Guys,

What are the symptoms of the intake / plenum gasket needing replaced on the 318 magnum motors in these trucks? My 2001 has 135,000 miles, and it feels very under powered. Also, when I step on the gas, my vents stop blowing air - which makes me think there is a vacuum problem? I have had this truck for 5 years - and only have put 10,000 miles on it. It is basically my weekend hauler and trailer puller a couple times a year. What do you think? Is there a way to troubleshoot if it is the intake gasket?

For me it's pinging and using oil

https://board.moparts.org/ubbthreads/ubbt...ow-to-test.html

Robert

As far as the Vacuum problem have you checked all your lines to be sure they aren't cracked or disconnected? A vacuum leak would cause poor performance. An easy plenum check is open the throttle body and look to see if there is oil in the intake.

Doesn't sound like a plenum leak. But I may be wrong.

As said, look down the throttle body with a flashlight. If you see oil pooled on the bottom on intake, the plenum is blown. Other signs including pinging with regular octane under medium to heavy throttle, high oil consumption with no external leaks, misfiring from oil fouled plugs, etc.

Lack of power may be an indicator as well, if you've plugged up the cats with oil residue then your engine can't breathe.

If plenum is blown, I recommend in addition to fixing the gasket, that you replace the spark plugs and O2 sensors too. Then determine the health of the cat, and replace if needed.

Have you had the truck for a long time and recently noticed it to be sluggish, or is it a recent purchase??? There's a lot to guess at here. The first thing I would say is that the 5.2 is slightly under-powered for a very heavy 2001 Ram. To see if the plenum gasket is leaking, remove your air filter assembly, open the throttle body, and look down into your intake. If it looks wet, it's leaking. As for the vents not blowing when you step on the gas, it might just be a bad blend door actuator. Those trucks are notorious for the blend door going bad.

When I was working in the dealership we would clamp off the pcv hose and pull off the vent that goes to the air filter housing at the valve cover. With that done put your thumb over the hole in the valve cover if it sucked your thumb in the intake gasket is blown if after a couple seconds you take your thumb off and it blows air out its building crankcase pressure and the gasket is good. Its about a 2 minute check when the engine is warm. But like said above if its bad enough you should see an abnormal amount of oil residue if you open the throttle and look in. For the vents switching to defrost when you are opening the throttle it could be the check valve in the vacuum line up by where the heater hoses go in to the core those went bad often. Check the intake first. If I had to bet I'm guessing the intake gaskets are bad if they are replace them and go from there.

Could be a plugged cat convertor , the blower changing is typical of a bad vacuum hose or one way valve.
My 01 Ram is not a real speed demon but never need any more power than is has.
Our 99 2500 Ran van with 5.2 easily pulled my open trailer and 68 Chrysler 300. 5.2 is no slouch.

Thanks for the info guys - I will poke around on it this weekend.

Vents diverting.... there's a check valve near the intake (vac line) to deter this that might be bad. There was also a check valve with a small reservoir on it from the mini vans we used to install on the trucks too that alleviated this issue.