ryan6351

'91 SE, Aztec Red!

Long overdo update - turns out the source of my intermittent front passenger wheel-area screeching was the brake. Pad was completely gone, and I pushed it a little too long, ended up melting the pad's backing plate and blowing out a piston in the caliper. Good thing I was already planning to replace the front rotors... it was a bear of a job but got it done, and it finally stops reliably, doesn't pull anymore, and doesn't make that terrible noise! Next step in restoration/repair, new muffler.

Very much so… but feels great to finally get it done. Thanks again for you guys’ help!

SUCCESS! https://imgur.com/a/qWyHVX8

Thanks.. better to spend $350 on a mechanic to tell me "You did it wrong" than to bend some valves and have to rebuild the heads! It's really hard to say - service records were incomplete, and there was no timing belt sticker in the engine bay. All parts were OEM Nissan inside, and it only just now hit 59k miles. I agree that a belt lasting 34 years seems unlikely but it was possible enough that I didn't want to chance it, especially with a lot of the other OEM parts starting to fail during my 6 months of ownership. Yes, tomorrow I will be dutifully and carefully lining up the dimples and counting teeth correctly. Hopefully it goes a lot faster second time around, especially since I won't have to scrape a 34-year-old water pump gasket off! Then, next project will be finally addressing this thread (ha!) - swapping out front end ball joints, center link, and brake pads and rotors to chase down my weird screech.

Another aside - this tech was great, AND he has his own ‘94 Hardbody with the 2.4L. He was like “wow I don’t envy you having to fit your hands in this engine bay” haha

Okay party people - the content you've been waiting for: an answer!! I got the timing wrong. I messed up the tooth counts (I must've gone from the marks on the cover, not the actual dimples on the cam gears), and ended up with the left cam two teeth advanced and the right cam 6 or so teeth behind. I really don't know how - they must've moved from spring tension while I was getting the old belt off, as I was probably at TDC on the exhaust stroke. Anyway, it's sparking and fueling at the right times relative to the crank/piston positions, but the valves aren't opening/closing at the right times. So this weekend I get to redo it, aligning the cams properly. At least I don't have to deal with the water pump again?

My belt does too! It's an OEM Nissan job (don't ask how much I paid for that, tensioner and water pump.....). The old one must have too, but the marks were worn off by.... 34 years of existence, I guess! It's also possible there was a water pump or timing belt job I didn't know about in the car's history, and they used a cheapo aftermarket item. IDK. Mechanic is here now - confirmed it's getting fuel, compression, and spark, and yet still won't start. He said the timing chart on his sensor computer thing looks good, and it's sparking at TDC, but it could 180 degrees out of time somehow. I worry that's the answer... I genuinely don't know if I had it on TDC compression stroke or exhaust. As an interesting aside, he was thrown for a loop by his sensors showing the fuel injectors pulsing twice each cycle in rapid succession. I know our ECUs are programmed to run rich on startup - apparently it does that by opening the injector twice, not just for longer.

I've got a mobile mechanic coming thursday - I don't have a timing light, but described the issue to them in detail and hopefully they'll be able to figure it out quickly. I honestly don't know if the dimples on the cam gears lined up when I set cylinder 1 to TDC when replacing the belt - there was enough surface discoloration on the gears that I couldn't really see them well, and I just don't remember exactly what was going on. Didn't do seals, either (I know.... I should have), so I never removed the cam gears. The marks on the old belt had also totally worn off, so I just counted teeth to confirm things were correct before removing and replacing (and the engine had run more or less perfectly for the 1,500 miles I've put on it in the last 6 months). Confirmed the belt tooth count, and as far as I can tell no weird sounds when cranking, though I honestly am pretty inexperienced so it could be something sounds subtly off and I just don't know it! Flooding is possible - I may pull a plug or two and scope out the cylinders to see. I didn't spray much of the carb cleaner, but I've cranked it a lot so it could be gas flooded. It's just really bewildering that in probably 5 minutes of cranking (spread out over 15 or so attempts), there wasn't a single cough/sputter/attempt to start running. The only thing I can think of is that somehow the cams slipped out of position while changing the belt? I only had it off for a few minutes between removing the old one and maneuvering the new one on. But again, if I was banging valves on pistons I don't think that would be a subtle sound. We'll see what I find out later this week.

Another update - getting spark at the plugs, and yet it wouldn't start at all even with a healthy dose of carb cleaner in the throttle body. I worry that somehow the timing is 180 degrees off and it's sparking on the exhaust? I don't know. At my wits end so I'm gonna call a pro to help.

That's all super helpful! I went ahead and grabbed a cheapo inline spark tester at AutoZone - easier to do and was only eight bucks (needed to snag carb cleaner anyway). Will report back soon! If it isn't a spark issue, I may throw in the towel and take it to a "real" mechanic. Getting onto week three with no car, and it's getting to be annoying.

Edited to answer your question - yes, I checked codes multiple times. Before doing anything to see if they were stored from my last attempt to start; after cranking for a good 30 seconds, multiple times; and even during cranking. Always showed a 55. To test for spark, when I pull the plug and crank the engine, do I just ground the plug to somewhere else on the block and visually look for the spark? Never done that before. Same question re: testing the coil wire for spark. Assuming I do see spark, I'll move on to the carb cleaner spray test. My first '91 with 300k+ miles had gotten to a point where I had to start it with carb cleaner every time - I don't miss those days.... Thanks again y'all.

Checked every wire I touched (and those I didn't) in the engine bay, as well as the ignition coil and spark plug cables - everything looks normal, connections are solid, no corrosion. I'm really at a loss here... it turns over super strong, fuel pressure is good, and just nothing. When I did the timing belt replacement I was really careful not to let the camshafts or crankshaft turn at all between taking the old belt off and putting the new one one. I double-checked my tooth counts, got the tension set appropriately, and closed everything back up with proper torque on every bolt and proper tension on every accessory belt. I truly can't imagine what it could be. Maybe the dizzy cap and/or rotor? They're original, but it was working fine before. Could I have somehow messed up spark plug #1 by removing and reinstalling it, causing that cylinder to lose compression or spark? Would the engine not even attempt to fire (no sputtering at all) if only one cylinder lost spark/compression?

Computer reads 55 - No Malfunction. Going to have to do it the hard way, checking each connection.

@Slartibartfast I keep forgetting to check codes - will be the next thing I do. It's getting fuel for sure, and I'm 99% sure compression (I pulled a spark plug for timing belt job but replaced it and torqued correctly - otherwise nothing compression-related was removed or changed), so spark seems to be the culprit. Hopefully codes will give an indication, and if not I'll start checking grounds. I did remove the dizzy cap at one point but not the whole assembly, so maybe I damaged or messed with the crank angle sensor? Who knows. I've been getting a lot of bike commuting done lately so silver linings, ha. @gamellott that makes sense re: pulley! As for connectors I sort of preemptively disconnected a lot of the front harness (throttle position sensor/dizzy/crank sensor/etc) when doing the belt in an attempt to keep as much out of my way as possible.