plenum gasket; now or later?

[regcabsplz]

Currently doing a few things in the engine bay, I’m pretty sure the previous owner(s) didn’t do the plenum gasket on this engine but from what I can tell it is intact and functional. purchased the truck with 110K miles I’m a little over 122K now.

is there a certain mileage that I can count on it needing done or is it just a ticking time bomb that I should take care of sooner rather than later?

thanks in advance.

 

[Joe w.]

If it's leaking fix it. If not then it's up to you to decide. I've been told you can stick a magnet down thru the throttle body and if it has oil on the end of it then it's leaking.

 

[Robeffy]

Mine intake went, while I was towing a small RV trailer... I had horrible gas mileage, and the engine knocked on any load at all. No knocking at idle or going down hills. I joked that I was burning more engine oil than gasoline....Nearly 1000 km drive home..
When I pulled the intake, and took it apart, the inside of the intake was oily as heck...
The kit from Hughes did the trick, and has a lifetime guarantee.
My truck instantly ran way better, and after I replaced the plugged CAT, power like crazy, from a 318 / automagic, stock rear gears. I find myself pulling away from most cars and trucks at the lights.
If you have a problem with this, the Mass Air Flow does not measure the air being sucked in thru the crankcase, so the engine runs lean. A great way to get knock, and if you ignore it, you can really wreck the motor.
It was quite a few hours work, but well worth it.
While the intake was apart I looked up a simple upgrade to the runners on the intake, a die grinder did the job, I assume it was good for a few hp. I also gasket matched the intake and new gaskets to the head, cleaned up the runners a bit.

 

[Yeret]

^ Pretty much what he said.

In my case, my engine was burning half a quart of oil about every 150 miles. Knocked like hell under load and cold starts eventually began yielding a less-than-amusing cloud of blue smoke. I don't even wanna begin to recount how many spark plugs met their end during this era.

After removing the manifold (and breaking one bolt in each head, %@%&*^$@!@$%^&!), I removed the pan, and what used to be a gasket came off in something like six, rock-hard pieces.

 

[crazy jerry]

probly look into the manifold and see if theres a bunch of oil. even if its leaking but the engine runs fine theres no urgency to change it. i suspect mine leaked for years as it would need a qaurt every 3k during highway driving. still ran well. no smoke ever. never did replace it before i sold the truck. it looked like a fairly easy job though