Bennn Posted December 24, 2013 Report Share Posted December 24, 2013 I just pulled my 720s motor apart and well the pistons look pretty bad, but honestly If it would run put back together I'm not worried. The cylinder walls aren't too great either but I just wanted to get some opinions! Thanks, Ben And just for fun here's the truck 1 Quote Link to comment
Bennn Posted December 24, 2013 Author Report Share Posted December 24, 2013 I have a head gasket kit for it and I'll clean it all up real nice just wondering on some time estimates of it's life. I know it's not the best idea lol Quote Link to comment
Eagle_Adam Posted December 24, 2013 Report Share Posted December 24, 2013 hone the walls clean everything up rings and bearings and i bet ur ok 3 Quote Link to comment
captaingamez Posted December 24, 2013 Report Share Posted December 24, 2013 Could run for another month could run for another year. nobody really would know honestly. Quote Link to comment
captaingamez Posted December 24, 2013 Report Share Posted December 24, 2013 What Adam said. I would not run her as is. Quote Link to comment
datzenmike Posted December 24, 2013 Report Share Posted December 24, 2013 Must ask.... did you block the timing chain tensioner so it cannot fall out??? Also is this apart to replace the head gasket? That the block surface??? Looks like it's been buried in the ground for years. That's got to be cleaned up like this... Or as clean and bare metal as you can possibly get it. For the cast iron block a wire wheel on an angle grinder should do. The head is much softer aluminum and you'll have to go easier with it. Z24s are famous for blowing their head gaskets every 100K. By the looks of the rust in the coolant holes a proper anti freeze/coolant was not used. That and re-torquing the head bolts once a year will go a long way to preventing gasket failure. Those pits on the piston tops are from something loose rattling around in there. My guess is the gasket blew and she over heated.This will dislodge any carbon deposits and they flake off. Before finding their way out an exhaust valve they do that. It's ok they are still good, but no way to know if the ring have broken or the ring lands that support them. If no vertical score marks on the cylinder walls we'll assume they are.. ok. How long will it last??? Well what's the history on it? Have you driven it at all? . Quote Link to comment
DaveZilla Posted December 24, 2013 Report Share Posted December 24, 2013 Hard to tell on how long it could last... I'd re hone the cylinders and re ring it at bare minimum... but even then it would be hard to predict it's lifespan, it could run well for several years, or it could go bad in just a few months... Another thing to consider is how well did it run before you took it apart? if it ran well, you might get away with a little more but if it had low compression or was smoking you'll definitely have to do a little more to it for it to last Quote Link to comment
jrock4224 Posted December 24, 2013 Report Share Posted December 24, 2013 Could run for another month could run for another year. nobody really would know honestly. this is true ..........i explained that to someone the other day Quote Link to comment
datzenmike Posted December 24, 2013 Report Share Posted December 24, 2013 I'm saying if it ran good but blew the HG then replace it and you're good to go. If there is a bare history replace the HG and you'll find out. Cost to find out one HG.. Quote Link to comment
jrock4224 Posted December 24, 2013 Report Share Posted December 24, 2013 Fwiw if I pulled my head and it looked like that I would start brainstorming alternatives Quote Link to comment
foxfan1992 Posted December 24, 2013 Report Share Posted December 24, 2013 Must ask.... did you block the timing chain tensioner so it cannot fall out??? Also is this apart to replace the head gasket? Yes he did, I made sure to tell him this when he posted on another forum. I wasn't about to let a fellow 720 owner make the same mistake as me ;-) As for the headgasket job, all I can recommend is cleaning the surfaces so they're free of old gasket debris and honing the cylinders. Also clean the pistons of any burned-on oil or carbon. I must admit it does look pretty rough at the moment, but it'll be a good idea to get it all done while you've got it all off. This is why I decided to take the opportunity to replace the whole timing chain and sprockets while it was all off. Anyway I hope you have the answers you're looking for, Ben. Quote Link to comment
Sealik Posted December 24, 2013 Report Share Posted December 24, 2013 Need more info.... Why did you take the engine apart and how did it run prior????? Good oil pressure....no knocks...etc...etc....?????? Looks like it was sitting for a while after the HG blew...?????....thus the horizontal lines/marks on that cylinder wall Quote Link to comment
