Plenum Gasket: What is it, where is it and what should I do about it? *INFO*

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Johnn123

Senior Member
Joined
Sep 23, 2013
Posts
2,090
Reaction score
1,099
Location
Ontario
Ram Year
2010
Engine
5.7L Hemi
Great post guys, lots of info! If I may add a bit, when changing the plenum gasket you may as well just do a full tune-up and replace commonly wearing parts on these trucks. I'm looking at you water pump and timing "chain"! Always recommend a new dizzy cap, rotor, spark plugs and wires, a new front o2 sensor, a new catalytic convertor, a new water pump and a good double roller timing set. The o2 and cat are a good idea because if your plenum is blown, all the burning will foul your o2 and cause poor mileage (well poorer then usual LOL), and a clogged cat, as DD94 said, will lead to cracked heads if left long enough! Water pumps areknown to go in these and your just a few bolts more from pulling it so might as well. Then you're at the timing cover so may as well pull it and install a real chain in there. Stock ones stretch over time. Seafoam when done! My 2 cents.
 

quadcab

Member
Joined
Oct 12, 2013
Posts
97
Reaction score
11
Ram Year
2001
Engine
360 Magnum
I willing to bet that the sucking noise yall are complaining of is the lack of a gasket between the air filter housing and the throttle body.

One more note for the plenum. If your on a budget you can do what many have done and reuse the stock plenum plate and shorten the bolts by a 1/4". While I had mine off I pulled all the lifters and cleaned them out really well as well as the pushrods.

Sent from my SAMSUNG-SGH-I537 using Tapatalk now Free
 
Joined
Apr 15, 2014
Posts
35
Reaction score
2
Ram Year
1997
Engine
magnum 5.9
Hi I am new to this forum and I have just bought a 1997 dodge ram 1500. The engine drinks about 1qt or more within 100 miles. (previous owner did not tell me) I took it to a shop and asked for a compression/diagnostic test to be performed on the engine. They did not do one and said they jacked it up walked under it and there were no leaks so it must be the rings and said I need a new motor and quoted me one for 2200$ motor+labor total. The only smoke that comes out of my truck is when I first start it and get going then its fine afterward. There is no noise or anything. It runs fine. I am going to take it to a 2nd shop for a 2nd opinion. I hope it is just the plenum gasket.

Edit: motor has 136k miles on it
 
OP
OP
dodge dude94

dodge dude94

Millennial Boomer
Joined
Sep 5, 2013
Posts
27,745
Reaction score
6,426
Location
East Texas
Ram Year
1998 Ram 1500
Engine
5.9 Magnum
Being that the engine only has 136k on it, unless it was either A) beat hard its entire life or B) it's not the original engine for what ever reason, the rings are not gone. You likely have a plenum problem at that age with MAYBE some valve guide seals.
 
Joined
Apr 15, 2014
Posts
35
Reaction score
2
Ram Year
1997
Engine
magnum 5.9
Being that the engine only has 136k on it, unless it was either A) beat hard its entire life or B) it's not the original engine for what ever reason, the rings are not gone. You likely have a plenum problem at that age with MAYBE some valve guide seals.

Thank you for replying. Is there anyway the shop can tell for sure if its the plenum before replacing it? I am not mechanically inclined at all. I am just hoping they will be able to tell before I have them break into it and change it. Thanks again!
 
OP
OP
dodge dude94

dodge dude94

Millennial Boomer
Joined
Sep 5, 2013
Posts
27,745
Reaction score
6,426
Location
East Texas
Ram Year
1998 Ram 1500
Engine
5.9 Magnum
Thank you for replying. Is there anyway the shop can tell for sure if its the plenum before replacing it? I am not mechanically inclined at all. I am just hoping they will be able to tell before I have them break into it and change it. Thanks again!

With the engine going through a large amount of oil like that, you could actually take the throttle body assembly off the engine and look down in there to see oil pooling.
 

WarrenRam

Senior Member
Joined
May 14, 2013
Posts
490
Reaction score
210
Ram Year
N/A
Engine
N/A
Thank you for replying. Is there anyway the shop can tell for sure if its the plenum before replacing it? I am not mechanically inclined at all. I am just hoping they will be able to tell before I have them break into it and change it. Thanks again!

With the engine going through a large amount of oil like that, you could actually take the throttle body assembly off the engine and look down in there to see oil pooling.

