Guest Anonymous Posted June 2, 2002 Share Posted June 2, 2002 I've done that before years ago, it was a old mechanic remedy for 'blowing out the carbon' . We'd get a fast idle going and then just slowly trickle in water a bit at a time. It actually did loosen things up a bit, if you held a shop rag in front of the exhaust while you did it, you could see little flecks of carbon/?? Anyway, yeah a bit at a time doesn't hurt, but you'll kill it from idling if you get to aggressive with the water, hydraulic lock would require quite a bit dumped in a once, but I'm sure its possible. This just made me remember, remember your dad's excuse for speeding when you were a kid? Mom would get to bitching and dad was all like "I'm just cleaning out the carbon!" (I never caught the last work as it was always under his breath... ). Ahhh, the joys of family vacation road trips, I don't believe I've seen people fighting at they're best as during those special times... Regards, Lone Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted June 4, 2002 Share Posted June 4, 2002 Originally posted by Lone:[QB]..,Ahhh, the joys of family vacation road trips, I don't believe I've seen people fighting at they're best as during those special times.., Lone, Be Quiet & quit slapping the back of my head; Keep your hands on your side of the seat or I'm telling! M-o-m! D-a-d! Lone wont quit touching me! Sorry, Didnt mean to diminish the importance of this thread. Kevin, (Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted June 4, 2002 Share Posted June 4, 2002 Great info here DAW and others... Anyway, I haven't seen any of the Maxima heads with a P79 casting. I have only seen them with the N47. I understood the N47 to be the Maxima head of choice. Anyway, If I had your choices Bang, I'd probably hunt for the Maxima head. It appears to be the best "Bang" for the buck It is more likely to be in better condition than the typical JY Z head. As we know, we tend to be a little harder on our motors than the typical Maxima driver Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted June 4, 2002 Share Posted June 4, 2002 In addition, although your current problems may lie in the head, replacing the head with a newly rebuilt head may find you new problems with the bottom end. Strong new top end + old bottom end = new bottom end soon Quote Link to comment Share on other sites More sharing options...
Guest Perry Posted June 4, 2002 Share Posted June 4, 2002 just a thought about "steam cleaning" engine internals, this may have become less common when catalytic converters showed up because of the risk of clogging. doing this too often may cause a problem. also, a clean piston top means less compression Perry Quote Link to comment Share on other sites More sharing options...
Guest bang847 Posted June 7, 2002 Share Posted June 7, 2002 Originally posted by Perry:just a thought about "steam cleaning" engine internals, this may have become less common when catalytic converters showed up because of the risk of clogging. doing this too often may cause a problem. also, a clean piston top means less compression Perry hmm... I was thinking that the added mass inside the cylinder displaces volume thus adding to compression but then I think the carbon will also absorb alot of heat transferring it to the engine block thus reducing cylinder pressure... a clean engine should keep the heat in the gases so I believe that there would be more compression if the internals were clean... (I guess this applies to a engine that is running on combustuion rather than a cold engine being turned from a outside source.) but back to what you said carbon inside should increase CR minutely though.Is my reasoning reasonable? Let me know.. Also I hope to get a good maxima head... spotted it and pulled it already and it is currently in stash until the 50% off sale... I hope it get it.. Quote Link to comment Share on other sites More sharing options...
DAW Posted June 7, 2002 Share Posted June 7, 2002 For those who haven't seen a Maxima N47 head flip side, it looks like a P79 peanut-shaped chamber but the roof of the combustion chamber is much lower and so uses the std L28 length valves rather than the shorter valves as found on the F54 ZX car engines. Would make a lot of compression on a F54 shortblock but may be better tolerated than e.g. an E31 because of the high quench design of the Maxima head. DAW Are we there yet?...Are we there yet?... Quote Link to comment Share on other sites More sharing options...
Guest bang847 Posted June 10, 2002 Share Posted June 10, 2002 I think im gonna beat this thread like a dead horse.. Well this is the latest.. I pulled the head and a valve is really burnt. two others seem to be starting to burn.. I felt by hand the cylinder walls but didnt feel any ridge is that a sign that there isnt too much wear on the block? on the last picture two od the head bolts are rusted while the others are normal does that imply that there was a headgasket leak? the next thing is that the motor oil has gas in it... before the engine was taken apart one of the carbs had a stuck float and was dribbling gas out the air cleaners.. if that gas made in into the cylinder would it make it pass the rings? or should i expect that the rings are bad? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 10, 2002 Share Posted June 10, 2002 Well now! Looks like a head gasket leak in about the middle and some major gas flow without much air ratio in the chambers. Remove the lifters from under the cam and off the springs where all the valves are closed shut. Set the head level upside down and pour gasoline or some solvent on top of the valves with the spark plugs installed to see how much or where the liquid drains thru or around the shut valves. This will give you an idea which are the bad valves or possibly the ones encrusted with carbon allowing the fluid to escape. Also lay a straight edge across the cylinder head to check to see if it is warped.Are all those pistons notched or flat toppped or just carbon build up covering the notched profile?????? Ocbaar has a good head off a Maxima. Ocbaar@hotmail.com Quote Link to comment Share on other sites More sharing options...
