixing the head whilst it’s off?

Sorry for bad news but mine did the same, I dropped in a second hand motor, the head had corroded through the water jacket into No6 cylinder, I suspect the casting is a bit thin there as I had heard of others finding the same problem, I had the same symptoms, I took the thermostat out to drop the temp, but I still had to fill up water regularly.

[blkmav]

Thanks for the help so far.

Any mechanic recommendations?

[BowTieGQ]

Ah yes, the dreaded TB42 curse. I just got back from Quickdrive Engineering in Dandy regarding my head. Yep, no. 6, between cylinder and water jacket is only about 10 mm apart and gasket eventualy lets go. If you don't cook it first, it's only a normal rebuild like any other head. Do everything that needs doing as per the machine shops recommendations. All up mine should be about $700ish. I'll know better Wednesday, if it's done. A new head only cost's about $1000. Much the same as a rebuid. But the heads are shit. Can't port a lot, big valves don't fit etc. Forklifts weren't meant to go fast anyway. Fit a Chev if you can afford it.

[BowTieGQ]

Ah yes, the dreaded TB42 curse. I just got back from Quickdrive Engineering in Dandy regarding my head. Yep, no. 6, between cylinder and water jacket is only about 10 mm apart and gasket eventualy lets go. If you don't cook it first, it's only a normal rebuild like any other head. Do everything that needs doing as per the machine shops recommendations. All up mine should be about $700ish. I'll know better Wednesday, if it's done. A new head only cost's about $1000. Much the same as a rebuid. But the heads are shit. Can't port a lot, big valves don't fit etc. Forklifts weren't meant to go fast anyway. Fit a Chev if you can afford it.

[Boopa]

Think mines gone as well! Same symptoms etc..no water in oil, no apparent leaks, but is consuming water...maybe a litre a week!

Any reason why once the heads done it won't last a shite load more k's?

As usual, just when I've saved up to do a few mods, another kick in the arse!

[MyGQ]

If you keep running the engine with a cracked head, you can do more damage as the oil dilutes and becomes less than a proper grade of lubrication, same as if it was hit with degreaser inside the engine due to the temps the water disolves the oil from the main gearings, piston rings and so forth

next is the heat issue, since the water is leaking into the engine, the rest of the cooling is deminished, increasing hte chances of cooking hte motor even more.

[DaveS3]

Thanks for the help so far.

Any mechanic recommendations?

Sandy Bowman - Aus4WD Specialists - knows how to make a 4.2 go!

Talk to him and he will tell you exactly what to do / get.

Did wonders with a mates Patrol!

Dave.

[krimnl]

Thanks for the help so far.

Any mechanic recommendations?

Sandy Bowman - Aus4WD Specialists - knows how to make a 4.2 go!

Talk to him and he will tell you exactly what to do / get.

Did wonders with a mates Patrol!

Dave.

9729 4899

[MyGQ]

I would get it repaired, the TB42 engine is just a fantastic workhorse

[Screwy]

i did a head gasket in mine about 4 months ago......

did warping to the head also....

so i had it fully recoed with new ports seals etc also had teh water jacket holes welded up and re drilled to get the corrosion out and then machined....

cost me abit but is running fine ever since

screwy

[blkmav]

Thanks for your help guys.

I just had it pressure tested and that showed up a leak in the lower driver's side tank of the radiator. Will get the radiator fixed and then see if it still uses coolant.

Fingers crossed it’s just the radiator.

[bogged]

Thanks for your help guys.

I just had it pressure tested and that showed up a leak in the lower driver's side tank of the radiator. Will get the radiator fixed and then see if it still uses coolant.

Fingers crossed it’s just the radiator.

if I remember a price I got for a mate few mths ago brand new head not reco but NEW is around $1200-1300

[blkmav]

if I remember a price I got for a mate few mths ago brand new head not reco but NEW is around $1200-1300

That is why I am hoping it's just the radiator

[Boopa]

Thanks for your help guys.

I just had it pressure tested and that showed up a leak in the lower driver's side tank of the radiator. Will get the radiator fixed and then see if it still uses coolant.

Fingers crossed it’s just the radiator.

if I remember a price I got for a mate few mths ago brand new head not reco but NEW is around $1200-1300

is that assembled....ie bolt on with valve gear etc?

[BowTieGQ]

No such luck, it's bare but a better casting. That's not a bad price either considering RRP is $1800!

[BowTieGQ]

No such luck, it's bare but a better casting. That's not a bad price either considering RRP is $1800!

[bogged]

is that assembled....ie bolt on with valve gear etc?

in ya wettest dreams!

No such luck, it's bare but a better casting. That's not a bad price either considering RRP is $1800!

[BowTieGQ]

Got my head back from Quickdrive Engineering in Dandy. Machined face, 6 new ex. valves, 12 K-Line guides, 12 valve seat inserts, baby sized port job, and they supplied the VRS gasket set for me all for less than a new head an a new one doesn't have the good seats and a small port job. Goes shit loads better now. Just need to do the rest now.

[Boopa]

Got my head back from Quickdrive Engineering in Dandy. Machined face, 6 new ex. valves, 12 K-Line guides, 12 valve seat inserts, baby sized port job, and they supplied the VRS gasket set for me all for less than a new head an a new one doesn't have the good seats and a small port job. Goes shit loads better now. Just need to do the rest now.

Got head recoed this week also....same deal including parts except no port work. After having it removed and tested, found a crack.
Cost me 1800 odd including labour, testing of dead head and parts etc.

and yeh...goes real good too!

[Rainbow Warrior]

Got my head back from Quickdrive Engineering in Dandy. Machined face, 6 new ex. valves, 12 K-Line guides, 12 valve seat inserts, baby sized port job, and they supplied the VRS gasket set for me all for less than a new head an a new one doesn't have the good seats and a small port job. Goes shit loads better now. Just need to do the rest now.

Did they thicken the edge of No6 where it corrodes from the water jacket into the cylinder or was yours good?

[hottiemonster]

Thanks for the help so far.

Any mechanic recommendations?

Sandy Bowman - Aus4WD Specialists - knows how to make a 4.2 go!

Talk to him and he will tell you exactly what to do / get.

Did wonders with a mates Patrol!

Dave.

i have heard this from a few people, just need to save up some coin first

[blkmav]

Well the radiator is fixed and she's still using water. Time to rip the head off

Any tips, gotchas, recommendations from those who have done this before?

[Rainbow Warrior]

Well the radiator is fixed and she's still using water. Time to rip the head off

Any tips, gotchas, recommendations from those who have done this before?

Just make sure the coins handy, bottom ends are rock solid so either drop a s/h motor straight in or just rebuild the head.

[BowTieGQ]

Rainbow, my head was really good. There was a small amount of corrosion where the head gasket had been leaking for some time, but that went with a light machine.

[blkmav]

The head is off and the head gasket had blown out over #6. Luckily the head is still good.