RidgeRunner Posted October 10, 2013 Report Share Posted October 10, 2013 My 197k mile 720 (Z24) just popped its head gasket from #4 to the coolant passage at the driver's side rear corner of the engine. Big geyser from the tailpipe! I seem to be lucky, I don't see signs of oil-antifreeze blending (but a complete fluid change is a given). I've got it apart (bought a pre-made timing chain wedge via ebay) and have begun cleaning the deck in preparation for re-assembly (still need to clean the head and check for signs of warpage though). 1. Do you think a Fel-Pro gasket set would be good enough? 2. Is head bolt replacement a requirement? Quote Link to comment
Eagle_Adam Posted October 10, 2013 Report Share Posted October 10, 2013 fel pro is fine ive used them several times and i have yet to replace the headbolts on any datsun motor all of them are still running Quote Link to comment
KlassicMotion Posted October 10, 2013 Report Share Posted October 10, 2013 I like the Felpro gasket. I know the L series head bolts do not need to be replaced. Probably the same as yours!? The torque-to-yeild head bolts (non-reusable) did start showing up around the mid '80's though.... Quote Link to comment
Eagle_Adam Posted October 10, 2013 Report Share Posted October 10, 2013 i just did a head gasket with a friend on a Z24 and reused the head bolts - motor is still running strong Quote Link to comment
datzenmike Posted October 11, 2013 Report Share Posted October 11, 2013 The Nissan cure for head gasket blowing is to loosen each head bolt one at a time and immediately tighten to the required 60 ft lbs. Do on a COLD motor and only one bolt at a time in any order. Re-torque every tune up but once a year is fine. 1 Quote Link to comment
KlassicMotion Posted October 11, 2013 Report Share Posted October 11, 2013 The Nissan cure for head gasket blowing is to loosen each head bolt one at a time and immediately tighten to the required 60 ft lbs. Do on a COLD motor and only one bolt at a time in any order. Re-torque every tune up but once a year is fine. Is this on a gasket that hasn't already gone? Or shall I try this on the gasket I just replaced and is already seeping? Quote Link to comment
datzenmike Posted October 11, 2013 Report Share Posted October 11, 2013 Once blown they are pretty much cooked. This is a preventative measure to keep the clamping force on the crushed gasket over time. Usually the Z24 blows them at 100K... that's a lot of heat cycles. Aluminum expands twice as much and faster than the steel block and the gasket it fixed to both surfaces. Over time it delaminates. The FSM says every tune up to torque the bolts on a cold motor, any order and only one at a time. You have nothing to loose re torquing the head if the gasket it 'seeping'. Give it a try. Quote Link to comment
RidgeRunner Posted October 23, 2013 Author Report Share Posted October 23, 2013 Updates... I've been taking my time on this. No big hurry, other than I don't have the use of my truck right now. 1. I bought the Fel-Pro set. What is the little copper ring for? It's in a tiny envelope by itself. I didn't see one on anything I took apart, but that's not to say I didn't miss it somewhere. 2. I plan to reuse the bolts after all. Just going to clean them with a die and go with it. 3. The head has a slight bow to it. It's right on the edge of the allowable tolerance, but since the block (which has the same tolerance spec) appears to be dead flat, I'm tempted to just go with it... just clean it up good and put it back as is. Any thoughts on this? Quote Link to comment
Eagle_Adam Posted October 23, 2013 Report Share Posted October 23, 2013 im never a fan of "untrue" surfaces..... id have the head checked by a machinist, no need to do this twice Quote Link to comment
datzenmike Posted October 24, 2013 Report Share Posted October 24, 2013 There is a copper 'o' ring for around the oil feed hole between the block and head.... but it's always crimped into the gasket. Never seen it loose. Quote Link to comment
RidgeRunner Posted October 24, 2013 Author Report Share Posted October 24, 2013 Yeah, that thought crossed my mind but you're right, that is crimped into the gasket. Quote Link to comment
RidgeRunner Posted November 3, 2013 Author Report Share Posted November 3, 2013 FACK! Timing chain wedge didn't work too good... tensioner came out of its bore. Front cover has to come off now. :angry: Quote Link to comment
datzenmike Posted November 3, 2013 Report Share Posted November 3, 2013 This can be from ... Trying to loosen the cam or crank sprockets AFTER wedging the chain. Loosen these before hand. Leaving vehicle in gear. Vehicle get's nudged while working on it and motion is transferred to the engine turning it. E brake and block tires. Quote Link to comment
RidgeRunner Posted November 3, 2013 Author Report Share Posted November 3, 2013 Vehicle was left in neutral, cam sprocket was loosened before inserting the wedge. Not sure if it's a matter of the wedge not going far enough down to begin with, or if it got moved somehow afterwards. Oh well. Started making some headway on gaining access to it. AC stuff is 2/3 removed now, went ahead and pulled the bumper to give easier access to the front, and I got the dizzy out after marking orientation of the rotor. Quote Link to comment
datzenmike Posted November 4, 2013 Report Share Posted November 4, 2013 I made a wedge back in the 70s it worked, but you had to really hammer it in tight. Kept an eye on it and if it looked like it moved I gave it another whack. Never had one fall out but sometimes hard to get the cam sprocket on. Some aren't a wedge as much as they just block the tensioner from pushing out. They are much longer and slide down between the guides. Quote Link to comment
KlassicMotion Posted November 4, 2013 Report Share Posted November 4, 2013 Buy one of these for the next time: http://www.amazon.com/Alltrade-648831-Nissan-Timing-Holding/dp/B0002Q8TV4/ref=sr_1_fkmr1_2?ie=UTF8&qid=1383594703&sr=8-2-fkmr1&keywords=datsun+chain+holder 1 Quote Link to comment
RidgeRunner Posted November 9, 2013 Author Report Share Posted November 9, 2013 Buy one of these for the next time: http://www.amazon.com/Alltrade-648831-Nissan-Timing-Holding/dp/B0002Q8TV4/ref=sr_1_fkmr1_2?ie=UTF8&qid=1383594703&sr=8-2-fkmr1&keywords=datsun+chain+holder I got one, but it didn't work out too well for me. Not sure if it's user error or what, but oh well. http://www.the510realm.com/viewtopic.php?f=30&t=14942 See that thread... there's a picture of both wedges... mine's the small one (apparently that's for the Z-motor, vs the bigger one for the L-motor?). Quote Link to comment
KlassicMotion Posted November 9, 2013 Report Share Posted November 9, 2013 I suppose in theory, the shorter one would do the same job, as long as it is in there tight. I tapped mine gently with a hammer to seat it in there, no issues for me. Quote Link to comment
hang_510 Posted November 10, 2013 Report Share Posted November 10, 2013 im never a fan of "untrue" surfaces..... id have the head checked by a machinist, no need to do this twice no time to do it right the first time, but plenty of time to do it over... 1 Quote Link to comment
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