I just finished up my vq40 d40 and bought a yd25 d40 auto with a blown head gasket or cracked head, the engine only turns half way by hand then stops, car has been sitting for a while, I took the injectors out and turned still the same, then I took the cams off and still the same, what could it be, I did not try to start it with the starter motor as I don’t know if it is a valve
Nissan yd25 won’t turn more than half way
- Thread starter The j man
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OldManBeard
Member
Start by removing the head and work your way down until you find the problem. It would be far easier with the engine out of the car.
^ Good suggestion.
You could just remove the manifolds and look in the ports to see if the valves are closed or not, but then measuring the lengths of the valve springs will also give you this information and won't require any more disassembly than you have now.
You might also have something in the water pump/fuel pump, which are driven by chains on the front of the motor (which you'd already have uncovered if you've pulled the cams out). You could test it by removing the lower chain.
You could just remove the manifolds and look in the ports to see if the valves are closed or not, but then measuring the lengths of the valve springs will also give you this information and won't require any more disassembly than you have now.
You might also have something in the water pump/fuel pump, which are driven by chains on the front of the motor (which you'd already have uncovered if you've pulled the cams out). You could test it by removing the lower chain.
I checked the oil filter and there are a few very small metal flakes on it but I’m pretty sure that’s okay, I was thinking I might rebuild it but it’s just a project that I’m going to sell so I don’t want to put too much money into it, I’m taking the head off now, I was going to remove the engine but it looks like it’s not easy the vq40 wasn’t hard to take out but this one looks like a mess
Wow, number 3 looks a mess, as do the coolant paths around it. Is that a hole in the top of #3 piston? I've only just written a post saying I've never heard of that happening in a Navara - please tell me it's just a shadow, or a fault in the jpg or something.
no not a hole just allot of rust, looks like the rust is surface I can scrape it away,
My question is the head is warped 0.50 maybe more and the block 0.020,
What are my options here,
Shave the block and have it honed maybe bored for oversize pistons and buy a new head for it, but I’m worried about the pistons clearance when the block is shaved I can’t find any information on that, thicker head gasket maybe, if I buy a new head it will be stock size brand new so I can get thicker head gaskets and make up the clearance, pistons should be okay with new rings unless there’s damage to the cylinder and I need bigger ones, I haven’t looked at the crank or bearings yet but there cheap so ile change them too, all together should cost $1200 for the head in Australia $100 for the piston rings $250 for the bore if not cheaper for the hone and $150 for the cylinder shave. So $1600 for the lot reconditioned engine will be $4500 here so seem like a good option but my question is will I have an issue with shaving the block at least 0.020 maybe 0.030 and use a thicker gasket ?
My question is the head is warped 0.50 maybe more and the block 0.020,
What are my options here,
Shave the block and have it honed maybe bored for oversize pistons and buy a new head for it, but I’m worried about the pistons clearance when the block is shaved I can’t find any information on that, thicker head gasket maybe, if I buy a new head it will be stock size brand new so I can get thicker head gaskets and make up the clearance, pistons should be okay with new rings unless there’s damage to the cylinder and I need bigger ones, I haven’t looked at the crank or bearings yet but there cheap so ile change them too, all together should cost $1200 for the head in Australia $100 for the piston rings $250 for the bore if not cheaper for the hone and $150 for the cylinder shave. So $1600 for the lot reconditioned engine will be $4500 here so seem like a good option but my question is will I have an issue with shaving the block at least 0.020 maybe 0.030 and use a thicker gasket ?
Gaskets come in different thicknesses, you can tell what thickness yours is by the number of notches in the gasket on the right-hand side rear corner of the gasket. There's a table:
0 notches = 0.900mm
1 notch = 0.925mm
2 notches = 0.950mm
3 notches = 0.975mm
4 notches = 1.000mm
5 notches = 1.025mm
If you shave off 0.25mm from the block, you could go up one size in gasket.
0 notches = 0.900mm
1 notch = 0.925mm
2 notches = 0.950mm
3 notches = 0.975mm
4 notches = 1.000mm
5 notches = 1.025mm
If you shave off 0.25mm from the block, you could go up one size in gasket.
The manual only lists 5 notches and does not allow for a second gasket to be used. You would have to consult a professional diesel mechanic for advice on getting a thicker gasket in there.
Hopefully you'll find that the block doesn't need too much removed and the piston at TDC doesn't protrude too far. The max protrustion allowed is 1.555mm measured at the point on the piston 1/8th of the way across (so, one quarter of the way from the edge of the piston to its centre).
Hopefully you'll find that the block doesn't need too much removed and the piston at TDC doesn't protrude too far. The max protrustion allowed is 1.555mm measured at the point on the piston 1/8th of the way across (so, one quarter of the way from the edge of the piston to its centre).
ile buy the measuring tool to measure the protrusion and go from there, hopefully the 6 notch was from the head and not a shaved block since the head will be original size i should be able to buy the right gasket for it, thanks for your help i will post updates here for you guys
Had my block shaved, not at all sure how much, and with a replacement head due cracked and the thickest head gasket i was good, the machine shop also mentioned that they only generally supplied the thickest possible head gasket, they pointed out that the difference in compression would really be negligible, ( different story if you are going for performance, but mine was just a daily driver)
Been a while not sure how many notches or what my protrusion measurements were
If your in Perth area i used Harris engines for the machining, i had a crank snap so had the tunnel bored as well and after 365k only needed a hone, but i didnt have rust, block machining, head replacement ( my existing valve train) plus bearing rings and all the gaskets ( except turbo), measured up my pistons and polished/measured my replacement crank was 2950 ish ................
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it actually cleaned up allot after a long hone, i measured the bore and it is still in spec 89mm, there is still some pitting from the rust but nothing i can feel with my nail, i have decided to keep the car and use it as a daily driver for now, i have called 3 different machine shops today and they all said over $500 for all 4 i want expecting that much and with the pistons, rebuild kit and new head i am way over budget for this project, so im just going to get the new head, piston rings gasket and bolts and just see how it goes untill i have enough to get some good pistons and bore later on
I have decided to do it properly, I’m getting the new head and having the block bored and honed also I bought a full rebuild kit with it new pistons and rings bearings everything, does anyone have photos of the engine bay left and right all put back together, I usually take photos before I start but some of it was already taken apart, I would rather photos than the manual just too complicated sometimes
joe2006
Member
What year and is it VSK or MNT?
