piston slap when cold ?

[2manytoys4menow]

It's been awhile since I have been on here . I was wondering if any of you have had a issue with possible piston slap during cold start ups on your Tercel's . I should note that I have a rebuilt cyl head and my compression is at 180-185 psi on all 4 cylinders . When I first start my terc , During the first maybe 3 second's it's run's ok then it makes the slapping " tac tac tac noise and I let it warm up for a few minutes and it goes away " sort of " untill it totally up to temp . You can just barely hear it right off idle right when you tip your foot into it and then it goes away . when it's warming up and I let the clutch out and lug it down a bit with the brake on the sound gets a bit louder and deeper but this is only when it's cold . when it's at operating temp it's fine . I have no issues with oil consumption and I'm running 10-40 Amsoil full synthetic . I allway's thought that you only had piston slap when the piston and cylinder had to much clearance and with my compression being what it is I didn't think that could happen . I thought maybe a slight rod knock but it's been doing this for 1000 miles and I think I would have spun a rod bearing by now . Any Idea ? I thought after I get my other terc running I would drop the oil pan on this 84 and cheak and maybe check the rod's out and maybe install new rod bearing's . I have check the valve clearance and it at spec so it's not valve clatter . Thank's guy's , Bruce

[Typrus]

Heh.....
Try a carbon-clearing process.
I have a writeup on the Seafoam treatment, Takza has his own carbon-clearing process.
Try that, then if it continues look into bigger issues.

I've heard that significant carbon deposits can make a piston slap sound as the head and piston deposits collide.

Just a thought,

[2manytoys4menow]

The head has about 2200 miles on it now and when it was being rebuilt the shop shaved a bit off from the head and that's why I have the high 180+ compression . The car run's great and pull's pretty good for a little motor If Rev it up a bit . I have seen that Seafoam stuff at the auto parts place so maybe I will try that . thank's T . Bruce .

[Typrus]

If that does turn out to be the issue, then I would switch gas brands?
What kind of mileage do you get? I'm curious if you are running rich (assuming carbon IS an issue)

I would REALLY hope this is not the case, but maybe the valves are slapping when cold? I dunno if they'd make the same sound or not, but maybe the clearance was adjusted while hot and when its cold the stem might shrink just enough to slap the seat? I don't even know if thats possible.

I wonder if the Amsoil worked something loose underneith thats making noise? That stuff will wick away old oil deposits.

Again, I am clueless if it's even possible, but perhaps your timing gets jacked up when cold and makes pings? Just random mumbling at this point, don't take my word as right lol... Well actually, looking at the combo of cold, brake on, and just off idle, maybe it could be vacuum related???


Just a random idea..... Check the tightness of your manifold bolts. Make sure they are spec-tight. Maybe there is a spot with a leak that seals when the expanding metal contacts???

Man I'm tired....

[takza]

With that higher compression you are likely to have carbon issues if you don't keep it real clean. Maybe running 2-3 oz per 10 G acetone in it will do that...and maybe you gain some mileage.

Ethos FR is something that will do the same kind of thing?

I had a bus once that had a sloppy piston for sure...and if the plug wasn't firing...it would knock/slap like hey...but as soon as you got the plug firing this went away. Probably a plug that isn't firing right when cold? I'd clean the plugs and see if this helps.

[xirdneh]

[quote="2manytoys4menow"]It's been awhile since I have been on here . I was wondering if any of you have had a issue with possible piston slap during cold start ups on your Tercel's .

i had two tercels that had symptoms like you describe. Both had a cracked piston . Both engines had well over 200,000 miles on them and were using quite a bit of oil between changes. Mostly from leaking seals. i suspect the previous owners did not keep the oil up. Never the less i drove one for three years, it ran fine and got great mileage. I finally tore the engine apart because of the leaks. Who knows how long it would have gone with the cracked piston.

[2manytoys4menow]

I have no oil consumption and the motor runs great . you can hear the noise just up off idle between 1000 to maybe 1300 and it goes away and this is when it's cold but when warm you hear nothing . I may just go through the outfit I got my tranny from and get a 3a motor for $495 or I can get a 4a for a extra $100 . I'm just going to drive it for now and focus on getting my green 85 sr5 running ( new cylinder head ) .

[takza]

You could have a slightly loose piston as you say...if the motor runs good and doesn't burn oil...just drive it? Just keep those plugs clean.....