str8up(81)720 Posted January 6, 2012 Report Share Posted January 6, 2012 Hey everybody. I am new to this site and am trying to build up my knowledge about Datsuns, being the owner of a 81 720 pickup. I am in the process of replacing a head gasket on what i believe to be a Z22 block, from the casting that is stamped on the block. I am lead to believe that the head doesnt match to the block due to some of the cooling passages being blocked by the head gasket. Then again, maybe the head gasket is not for my application even though i specifically asked for a z22 head gasket set. Has anyone ran into this problem? any input would help. maybe i just need to cut out the holes on the gasket..? or if anyone has a picture of the cooling passages through the head, would be very much helpful. Thanks again! Quote Link to comment
ggzilla Posted January 7, 2012 Report Share Posted January 7, 2012 Don't guess, verify. The engine type will be stamped (not cast) on the side of the block. The head can sometimes be identified by the casting numbers. Quote Link to comment
datzenmike Posted January 7, 2012 Report Share Posted January 7, 2012 Not every hole in the gasket is used and not every hole in the head matches a hole in the block. L20B timing cover. Front of head gasket is very square. Two 10mm bolts at front left and right attach it to the head above. Two 12 mm bolts on each side below hold it to the block behind it. Z20 and Z22 timing cover. Head gasket rounded at front. Four 10mm bolts attach it to the head above. Has the same two 12mm bolts on each side holding it to the block. Z24 timing cover. Same head gasket shape as the Z20/22. Asme 4 10mm bolts attaching it to the head. The two 12mm bolts on each side at front are wider spaced. KA24E timing cover. Same gasket shape as the Z20/22/24. Same 10mm bolts. Single 12mm bolts at front. Measure the bore. The Z22 will be 87mm across. . Quote Link to comment
wayno Posted January 7, 2012 Report Share Posted January 7, 2012 Welcome to Ratsun What side is the carb on, drivers side or passinger side? Photos would help greatly. Quote Link to comment
str8up(81)720 Posted January 10, 2012 Author Report Share Posted January 10, 2012 Wow ! those pictures are a great start! i will have to verify my timing cover. Very much appreciated!! The carb is on the passenger side, and i will post some pictures of the head, gasket , and block deck as soon as i get back on the job. Been lagging on it a bit. It is interesting point that not all holes in the gasket are used and the head/block holes matching.. I will get back to this point once pictures are up. The main reason i started doing this job, was because i was lead to believe the head gasket was blown due to A) a previous hack head gasket job done B) excessive white smoke coming out of the the tail pipe when the engine warmed up. I am talking as if i were doing a burn out amounts of smoke! and C) traces of coolant found in the oil and cylinder bores. Any thoughts? Quote Link to comment
wayno Posted January 10, 2012 Report Share Posted January 10, 2012 White smoke is likely water getting into the bores and turning to steam, blown headgasket is likely, water in the oil is another clue, napZ engines are known for blowing headgaskets, I have heard your supposed to re-torque the head bolts every tune-up, but there are a lot of cheap 720s out there with blown headgaskets, easy fix, good driver afterwards. Quote Link to comment
str8up(81)720 Posted January 10, 2012 Author Report Share Posted January 10, 2012 From what i have read, i have also heard about these engine being prone to head gasket failure. Good thing you bring up the head bolts. I was told the head bolts for these engines are torque-to-yield type head bolts, which stretch when they are torqued, thus makes them non-reusable. Any truth to this? i didn't want to risk it so i went a head and purchased new ones anyways. Quote Link to comment
wayno Posted January 10, 2012 Report Share Posted January 10, 2012 From what i have read, i have also heard about these engine being prone to head gasket failure. Good thing you bring up the head bolts. I was told the head bolts for these engines are torque-to-yield type head bolts, which stretch when they are torqued, thus makes them non-reusable. Any truth to this? i didn't want to risk it so i went a head and purchased new ones anyways. I do not know the answer to this question for sure, the guy down the road doesn't buy new headbolts, and the way I heard your supposed to re-torque the headbolts is to loosen each one in no paricular order one at a time, and then re-torque them, making sure you re-torque them all, it is weird the no paticular sequence part, but that is what I heard. There are a lot of weird things like this I have heard about nissan engines. Quote Link to comment
datsunaholic Posted January 10, 2012 Report Share Posted January 10, 2012 When you're doing a re-torque one at a time order isn't important. It is for Initial torque and removal. But it doesn't hurt to follow the pattern, to build the habit. Quote Link to comment
wayno Posted January 10, 2012 Report Share Posted January 10, 2012 When you're doing a re-torque one at a time order isn't important. It is for Initial torque and removal. But it doesn't hurt to follow the pattern, to build the habit. I agree with you, do it the same way(correct sequence) everytime, and you likely won't screw it up later. Quote Link to comment
str8up(81)720 Posted January 10, 2012 Author Report Share Posted January 10, 2012 im trying to insert pics, how do i go about it...? Quote Link to comment
wayno Posted January 10, 2012 Report Share Posted January 10, 2012 im trying to insert pics, how do i go about it...? Do you have a photobucket acct? Quote Link to comment
str8up(81)720 Posted January 11, 2012 Author Report Share Posted January 11, 2012 "> Quote Link to comment
str8up(81)720 Posted January 11, 2012 Author Report Share Posted January 11, 2012 i think i figured it out!. i think miss posted as well. as far as the picture above, concerning numbers one and two, those two holes are not cut out on the gasket. I would imagine it is for a reason, but i would like to verify it. As far as number 3 those are on the gasket just a lot smaller which makes me wonder why and if this is the right gasket?? "> Quote Link to comment
str8up(81)720 Posted January 11, 2012 Author Report Share Posted January 11, 2012 "> On the cylinder head picture, all the coolant passages on the right side of each Cylinder are not on the gasket as well. Neither is the furthest right hole, to the bottom left of the first cylinder. any reason for this?? any ideas would be much appreaciated. i don't want to screw this build up. Id rather be sure about it. Quote Link to comment
ggzilla Posted January 11, 2012 Report Share Posted January 11, 2012 The head bolts are reusable on L and Z engine. They are not TTY. Quote Link to comment
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