Bennn Posted December 24, 2013 Author Report Share Posted December 24, 2013 Woah! Thanks for all the replies everyone!!! And yes I did block off the timing chain before hand. It was suppose to just be a head gasket and then all this ha. I'm assuming the truck say for a longtime because the radiator had a lot of rust in it as well. The truck seemed to run great before the head gasket blew out on the drive home but when I pulled the head one of the headstuds wasn't torqued down at all which is I believe why it died. Other then the head gasket going it it drove great! I was still able to get it up my drive way as well when I got it home. If I didn't drive it up i would be workingon it in the street. I have a stupid steep driveway. The timing chain and sprockets look good and I figured if I give the block a little love to clean the surface and put the new gaskets in it could be okay for a while. I just want to run it till it dies I've got almost 300k miles so I figured at some point I'll have to do more but for now I just need to get around. Hope this helps with input! Quote Link to comment
tr8er Posted December 24, 2013 Report Share Posted December 24, 2013 300K and it sat for unknown amount of time. I'd not put too much into it. This would be a good time to source a new engine. But pop a gasket on her and torque those bolts right. Fire her up and watch that gauge close. I would half expect your water jackets are all messed up with age old gunk and rust. You should not expect much and hope for a little. That way you are bound to be happy. Put the money into the brakes that are likely just as bad. 1 Quote Link to comment
wayno Posted December 24, 2013 Report Share Posted December 24, 2013 I would just put it back together unless you overheated it getting it home, if it was smoking hot by the time you got it in your driveway, then you likely need to tear it down to check for a warped head and/or block, you should also look for cracks between the water jacket and the headbolts, I will post some photos below of the cracks I am talking about, if you have cracks, I would not put a lot of money into the engine unless they are very minor/small. I would also before doing anything, check the threads in the hole of the loose headbolt, make sure they are good, it will do you no good to put the head on, just to find out that the loose headbolt will not torque down, and is just ripping the rest of the threads out. These cracks I believe are on the driverside between cylinders 2 and 3, but you need to look at/around all the headbolt holes. 1 Quote Link to comment
Bennn Posted December 24, 2013 Author Report Share Posted December 24, 2013 300K and it sat for unknown amount of time. I'd not put too much into it. This would be a good time to source a new engine. But pop a gasket on her and torque those bolts right. Fire her up and watch that gauge close. I would half expect your water jackets are all messed up with age old gunk and rust. You should not expect much and hope for a little. That way you are bound to be happy. Put the money into the brakes that are likely just as bad. I never have high expectations for that exact reason! haha Actually the brakes are okay oddly enough. I haven't put too much into it yet but I'm still looking for ways to source a motor still just in case. s I would just put it back together unless you overheated it getting it home, if it was smoking hot by the time you got it in your driveway, then you likely need to tear it down to check for a warped head and/or block, you should also look for cracks between the water jacket and the headbolts, I will post some photos below of the cracks I am talking about, if you have cracks, I would not put a lot of money into the engine unless they are very minor/small. I would also before doing anything, check the threads in the hole of the loose headbolt, make sure they are good, it will do you no good to put the head on, just to find out that the loose headbolt will not torque down, and is just ripping the rest of the threads out. These cracks I believe are on the driverside between cylinders 2 and 3, but you need to look at/around all the headbolt holes. Awesome! Thank you for the input! I'll be looking at that tonight when I get off work! I made some good progress though last night! It's amazing what you can do with some razors, your dads grill brush, and some brake clean! haha and just for kicks one of the spark plugs Quote Link to comment
Bennn Posted December 24, 2013 Author Report Share Posted December 24, 2013 OH, does anybody know what that plastic thing on the intake manifold is cold? It's an odd brownish color? It has three what look to be vacuum ports on it? I broke it. lol I'll try to find a picture. Quote Link to comment
