Clacking On Starting *Update* Compression Test
-
- Advanced Member
- Posts: 90
- Joined: Sun Oct 03, 2010 4:08 pm
- My tercel:: 1985 SR5
- Location: Wheat Ridge, CO
Clacking On Starting *Update* Compression Test
I just got home from a 3,000+ mile road trip out to California in my Tercel. The last 600 miles or so, the engine would clack for the first minute or so after startup. Once it got some heat going it would go away. Even stopping for gas it would a bit but less than a cold start. I pulled each spark plug wire and none of them stop the clacking. It doesn't sound like valve train either. It's more to the left and down. Like water pump area. Definitely up front and not the fuel pump.
Maybe exhaust leak? But I've always had exhaust leaks get worse with heat.
Any thoughts?
Maybe exhaust leak? But I've always had exhaust leaks get worse with heat.
Any thoughts?
Last edited by Devin on Thu Sep 19, 2013 11:17 am, edited 1 time in total.
- dlb
- Highest Ranking Member
- Posts: 7447
- Joined: Mon Jul 06, 2009 9:03 pm
- My tercel:: '87 sr5, '83 dlx parts car
- Location: bc, canada
Re: Clacking On Starting
sounds like piston slap. that means the rings are worn a little bit and allow lateral play of the pistons when the engine is cold. once it warms up and everything expands and tightens up a bit, the slap goes away. i think the best test for this would be to do a compression test when the engine is stone cold, and again after it has warmed up.
i know you said it doesn't sound like the valve train but you could still check the valve lash just to rule that out, too.
i know you said it doesn't sound like the valve train but you could still check the valve lash just to rule that out, too.
-
- Advanced Member
- Posts: 90
- Joined: Sun Oct 03, 2010 4:08 pm
- My tercel:: 1985 SR5
- Location: Wheat Ridge, CO
Re: Clacking On Starting
I will check the valve lash. What is the clearance for intake and exhaust?
I thought that piston slap would stop if the spark plug wire was pulled for that cylinder? I pulled each wire and none of them stopped the clacking.
I thought that piston slap would stop if the spark plug wire was pulled for that cylinder? I pulled each wire and none of them stopped the clacking.
- dlb
- Highest Ranking Member
- Posts: 7447
- Joined: Mon Jul 06, 2009 9:03 pm
- My tercel:: '87 sr5, '83 dlx parts car
- Location: bc, canada
Re: Clacking On Starting
i can't remember the valve lash clearances offhand but they're in the FSM in the tune up or maintenance section.
i don't think pulling the spark plug wire would stop piston slap since the piston would still be rattling around as it goes up and down. the issue in piston slap is too much clearance between the rings and cylinder wall, and that would be present regardless of whether or not there is spark or combustion.
i don't think pulling the spark plug wire would stop piston slap since the piston would still be rattling around as it goes up and down. the issue in piston slap is too much clearance between the rings and cylinder wall, and that would be present regardless of whether or not there is spark or combustion.
- marlinh
- Highest Ranking Member
- Posts: 1586
- Joined: Sun Apr 08, 2012 9:15 am
- My tercel:: 'Everett' Blue 87 4WD Wagon (Rocky 86, recently retired)
- Location: Kootenays
Re: Clacking On Starting
Piston slap is clearance between the piston and cylinder wall. Pulling the wire would change the sound in that cylinder because you don't have combustion pressures on that piston.
- dlb
- Highest Ranking Member
- Posts: 7447
- Joined: Mon Jul 06, 2009 9:03 pm
- My tercel:: '87 sr5, '83 dlx parts car
- Location: bc, canada
Re: Clacking On Starting
eep, my bad. sorry for the misinformation.
i was just looking this up more and it sounds like pulling the plug wire will reduce the slapping sound but not eliminate it, so when you pull the plug does the sound change at all?
i was just looking this up more and it sounds like pulling the plug wire will reduce the slapping sound but not eliminate it, so when you pull the plug does the sound change at all?
- irowiki
- Highest Ranking Member
- Posts: 3469
- Joined: Tue Apr 02, 2013 10:02 am
- Location: Farmington, NM
Re: Clacking On Starting
You might try the old ear to long screwdriver over each piston trick as you disconnect each spark plug to check if it changes at all.
Former Tercel Enthusiast (not a practical family car anymore but they still have a place in my heart)
Site administrator, if something is broken, PM me!