Problem is, with him not being too mechanically inclined they could possibly rip him off with him none the wiser (sounds like they're already trying. I mean really, they simply looked under the truck and announced you needed a new engine??). Do you have a friend or someone you trust that can go through the TB and possibly even do the plenum repair before you drop that kind of coin on a new engine?
 
Joined
Apr 15, 2014
Posts
35
Reaction score
2
Ram Year
1997
Engine
magnum 5.9
Problem is, with him not being too mechanically inclined they could possibly rip him off with him none the wiser (sounds like they're already trying. I mean really, they simply looked under the truck and announced you needed a new engine??). Do you have a friend or someone you trust that can go through the TB and possibly even do the plenum repair before you drop that kind of coin on a new engine?

You are correct. This shop simply put it on a lift walked under it and saw no leaks and said since its drinking 1qt/100 miles that its bad rings and I need a new motor. I was 10 minutes from telling them to buy the new engine and put it in before my brother said I need another opinion. I am not going back to that shop. I am looking for someone local to do this for me now.
 
OP
OP
dodge dude94

dodge dude94

Millennial Boomer
Joined
Sep 5, 2013
Posts
27,745
Reaction score
6,426
Location
East Texas
Ram Year
1998 Ram 1500
Engine
5.9 Magnum
Problem is, with him not being too mechanically inclined they could possibly rip him off with him none the wiser (sounds like they're already trying. I mean really, they simply looked under the truck and announced you needed a new engine??). Do you have a friend or someone you trust that can go through the TB and possibly even do the plenum repair before you drop that kind of coin on a new engine?

Brilliant point there, sir.:happy160:
 

WarrenRam

Senior Member
Joined
May 14, 2013
Posts
490
Reaction score
210
Ram Year
N/A
Engine
N/A
You are correct. This shop simply put it on a lift walked under it and saw no leaks and said since its drinking 1qt/100 miles that its bad rings and I need a new motor. I was 10 minutes from telling them to buy the new engine and put it in before my brother said I need another opinion. I am not going back to that shop. I am looking for someone local to do this for me now.

Smart move. So, where are you at? There are plenty of folks here who have Magnum plenum experience and would be glad to help out for the price of a few pints of their favorite beer. On the other hand, I wish I was smart enough to tell that you need a new engine just by looking at the ground under the truck! :smoke2:
 
Joined
Apr 15, 2014
Posts
35
Reaction score
2
Ram Year
1997
Engine
magnum 5.9
Smart move. So, where are you at? There are plenty of folks here who have Magnum plenum experience and would be glad to help out for the price of a few pints of their favorite beer. On the other hand, I wish I was smart enough to tell that you need a new engine just by looking at the ground under the truck! :smoke2:

I'm in Martin, TN. I am willing to pay anyone labor of course for the repair and parts etc. The shop I was at quoted me 400$ for a plenum gasket repair total but still suggested a new engine saying it was rings because the engine wasn't leaking oil (I'm serious lol) the 400$ didn't scare me for the repair but the fact they just kept on wanting to sell me a newer engine...
 
OP
OP
dodge dude94

dodge dude94

Millennial Boomer
Joined
Sep 5, 2013
Posts
27,745
Reaction score
6,426
Location
East Texas
Ram Year
1998 Ram 1500
Engine
5.9 Magnum
I'm in Martin, TN. I am willing to pay anyone labor of course for the repair and parts etc. The shop I was at quoted me 400$ for a plenum gasket repair total but still suggested a new engine saying it was rings because the engine wasn't leaking oil (I'm serious lol) the 400$ didn't scare me for the repair but the fact they just kept on wanting to sell me a newer engine...

I paid like low $500 and change for my plenum repair, but I agree, the shop wanting to sell you an engine is disturbing.
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,413
Reaction score
3,179
Location
under the truck
Ram Year
81 93
Engine
5.2
before doing the plenum repair you might want to have a compression test and possibly a leak down test done on your engine. it is possible your engine is worn out but a compression and leak down test will tell you. you may also want to possibly replace your PCV valve with a mopar one from the dodge dealer. if the pcv valve is bad it can allow the engine to burn more oil than it should.
 

