I recently bought a '97 Ford Ranger from a guy for 'really cheap'. 44 miles later it developed some rowdy rod knock. Being hard headed, I decided to rebuild another engine and install it myself. I had zero experience at such things, but figured 'how hard could this be?'... famous last words. I finished the rebuild and tried to start it today. Before starting it I: 1) disconnected the coil packs and cranked the motor over a few times. 2) Removed the oil filter 3) Cranked it a few times to confirm that oil was pumping and the pump was primed. Then I reconnected everything and cranked the ignition. It started but immediately began to make a loud klank/knock sound. My brother (who was in operating the ignition) cut the ignition off as soon as he heard it. Since I only got a second or two of the sound I wasn't able to locate it or get a good fix on what it really sounded like, aside from it NOT sounding like the rod knock I had before. A few mins later (maybe 5) we cranked it again and it started again. This time, there was no abnormal noise, but the idle was rough. It idled for a few seconds and then died. We tried again and it didn't restart. While it was running oil pressure was normal. I am mostly sure that the wiring is correct and that the vacuum lines are properly connected. I have no idea what it could be at this point. For what its worth, the engine is from a 95 ranger and the ECU in the truck is from a 97.
If the timing chain was not installed correctly, valve to piston top timing can be off. This causes the valve and piston to hit, either bending the valve or punching a hole in the top of the piston. When this happens, you'll hear the banging for a second, followed by rough running due to loss of compression and incorrect valve timing. Check the compression on all cylinders to see if any valve interference happened. If you have good compression on ALL cylinders then follow the trouble shooting steps in a manual like Chiltons or Haynes. I probably don't have to tell you what to do if you have poor compression on one or more cylinder..."rebuild" the reuild. BTW - been there, done that. LOL
I had thought about that possibility, however I checked the timing assembly very carefully. I turned the motor several times by hand and listened carefully for any valve/piston contact. We cranked the motor MANY times with the coil packs unhooked. Never did I hear any sign of piston/valve slap. It seems to me that, were timing the problem, wouldn't I have heard something along the way? Either way I will be checking the timing and compression next time I am out there. Please [insert list of deities] don't let there be a broken piston.
There are lots of things that can make intermittent knocking sounds. Missing thrust bearing on the crankshaft or the camshaft will create a knock when under load. Poorly seated main bearings cause a knock, also under load. Oil pump shaft not inserted correctly. Collapsed lifter...this can also cause noise if you did not prime a hydraulic lifter before installing it...it will temporarily collapse, until oil pressure pumps it up. Priming it with oil prevents that problem. Also, during assembly of the crankshaft and piston rods, special ultra-slick assembly-oil provides good lubrication until the oil pressure comes up, preventing initial start-up knock. Another source of "knock" is piston slap. This occurs if the cylinder is worn excessively and the new piston and ring assembly slaps the side of the cylinder when under power. Even if you honed the cylinder prior to installing standard size pistons, the "hole" can still be too large. The solution is to over-bore the cylinder and install a wider piston/ring assembly. The last thing that comes to mind is timing knock. If your timing chain is even a little off (one tooth) it can create pre-ignition that sounds like a knock inside the engine. Hope these ideas help you trouble shoot. I built many race engines when I was young and still enjoy hotrods when I have time...mostly helping friends with theirs since I don't own one anymore.
I used the Lucas assembly oil/grease blend on all of the bearings that I touched, so I think that isn't the issue. I also did not touch any of the lifters, so I think they should be fine. The thing that bothers me is that the noise went away. If it was a piston slapping the cylinder wall it SHOULD keep making noise right? Same with a lifter or stuck valve (until it un-sticks) Noise aside, why the rough idle? I may unhook the battery, allow the ecu to reset, then see if anything repeats. That would eliminate a fuel map related problem right?
If you used the old lifters, one may be bad. It would make distinct tapping sounds that can come and go as the lifter reacts intermittently to oil pressure. If everything else is okay, the most likely sources of rough running (in this order) are 1) bad plugs, 2) bad plug wires, 3) bad fuel injector(s)--if throttle body style fuel injection, then check throttle body for air leakage/bad gaskets, 4) intake manifold air leak/gasket failure, or 5) bad/poorly seated head gasket. You might also want to take the ECU to an auto parts store with a free tester. This will eliminate timing problems from the ECU. If all this fails, pull the engine out, purchase a 400 cu in Ford crate motor and turn that little truck into a street screamer! LOL
I wish I could afford to do that! Both the engine that I put in and the one I took out ran in December. I have a sticky lifter on my MR2 and the truck doesn't make that sound. Aside from the whole, put-put-die part, it sounded nice (after that initial noise). Oh well, I can't touch it until Tuesday morning. Its all speculation at this point. I just want it to not involve pulling the motor back out to fix. Head gasket only goes one way, pegged between two dowels, so it should be correct. I will double check the plug/wire settings after I pull them. I want to see if the cylinders are flooded/fouled. It may be possible that the wires didn't get snapped on fully (although since there are 8 plugs [yep, 2 per cylinder] I'd hope one or two bad connections would be unnoticed). I appreciate you helping out. You have given more assistance then the combined effort of 5 ford truck forums.
Well the only things I could think of NaCl has already said. My first thoughts were the timing cause it sounds really similar to what was going on with my car when the timing was slightly out. The timing is a hard one to get right, my father always hates messing with the timing after the many hundreds of cars he has worked on with all us kids and other people.
