OK, Plenum seal.

Bought new plenum repair kit from hughes.

I figured while I was in there, I might as well replace the timing chain/gears (125k miles).

While I was in there, i figured I'd replace the water pump, crank seal, bypass hose, thermostat, and temperature sensor.

Anything else I should replace while I'm in there?

Heres my full list:
Plenum plate
Plenum gaskets (upper and lower)
Thermostat and gasket
Temperature sensor
Distributor and rotor
Timing set
Water pump
Water pump bypass hose
lower radiator hose
Front crank seal
oil/filter

I stopped short at the other gaskets seals because I haven't heard of anyone having issues with them (are there any others I should replace?)

Plugs and wires are under 1k old, so I was planning on re-using them unless any appear fouled.

 

Other than getting a new PCV from the dealer, I'd say you are good to go.

Edit: And maybe flush the heater core.

 

Distributor cap and rotor.

 

I think that is in his list.

 

Reading > Me

 

-new o-rings for the injectors. It's not recommended that you reuse those when you pull the injectors out.

 

No need to pull the rail and injectors, unless you want to clean them. The rail can stay in the keg.

additional parts:
-Water pump needs a gasket.
-Timing chain cover needs a gasket, should come in a kit with the WP gasket, can also get a felpro kit with the sleeve N' seal for the front crank seal with those 2 other gaskets.
-Will need some RTV for the corners of the manifold gaskets. I recommend the orange high temp permatex stuff. This stuff will also work to reseal the oil pan gasket when you rip it pulling the timing cover off.
-Might want some of that gray coolant RTV to reseal the heater return line tube, if you can get the old one out of the old water pump undamaged. If not, they make a HELP! replacement part for that tube, about $10. Might want to buy it and return it if not needed, as you can't put the truck back together without it.
-2 gallons antifreeze, and 2 gallons of distilled water.
-I think a 5/16" fuel line disconnect tool, or else its 3/8". I have a set, so I just remember to use the gold colored one.
-dielectric grease for the spark plugs, and terminals on cap. Keeps moisture out and helps with hard starts on rainy days.
-inch/lbs torque wrench. You can't avoid using it and expect the manifold gaskets to seal properly.
- #25 torx head screwdriver if you want to pull the sensors off the throttle body and clean it.
- Harmonic Damper puller to get the Harmonic Damper off without trashing it. use the same type that they use for steering wheels, not the jaw puller type.
- heavy duty Strap Wrench and I believe a 38mm wrench to remove the fan clutch, I just used a large crescent wrench. The strap wrench goes on the WP pulley and the crescent wrench goes on the fan clutch nut near the WP. Get a strap wrench that the strap doubles over on itself, as they hold tighter. The Lowes Kobalt brand worked well for me.
-You'll need a way to remove the big *** crank nut off the crank. Gotta buy the right sized socket. An impact wrench will work, but just a breaker bar will probably spin the engine before the bolt lets go. This tool works by screwing into the harmonic damper where the pulley bolt holes are, and then you can put a 1/2" drive socket into the end of the square hole and get counter torque on the crank bolt.
- may want to add a timing chain tensioner to the mix. It'll take up the slack as the new chain gets older. Not essential, but good maintenance practice, IMO.
- antiseize for the spark plugs and any water pump or timing cover bolts that go into the water jacket.
- Loktite for the cam gear bolt.

 

Ya, I tried that on mine, could never get the fuel disconnect apart. So I just pulled the injectors up still attahced to the rails and ziptied the rails back out of the way. It worked out better this way for me since I was putting on the new modded kegger in place of my original intake, so my injectors had to come out anyway.

 

fuel line disconnect is 3/8". spray a little wd40 in it if its stubborn.

timing cover gasket and front seal comes as a set. get the felpro.

intake manifold gasket (4 pieces - sides and front/rear) might come from hughes if you bought the whole kit.

i think your 98 has the single temperature sensor in the manifold. its a good idea to replace it since it'll be dirty and crusted. if your truck has the 2 temp sensors (i doubt it), replace them both.

you'll need a harmonic balance puller. you can rent/borrow one. 1-1/4 socket on crank bolt. you'll need an impact wrench or a clever way to hold the engine from turning. there are some pictures here on DF of clever home made tools to hold the engine and the water pump pulley. search them out.

rtv where rtv goes.
anti-seize on spark plugs.
forget the timing chain tensioner. not oem. not needed. (sorry squirrels).

if you have the time and energy, remove the block drain plugs on each side behind the engine mounts and flush the block and back flush the heater core. when reinstalling the pipe plugs, use rtv, anti-seize, or teflon and just snug them.

good luck.

 

I found that some of the quick disconnect tools dont have a deep enough groove for a dodge. Its usually the 5 pack of plastic ones that suck. The five pack of metal ones I picked up at Harbor freight have worked great.