QD32 Replacing pistons in situ

[Boriskov]

I thought I'd do a write up of this as I've searched for ages, and found very inconclusive stuff relating to the QD32 engine in the navara. Lots of stuff relating to the 2.7 engine, but this is a very different block.

Set the scene: I had 0 compression on cyl. 4 (at the back). What do you read online? "you need to decouple the gearbox to get the sump off and cant get the head off bla bla". Kinda disconcerting.

NOT TRUE. the QD is a different animal, and be thankful of that.

On the QD32, the head is nice and simple, No cam chain, and is a Push rod engine. It can't be simpler. 2-3 hours of orderly work will have the pistons looking at you. I have an aftermarket turbo fitted with the 2.7 manifolds, so it'll be about 30 mins faster if you have the NA engine.

I found 1 of the pistons to be cracked, no other damage. So I'll replace the set.

REMOVAL OF THE SUMP/oil-pan if you're a colonist:
this is relatively easy.

Go underneath and disconnect the drive shafts and prop shaft only at the front diff end. 16 bolts total. You don't need to remove any of the shafts. If you have manual front lockers, consider this a godsend for shaft disconnection. you can lock them to loosen a bolt, then unlock it to rotate the shaft to the next bolt, then lock it again.

You can now drop the front diff. It's held on by 4 big bolts, and IS NOT very heavy. About 40-50kg. Unless that's your bodyweight, then you won't struggle. (Don't forget the breather tube) I did this with all the wheels on the floor, but I do have a bit of a lift on, and 33's.

There's a cast plate that's held on by 3 large bolts that covers part of the sump. Off with it.

Now the sump can come off, and that's it.

Let's say it took 3 hours for the head removal, and 2 hours to get the diff out if you take your time. Not so hard right?

My condolences all you other-engine types.

 

[doug696]

hey mate thanks for the info as a fellow qd32 owner that's good to know, i am wondering if you have any idea what caused the piston to crack? did you replace the pistons with standard or did you find some ceramic top?
CHEERS DOUG

 

[Boriskov]

Honestly no idea. I bought it about 3 weeks ago as is. I'm guessing it could be a case of over-boosting, as the crack is parallel to the gudgeon pin. I don't think it's due to lack of maintenance, as the car is immaculate with every aftermarket part imaginable, and the oil wasn't that bad when I dropped it.

Pistons are hard to come by. OEM ones are $rape if you can get them, and the aftermarket ones I'm not sure of the quality. Oh the world we live in...

Needless to say, once it;s back together it'll have an intercooler, EGT, boost gauge and boost controller fitted, and no more than 7psi of boost along with a grade 3 head gasket because every little helps.

From what I've read online about the aftermarket turbos, people are running upwards of 14psi which seems to be asking for trouble in my opinion in a stock engine.

 

[bestera]

Thanks for the insight and the humour to boot!
My D22 used to have the QD32, but I swapped it out for a QD32ETi 80,000km ago.

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[tweak'e]

Honestly no idea. I bought it about 3 weeks ago as is. I'm guessing it could be a case of over-boosting, as the crack is parallel to the gudgeon pin. I don't think it's due to lack of maintenance, as the car is immaculate with every aftermarket part imaginable, and the oil wasn't that bad when I dropped it.

Pistons are hard to come by. OEM ones are $rape if you can get them, and the aftermarket ones I'm not sure of the quality. Oh the world we live in...

Needless to say, once it;s back together it'll have an intercooler, EGT, boost gauge and boost controller fitted, and no more than 7psi of boost along with a grade 3 head gasket because every little helps.

From what I've read online about the aftermarket turbos, people are running upwards of 14psi which seems to be asking for trouble in my opinion in a stock engine.

boost in it self is not an issue like people tend to think it is.
biggest thing is egt's, afr and timing.
one of the catches is increases in inlet temp tends to act like advancing the timing.

do not fit an thicker head gasket, it will run like crap.

aftermarket turbo could mean its not a well matched turbo. to much back pressure causes excess end gas which increases the air temps inside the cylinder where you can't measure it.
a back pressure gauge can be useful for this.

fitting an intercooler is one of the best things as well having enough boost within the turbo operating range. lots of cool air mass is important.
because inlet temps changes the required timing, keeping inlet temps fairly low means you can use stock timing.

lack of a boost comp is often a common cause. without it AFR's go to crap when your accelerating, which gives momentary high egt's. egt damage is accumulative.

 

[Boriskov]

Just another QD-tip for the sump removal. The tie rod is in the way of dropping the sum. Rather than unbolting both of the tie rod ends, you can take off the pivot bracket inside the LHS wheel arch and "toe in" the wheel to move the shaft out of the way.

