Brad b 2009-06-14 21:54:37
I have a 1999 Dodge Ram 1500 1/2 Ton with the 5.2L V8. I notice that
when I accelerate or otherwise put the engine under load, I hear a
sound like spark knock. Also, the truck feels “jerky” at times – even
when there is no knocking sound.
I’ve heard that this could be a result of the EGR valve, but all of my
searches for an EGR valve on this model come up empty. I’ve tried the
major auto parts chain sites, and the best I could find was the
gasket. There are EGR valves listed for earlier models, but not
1999. I’ve looked under the hood and cannot see anything that
remotely looks like an EGR valve, either.
Is there an EGR valve on this truck? If so, could this be the source
of the problems I’m experiencing?
Thanks in advance;
Tom lawrence 2009-06-14 21:54:38
No, no EGR on that model. Most likely, you’ve got a leaking plenum gasket,
which is sucking oil into the intake, causing carbon buildup in the
combustion chambers, and in turn causing the engine to knock/ping. To test
this, with the engine running, remove the PCV valve and put your thumb over
the hole. If you feel any vacuum, then you’ve confirmed the problem. If
you have access to a bore scope, you can also look down inside the intake,
and look for oil deposits.
The cure is to remove the intake manifold, and replace the belly pan with
one from Hughes Engines (part# HUG7714, http://www.hughesengines.com). The
problem with the stock intake is the intake itself is aluminum, and the
belly pan is steel. They expand and contract at different rates, eventually
pulling the gasket apart. The replacement pan is aluminum, so everything
expands and contracts at the same rate.
Once the new gasket is in place, run two cans of Mopar Combustion Chamber
Cleaner through the engine to clean out the carbon. Once that’s done, put
in a new set of plugs, as the CC cleaner really fouls up the plugs.
Brad b 2009-06-14 21:54:39
Thank you for this advice – I will give it a try. I was hoping that
the issue would require a small fix, but it sounds like it may be a
bit more complicated than I’d originally thought.
Thank you again;
Tom lawrence 2009-06-14 21:54:40
Yeah, removing the intake manifold is a bit of a pain. Nothing too special
about it, though. You will need a 3/8″ fuel line disconnect tool, to
disconnect the fuel line from the fuel rail. Make sure you relieve the
pressure in the rail first. The easiest way to do this is to run the
engine, then pull the fuel pump relay from the Power Distribution Center.
The engine will run for a bit, then sputter and die. At that point, the
pressure in the rail is minimal.
It’s just easier to remove all the front accessories and the accessory
bracket. You can just unbolt the A/C compressor and PS pump, and set them
aside – no need to disconnect hoses. When removing the bracket, make a
little cardboard template to keep track of the bolts – they’re several
different lengths, and easy to confuse.
Obviously, before starting this, you’ll have disconnected the battery
(you’re going to be messing with the alternator), and drain about a gallon
of coolant from the system – that will bring the level low enough for you to
work on. If it’s been a while since your cooling system was flushed, you
might as well drain it all, flush it with water, then replace with new.
And, if the hoses are a little old, this is the best time to replace them.
Ditto on the thermostat and serpentine belt as well. When replacing the
hoses, chuck the factory “constant tension” clamps, and replace ’em with
regular hose clamps. The CT clamps are fine when new, but they lose tension
over time, and become more trouble than they’re worth.
And not to over-state the obvious, but you’ll also need a full intake gasket
set (front, back, and two sides) when you go to put the manifold back on.
Any auto parts store should have this. Plan on spending the better part of
the day doing this, and if you don’t have one, pick up a service manual from
the parts place. I tend to like the Haynes manual over the Chilton – better
pictures. They’re only $12 or so, and well worth it, especially if you
haven’t done this before.
Miles 2009-06-14 21:54:41
2001 and prior 5.2L and 5.9L engines are well known to have pinging
problems. The mentioned intake plenum is quite common to be the problem
but its not the only cause. Rerouting plug wires, replacing them or
just spreading them apart may help.
If the plenum is the problem you most likely would notice a minor to
medium loss of oil but no signs of any leaks.
Others have had to use cooler plugs, change to a 180 degree thermostat
and use 91 octane.