Mike C Posted June 10, 2002 Share Posted June 10, 2002 Some of the head bolts thread into water jackets so a little water on the threads is not unusual. You should use some sort of sealer when installing the head bolts so coolant doens't leak past the threads. Carbon build up in the cylinder increases compression which ISN'T bad, but it's not even which means hot spots in the cylinder which contributes to pre-ignition which IS bad. All in all you don't want it. Quote Link to comment Share on other sites More sharing options...
DAW Posted June 10, 2002 Share Posted June 10, 2002 Don't worry about the headbolts, some will show rust. It can be enough to weaken the bolt but you would already know that because they would have snapped on removal. I like to put bolts back with the threads they were with, but with the rusted head bolts I'd swap them to a hole with no rust on reassembly use anti-seize compound on all. I'm wondering about #6 piston vs 5 & 4 in the photo. It looks like #6 has no valve reliefs and the others have the reliefs (it may be camera angle). Also, if this is a factory L26 it should have horizontal valve reliefs at the top of the cyl bores on the exhaust side for clearance of the 35mm valves with the 83mm bore. I don't see them but again it might be the photo. Nissan blocks are incredibly tough and a ridge is rare. Washing the cyls down by dumping fuel from a stuck float isn't good but if the rings were really bad you would expect to see oil in the upper cylinder and/or scoring of the wall. Pull the rockers as suggested (keep them in order) and use solvent (I think I've heard kerosene works well) to leak test for a valve seat leak (or a crack). If there are a mix of piston top types, you should take big steps back away from that engine and look for a replacement. DAW Quote Link to comment Share on other sites More sharing options...
Guest bang847 Posted June 10, 2002 Share Posted June 10, 2002 well actually I wasnt planning to reinstall that head... but I was just thinking about Z-Gad's comment.. "In addition, although your current problems may lie in the head, replacing the head with a newly rebuilt head may find you new problems with the bottom end. Strong new top end + old bottom end = new bottom end soon " I was wondering if I could scope out the condition of the block by looking at the head..I'm pretty sure that I can pull a really clean Maxima head for around 30 bucks.. actually I already pulled it but I stashed it so that I could take advantage of the 50% off sale... I'm gonna pick it up this saturday! by the looks of the head I would guess that it has less than 5k miles on it... Well guys... Thanks for all help.. till the next step... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 10, 2002 Share Posted June 10, 2002 LOL Bang! pulled it,stashed it and waiting for the 50% off sale. $15.00 0n a Maxima head. If you get up my way, Let us go to the junkyards. Quote Link to comment Share on other sites More sharing options...
Guest bang847 Posted June 10, 2002 Share Posted June 10, 2002 naw man.. they wanted like 75 for a maxima head!!! then I told the guy to shove it... then he kicked my A$$... actually the guys at the counter told me to stash it because he said the prices are really out of whack too.. besides im gonna save that day to pick up a alternator too... any request guys? and no.. I dont want to pull a diff.. did that last time.. for the last time... I never knew that crap was so heavy!!! (pushed it with one hand while the other is working the wrench.. I was sore for a week!! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 11, 2002 Share Posted June 11, 2002 let's see, chronological order of Maxima head: shove it,kick it, whack it, pulled it, stashed it and waiting for 50% redemption? Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted June 11, 2002 Share Posted June 11, 2002 You guys KRACK me up Quote Link to comment Share on other sites More sharing options...
DAW Posted June 11, 2002 Share Posted June 11, 2002 I just now pulled the full width of your block photo into view...it definitely looks like pistons in cyls # 1, 3, & 6 are from a different source than those in #2, 4, & 5. That's a big problem and once you see something like that you should assume nothing in that shortblock was done correctly. DAW Quote Link to comment Share on other sites More sharing options...
Guest bang847 Posted June 11, 2002 Share Posted June 11, 2002 Whoa!! are they not matching?? dude i didnt notice... I'll get more of a close up to night!! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 11, 2002 Share Posted June 11, 2002 Bang.. that motor may not be dealing with a full deck or someone dealt a bad hand of mismatched cards (pistons) Quote Link to comment Share on other sites More sharing options...
mustard-z Posted June 11, 2002 Share Posted June 11, 2002 Bang, I rebuilt the head on my 77 but not the bottom end. In less than 2 months I had the engine torn apart and installing new rings, which had shattered in cyl. #2,3,4,5,6. If you have the cash, it might be worth the effort. It would deffinately be worth the effort if the pistons don't match. Quote Link to comment Share on other sites More sharing options...
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