99 SL SOHC 5 speed Pinging when warm

My SL is fine when it is cold, but when it is warm it pings almost
constantly, especially in higher RPMs. The previous owner changed the
thermostat to a lower setting 170, I think. I also did not have any (less
than piss warm) heat over the winter. I was wondering if these 2 problems
are related. I do not have any service engine lights on.

Thanks
Wayne

 

oil viscosity and gas quality? thats my guess.

 

You might check the coolant temperature sensor.

 

One cause of pinging can be too low of a combustion chamber temperature.
I believe that the SL engine had a 195 degree thermostat as standard
equipment, and if so, 170 is a huge difference. You should try the
proper thermostat. Usually people go down by 5 degrees at a time if the
engine is running too hot, to go down by 25 degrees is a really bad idea.

Was he having an overheating problem that caused him to put in such a
low temperature thermostat or was he mistakenly thinking "the cooler the
better?" Was the cooling fan temperature sensor also changed to a lower
temperature? Some owners have had a problem of overheating when at idle
because the electric cooling fan didn't come on soon enough, and changed
the cooling fan sensor (though you want to be careful that it's not set
to a level that's so low that it's on all the time).

A lower temperature thermostat would mean that lower temperature coolant
is circulating through the heater core, though it shouldn't have had
that much of an effect on heat, unless you're in an extremely cold
climate, though again, 25 degrees is a huge difference, and the heater
was designed for higher temperature coolant.

 

Please oh please cite your source for this.

To go down at all is a bandage fix. Something a bubba like you should be
familure with.

Cooling fan sensor? Never heard of it.

Set what so low? What the F#@K are you blabbing about?

Yeah the heater was designed for high temp coolants... <roles eyes>

Why is a guy who has NO background in automotive service and repair
giving advice here?

Here are the things Wayne should actually be looking for:
--Low coolant
--Loose drive belt
--Restricted air flow through radiator, or restricted air flow through
condenser (if A/C equipped)
--Proper cooling fan operation
(IIRC the cooling fan for the S-series should come one around 215-230
deg if the ECT sensor is working correctly)
--Front air dam missing or damaged
--Knock Sensor Circuit System
--EGR (becomes clogged)
--Poor quality fuel (no you should not goto a higher octane fuel. It is
another bandage fix.)

(Stick with bicycles Steve. You're way out of your league.)

 

One more thing you might try is decarbonizing but go through the other
things first.

 

Oh look Scharf posted again. Obviously Scharf is "pretending" to have me
kill filtered. (Typical tactic he has been known to use.) Why else would
he make such a lame out of the blue post after I called him on his bs.
He's trying to change the subject... I'm not going to let that happen.
I'm tired of him regurgitating stuff he knows nothing about.

 

Thanks for everyone's help. The car does almost have 150,000 miles. Every
hear of seafoam and will it be a fix or make things worse. I didn't have any
problems since it was a cooler temp outside. I don't get it! BTW The
cooling fan comes on when I turn on the A/C.

Thanks,
Wayne

 

You might try higher octane gasoline. That's a workaround, but it can
prevent pinging. It's very destructive to the engine to not stop the
pinging.

The cooling fan is supposed to come on when you turn on the AC. You must
have sufficient airflow over the condenser at all times, even when stopped.

 

Wow a bandage fix offered up by the wannabe mechanic.
As I said before, you have no business giving anyone any advice on
servicing a car.

You wrote that. That was bit of blunderous information was posted by
YOU.

I still would like to know wtf a "cooling fan temperature sensor" is and
how you get one with a "lower temperature".

Also a thoughtful post was already provided to the OP.
Its a shame you couldnt see it do to your ego.

 

I would use GM's Top Engine Clearer myself. I think I posted a
walkthrough for it here in the past. Look in google groups archives.
Saturnfans has a few walkthroughs and discussions for seafoam IIRC.

If I were you I might start by installing a brass ECT sensor, if it has
a plastic tipped ECT sensor, and then remove and clean the EGR and
passages. If it looks bad then the engine should probably be
decarbonized. (also be sure you have an air damn and an unobstructed
radiator...)

 

One more thing, while changing the thermostat back to the proper
temperature may help the pinging problem, it could also exacerbate it.
It's possible that the previous owner switched to the lower temperature
thermostat as a bandaid solution to pinging that was even worse.

This is the type of problem where it may be worth paying a master
mechanic to diagnose the root cause of the pinging. OTOH, trying
inexpensive fixes such as using the proper thermostat, or changing
fuels, may be worth a try. You can always go back to the way it was before.

 

Ummmm.... no, it can't.

Pinging occurs when the fuel/air mixture is detonated too early. You
wanna explain how low temperatures can cause premature detonation?

 

(8 hours and many Scharf post later...)
Well hows it feel to be on Scharfs kill-filter Doug?

 

Like I said... you wanna explain that?

No, it's nonsense.

Of course. But having it too low will *not* cause predetonation.

 

This is what I read, "knock occurs more prevalently in too high a
combustion temp which is why engines with aluminum cylinder heads can
run higher compression as they dissipate heat better. But too cool a
combustion temp can also increase knock."

Yes, it's counter-intuitive. In any case, it's best to keep the engine
temperature at what it was designed for.

 

It took him about "24" hours to respond, nearly "5" hours after his last
post here, but he finally found something to use as an excuse.

He copy-pasted an excerpt from this
02-26-2008, 02:56 PM
http://www.northamericanmotoring.com/forums/showthread.php?p=2062390

Yeah who needs training, ASE certs, and facts when you can just
regurgitate a forum posting...