dhp123166 Posted August 5, 2012 Report Share Posted August 5, 2012 I purchased an '80 Datsun 720 Pickup that someone dropped a diesel engine in. It does not look like an SD-22, SD-23, or SD 25. It looks like a Maxima diesel engine minus 2 cylinders. I think I need a head gasket for it as I am starting to see black specks and oil tendrils in the coolant. The head and exhaust code are "W17". The block numbers are covered w/ grime. I did search and cannot find anything about this, anyone? Quote Link to comment
ggzilla Posted August 5, 2012 Report Share Posted August 5, 2012 That's a Nissan OHC Diesel 1 Quote Link to comment
ggzilla Posted August 5, 2012 Report Share Posted August 5, 2012 LD20 we talked about this last month: http://community.ratsun.net/topic/13245-help-to-id-an-engine/ Quote Link to comment
dhp123166 Posted August 5, 2012 Author Report Share Posted August 5, 2012 Thank you, that was fast I am sorry I did not search better, you are a lifesaver! Best Regards, Daniel P. Quote Link to comment
DAT510 Posted August 5, 2012 Report Share Posted August 5, 2012 That looks sooo cool. Quote Link to comment
dhp123166 Posted August 5, 2012 Author Report Share Posted August 5, 2012 After some research, it appears that it would make perfect sense for someone to do this swap as the LD-20 bolts right up to the stock mounts and drive train on the 720. Even better, a cursory glance at the tranny makes me believe that the 5 speed I had on my 280z will also bolt right up to this engine when this one heads south. Here's to inscrutably efficient Japanese engineering! 1 Quote Link to comment
Dawa Posted August 5, 2012 Report Share Posted August 5, 2012 aww, i want a nissan diesel engine :( and youre right about the 5 speed z trans being able to fit, im going thru that now. Quote Link to comment
ggzilla Posted August 5, 2012 Report Share Posted August 5, 2012 are you sure the Z transmission fits this L-series engine? Quote Link to comment
Dawa Posted August 5, 2012 Report Share Posted August 5, 2012 are you sure the Z transmission fits this L-series engine? eek sorry GGzilla, wasnt try to spread misinformation. i SHOULDVE said that the Z trans( FS5W71B) should fit your truck i dont know anything about it fitting THAT engine. sorry sorry Quote Link to comment
dhp123166 Posted August 6, 2012 Author Report Share Posted August 6, 2012 are you sure the Z transmission fits this L-series engine? It looked like it might, more research is required. Thanks, Daniel P. Quote Link to comment
elfirebeasto Posted August 6, 2012 Report Share Posted August 6, 2012 I want a Nissan diesel too. You west coast guys always get the best stuff! That engine looks very nice in your truck. Good luck with your research! Quote Link to comment
dhp123166 Posted August 6, 2012 Author Report Share Posted August 6, 2012 Thanks elfire! This is from Wikipedia; "However, in case of a conversion of a gas powered 720 to diesel, it will be much easier to use a LD20 because it fits on the original gearbox and engine mounts." I distinctly remember when pulling apart an LD28 the tranny metal plate (the thing that bolts over the tranny that needs to be removed before accessing the flywheel bolts) was two pieces as opposed to the one piece on a gas powered L28 engine (or was it the other way around?) but was the same diameter, maybe not the same thickness. I still have it in my garage actually, I can check. In my boilerplate theorizing the LD20 looks to be a 4 cylinder version of an LD28 so I am crossing my fingers that this will work. At any rate finding parts for this is probably going to be a bear, as this engine was originally offered in the Bluebird 910 and the Vanette. Never even heard of these models before!!!! Quote Link to comment
ggzilla Posted August 6, 2012 Report Share Posted August 6, 2012 Yes, they bolt on, but Z transmissions lean a different way than L transmissions. Quote Link to comment
dhp123166 Posted August 6, 2012 Author Report Share Posted August 6, 2012 I am still learning as I go, forgive me if this is something I should know, but what does "lean" mean? Here is a picture of an '84 gas powered 720 tranny. This really looks like my 280zx 5 speed tranny that is still sitting on my dead 280z. Are the internals different? Quote Link to comment
ggzilla Posted August 6, 2012 Report Share Posted August 6, 2012 Transmissions lean (slant) differently. Otherwise the bolt pattern is the same. L-series engine leans to the right Z-series leans to the left Quote Link to comment
wayno Posted August 7, 2012 Report Share Posted August 7, 2012 Thanks elfire! This is from Wikipedia; "However, in case of a conversion of a gas powered 720 to diesel, it will be much easier to use a LD20 because it fits on the original gearbox and engine mounts." I distinctly remember when pulling apart an LD28 the tranny metal plate (the thing that bolts over the tranny that needs to be removed before accessing the flywheel bolts) was two pieces as opposed to the one piece on a gas powered L28 engine (or was it the other way around?) but was the same diameter, maybe not the same thickness. I still have it in my garage actually, I can check. In my boilerplate theorizing the LD20 looks to be a 4 cylinder version of an LD28 so I am crossing my fingers that this will work. At any rate finding parts for this is probably going to be a bear, as this engine was originally offered in the Bluebird 910 and the Vanette. Never even heard of these models before!!!! This is confusing to me, as the 720 came out with an L20b only the first year, and came with the Z block all the remaining years except for the SD series diesels(81-82 for the most part) which have the starter on the left side(driverside/US models). The blocks(L & Z) both have the same bolt pattern for the tranny, but since the L block leans to the right so the intake doesn't hit the brake master cylinder, and the Z block leans to the left to make room for the intake on the otherside, they made the tranny bellhousing/case twisted differantly depending on the engine, if an L block tranny was put onto a Z block, I beleave the transmission shifter would be pointed into the drivers leg, and if the Z tranny was bolted onto an L block, I beleave the shifter would be pointed into the passingers leg, both situations the shifter will not be pointed strait up. I don't know which way the LD20 is tilted, but I suspect from the looks of the engine, it is tilted towards the right, that would mean that you would use an L block tranny assuming it really does have that pattern and the starter is in fact on the passinger side on that diesel series. Quote Link to comment
