This is one for a tech. dose the LBZ have a dedicated cylinder wall lubrication system ( con-rod squirt holes, oil jets to supply the oil rings) or dose the motor rely on the cooling jets for this process?

geabis, im not sure about the cylinder lubrication, but i know the d-max does have piston cooling jets at the bottom of each cylinder (you can see them in the sales catalog at the dealership), what they do is- spray a jet of oil directly at the bottm of the piston this helps with piston cooling, it may seem trivial but they do work!!! we had a guy at work when he took a worn out engine (3406 B cat - like in a semi) apart he bent 3 of the cooling jets ( didnt know it obviously:rolleyes: ) and he ended up rebuilding the engine 2 time before he figured out that each time it was the same 3 cylinders seizing!!!Censored :eek: its usually a standard thing for us to check and/or replace these jets just because of how important these cooling jets are. as for the cylinder wall lubrication, maybe the jet shoot enough to lubricate the cylinder walls? i dont think its a big issue - never heard of a PROPERLY running ( and full of oil ) engine not getting enough wall lubrication!! hope that helps ?;) keep on truckin':ro) kenny

Geabis is asking the question to determine if cylinder wall lubrication has a dedicated oil provision, apart from the cooling squirters. It is rumored that under 29 psi, piston squirters stop. As to why this has been designed this way I can't say. I have ideas, they are just speculation.

Geabis is asking the question to determine if cylinder wall lubrication has a dedicated oil provision, apart from the cooling squirters. It is rumored that under 29 psi, piston squirters stop. As to why this has been designed this way I can't say. I have ideas, they are just speculation. I assumed they were always "on" but if your point is true might it be Emissions related? Just thinking out loud):h

where does it squirt the oil? on the lower skirt, or up inside the piston? where are these jets located?

do the cummins/powerstroke's have 'em?

where does it squirt the oil? on the lower skirt, or up inside the piston? where are these jets located?

do the cummins/powerstroke's have 'em?

yes most diesel engines have them to cool the aluminum piston. PSD had a problem with them a few years back 7.3L i believe with the jets falling off and the cylinder wall wearing. its been rumored that the dmax disables cooling jets below 29psi. and I'm trying to determine if this is true or not. as to the purpose of the jets disabling i do not know why they would disable them but as far as i can see there is no mechanical valve or regulator that dose so i think it may be a factor of achieving enough pressure on hot thin oil to be able to squirt to the piston bottom (may bee a design flaw, may designed to achieve some purpose or may not even be true)

where does it squirt the oil? on the lower skirt, or up inside the piston? where are these jets located?

do the cummins/powerstroke's have 'em?

Just re read your question. the jets are located on the lower block and squirt towards the under side of the piston. and being as the jets are stationary and the piston is reciprocating i think the stream would hit both the underside and the skirt. just and assumption

I assumed they were always "on" but if your point is true might it be Emissions related? Just thinking out loud):h
I don't think it would be emissions related. rather an over site in the design of the amount of hot oil a dmax consumes in its lube system or designed for some other reason that i can't figure out. or just not true. i could assume it was true if the dmax had another dedicated lube system for cylinder wall lubrication.

I don't think it would be emissions related. rather an over site in the design of the amount of hot oil a dmax consumes in its lube system or designed for some other reason that i can't figure out. or just not true. i could assume it was true if the dmax had another dedicated lube system for cylinder wall lubrication.

If they do in fact turn off, I would ASSume it is due to flow. At 29 psi the engine is not "working" and therefor should not need the cooling jets. Also a lower volume of oil is going through the passageways (lower rpm) so they probably want to make sure as much oil gets to the bearings as possible where it is needed more, rather than being starved by the cooling jets.

I have no proof or intimate knowledge of this engine, but it would seem to make sense FWIW.

If they do in fact turn off, I would ASSume it is due to flow. At 29 psi the engine is not "working" and therefor should not need the cooling jets. Also a lower volume of oil is going through the passageways (lower rpm) so they probably want to make sure as much oil gets to the bearings as possible where it is needed more, rather than being starved by the cooling jets.

I have no proof or intimate knowledge of this engine, but it would seem to make sense FWIW.
i had this idea too. but it would seem that even an engine that isn't doing work could have heat soaked pistons that would still need cooling and the resivour of oil that the rings can hold wouldn't last more that 20-30 seconds before drying up and the cylinder walls would be starving for oil