I've read numerous threads about replacing the plenum gasket, i'm trying to find an answer about whether or not to put rtv on the manifold gaskets where they attach to the block and heads. Some say to put rtv around the coolant ports some say don't. some say to put rtv inbetween the runner gaskets and the gaskets at the front and back of the block. im getting confused with all the contradicting information so im looking for a solid answer. Where do i use rtv sealant when i do the plenum repair if im supposed to use any? Also i plan on using the hughes plenum kit but ive heard the supplied gaskets aren't the best. Are fel-pro gaskets a better option?
Thanks

 

I use RTV around the front coolant ports, on both sides of the gasket. Just a THIN bead, also in the corners where in intake/head gaskets meet the front/rear seals. Been doin' this a long long time. Trust me on this one.

The plenum gasket that comes in the fel-pro intake set was better than the one I got from hughes, although, I hear rumors now that the hughes kit COMES with the fel-pro set... When it shows up, check and see what ya got. if all you get is the steel gasket, use the one in the intake set.

 

Ok sounds good. Is there coolant ports at the back too? If so why no rtv there? Also what kind of rtv should i use, i have ultra black, and the blue. Would high temp red be a better option since its on the engine? Also what size fuel line disconnect tool do i need?
Thanks

 

There are ports on the back, but, there are no corresponding ports on the intake. I don't even think there are holes in the gasket...... so, not quite so critical there.

black will be fine.

Fuel line is 3/8ths I do believe. (conveniently enough, same size as the trans lines.)

 

I always use Fel-Pro when every I can... never an issue... the exception to this is Remflex for exhaust manifolds/headers.

Like HeyYou, I use silicone at the end of the rubber valley gaskets.

The gaskets that came with my Hughes FI Airgap (~15 months ago) were Made in India.

 

The part I've always been careful about was setting the manifold in place, aiming to set it once and never budge it again -- use four guide studs, set the manifold, start all of the other bolts, then replace the guide studs with bolts. Nuthin' to it but to do it.

Some manuals I've seen have said that blue RTV should be used around the coolant ports and black at the corners, and I've done it that way as well as to use all blue or all black, and have yet to have a leaker. My belief is that the more important thing is to set the manifold properly and never move it again, but I could be wrong.

 

Ok thanks everyone. I'll be sure to use rtv at the corners where the runner gaskets meet the front and back block gaskets as well as the front coolant ports. I'll definatly use 4 of the old bolts with the heads cut off as a guide. There is only 21000 km on this engine (reman) but my intake is leaking. I Pulled the throttle body and seen pooled oil, didnt even need a mirror to see it so id say its bad. Also has pinging under light load, and rough idle. when i start the engine it idles good for about 2 minutes, then idles rough and smells very rich as well as a loud sucking sound from the intake. If i rev it to 1500-2000 rpm and keep it steady for about 45 seconds to a minute then let off it'll idle good (ive let it idle for 30 minutes after doing that and it never missed). Does that sound like a bad pre cat o2 sensor caused by burning oil from plenum leaking. The cat is gutted so id say its been burning oil for awhile.

 

Yeah, I would replace the pre-cat O2 along with the plenum job.

 

Yes, it does. Those are the classic symptoms of a failing oxygen sensor, and nothing else behaves in quite the same way. Be sure that your replacement, if it doesn't come from the dealership, is either Denso or NTK brand. The Bosch parts react too quickly and confuse the hell out of our PCM's.

 

Ok cool, Is removing the intake manifold a difficult job or just time consuming? So far ive replaced the rear axle assembly, rear brakes, front wheel bearings, starter, and oil pan gasket on this truck. Ive done numerous brake jobs on different vehicles and some suspension work, so i do know how to work on vehicles. I havent done much engine work other than typical maintenance (plugs, wires, fluid changes).