1987 Silverado 350 TBI Knocking Pinging Intermediately - Engine overheating once

[Mike Phillips]

1987 Silverado 350 TBI Knocking Pinging Intermediately - Engine overheating once in a while?

Okay so I've had my truck for about 3 months now and it runs great except some type of overheating problem that's happened three times, not sure what that's about but it could be time to core the radiator.

Now it's started knocking or pinging, like a detonation problem.  I have not changed anything except the oil since I bought it.  The check engine light also comes on sometimes.

Friend of mine showed me how to get the motor to talk to me using a paper clip.  Have not checked since disconnecting the battery for about a half hour to clear any old codes.

I've never had to deal with sensors before so new to this garbage. 

Any suggestions or anyone dealt with this with their truck?

[bd]

Check your basics.  Make sure the radiator is full of clean coolant.  Make sure your belts are properly adjusted.  Check the fan clutch.  Look through the radiator core using a light on the backside and see if the fins are restricted with bugs, birds or debris (one of the most common and overlooked issues).  Check your ignition timing.  Check EGR operation.  Try filling at a different station.  Then drive it until the Check Engine light comes back on and retrieve the code before disconnecting the battery.

[Irish_Alley]

to add to what bd said the overheating and knock are related. as for what causes it coolant problems or spark problems. since bd covered the coolant ill cover the spark. if you have problems when your running the truck harder than normal it could be spark and a colder plug might be your fix. when your checking things out remove a plug and post the numbers on it. you could step the up the octane on the fuel also to see if that helps. some low quality and/or low octane fuels can burn hotter than the higher ones. also timing be too advanced and/or a lean running tune will cause this problem

[Stewart G Griffin]

Overheating while driving or idling?

[tj wand]

i had a problem with overheating i found out that my hose had a whole in it not a big one but big enough for a leak and the core may be a problem

[Irish_Alley]

what im thinking and this is just me but i never had a engine overheat then cause a ping. to ping the temp in the engine would have to reach 1472° unless the timing is advanced too much. normal operating temp should be about 842°. a ping would cause the engine to overheat since the combustion chamber is almost twice of what it should be this would radiate out to the rest of the motor, same deal if he was running lean. now this is just my thinking/logic, could very well be wrong but its what makes sense to me.

[Mike Phillips]

Check your basics.  Make sure the radiator is full of clean coolant.  Make sure your belts are properly adjusted.  Check the fan clutch.  Look through the radiator core using a light on the backside and see if the fins are restricted with bugs, birds or debris (one of the most common and overlooked issues).  Check your ignition timing.  Check EGR operation.  Try filling at a different station.  Then drive it until the Check Engine light comes back on and retrieve the code before disconnecting the battery.

Belts look worn but are tight.  This was supposed to be a "Fresh Rebuild" and I think the motor was rebuilt but I think they hobbled everything back together again using the old extraneous parts.  Just a guess but a lot of things look "original" and by that I mean old and worn out.  No big deal to me but when I do these types of projects I replace everything with new good parts.

Fan clutch feels good when I spin it with engine off.  I'll replace it with the one I installed on my Jimmy down the road, everything all rebuilt and the fan off a 1971 Cadillac Eldorado.

Fins on radiator are severely smashed in.  Lets just assume a Caveman removed it and re-installed it.  I'm going to install the 2-core aluminum radiator that was "new" when I installed it into my Jimmy 4 years ago.

The truck runs "really good", I mean it really sounds smooth and like new when you start it and drive down the road.  The pinging started at least a month after I bought the truck and until last week I was running RaceTrac "Regular".

[Mike Phillips]

to add to what bd said the overheating and knock are related. as for what causes it coolant problems or spark problems. since bd covered the coolant ill cover the spark. if you have problems when your running the truck harder than normal it could be spark and a colder plug might be your fix. when your checking things out remove a plug and post the numbers on it. you could step the up the octane on the fuel also to see if that helps. some low quality and/or low octane fuels can burn hotter than the higher ones. also timing be too advanced and/or a lean running tune will cause this problem

Last weekend I removed the #1 plug and it looked like it was burning clean.  Just to repeat, this engine/truck ran great when I first took possession of it.  I put "regular" gas in it since I bought it but the last gas fill-up, that's last week, I put Premium in in it.  I'm going to fill the tank tomorrow and again, put Premium in the tank.

I wrote down the Spark Plug #number, don't know what it is off hand but I do have the number. 

Just to note, the engine runs good sometimes, and pings sometimes.

It seems to be very erratic.  I have not noticed it to be a first thing when the engine is cold, or down the road a while when the motor is warmed up.

[Mike Phillips]

Overheating while driving or idling?

Driving.

I check the radiator level every day or every other day and it's losing fluid.  I've seen leaking somewhere around the radiator, not sure where.

Again, as soon as I get a chance, I'm going to remove the current radiator and replace it with the aluminum radiator I installed in my 1975 Jimmy that I built while I lived in the Mohave Desert and never had any overheating problems.

[Mike Phillips]

i had a problem with overheating i found out that my hose had a whole in it not a big one but big enough for a leak and the core may be a problem

Now days, time has been kind of short.  That said, the last two weekends I replaced the axle shaft gaskets because,

1: The driver's side was leaking gear oil all over the wheel and tires.

2: The passenger side because when I found out when I replaced the driver's side gasket all 8 bolts were hand tight.


But... I've seen "someplace" is leaking fluid when the system gets hot.  So after I rebuild the starter solenoid, next is the radiator..

[Irish_Alley]

well im lost, but i wont keep guessing lol. hows the timing?