87 Corolla FX16, 105k
94 Jamboree RV (Ford E-350), 90k
95 Camry Wagon, 197k
05 Avalon, 199k
Site administrator, if something is broken, PM me!
87 Corolla FX16, 105k
94 Jamboree RV (Ford E-350), 90k
95 Camry Wagon, 197k
05 Avalon, 199k
- Petros
- Highest Ranking Member
- Posts: 11941
- Joined: Sun Jan 28, 2007 6:31 pm
- My tercel:: '84 Tercel4wd w/extensive mods
- Location: Arlington WA USA
Re: Clacking On Starting
try removing both the power steering belt and the alternator belt and run it for about 30 sec to a min max, just to listen for the noise. there will be no coolant circulating, but this is a simple test, if the problem is in the power steering pump, water pump or alternator, you will find out this way.
Also check the valve clearance at the rockers. if one came loose and it has a lot of clearance it will act this way, and pulling a spark plug will not stop the clacking. possible even a broke valve spring, but not likely. I have had an adjuster come loose and the valve clearance opened up to a 1/4" or so, sounded really bad. easy fix and no harm done.
Also check the valve clearance at the rockers. if one came loose and it has a lot of clearance it will act this way, and pulling a spark plug will not stop the clacking. possible even a broke valve spring, but not likely. I have had an adjuster come loose and the valve clearance opened up to a 1/4" or so, sounded really bad. easy fix and no harm done.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
-
- Advanced Member
- Posts: 90
- Joined: Sun Oct 03, 2010 4:08 pm
- My tercel:: 1985 SR5
- Location: Wheat Ridge, CO
Re: Clacking On Starting
Finally got some time to wrench on the Tercel. I took off the two belts like you said Petros and ran it for 30 secs or so. No change in clack.
Took off the valve cover and checked out the valve clearances, nothing out of the ordinary.
I fiddled around more removing spark plug wires and removing the number one wire definitely stops the sound. So I'm thinking piston slap, but check out these compression test numbers.
Cold: Cold with oil: Hot: Hot with oil:
1) 120 1) 135 1) 115 1) 115
2) 120 2) 130 2) 90 2) 105
3) 95 3) 110 3) 100 3) 110
4)122 4) 130 4) 105 4) 110
Weird because the sound definitely is from #1 not #3. You guys know what these compression numbers say more than I do. Any thoughts?
Took off the valve cover and checked out the valve clearances, nothing out of the ordinary.
I fiddled around more removing spark plug wires and removing the number one wire definitely stops the sound. So I'm thinking piston slap, but check out these compression test numbers.
Cold: Cold with oil: Hot: Hot with oil:
1) 120 1) 135 1) 115 1) 115
2) 120 2) 130 2) 90 2) 105
3) 95 3) 110 3) 100 3) 110
4)122 4) 130 4) 105 4) 110
Weird because the sound definitely is from #1 not #3. You guys know what these compression numbers say more than I do. Any thoughts?
- dlb
- Highest Ranking Member
- Posts: 7447
- Joined: Mon Jul 06, 2009 9:03 pm
- My tercel:: '87 sr5, '83 dlx parts car
- Location: bc, canada
Re: Clacking On Starting *Update* Compression Test
i don't know how good my advice to do cold/hot compression tests was. i misunderstood the cause of piston slap so i'm not sure how much use the cold #s actually are. sorry about that. usually, compression tests are done once the engine is warm.
that being said, those #s don't look good. new, these engines should be around 180 psi so considering how low those #s are and the likely piston slap you have, it looks like it's time for a rebuild.
did you make sure to have the battery fully charged, all the spark plugs removed, throttle wide open, and crank the engine the same # of times for each cylinder? those are all very important to accurate readings.
that being said, those #s don't look good. new, these engines should be around 180 psi so considering how low those #s are and the likely piston slap you have, it looks like it's time for a rebuild.
did you make sure to have the battery fully charged, all the spark plugs removed, throttle wide open, and crank the engine the same # of times for each cylinder? those are all very important to accurate readings.
-
- Advanced Member
- Posts: 90
- Joined: Sun Oct 03, 2010 4:08 pm
- My tercel:: 1985 SR5
- Location: Wheat Ridge, CO
Re: Clacking On Starting *Update* Compression Test
Oh snap, wide open throttle? I missed that part. Should I do it again?
