Peculiar engine knock due to lack of proper maintenance

[Aubrey Falconer]

I recently acquired a fairly nice '85 SR5 which the previous owner had run out of oil (due to negligence rather than a sudden leak).

Engine now smokes a bit (though not too excessively), and produces an alarming ticking/rattle noise.
I haven't tested it under load, to hopefully prevent more damage.

Here's a video of the engine idling to help describe the sound:
http://www.youtube.com/watch?v=c_qNhAvzViU

Is there a chance that this could be a fairly straightforward repair, or would I be better off looking for a new engine right now?
I am fairly mechanically competent, but have little experience with automotive repair and welcome everyone's input.
Could this be a valve sticking? What is the best troubleshooting procedure?

[squiggle]

if you need to replace the motor it costs around 500 bucks. because its just a basic Toyota engine

[Petros]

Welcome to the list. where are you located?

running low on oil can cause two types of damage, connecting rod bearings and cam shaft bearing. The number four rod bearing gets starved of oil first because it is furtherest from the oil pump. You can remove the oil pan without removing the engine, you unbolt the front engine mounts and jack the engine up as high as you can go by lifing the trans, it also helps a lot to lower the front cross member by unbolting the four mount bolts and the steering shaft and lower it (not necessary but helful). you can than remove all the pan bolts and than the oil pick up and wiggle the pan out. You will need a 1/4 in drive socket with extensions and a u-joint to get to all the bolts, plus a 10 mm open end wrench to get to all the pan bolts (the three over the front diff are the biggest PIA to reach, but it can be done, I have done it).

Almost certainly the bearing on the connecting rods need to be replaced, these get damaged after running with out oil even for 30 seconds. The mains are usually okay, they hold up well, so just replace the rod bearings (they are not expensive at all). If the rod journals are scored take some strips of 400 wet and dry and polish the road journals just enough to clean them up (do not try to remove all of the deeper marks, you just want to clean and polish the wear surface). You should still be able to get by with standard size bearings.

You remove the valve cover to inspect the cam lobes for wear. Check the valve clearances (see the FSM for the procedure), which alone could be reason for ticking. I would also remove the front cover and slacken the timing belt and see if you can turn the cam by hand. If not than remove the rocker arm shaft to take the valve spring pressure off the cam and see if you can turn it by hand. If the cam shaft is frozen or is very difficult to turn by hand you need to move the cam and inspect the bearings where the came rotates. The front one always seems to fail first when run low on oil. The bearing surfaces should be smooth, same with the cam journals on the shaft. You can also clean them up with wet and dry sand paper to get them smooth again. put some anti seize or graphite grease on the bearng surfaces before you assmble it. Verify it truns freely by hand, and than reinstall the rest of the stuff. Make sure you put the cam bearing caps back on exactly the way the came off, both location and direction (see the indicator marks on them). You will have to install the timing belt with the timing marks lined up correctly (see FSM) and also set the spark timing, there is a repair guildes thread on installing the distributor and setting spark timing.

You might opt for a new engine, but both of these procedures are actually easier and far less costly than replacing the engine.

Good luck.

[Aubrey Falconer]

Thanks! Northern Idaho.

I should be able to get to this within the next couple days, and will let everyone know of the results.

[copenhagenfiend]

a little off topic, but your video is private on YT - i couldn't view it

[Aubrey Falconer]

Ah - I meant for it to be unlisted, not private. Here's the original, now with fixed permissions:
http://www.youtube.com/watch?v=c_qNhAvzViU

And another I recorded this morning:
http://www.youtube.com/watch?v=0Iy2Sb2rXbo

Knocking seems directly related to the temperature of the engine - the longer it runs, the more regular the knocking becomes.
Can't wait to begin the repair project!

[ARCHINSTL]

Caution - Thread Hijack...
I noticed your video on the 1945 Beck bus. I'd never heard of the company, so Googled it and found precious little - that seems strange, considering it bought Ahrens-Fox in 1953, which made the ne plus ultra of fire engines way back when (from 1868 onwards). Fascinating project! Send some info to our Off Topic Forum!
Tom M.

[Aubrey Falconer]

Nothing wrong with a good 'ol thread hijacking now and then!
Here's the links to my personal site and Picasa gallery for the Beck Mainliner project:
http://aubreyfalconer.com/view-6777
https://picasaweb.google.com/aubreyfalc ... directlink

[dlb]

the interior on that bus looks amazing!

[Aubrey Falconer]

Thanks! It's finished with 1/8" mahogany paneling, and bamboo flooring. I have rigid, highly insulative aluminum faced foam in the walls and ceiling and under the floor - and managed to survive last winter with it's -17 degree farenheight days just fine using a single 1000 watt electric heater. Next on the bus agenda is learning more about woodworking, and building the interior furnishings.

Today I pulled the valve cover, timing belt, rocker arm shaft, and distributor off the Tercel. Here's a couple pictures for reference:
https://picasaweb.google.com/aubreyfalc ... directlink

None of the valves appeared to be stuck or otherwise malfunctioning.
Cam lobes looked great, no visible wear and only minor pitting on two of them.
Cam bearings seemed fine, the cam rotated freely once I removed the rockers. I pulled one of the cam bearing caps off, and it looked perfect.
I'll procure a feeler gauge tomorrow to set the valve clearances.