dhp123166 Posted August 7, 2012 Author Report Share Posted August 7, 2012 I am still learning as I go, forgive me if this is something I should know, but what does "lean" mean? Here is a picture of an '84 gas powered 720 tranny. This really looks like my 280zx 5 speed tranny that is still sitting on my dead 280z. Are the internals different? I knew that was a "duh" question! Thanks for your time in answering. However those pictures are of L series and Z series engines. Apples and oranges no? LD 20 and L 6 are both L series are they not? This is confusing to me, as the 720 came out with an L20b only the first year, and came with the Z block all the remaining years except for the SD series diesels(81-82 for the most part) which have the starter on the left side(driverside/US models). The blocks(L & Z) both have the same bolt pattern for the tranny, but since the L block leans to the right so the intake doesn't hit the brake master cylinder, and the Z block leans to the left to make room for the intake on the otherside, they made the tranny bellhousing/case twisted differantly depending on the engine, if an L block tranny was put onto a Z block, I beleave the transmission shifter would be pointed into the drivers leg, and if the Z tranny was bolted onto an L block, I beleave the shifter would be pointed into the passingers leg, both situations the shifter will not be pointed strait up. I don't know which way the LD20 is tilted, but I suspect from the looks of the engine, it is tilted towards the right, that would mean that you would use an L block tranny assuming it really does have that pattern and the starter is in fact on the passinger side on that diesel series. Well both LD 20 engines and L6 engines lean the same direction (right) as evidenced by the picture of my specific vehicle at the top of the post. I don't have a picture of a stock ZCAR but that engine also leans to the right. They are also configured identically as alluded to by Wayno, the intake/ exhaust is on the left and the starter/ injectors are on the left. This looks promising. Quote Link to comment
datsunaholic Posted August 7, 2012 Report Share Posted August 7, 2012 He said is has a 280Z transmission... which is an L-series transmission. "Z" (NAPS-Z) and "Z-car" isn't the same thing. A 280Z/280ZX transmission will bolt up to a LD20 just fine. Correct tilt and everything, though the gear ratios for the 280ZX trans would be way too "close ratio" for the Diesel, at least not without running a lower rear gear like a 4.88. Quote Link to comment
dhp123166 Posted August 7, 2012 Author Report Share Posted August 7, 2012 Thanks datsunaholic, so I guess what it comes down is cost effectiveness (free 5 speed tranny in great shape) minus difficulty of operation (close ratio tranny (barring any additional rear gear work)) plus usual usage (mainly freeway 5th gear, long distance, very light flat land hauling). A transmission replacement is still a while away (hopefully!) I just need to know if I am keeping the one on my parting out dead ZCAR. On a great note, I found a local mechanic to do the head gasket for a very reasonable price, he knows the engine and can source parts and gaskets. To hear his tone on the phone it was no big deal to him, another job that he can handle! I still have a couple months before it needs to get done and after talking to three other mechanics who flat out refused I was starting to think that maybe this vehicle was not such a smart purchase after all. Quote Link to comment
datsunaholic Posted August 7, 2012 Report Share Posted August 7, 2012 A 280Z transmission won't be overly close-ratio. It's the 280ZX one, and then only the 80 and later ones. A 77-78 280Z and a 79 ZX trans has the same 1st -4th ratios as the 720 Diesel Truck trans, just not as much overdrive. In fact it probably is the EXACT same ratios you already have, if the 5-speed in the '80 720 is original to the truck. Quote Link to comment
dhp123166 Posted August 7, 2012 Author Report Share Posted August 7, 2012 Actually I am not even sure at this point if it is a 280zx (which I thought it was) or a 280z. I had the transmission changed over using the shifter portion from my previous transmission as it had been machined to allow for the use of a short throw shifter and that was from a 280zx (I believe early) but I am not sure what it was replaced with. Hell, your info sounds great ( thanks!) so I will probably just put it on when necessary and see what happens!! It's free!!! Quote Link to comment
dhp123166 Posted August 8, 2012 Author Report Share Posted August 8, 2012 QUESTION OF THE DAY; What is the point of designing this all one piece ( water pump, pulley and fan clutch), clearance issues? This is the fan / water pump combo deal that was on my LD20. I chopped it apart to get the pulley which was then modified to work with a 280z water pump in addition to a spacer being used. This is stock ; Datsun 510 610 200SX & 710 New Water Pump with Fan Clutch Quote Link to comment
ggzilla Posted August 8, 2012 Report Share Posted August 8, 2012 That is normal L-series engine practice. A lot of L20Bs are like that. Quote Link to comment
dhp123166 Posted August 9, 2012 Author Report Share Posted August 9, 2012 Well I guess my question is why it was done for these vehicles, and not on s-30 ZCARs for example which have the usual style of being able to be disassembled? Quote Link to comment
datsunaholic Posted August 9, 2012 Report Share Posted August 9, 2012 Z cars have more room. The 620, and most Datsun 4-cyl cars, were designed for the OHV "J" and "A" series engines and they wedged the L-series in. Getting enough clearance to the radiator meant compressing everything, especially when the fan clutches were added in '75. Quote Link to comment
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