[bd]

...Fan clutch feels good when I spin it with engine off....

...Fins on radiator are severely smashed in....

...The truck runs "really good", I mean it really sounds smooth and like new when you start it and drive down the road.  The pinging started at least a month after I bought the truck and until last week I was running RaceTrac "Regular".

Does the fan clutch allow more than ~3/16" play at the fan blade tip if you wiggle the blade fore-and-aft?

Estimate the percentage of radiator surface that's blocked to airflow due to mashed fins, etc.  If you have access to the front of the radiator, do you feel any 'cold spots' as you move your hand back-and-forth across the core with the engine running at normal temperature?  Is the fan shroud intact?

Run the engine to operating temperature and verify the ignition timing with a light after bypassing EST by unplugging the single tan/black in-line Weatherpack connector located near the driver side bulkhead plug at the firewall.

...I check the radiator level every day or every other day and it's losing fluid.  I've seen leaking somewhere around the radiator, not sure where....

Diagnose that "fluid leak."  Does the 'leak' appear to account for the amount of coolant you have to keep adding to the radiator?  Is there "white smoke" issuing from the exhaust pipe?

...The check engine light also comes on sometimes....

Retrieve and post the diagnostic code(s) the next time the SES light comes on with the engine running.  In the meantime, since the engine was previously removed or rebuilt in-frame, verify the grounds.  There should be an ECM ground wire plus a braided ground strap from the firewall bolted to the back of the right cylinder head, an ECM ground wire should connect to the right front of the intake manifold, the battery ground cable should fasten to the air pump bracket at the right front of the engine and a jumper should connect between the right frame rail and battery negative terminal. 

In addition, you can check for exhaust restrictions by measuring the exhaust backpressure.  It shouldn't be greater than ~1.5 PSI at 3,000 RPM.  Also, verify the EGR valve is working.

-------------------------

Thus far, our strategy has been painfully broad, because we're fishing for something tangible that may benefit you.  The trouble code(s) could prove key to a solution.

[Irish_Alley]

wow missed the fact of the red leaking and cel

[Mike Phillips]

Does the fan clutch allow more than ~3/16" play at the fan blade tip if you wiggle the blade fore-and-aft?

No play at all.

Estimate the percentage of radiator surface that's blocked to airflow due to mashed fins, etc.  If you have access to the front of the radiator, do you feel any 'cold spots' as you move your hand back-and-forth across the core with the engine running at normal temperature?  Is the fan shroud intact?

30% to 40% smashed fins.  Looks worse than any radiator on any car I've ever owned.  Can't really access the front radiator without removing the grill.  In the next few weeks I'm hoping to remove the 454 out of my Jimmy and when I do that I'll also remove the aluminum radiator out of the Jimmy and put it into this truck.

The Fan Shroud is all intact.

Id say

Run the engine to operating temperature and verify the ignition timing with a light after bypassing EST by unplugging the single tan/black in-line Weatherpack connector located near the driver side bulkhead plug at the firewall.

Checked and noted.  Can't do it this weekend but maybe next weekend.

Diagnose that "fluid leak."  Does the 'leak' appear to account for the amount of coolant you have to keep adding to the radiator?  Is there "white smoke" issuing from the exhaust pipe?

Yes.  I lose a little and add a little.  I stay on top of it because it appears that if I loose a quart or more the engine overheating starts in.

No white smoke coming out of tailpipe, I know what that looks like and smells like.

...The check engine light also comes on sometimes....

Retrieve and post the diagnostic code(s) the next time the SES light comes on with the engine running. 

The above is new to me.  A mechanic buddy of mine, ASE certified, Level ? GM Mechanic, has subscription to some kind of GM software and online access to GM service info.  (Works at American Yachts right now but pulled all this stuff up on his computer to show me).

He showed me to take a u-shaped paper clip, stick it into "B" and "A" terminals, to the key to ignition on and then showed me how the computer will talk to me with a series of flashing lights. Told me to write down the numbers and then I can use these to get the error codes.

But he showed me how to do it with the engine off, key on.  You're telling me to do this with the engine running?  You probably mean if I had the actual tool that you plug in to check codes, I just have the paper clip. 

In the meantime, since the engine was previously removed or rebuilt in-frame, verify the grounds. 

• There should be an ECM ground wire plus a braided ground strap from the firewall bolted to the back of the right cylinder head,
  an ECM ground wire should connect to the right front of the intake manifold,
  the battery ground cable should fasten to the air pump bracket at the right front of the engine
   and a jumper should connect between the right frame rail and battery negative terminal. 

Thank you.  That is some good information.  I've only owned older trucks without all this fancy electrical "crap".  I'll try to check this out as soon as I can, it's already about 95 degrees outside so I'll probably wait till I can pull her into the air conditioned studio.

In addition, you can check for exhaust restrictions by measuring the exhaust backpressure.  It shouldn't be greater than ~1.5 PSI at 3,000 RPM.  Also, verify the EGR valve is working.

The truck has a brand new exhaust system, mufflers and pipes and brand new headers on it, looks like some good stuff and everything is bolted in real good and tight.  Even has the little locks to keep the header bolts from loosening.

Thus far, our strategy has been painfully broad, because we're fishing for something tangible that may benefit you.  The trouble code(s) could prove key to a solution.

I have the print out showing me where to stick the U shaped paper clip into the terminal under the dash to get the computer to talk to me, I'll do that today and write down the codes.

The bottom of the print out says,

2013 Mitchell Repair Information

This was given to me by this other mechanic that is a good friend of my buddy Dave.

[zieg85]

Does it have the O2 sensor?