350 vortec lifters (and other maintanence items)

[andyvr4]

UPDATE: over the weekend I've got the old intake manifold off and the leak that I was seeing is definitely coming from the lower intake manifold gasket. The entire gasket came out in one piece except right around the water feed on the front passenger side.

The lower intake manifold also has a significant amount of pitting right around where the water feed gasket goes so I suspect that this either was the cause of the gasket failure or a resulting factor of the leak and will probably cause significant problems if I try and just put another gasket over the pitting. Do you guys know where the best place to get a new lower intake manifold is or how to fix the pitting?

I also ran a compression test on the motor before I started pulling everything apart and got between 170-190 on all 8 cylinders. Being that this was on a cold engine I'm thinking these numbers probably indicate that the lower-end is still fine correct?

Thanks!

 

[qdeezie]

Grey RTV (along with the gasket) is your best friend when it comes to pitted coolant surfaces. Have not had a leak yet with this approach.

 

[asand1]

JB Weld

 

[ironman_gq]

I've cleaned up the pitted surface really well and filled the pits with JB, carefully sand it back flat when it hardens up and a light coating of gasket sealer should have things sealed up good.

Don't bother with the lifters unless they are making noise, those engine have roller lifters and they hold up great if the oil was changed somewhat regularly. If anything spend the money on a new water pump.
I honestly wouldn't put any more money into it unless there's other problems, they are a durable engine and the major complaints I hear from them other than the LIM is the occasional water pump and plugged catalytic converters causing some strange drive ability issues.

 

[andyvr4]

Originally Posted By: ironman_gq
I've cleaned up the pitted surface really well and filled the pits with JB, carefully sand it back flat when it hardens up and a light coating of gasket sealer should have things sealed up good.

Don't bother with the lifters unless they are making noise, those engine have roller lifters and they hold up great if the oil was changed somewhat regularly. If anything spend the money on a new water pump.
I honestly wouldn't put any more money into it unless there's other problems, they are a durable engine and the major complaints I hear from them other than the LIM is the occasional water pump and plugged catalytic converters causing some strange drive ability issues.


Thanks, I went ahead and ordered the dorman replacement intake manifold. I decided with all the problems these factory ones seem to have I'd almost like to just give the aftermarket one a try and see how it holds up!

I also decided not to do the lifters, like you were saying they're not known to give problems on these engines and it's really just an added expense (and possiblity of messing something else up) by replacing them!

I had also debated the water pump as well, but it just had a new water pump about 15k ago so I decided it probably wasn't worth it right now!

 

[andyvr4]

As an update to anybody that finds this thread I ended up not replacing the lifters and the factory lifters are completely silent so I'm glad I didn't go to the extra effort and expense of replacing them.

I did end-up replacing the intake manifold (with the dorman part), intake gasket (with the newer metal felpro), the distributor cap, distributor rotor, new acdelco iridium plugs, wires, all new heator hoses (at least the ones in the engine bay), and I put on the MFI fuel injection unit and everything appears to be working great. It fired right up and dropped to a happy 500 rpm idle with no noises out of the engine! I've put around 200 miles on it so far since firing it up and everything appears to be working great!

Thanks for all the advice while getting it back running!

 

[NYEngineer]

I'm a little late to the party, but I had a 98 Yukon that I bought in 2000 with 50,000 miles and drove it til 2010 with 230,000 miles.
I then gave it to my brother who ran it up to about 285,000 miles.
My truck had I think 3 total transmission rebuilds. Once, even got a new transmission computer.
I replaced the intake gasket at 96,000 miles and switched away from Dexcool. Never had another intake issue.
I swapped the EFI spider when the truck started detonating under load unless you ran it on premium. Helped a little.
Once, upon acceleration, I got a check engine light. When I checked it out, it said "Random Misfire". I can't remember exactly why that made me change the timing chain, but I did and home run, the truck ran perfectly after that. No more CEL for random misfires ever.
Brakes for those trucks are cheap. I was changing rotors and calipers almost annually.
Couple of upper ball joints... Catalytic converters and 02 sensors, nothing unreasonable considering how many miles I put on it.
I may have changed the distributor. Can't remember.
I did not change the cam and lifters.