datzenmike Posted December 24, 2013 Report Share Posted December 24, 2013 Z24s are famous for blowing their head gaskets every 100K. By the looks of the rust in the coolant holes a proper anti freeze/coolant was not used. That and re-torquing the head bolts once a year will go a long way to preventing gasket failure. Later I would definitely flush the rad and the block to get that rust out of there. Pull both heater hoses off and with the heater set to HOT, use a garden hose to flush the heater core. Run the flush in both directions until the water runs clear. They fill with a GOOD quality antifreeze/coolant to protect everything. . I'm saying if it ran good but blew the HG then replace it and you're good to go. If there is a bare history replace the HG and you'll find out. Cost to find out one HG.. The loose head bolt is why Nissan recommends re-torquing the bolts every tune up. It keeps the head tight against the gasket as it compresses over time. In a few hundred miles after you get her going and when the motor is COLD, loosen each bolt one at a time and torque to 60 ft lbs. Do at least once a year. That spark plug look perfect. A good indicator that it's not burning oil. . OH, does anybody know what that plastic thing on the intake manifold is cold? It's an odd brownish color? It has three what look to be vacuum ports on it? I broke it. lol I'll try to find a picture. That is a temp sensitive vacuum bleed. When the engine is cold air from the air filter enters at C (the top) and leaks air into the two vacuum lines below it. The second down from the top goes to the EGR control and the bottom one goes to the vacuum advance on the distributor. Basically there is no EGR or vacuum advance if the motor is cold. Now you can easily do without the EGR but you should have the vacuum advance working for best part throttle mileage and response. I would pull the very bottom hose off the T V V (thermal vacuum valve? and seal the end. This will allow vacuum advance when the motor is cold and change nothing else. Quote Link to comment
Bennn Posted December 24, 2013 Author Report Share Posted December 24, 2013 Some of the other spark plugs had some weird sludgy stuff on them but besides that they looked like this. I'm surprised it was running as well as it did before the head gasket went out. My problem with my TVV* is I broke the top nipple off? Is there a way to run without it? Or is that a bad idea. I also found this http://forums.nicoclub.com/post6539151.html#p6539151 a vacuum delete thread which I figured now would be the best time to do it! I was planning on flushing the radiator out and use vinegar and run it through to clear out the rust because I heard that works well? Ben Later I would definitely flush the rad and the block to get that rust out of there. Pull both heater hoses off and with the heater set to HOT, use a garden hose to flush the heater core. Run the flush in both directions until the water runs clear. They fill with a GOOD quality antifreeze/coolant to protect everything. . The loose head bolt is why Nissan recommends re-torquing the bolts every tune up. It keeps the head tight against the gasket as it compresses over time. In a few hundred miles after you get her going and when the motor is COLD, loosen each bolt one at a time and torque to 60 ft lbs. Do at least once a year. That spark plug look perfect. A good indicator that it's not burning oil. . That is a temp sensitive vacuum bleed. When the engine is cold air from the air filter enters at C (the top) and leaks air into the two vacuum lines below it. The second down from the top goes to the EGR control and the bottom one goes to the vacuum advance on the distributor. Basically there is no EGR or vacuum advance if the motor is cold. Now you can easily do without the EGR but you should have the vacuum advance working for best part throttle mileage and response. I would pull the very bottom hose off the T V V (thermal vacuum valve? and seal the end. This will allow vacuum advance when the motor is cold and change nothing else. Quote Link to comment
datzenmike Posted December 24, 2013 Report Share Posted December 24, 2013 The top just lets filtered air in. It will work the same if the nipple is broken off. The air won't be filtered is all. No biggie. Quote Link to comment
Bennn Posted December 25, 2013 Author Report Share Posted December 25, 2013 Sooo I was about to put everything back together but while cleaning the headbolts i realized one of them was split in between some of the threading :( Sooo gotta find some of those now. Quote Link to comment
Bennn Posted December 25, 2013 Author Report Share Posted December 25, 2013 Any ideas on where to buy head bolts? Quote Link to comment
Eagle_Adam Posted December 25, 2013 Report Share Posted December 25, 2013 Rockauto.com Quote Link to comment
datzenmike Posted December 25, 2013 Report Share Posted December 25, 2013 The good is that there is only one length for the Z heads. 11057-H5700 is the Nissan part number to cross reference for the Z24. Earlier Z20 and Z22 use a different bolt length Quote Link to comment
Z-train Posted December 25, 2013 Report Share Posted December 25, 2013 For the money spent on headbolts,you'll be better off buying ARP studs. Quote Link to comment
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