-
- Advanced Member
- Posts: 90
- Joined: Sun Oct 03, 2010 4:08 pm
- My tercel:: 1985 SR5
- Location: Wheat Ridge, CO
Re: Clacking On Starting *Update* Compression Test
Ok new numbers. I redid the test with the engine hot, spark plugs out, wide open throttle , cranked it 8 times each and had someone watching the gauge, so I think these are the good numbers:
115 psi across the board with no oil. 120 psi on #1 and #4 with oil. 125 psi on #2 and #3 with oil.
I guess now I'm just wondering how long I should drive this motor. Are the numbers really low for 230,000 miles?
115 psi across the board with no oil. 120 psi on #1 and #4 with oil. 125 psi on #2 and #3 with oil.
I guess now I'm just wondering how long I should drive this motor. Are the numbers really low for 230,000 miles?
- dlb
- Highest Ranking Member
- Posts: 7447
- Joined: Mon Jul 06, 2009 9:03 pm
- My tercel:: '87 sr5, '83 dlx parts car
- Location: bc, canada
Re: Clacking On Starting *Update* Compression Test
yes, those are at the bottom end of the scale. you can definitely still drive it for a while but it's time to either start looking for a known good engine, or a bad one that you can rebuild at your leisure and throw in when your current one kicks the bucket.
Re: Clacking On Starting *Update* Compression Test
Devin-
You might want to see if the crankshaft pulley bolt is tight (the 17 or 19 mm one in the center of the crankshaft.) Years ago i was given a 2wd wagon by a former GF (long story-not going into it here.) Anyway, the engine had a loud knock that sounded just like a rod knock. Also the spark timing was all over the place. Turned out the c/s bolt had worked loose and allowed the pulley to move back and forth radially with respect to the crankshaft. I wound up replacing the pulley, crank timing gear and woodruff key with "new" used parts (the keyway in the crankshaft was a little boogered-up to, but i smeared loctite on everything and put it back together.) 50k later that engine's still running strong and is currently in my work beater.
Good luck- hope this helps!
You might want to see if the crankshaft pulley bolt is tight (the 17 or 19 mm one in the center of the crankshaft.) Years ago i was given a 2wd wagon by a former GF (long story-not going into it here.) Anyway, the engine had a loud knock that sounded just like a rod knock. Also the spark timing was all over the place. Turned out the c/s bolt had worked loose and allowed the pulley to move back and forth radially with respect to the crankshaft. I wound up replacing the pulley, crank timing gear and woodruff key with "new" used parts (the keyway in the crankshaft was a little boogered-up to, but i smeared loctite on everything and put it back together.) 50k later that engine's still running strong and is currently in my work beater.
Good luck- hope this helps!
if it aint there, there's a good chance it won't break!
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)
- Petros
- Highest Ranking Member
- Posts: 11941
- Joined: Sun Jan 28, 2007 6:31 pm
- My tercel:: '84 Tercel4wd w/extensive mods
- Location: Arlington WA USA
Re: Clacking On Starting *Update* Compression Test
The compression numbers are low indicating worn rings and cylinder walls, but it will not harm it to drive it. It just means it will be down on power a bit. Use an oil additive that thickens the oil like STP and that will reduced the piston slap (if indeed that is what it is). I have also had good luck with "Restore" (best used on a long drive), make sure you shake it up good to get the stuff that settle on the bottom back in suspension before you add it. As long as you keep the slap down, it will run fine. continuing to run with noticeable slap will fatigue the piston skirt and have it fail, usually rendering the engine unusable (even if still running). So you may have some time before that happens, but it can fail at any time (I have had it happen on old tercel engines twice, and seen it on other engines). Or it might run that way for another 50k miles (espically if you keep oil thickening additives in it), you just do not know.
The engine needs to be over-bored and new over-sized pistons and rings installed, while you are at you can have the head rebuilt with new exhaust valves, recut valves seats and new valve stem seals. Or you can look for a low mile engine, if you can find one, and swap it out. You might consider finding a 4ac engine in a wrecking yard, take your time rebuilding it over the winter, and than swap it out over a weekend.
Good luck.
The engine needs to be over-bored and new over-sized pistons and rings installed, while you are at you can have the head rebuilt with new exhaust valves, recut valves seats and new valve stem seals. Or you can look for a low mile engine, if you can find one, and swap it out. You might consider finding a 4ac engine in a wrecking yard, take your time rebuilding it over the winter, and than swap it out over a weekend.
Good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)