I have had a small knock at idle for a while now an i cant figure out what it is. if its an internal engine problem thats fine ill fix it but i am wanting some sugjestions as to any other possible noise makers to check first so i dont pull the motor and have it not be the culprit.

the knock is usually very quiet but gets a bit louder at times. the best way i can describe it is that it sounds like what most engines do after you change the oil and are starting it with a dry filter, only not as consistent. it kinda goes up and down every few seconds. I have tried running Really heavy oil(20-50) bought cheep and removed after seeing no improvement.) all kinds of additives. i keep the oil level up. It does see up to 5k on a regular basis. (where the trans shifts at WOT). Oh and the noise seems to go away anytime the motor spins above 750rpm.

Probably an unrelated coincidence but i was at oriellys the other day waiting on a car to move with my car in park and my foot on the brake and it started making a slipping brakes(right before they lock at slow speed) kinda sound and vibrating. i couldnt figure out what it was so i was gonna shut the car off and i poped the trans in N and the noise went away. im thinking WTF? so i put it back in gear no noise so i pull into a spot and check my trans, almost a 1/2 qt low. well its nocking at that point as i go in and get some trans fluid and as soon as about 1/4qt of the fluid was in it stoped nocking completely and didnt then nock didnt return untill i drove out of town at 75 on the highway for a while. now its back again.

So any Ideas?

 

Your telling me that there are people out there that don't put oil into the filter before installing it?

 

I don't On my 350 Tpi, And i don't do it with customers vehicles where i work. Its something that helps i guess if your **** about your car but.. most of the time it almost less then a second anything is starved, if at all.. especially with residual oil in the system.

 

I put it on empty, makes too much of a mess if it's full when you put it on. Do you know how to properly check trans fluid? I ask because most people don't. Where does the knock seem to be coming from? Check if it's coming from the oil pan.

 

yes i know how to check trans fluid. After 20 mins at 75mph it now reads right at the full mark.

And i do between 10 and 30 oil changes per day. i have tried priming the filters before hand but it makes no real difference in the time that they clatter because you cant fill the filter galleys that feed the filter so you still run it dry for a bit anyway. I do prime diesel engines, turbo, and supercharged engines because we dont get many, plus i dont want to take a chance with them.

 

well, this reminds me of my spun rod bearing incident, it probably isn't this, since you would have very severe symptoms (power loss, very loud knocking) but when I first spun one of my rod bearings, and the engine was running, the knocking from the engine would seem to disappear when I got it anywhere near 1000 rpm, except under load(in gear) then it would get very loud and make screaching noises LOL. But back at idle, the sound would vary in intensity.

 

well its not there at all untill the engine is hot. started the car up cold drove 1 block to MCdonalds and sat in line waiting during which the motor warmed up(where i notice the nock most sitting next to a wall with the engine noise bouncing back to me). there was no nock till the motor hit 190*ish then it was there but quiet. It gets louder if the car has been run hard for a while and the motor gets real hot IE 220*ish. if i let it idle and coolback of to 190*ish (where it normaly stabilizes at idle) the knock gets quiet again. the hotter it is the louder the knock. funny thing is i have been paying attention to other 60*V6 cars i have been working on and all but the newest seem to make the same type of sound.

as far as i can tell its not in the bottom of the motor and its not gotten any worse since i have owened the car. If i disconnect the EST wire and pull the timing back to like 0* i dont hear it anymore but as soon as i reconnect it the timing goes to like 25* advance or more. Flick the trottle and it drops back to base and then jumps back to like 18* and increases with rpm. The nock seems to coinside with the level of timing. Could i have a hotspot causing predet? i believe the motor has been bored a bit. and how would i check for something such as a hotspot? I dont wanna have to pull this thing. may have to tho.

 

If preignition is the problem the more likely culprit would be the sp plugs. I doubt that it's detonation/preignition though, if it were the ecm would pull a ton of timing and you'd notice the lack of power. You're sure it's not valvetrain noise? Lifters tend to get quite noisy as they age.

 

 

Filters - do what you want Prime it, dont prime it. i have never primed any of the filters i put on my parrents vehicles and some are past the 200K mark. I dont prime them at work and have never had any problems, as far as i know nobody i know of arround my area primes filters other than on highend/specialty motors.

Knock - I dunno. how would i check the lifters to see if they are bad? if so is it worth it to try to fix the 2.8 or should i just bite the bullet and try for a low mileage 3.4?

 

Get a funnel and a length of hose and try to pinpoint where the noise is coming from. It might be difficult to discern between injector noise and lifter noise to the untrained ear, but concentrate on where it's coming from. If the lifters are bad you can easily replace them, but it depends on the value of the engine to you. Stepping up to a 3.4 block is never a bad idea, and could be had fairly cheap if you want to transfer the equipment over from your 2.8. The stock equipment runs fine despite the larger engine.

 

VALVE TAP/CLATTER IMO.

Sounds exactly like what i had in my last car, 87 celica GT,
ran it like that for 30,000, no power loss or anything, car ripped right along.
And it wasnt even that, what took her in the end... it was a battery fire!


Keep her oiled, keep it clean, I wouldnt do anything drastic at this point like switch to synthetic.
Its not the seals/gaskets you have to worry about, its the additives/synthetic taking the carbon sleeve, so to
speak, off you engine walls, and changing clearances.
You could start with synthetic blend.. run that for 1000 miles, change it, run more synthetic blend,
and than maybe after that, you can switch, might totally quiet her up.
Stay with stock weight oil.. adjust for winter/summer
keep it clean, use one of the K&N gold filters with the anti drainback valve.

Run a little marvel thru your gas tank, see what happens.
After that, run a little acetone, or sea foam .

You can also try lucus oil in your crank case, nice sticky thick stuff.

I hope you havent been using additives like 'valve quiet' or 'engine restorer' or any of that crap.

This could also just be a trans noise, dont go putting any trans additives in there either.
You will have so many different kinds of junk clogging up your car it can only get worse.

 

What's wrong with engine restorer? I've used it for years and it's been nothing but good.