Hi All,
I have a 91 Tracker with a 1.6 8v. It has developed a noise in the motor that is driving me nuts. When I start driving my truck I get a noise that sounds like valve rattle. I know that the valves are set correctly as I just did them. It is most noticable between 2500 and 3500 rpm and under load. If I let off the gas the noise subsides. It doesn't seem to matter much if I let my truck warm up for 10 minutes or so before driving, the noise is still there. After driving it for 3to 5 minutes the sound appears to disappear. If I let the truck sit for a bit and cool down some the noise returns just not as loud. It seems to be worse in the morning after sitting all night. It seems like once the motor is driven for a bit and builds up a good heat through the motor that the noise goes away. I have checked everything that I can think of that I can without actually tearing the motor apart and am coming up empty handed. I've even tryed listening to the motor all over with a stethoscope and find nothing as it only does it under load while driving and is directly related to throttle being applied.
I am here asking you guys as you seem to be well informed on these little trucks and I am hoping that someone may have run across this and know a cure or at least what's going on.
Thank you in advance for any light you may be able to shed.
Biker

LOL, ahh the old  piston slap, not realy
a problem, I've had it for years.

Thanks Wild,
I hadn't thought about slap. One thing still leaves me a little unsure is that I recently talked to a mechanic and he seemed to think that if it was slap it should go away after letting it warm up for 10 minutes. He suggested that it may be a wrist pin. Since talking to him I had another thought but am unsure if it is feasable. Could there be a crack in the manifold that would cause a similar noise and that wouldn't be apparent at idle. Sorry for the ramblings but I really don't want to pull the motor down unless I really have to.
Thanks again for your help,
Biker

Well lets give this a more through look.
What you described as Valve Train noise
would be an internal sound, piston slap and
wristpins have this similar internal noise,
wrist pins would be more of a single knock
as the cylinder fires, where as piston slap
is all cylinders (usually) from wear and would
sound more like the valves loose.

You can pull a sparkplug wire, and run the
engine, if the sound goes away, it could
be a wristpin or a bad rod bearing, if the
sound stays after warmed up try this one
wire at a time and drive a short distance,
it will run like crap tho with one wire off.

Rods are more noisy when warm, as the
oil is now thinner and offers less cushon.

What weight and Brand oil are you using?

An exhaust leak on the other hand is an
external noise, and sounds like, well excaping
exhaust under pressure, air excaping sounds.

Piston slap is a sort of loose fit of the worn piston
until it expands with heat and fits the bore better.
remember these engines are Aluminum, with steel
cylinder sleeves, so it takes a few min of driving
to get all warmed up.

If after you are all warmed up, engine at norm temp
and the sound is still there, it could be somthing else,
but you described that it goes away when warm.

You didn't say how many miles you have on the engine,
this would help to pinpoint normal wear, or another
problem that could get more serious, like a hole in the
engine block,       :-/


Good Luck with finding your noise,
Darrin

The noise does sound like a metalic noise, although it is really hard to desribe a sound. The noises just don't have the sound of a knock as I have had motors with a knock before. Bringing the motor up to temp in the driveway does not get rid of the noise but after the heat really builds in the block is when it dissapates. I am running 0w30 synthetic oil in it and it has 270,000km's on it. I'm going to plumb in an oil pressure gauge today and see what my pressures are doing for a few days.  One other thought came to mind this morning while pouring my first cup of coffee down my gullet, what about the egr valve, could it make a metalic rattle.
Anyway thanks for your feedback, I'm off to do some more tests and see if I come up with anything.
Cheers,
Biker
P.S. I got my 4 inch suspension lift done and on the road, seems to work ok so far, still needs some minor tweaks.

4" suspension lift??

Lets hear about it dude. Email me some pics if you dont mind.

Thanks,
Bill

Worn cam?  If I recall, there aren't cam bearings as in inserts the  cams just sit in the saddles in the head.  Once warm up takes place, the metal expands and the excess clearance is no longer an issue.

I had a mopar 2.5 with that very problem.  Unfortunately, it would have taken a new head to fix it and mom totalled it the exact day I paid it off.  Nevertheless, I ran many thousands of miles like that and true to your story it only happened when it was cold.

i had a noise that i could only here when the motor was in neutral no strain. drove me crazy LQQKed for the screws in the valve area. LQQKed at the bottom end. nothing.


ready for this 3 of the bolts in the fly wheel had come loose.

just  a  suggestion

270,000 Km is 180,000 Mi,
I'd say it's a loose motor.
0-30W as in Mobil1 or Syntec
great cold weather oil, at next
change try 5-30 or 10-30 and
see if the noise is reduced.

I don't think the EGR would make
a heavy metalic sound, too small
to be that noisy, maybe a rattly one tho.
But 0-30 oil won't cushon the pistons
well at cold temps so that might be what
you hear, it's not bad, just noisy, besides
loose motors put out more power- less
friction LOL.

Get a good oil PSI reading and let us know,
could be a slightly heavier oil will help with
all the Km you have.

My dad had an old truck that was so loose
in the rods and mains it sounded like a
diesel engine at idle, we put in 50W oil
to help quiet it down, but it still sounded
like a diesel.

     I agree, you need a little more oil pressure in there.   I ran 20-50 in my Trooper( I'm, NOT recomending that for the Zuki) at least a step up to 5-30 or 10-30 should do it.  But a little thicker oil should help.  Dave

The "factory recomended weight oil"
is usually for fuel mileage, and really
has little to do with the engine or the
size of the passages, and such.

I have used 5-30 - winter
I have used 10-30 - spring
I have used 20-50 - summer
for the life of the zuki and only
got 250,000 Mi (330,000) Km
out of my engine.
Dang did I get ripped on miles???

Yepper, you got ripped  My boss at work was able to get 275,000 out of his 1.3 Sammi.  Oh well, we'll check back with you when you hit 500,000 miles and see how THIS one is holding up  Talk to you later,  Dave

I checked my oil pressure and found that I have 30lbs at idle and about 65lbs at 4000 rpm, seems pretty good for an old motor. I'll switch to a little heavier oil at next change and try that. I was under the impression that a lower number oil was better in cold weather so I thought the 0w30 would be best.  There will be a tech page on my low buck buildup complete with pics appearing on Island4x4.com in the very near future.
Thanks for all your input guys and I will post back once I find out anything else.

Is that pressure with a hot or cold engine?
other than that, 30 PSI at idle sounds fine.

Old rule of thumb is 10 PSI per 1000 RPM
engine speed.

That is with a hot engine, so in theory the pressure in a cold engine should be higher as oil is thicker.