two days ago i noticed a small knock between 2000 and 3000 rpm.....only under load and it goes away when it is warmed up......i set the valves....changed cap and rotor ....did a vacuum test and checked compression....everything turned out good.....usually the car has new oil every 3000 miles...mobile 1 15w50 synthetic and always sees full 1 minute warmups even in summer time......my warranty just finished so my dealer wont look at it unless i pay......any ideas....thanx in advance...

 

I have run into other people who have developed piston slap while using mobil one synth.

When was the last time you had your timing belt changed? It could be stretched out causing valve noise.

 

the whole motor was rebuild 25000kms ago just to make sure it lived a happy life in my hands....including the belt was changed.......do u recommend i change oil or is it too late?????

 

another reason i plan NOT to use mobile 1 synthetic oil at all......... i have heard of similar situations form people using that oil...............Castrol Syntec or Valvoline Synpower seems to be pretty good......

 

if possible....could someone explain to me how a lubricant such as oil could lead to piston slap??????this motor has a canadian winter and 25000kms on it....why would it start slaping in the mid summer cause of oil......????????

 

I don't think that's realated to your oil....but why are you running such an high grade of oil since you live in New-Brunswick?

10-40 in the summer and you should be fine.

Like I said,this as nothing to do with your piston slapping or could it be????

 

i have an oil pressure gauge....i find in the hot traffic the pressure drops low....so in the summer i run 20w50 and it doesnt go so low........and when reved up it doesnt go any higher......from what i can hear...if i warm the car up for about two minutes ..it doesnt seem to knock at all.....also i went on the highway today and reved it out....no hesitation ,no smoke...and it didnt blow up....so i dont really know.....

 

Vtec heads have a hydralic lost motion assembly, basically its a lifter. If one is has a bad checkvalve it may not hold oil pressure. It will have to fill every time you start your car. It will make a knocking sound similar to excessive valve lash. Maybe it could be that.

I once had a spun bearing and it started out as a slight knock but it was definetly a noise in the engine. When I put the clutch pedal to the floor, I could feel it. It was about 1500 miles after a machine shop rebuilt it and didnt use factory bearings. Hopefully its not that.

As for Mobil1. As long as I have been pouring oil into my own Hondas, it has been Mobil1. I used to buy it but now its free so Im not about to go and buy other oil, however I would pay for it if I had to. I have yet to experience any problems with it, and I change my oil religiously every 3k. All my friends use it and so does Porsche. Why would they use it if it was bad? They used to use 15w-50, but they have now switched to 0w-40. I used both with no problems. But my engine is stock and never been opened up.

 

i figure it cant be a bearing cause its got 25000kms on it now....and also i rev it hard lately to try and see if it is major enough to blow it and it dont vibrate or anything and my engine oil is clean with no copper particles.....it does make lots of sense about the lost motion....but is there a way to check them....when i set the valves i pushed on them to make sure the spring in them didnt break.....they were all tight.....should i go back to 10w30 maybe????????

 

can anyone tell me how to make sure it is piston slap.....how can i check that????i changed the oil back to 5w30 today just in case......

 

It's most likely valve train noise. I thought I had piston slap in my GSR but when the motor was tore down the pistons were in there as tight as hell.

 

here is a good test.

accelerate WOT shifting at 2K. if you feel a hesitation... you have
a rod bearing that is weakening. been there, its fixable if you catch it
but you still need to open her up.

 

it probably aint a bearing i guess...cause i can accelearate from 1500 wot and its smooth and responsive and also i think the compression would of been low on that cylinder ........i put 5w30 in it and this morning the noise isnt as bad......so i think it must that lost motion assembly.....one of them must be plugged or something.....i figure with thinner oil it should get louder not quieter and also the oil i took out was very clean....no copper material or anything else in it....also when i touch the clutch pedal while rolling it is smooth....i dont feel a knock or anything.....

 

it probably aint a bearing i guess...cause i can accelearate from 1500 wot and its smooth and responsive and also i think the compression would of been low on that cylinder ........i put 5w30 in it and this morning the noise isnt as bad......so i think it must that lost motion assembly.....one of them must be plugged or something.....i figure with thinner oil it should get louder not quieter and also the oil i took out was very clean....no copper material or anything else in it....also when i touch the clutch pedal while rolling it is smooth....i dont feel a knock or anything.....but i really appreciate the response on this subject ....thanx for the info and keep the ideas rolling in so i can check everything.......

 

sorry to bring this old post back but i felt i should update it.......anyways...i changed my oil to 5w30 mobile 1 and went on the highway for a cruise...i kept the revs around 4000rpms for about one hour and a half....the next few weeks it was super quit and all....suddenly yesterday morning that knock was there again......almost sounds like a hammer on the crank......but it will only do it on the first startup of the day and same as before only under load......so i drove the car a bit hard yesterday and today quit again.....could it be carbon deposits creating a loud sparkknock????or something like that.....????cause it wont blow up or show any signs of anything else......

 

does nt anyone have any ideas??????????????

 

at idle today with the car fully warmed up.......i just started it and i could hear a small click clack.....i gave it a shot of gas and it went away......my valves r all set......so now i really think that the lost motion assembly is screwed up........is it common for those lifter to screw up????????????

 

You are exactly describing a spun rod bearing.

Sorry for the really late response

 

take your spark plugs out and pour a bit of oil into each cylinder before you start it in the morning. If the first few seconds (15-20 sec) of startup doesn't have the noise, you have piston slap...I doubt you have piston slap


[Modified by Mover, 2:41 PM 9/7/2002]

 

sorry bro, its not likely to be the LMAs
if it is anything it is a spun rod bearing
beginning to rear its ugly head

 

what happens if you do find cooper particals or something in your dip stick....

checked up on a friends car and found it in there....????

 

Spun Bearing

Also, synthetic oil is bad for new rings.

 

Is it damaging to have piston slap with forged pistons or somewhat normal.

 

If the knock is easily duplicated when the car is cold, there is a way to isolate which bearing is to blame. Duplicate the noise and pull plug wires one at a time. If the noise goes away when one particular plug wire is removed, that is the cylinder with the failing rod bearing.