1985 Nissan 720 King cab 2.4L Manual 3rd owner for 5 years now
That's the resting beauty that I had accidentally (while distracted at night) driven sixty plus miles through a multi altitude section of interstate at thirty-five miles an hour since that was as fast as she would go. A previous issue with the headlights and the instrument panel lights working at the same time and this drive being at night after a snow storm were only a few factors that lead to me overlooking the oil pressure gauge which was at half it's required operating level. The low oil pressure was realized before catastrophic failure occurred and all issues relevant to it were fixed the following morning (or all relevant issues I was aware of at that time).
So a few weeks later on a different section of interstate at approximately 65 mph a loud sound that will be identified by the onomatopoeia "Clanking" with a clear pause after it. The truck was then driven at a speed below 15 mph to a parked position, after that it was test driven once, started multiple times for a compression test and for two possible buyers. Other than that it was towed on a trailer or as the brakes in tandem with a larger truck. The compression test showed lower (still within acceptable limits for operation) compression on cylinder two, I'm unsure if both sides were treated for each cylinder but I'm fairly certain that both sides were tested of each cylinder and only cylinder two was different from factory specs.
I felt how I got to this point was important to show the amount of time and consideration this engine has been given getting to where it is today, less that 10k miles ago a new cylinder head was installed by a professional mechanic shop (whatever qualifies for that these days) when the timing chain guide had broken and the engine began to "jump" timing when it had advanced it's timing enough to only drive in reverse at less than 5 mph then would not start again. That was when I had it towed to a reputable shop for the work and if the shop were still open I'd consider taking back there but that beginning to segway from the actual subject.
So a 1985 Nissan Z24 engine with the stock 5 speed manual transmission that had fused the rod bearings on cylinder two together and one of them had fused to the connecting rod. Basically the rod bearings for so hot they started to act like metal being forged, they thinned out, after having probably spun one, it eventually took up all the extra space that the oil wasn't in on top of the other bearing. Then the loud Clanking was the bearings, having changed shape only slightly as it spread out, then the top one fused causing resistance depending on the operation of that cylinder on the connecting rod and giving me one of the most hellacious piston slap symptoms. It was thought to be the bearing, or maybe the wrist pin, check out the photos I didn't get any that really show what happened.
After the application of heat and force I was able to remove the fused rod bearing from the connecting rod, I got the lobe machined and measured, (SUPER LUCKY) the lobe was still at factory spec (or after painfully measuring every component, close enough) so I replaced the bearings, assessed what other parts needed to be replaced like the rings, head bolts, gaskets, as well as cleaned up the pistons so there wasn't so much carbon build up because there have been home mechanic fixes that I have been fixing on this since I got it. It's a pseudo rebuild because I did not replace everything as would be considered a full rebuild; that considered I've gotten the engine to run for up to a minute if I control the throttle.
That's what brings us to the pseudo rebuild and the idling issues of today hope I didn't lose you before here......
I have set everything back to how it was before I started taking it apart in an attempt to start at stock so to say and go from there. So with everything put how it ran before and adjustments being made first in the direction towards stock I can get it to start if I press the throttle, then I have to just barely press the throttle and it'll idle around 600 rpms. If I press the gas harder it seems to cut the fuel even though I have the throttle positive sensor disconnected, if I stop pressing the throttle it just dies out like it has no gas. Before I had a copper ball valve inline right before my pressure regulator. The vacuum system is sealed and there is sufficient pressure to the regulator which I was told was bad and that was why the ball valve had been placed there.
The ball valve started leaking and spraying gas on my belt which then began to slip so I removed it and used to feather my gas before the Clanking began because it seemed to flood out and feathering worked until the rpms got higher.
Here is the bearing still fused to the top.
So lucky only material from the bearings got transferred to the connecting rod and cap, here's a shout out to the company that I ordered due to reviews, price, availability, and a few other factors. By far the lowest cost is anything I had to buy for this rebuild.
Thank you all who have commented or started other subjects about this engine it helped me tremendously with this rebuild. I'm hoping there is something easy I'm not thinking about cause it's been months and there is no reason this motor shouldn't be running.
I'll include pictures as requested beyond what I have just to not convolute the thread too early.