Okay guys. First time poster here, just have a quick question about my 94 team with the 5.9... 2 years ago it started smoking and I stopped daily driving it. Well the truck has sentimental value and now I'm ready to get it back on the road and have been considering an engine swap thinking the rings were shot... well I've recently been told that a leaking plenum could cause my truck to smoke, is that the case? Truck has 213,000 miles on it and to my knowledge the plenum gasket has never been replaced and I'm the second owner of the truck and my grandfather owned it first... truck still runs strong, no engine misses, just smokes... does have vacuum issues bc back when it was my daily I battled the vacuum for the ac controls during the summer, would lose vacuum under heavy acceleration... so does this sound like my plenum??? Thanks

 

Replace the plenum gaskets and the pcv valve with one from mopar. Couldn't hurt, and they're cheap, easy to do.

 

Honestly, I would take a few minutes and do a compression check on it first. With that many miles on it, it could be worn rings. Pick up a cheap compression tester from somewhere like harbor freight and test the cylinder compression before you dump any substantial time or money in it. Your plenum gasket may be blown, but the smoke may be from a bigger issue.

 

I gotta agree with this assessment. That is a lot of miles on the motor.....

 

If you replace the plenum, it's a really good time to replace the timing chain and water pump. Burning all that oil can also clog your catalytic converter. A cylinder leak down test or a compression test would be a good idea. I have a feeling that if you fix the plenum, timing chain, clean the passage for the IAC, fix any vacuum leaks, change the plugs, cap, rotor, and O2 sensor, make sure the Cat isn't plugged, it will run very well for a long time yet.

 

The cat has been gutted. Since it's a 94 it doesn't have a downstream 02 sensor so I gutted the cat YEARS ago when the internals broke loose and were rattling. The 02 sensor was also unplugged sending the ecm into bypass, made the truck run ALOT better but as I reflect back it was around the time of all this maybe a little after I started noticing the smoke on heavy acceleration

 

My grandfather owned this truck and it was babied for the 170,000 miles before I took possession. So high miles yes, but not a rough life. But again, I know that it COULD be worn rings... i'm just curious to see if I can solve the smoking issue on the old girl until I can drop a new one in or rebuild this one...

 

I'm a level 3 diesel mechanic, so I know the "probability" of it being rings. I'm simply just curious as the "possibilities" of it being the plenum or something else... I'd much rather pull the plenum, find the gasket bad and repair that and get by for awhile vs. Pulling the engine and tearing it apart... the truck has been retired from a daily driver, just wanna be able to drive it to work if I want and not kill all the mosquitoes for that 35 mile trip. Lol

 

Could be plenum, PCV valve, valve guides/seals, or rings...... Won't know till you poke at it a bit.

 

Im gonna look down the throttle body when I get home from work and see if I can see any oil in the bottom of it. I was basically just curious if anyone had the same issue, or if the plenum would actually cause it to smoke. I know the dodges are notorious for the plenum leaking, just curious if that would cause it to smoke... lol. It did show all the signs of it being bad i.e oil consumption, vacuum issues under heavy acceleration. Lol