Rotating the cam by hand produced a rather loud ticking/clunking noise near the back of the engine. This turned out to be the distributor, which I removed and partially disassembled for inspection.
It appears to be intact, but rattles when it is shaken and clunks when it's shaft is turned. Is this normal, or could it be the source of the engine noise? It seems nearly impossible, but I'd hate to overlook something potentially simple before probing deeper:
https://picasaweb.google.com/lh/photo/C ... directlink

[dlb]

the rattling is probably the weights for the mechanical advance. they can move a little bit before the springs that hold them in place stops them. the clunk is probably the weights as well: when you turn the gear, the weights will alternately hang in place and then fall against the cutouts of the governor shaft. you can verify this without having to really disassemble much. in your photo i can see you already have the cap off the dizzy so just shine a flashlight down into its internals while you rotate the shaft and through a few small cutouts you should be able to see the weights moving around and verify if it is in fact them making the sounds. if the clunk winds up coming from the dizzy shaft and it turns out to be faulty, the whole dizzy must be replaced. there's a factory service manual available on the site here, there's a link to it at the top of every page. click it and go to page 221 and you'll find lots of info on the dizzy.

i just took one apart to clean and regrease both the mechanical and vacuum advance mechanisms but there's not enough resistance now and it advances way too far. not sure if i did something wrong, i'll talk about it more in another post.

so is the bus your stationary home or do you plan to make it a mobile one? i imagine with the desk and furniture in the back you couldn't drive around with everything toppling in the back.

[Aubrey Falconer]

Though it runs fine, the bus currently serves as a stationary home due to the free floating furniture. Next phase of the project will building in custom furniture and specialized appliances, then thoroughly overhauling the running gear and doing some external bodywork, and finally - touring America!

1) Your explanation of mechanical advance weights makes sense - the distributor/governor assembly seems to be fine. Page 226 of the fsm ( http://tercel4wd.com/fsm/1985_Manual00226im.jpg ) says to "align the "center of the flange with that of the bolt hole on the cylinder head" to ensure proper timing, but I can't figure out what flange it is referring to. Does this alignment look correct? https://picasaweb.google.com/lh/photo/X ... directlink (In picture, distributor is rotated clockwise as far as it will freely spin).

2) I can depress all the valves about 1/4" by hand, they all feel uniformly springy and not weak or sticky at all.

3) I just removed the spark plugs, and all four combustion chambers are covered with slimy oil gunk inside. I am thinking that this engine may not have been run out of oil, but that the knock may rather be due to a lack of oil changes - and finally someone checking the dipstick and being alarmed at the low level rather than at the sludge as they should have been. Here's a picture of the spark plugs: https://picasaweb.google.com/lh/photo/V ... directlink
And a view of the top of the #1 piston through the spark plug hole: https://picasaweb.google.com/lh/photo/S ... directlink
How could all cylinders get this uniformly bad? What would be the next logical troubleshooting step? Would it be useful to buy a pressure gauge and check the cylinder compression?

[dlb]

looks oily as all hell. do you have a compression tester? if not, i would get one and do the following.

pull all the spark plug wires. remove one spark plug at a time and thread the compression tester in to the empty spot. crank the engine 8-10 times and check the reading. write the PSI down and do the same for the other 3 cylinders. your #s should be between 130 (low, bad) and 180 (high, good) and within about 10% of each other. if one cylinder is significantly different from the others, that's a sign of a problem.

if the #s are on the low side, repeat the entire procedure but dribble some oil down the spark plug holes first before doing the test. if this results in higher #s, it means that the rings on the pistons are worn out. i think this is your problem because worn rings will allow oil to travel from the crank area up past the rings and into the combustion chamber. anyway, if this is the case, you will need to pull the engine to do the rings--big job. if the #s are good, get a few cans of seafoam from any automotive store, fill each combustion chamber with it through the spark plug hole, and let it sit for a a day or two. then with the hood open, spark plugs out, and nothing in the way that you care about, crank the engine. it'll spit the dirty seafoam everywhere and that will have cleaned your combustion chambers. drive it for a while and see how it runs.

i think that petros's advice on the connecting rod bearings is the likely culprit of your ticking and that the engine may just have worn rings as well but no harm in checking it all out.

[Aubrey Falconer]

Will do.

I just found Petros's excellent head gasket replacement thread ( https://tercel4wd.com/forums/viewtopic.php? ... eam#p44962 ), and was rather intrigued by Tazka's steam cleaning idea. Would this work any better than / be riskier than / the sea foam method?

One more question: is the 3A an interference engine - and could I damage anything by rotating the crank or cam shafts independently?

[dlb]

no, the 3A is a non-interference engine. crank away but mark the belt and pulleys to make reassembly easier.

yep, petros is a smart dude. he's away on vacation (a petros vacation anyway, rebuilding his daughter's CRX in texas) otherwise he'd be in here like a dirty shirt, i'm sure. his head gasket mod is pretty sleek.

for cleaning the combustion chamber, you can use takza's method or the seafoam method or even combine them. you can use seafoam the same way as takza mentions or you can just pour it in your gas tank. i like soaking the chambers for a day or so though because it gives it a chance to break down old build up but i don't know if one method is any better than the other. water's cheaper, certainly!