The Toyota grenade.

[rowenb]

My ol 1HDT is still going with worn rings and bearings, been like that for 4 years. Don't have the money to replace it yet but she hasn't let me down.

[KiwiBacon]

I think you will find that the "boost spike" is not the root cause. There are a few problems that compound into the grenade effect. 1 being the crank case breather, breathing from the intake before the air flow meter, coating the wire in oil therefore over boosting. 2 the EGR valve dumps almost directly back into no.3 cylinder, and mixed with the oil coming back from the crank case breather, carbon builds very rapidly leaning out the cylinder, causing detonation. 4 its a Nissan!!. The easy way to get around this is, block of the EGR valve, remove the intake plenum/intake pipes and clean all the gunk out, fit a catch can to the crank case breather, fit a boost guage to moniter the boost incase it starts spiking and buy a Toyota.

Sorry mate, but this isn't a petrol engine. Diesel engines don't care about boost spikes, leaning out or detonation.

[UPPY]

I think you will find that the "boost spike" is not the root cause. There are a few problems that compound into the grenade effect. 1 being the crank case breather, breathing from the intake before the air flow meter, coating the wire in oil therefore over boosting. 2 the EGR valve dumps almost directly back into no.3 cylinder, and mixed with the oil coming back from the crank case breather, carbon builds very rapidly leaning out the cylinder, causing detonation. 4 its a Nissan!!. The easy way to get around this is, block of the EGR valve, remove the intake plenum/intake pipes and clean all the gunk out, fit a catch can to the crank case breather, fit a boost guage to moniter the boost incase it starts spiking and buy a Toyota.

Sorry mate, but this isn't a petrol engine. Diesel engines don't care about boost spikes, leaning out or detonation.

Belive what you want. Try running 50psi of boost and see if it doesn't lean out and die. I am talking about Detontaion as in KA BOOM, not pre or post detonation. I have seen it with my own 2 eyes, not something that my brothers dogs mothers cousin once told a mate that had one!!

[KiwiBacon]

Belive what you want. Try running 50psi of boost and see if it doesn't lean out and die. I am talking about Detontaion as in KA BOOM, not pre or post detonation. I have seen it with my own 2 eyes, not something that my brothers dogs mothers cousin once told a mate that had one!!

Diesels always run lean, AFR's from around 80:1 at idle to around 18:1 at full power. It is not possible for them to "lean out and die", except of course conking out when they run completely out of fuel.

50psi boost could cause a blown head gaskets, crack the heads or even put a leg out of bed, but these are mechanical damage. High boost on a diesel cannot cause detonation or melt-down.

[tweak'e]

if i remember right the zd30's where only boost spiking up into the 30's. however if you up the fuel, diesel or oil via breather, then you could get more boost.
boost isn't a problem. however at 30psi your probably looking at 40psi or so exhaust back pressure. depending on cam timing that can leave a lot of end gas in the cylinder which increases egt's.
now if egr valve is open at the same time, it swallows a lot of very hot exhaust gas.

boost is more of a symptom rather than the cause.

[Yom]

The engine in that link is the VP44 model, not commonrail. Are there any reports of VP pump models grenading or is it a common-rail thing?

The main difference being a single commonrail injector can have a bad day and dump fuel, but on a VP44 pump motor all cylinders get roughly the same dose.

nah its the VP44 models which grenade.

the common rails are yet to get a reputation for piston cracking.

one bloke on patrol4x4 had his grenade and found the pistons which were cracked were being fed by partially blocked injectors.