So out come the pistons, and they're in annoyingly good shape to be chucking the set because of 1 cracked idiot

 

[Rumpig]

Wasn't the qd32 a cut down td42 ? Are td42 pistons the same size?

 

[tweak'e]

Wasn't the qd32 a cut down td42 ? Are td42 pistons the same size?

no
TD27 is a cut down TD42 with the same sized pistons. QD32 is based off TD27 but theres a few differences.

 

[Boriskov]

No, even the maths doesn't work for that.

Pi*d/4^2*stroke*cyl number with a stroke of 102mm and diameter of 99.2mm = 3.15 for QD32. For 6 cylinders would be 4.7L

I ordered the Mag engines pistons after talking to the guys on the phone for a while. For those interested in QD32ETi vs QD32 pistons, take note:

FOR TURBO PISTONS:
On observation, they're strengthened in the right places which would prevent the cracking mine suffered from. The compression zone is 0.1mm less. The overall height is the same. Gudgeon pin is still 33mm.

YOU CANNOT FIT TURBO PISTONS TO STANDARD ENGINE BECAUSE:
The turbo engine uses slimmer conrods, and as such, the "gap" at which the small end sits in the piston is narrower. You could maybe shave this to make room, but you'd be compromising the strength and unbalancing the pistons.

RE: the head gasket thickness... I may have to order a seperate graded one, as the one they're sending seems to be a "standard type" of aftermarket gasket. Read this as "so thick it covers all bases", but I don't have a part number to check as of yet.

When it arrives, I'll review them as there seems to be 0 info online, and they're one of the only suppliers I managed to find.

 

[doug696]

more good info mate, i am wondering if you could use the eti pistons and conrods or are they wrong at the big end as well?
cheers doug

 

[Boriskov]

If the stroke and crank journals are the same measurements, then yeah, you could fit the eti conrods. I imagine that those are the only 2 differences between the engines in all honesty, as the reinforcement material in the eti pistons is pretty noticeable to avoid cracking like this.

 

[Boriskov]

So final update (for now) of this build:

Firstly:
DO NOT BUY THE GASKETS FROM mag engines. The pistons themselves are fine, and do the job. However, the gaskets are terrible. Fibre is used where metal is OEM etc.

And most importantly. The head gasket is the worst I've experienced. Mine cracked after less than 500km and pressurised my coolant. I thought the worst, maybe cracked block or something? But nope, after taking it apart and seeing cracks runnnig around the inside of the compression seal of the gasket, I sent off some angry emais.

New gasket set later, and a day of hating arabs, it's back and better than ever.

Just seeking a way to put an intercooler in that doesn't look like a redneck beer can (as with everything relating to it online)

Maybe incoming if I didn't get killed by the giant seagull...

 

[jonney]

fit a late model intercooler and buy a bonnet scoop or another bonnet with the scoop fitted.

 

[Boriskov]

I've got the bonnet scoop already, but the intake manifold is very different to the TD27, hence why a top mount might not be possible. I've got a full water-to-air intercooler setup but there's no way to effectively fit this lot. Hence attempting to get an air-to-air at some point.

 

[doug696]

nice mate the truck is looking good, so which pistons did you end up going with new stock standard or the eti?

 

[bestera]

I had my IC on my QD32ETi front mounted.

 

[Boriskov]

Looks decent, but I'm trying to avoid that kind of setup mainly because of the comparable lag it would cause. I'm on the hunt for a "slim" same side intercooler that I can top mount if such a thing exists. Then I can mount it on the plenum, get a straight pipe from turbo to intercooler, then a 180 bend from intercooler to plenum.

I ended up fitting the standard pistons, but I did notice that the conrods have a taper on the small end, meaning the turbo pistons are VERY LIKELY to fit. If it blows again (hopefully not) I'll be fitting turbo ones, as they do seem to be much more reinforced.

 

[bestera]

Yup, I was concerned about the lag, but heatsoak overrode my option to do a top mount. No space for otherwise either.

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[tweak'e]

Looks decent, but I'm trying to avoid that kind of setup mainly because of the comparable lag it would cause.

reality is the lag is negligible.
you would have to over size the pipes and intercooler a fair bit to get it bad enough.

 

[nedm1989]

When I had my D22 with a QD32 and then turbo'd it, I eventually used a 2001 WRX top mount intercooler which sat off to the side a little but had very little pipe work and worked great.

Plus I was actually going to use an old Subaru liberty water to air intercooler which I still have, still the same size as a wrx top mount and has the cap on the intercooler itself for filling, I also have the standard heat exchanger with it too, just needs a water pump and hose if you were interested.

I spent a lot of time researching turboing the qd32 and the most beneficial ways of doing anything before picking up the tools just so I didn't have to do it twice, and still do the same thing with my D40 550.