Loud knocking after low/no oil episode (626 LX 2.5L)

[rockymarsh@gmail.com]

My son, who rarely bothers to check his oil, became alarmed driving home when his 626 LX 2.5L started making loud noises. Fortunately he was near an exit and imeadiatly stopped and brought the oil level up to full (there was none showing). The car then quieted some and he drove it about 100 miles home. I have checked it over and it starts and runs with a loud knock (sounds like a collapsed lifter) which then goes away (mostly) after a few seconds. I'm not familiar with this engine configuration but the cylinder pressures seem OK. Anybody care to hazard a guess as to the cause of the tapping and proscribe a cure. Left to my own I intend to drain the oil and replace it. Then drive it on short hops to see if things improve. I am also considering pulling the valve covers to see if I can detect anything amiss. Can anything be corrected without pulling the heads?

[millyowner]

He may have spun a rod bearing. Change the oil and filter and hope the noise goes away. If the noise gets louder or the oil pressure light comes on later, you know the engine is toast. If you're lucky, the hydraulic lash adjusters just got some air in them. The bleeding procedure involves warming the engine to operating temperature and slowly increasing the engine revs to 3500 over the course of 30 seconds and slowly bringing the revs back down to idle speed the same way and repeating until there's no more ticking.

[psychoholic_genius]

He may have spun a rod bearing. Change the oil and filter and hope the noise goes away. If the noise gets louder or the oil pressure light comes on later, you know the engine is toast. If you're lucky, the hydraulic lash adjusters just got some air in them. The bleeding procedure involves warming the engine to operating temperature and slowly increasing the engine revs to 3500 over the course of 30 seconds and slowly bringing the revs back down to idle speed the same way and repeating until there's no more ticking.[/b]

Rod bearing possible. Engine looses oil pressure top down, mains and rods get oil first, cams and cam followers last. I had a 2.5 that the shim poped out of a lifter, made a heck of a noise. When draining the oil, does it look like metal flake paint? If so, the engine will have to come apart to find the damage. Another old timers trick, with the engine idling, remove one spark plug lead at a time. A rod will quieten down as the pressure from combustion is removed.

PS any metal found in the oil will most likely not be magnetic, bearing surfaces are non magnetic. If you find magnetic particles in the oil thats iron and not a good sign. Relacing just the bearings is not a good idea as when a bearing spins, it kills the crank too.

If you need an engine try Japanese Engines in California. For some reason Japan requires engine replacement every 30K miles, something about emmisions. They ship these low milage engines over here. I use them quite often. Have not had any complaints yet.

[rockymarsh@gmail.com]

These are all good ideas. I'm going to start by changing the oil and filter and checking the oil out. I'll report later with results and next steps. One point I once repaired a perkins 4 cylinder diesel engine with a spun brg by using emery cloth to sand the melted brg residue off the crank and repacing the bearing. That was 15 years ago and its still running.

If there are any other opinions out there my ears are wide open. The truth is I think there isn't too much wrong with this car that careful and thoughtfull work won't correct.

[Renboy]

Engine swaps on these cars are easy and fairly cheap, if they aren't 98+. In 98 the heads on the 626 were changed so that they had solid lifters, different cams, and no cam sensor on the right side of the front head (distributor replaced with coils). To do an engine swap on this you'll need to either find an aspec engine from a 98+ 626, or swap heads and everything onto the jspec KLZE engine.