Merc225hp

Senior Member
Joined
Jan 13, 2013
Posts
5,145
Reaction score
3,130
Location
NA
Ram Year
truck
Engine
gas
Blue puff on start up is most likely valve seals. Valve seals are cheap and they can be changed out with the heads still on the motor. You just need some minor special tools. As posted above start with a comp or leakdown test see what shape the motor is in before you start spending money on it.
 
Joined
Apr 15, 2014
Posts
35
Reaction score
2
Ram Year
1997
Engine
magnum 5.9
Blue puff on start up is most likely valve seals. Valve seals are cheap and they can be changed out with the heads still on the motor. You just need some minor special tools. As posted above start with a comp or leakdown test see what shape the motor is in before you start spending money on it.

Thanks for the reply's everyone. I am going to attempt to replace the pcv today after work. I read it is very easy that no one can mess it up lol we'll see. Can y'all give me an idea of how much a comp/leakdown test would run me? I want to compare when I call this shop to see if they are ripping me off as well. Thanks
 
OP
OP
dodge dude94

dodge dude94

Millennial Boomer
Joined
Sep 5, 2013
Posts
27,745
Reaction score
6,426
Location
East Texas
Ram Year
1998 Ram 1500
Engine
5.9 Magnum
Thanks for the reply's everyone. I am going to attempt to replace the pcv today after work. I read it is very easy that no one can mess it up lol we'll see. Can y'all give me an idea of how much a comp/leakdown test would run me? I want to compare when I call this shop to see if they are ripping me off as well. Thanks

A word of caution with the PCV: if it doesn't come out without making creeking noises, start the engine and let it heat up a bit. If it still doesn't come out, you have a problem. lol When I replaced mine, it snapped in half and there was a major pucker factor when it did.
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,413
Reaction score
3,179
Location
under the truck
Ram Year
81 93
Engine
5.2
you probably want to run the engine for a bit before you replace it anyways just to soften up the grommet a bit.

i don't know exactly how much a compression or leak down test would cost but i have a feeling most places would charge at least $50-$100 but a leak down test does usually require some somewhat expensive tools. you cold get a compression tester for less than $30 if you want to do it yourself
 
Joined
Apr 15, 2014
Posts
35
Reaction score
2
Ram Year
1997
Engine
magnum 5.9
you probably want to run the engine for a bit before you replace it anyways just to soften up the grommet a bit.

i don't know exactly how much a compression or leak down test would cost but i have a feeling most places would charge at least $50-$100 but a leak down test does usually require some somewhat expensive tools. you cold get a compression tester for less than $30 if you want to do it yourself

I called another auto place. I told the owner what was happening he said it sounds like rings also. I am scheduled to have the test ran tomorrow afternoon to check the rings first (72$) then we will go from there. Thank you to everyone who has replied. Maybe it won't require a new engine. The guy I bought it from did not tell me about this and of course it was full of oil and only test drove it a few miles so of course the oil level was still fine. Also it was at night when I test drove so I never saw the smoke on first start up. I did text the guy and tell him that it wasn't right and I know he didn't tell the truth. This guy actually replied telling me to grow up and sell it or keep it cause I have a great truck then he said he was going to do things to my gf lol I can't even post what he really said. Sad part is he is in his 40s...oh well once I get this oil burning fixed I'll be good to go :) must stay positive (my first dodge)
 
OP
OP
dodge dude94

dodge dude94

Millennial Boomer
Joined
Sep 5, 2013
Posts
27,745
Reaction score
6,426
Location
East Texas
Ram Year
1998 Ram 1500
Engine
5.9 Magnum
I called another auto place. I told the owner what was happening he said it sounds like rings also. I am scheduled to have the test ran tomorrow afternoon to check the rings first (72$) then we will go from there. Thank you to everyone who has replied. Maybe it won't require a new engine. The guy I bought it from did not tell me about this and of course it was full of oil and only test drove it a few miles so of course the oil level was still fine. Also it was at night when I test drove so I never saw the smoke on first start up. I did text the guy and tell him that it wasn't right and I know he didn't tell the truth. This guy actually replied telling me to grow up and sell it or keep it cause I have a great truck then he said he was going to do things to my gf lol I can't even post what he really said. Sad part is he is in his 40s...oh well once I get this oil burning fixed I'll be good to go :) must stay positive (my first dodge)
Oh damn. Time to call the po-po on this ********! :smoke2:

Good luck with the engine.
 
Top