Upgrading to mpfi should i do the lower intake gasket?!

[McSweeney]

Hi so i just got my new mfi spider injectors and I realized that these trucks are infamous for the lower intake manifold gasket leaking. To put the injectors in you have to take most of the stuff off that is needed to do the gasket job so would it be wise to do it too? I only ask because i havent had to remove a distributor before and im pretty worried that ill f up the timing. Any suggestions?

 

[Joe Dirte]

Mark ur timing on TDC #1 if u wanna do it. Itll help a lot! I got lucky stabbin mine in (4th or 5th time). I go by the motto dont fix what aint broke. My 305 was 200k some odd miles when i did injectors. Didnt mess with lower. Engine ran fine til day trans puked.

 

[McSweeney]

Mark ur timing on TDC #1 if u wanna do it. Itll help a lot! I got lucky stabbin mine in (4th or 5th time). I go by the motto dont fix what aint broke. My 305 was 200k some odd miles when i did injectors. Didnt mess with lower. Engine ran fine til day trans puked.

yea you’re right i should probably leave it alone and just do the injectors, i have bad luck with fixing things that didnt need fixing lol.

also, how many miles did u get on that motor? Ive got 202k on ky 305 right now and it runs great im just getting a little worried itll throw a rod or bearing or something

 

[Joe Dirte]

yea you’re right i should probably leave it alone and just do the injectors, i have bad luck with fixing things that didnt need fixing lol.

also, how many miles did u get on that motor? Ive got 202k on ky 305 right now and it runs great im just getting a little worried itll throw a rod or bearing or something

It was still runnin when i pulled it. 203k when 4L60 **** the bed. Upgraded to 350 n 4L80. Still ran just fine. Cant sell it so its just sittin in garage on floor.

 

[stutaeng]

I did the intake manifold gasket (no injectors work though) on my 4.3 that had about 220k, but had problems reinstalling the distributor. I felt bold and tried to do the TDC, and installed it 180 off. Struggled for like 2 days. What I should have done is just mark it and reinstall it in the same spot. Finally had to get my mechanic to install it. Engine lasted to 260k when I pulled it due to low oil pressure. Injectors were still original and surprisingly still passed an injector balance test.

On another truck I have with the 5.7 I did the injectors because one was stuck closed. I left the lower intake manifold gasket alone, since it wasn't leaking. Truck had like 204k when I bought it and after 3 years it's at 208k. I don't drive it daily. It's a weekend work truck.

 

[alpinecrick]

yea you’re right i should probably leave it alone and just do the injectors, i have bad luck with fixing things that didnt need fixing lol.

also, how many miles did u get on that motor? Ive got 202k on ky 305 right now and it runs great im just getting a little worried itll throw a rod or bearing or something

I currently have 262k on my 96 G1500 with the 5.0, 267k on my K1500 with the 5.7.

Odds are the lower intake has had the gaskets replaced already.

Lower intake removal also involves disconnecting the heater hose from the intake without breaking the connector (which can be problematic),removing EGR line from the manifold (which can problematic), unbolting AC compressor, preferably loosening AC compressor bracket and moving it forward or removing it altogether (which involves removing ps pump pulley). Plus the distributor………..

 

[mattillac]

Did the spider injector replacement on mine (a couple of years ago) and......

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.....IIRC, unlike when I did the lower intake/gaskets (many years ago), the oil, the coolant and the distributor stayed in place (while replacing the injectors).

When I did remove the distributor for the lower intake/gaskets, I thoughly marked reference points for the position of the rotor and shaft etc, must have worked alright, because when I did finally check the CMP retard when torque pro came out(some years later), turns out it was right where it should be.

Food for thought.

 

[McSweeney]

Awesome thanks so much everyone!!!

yea alpinecrick odds are it probably was already replaced so I probably should just leave it alone because i might break more stuff then its worth

so my 5.0 is great and all and i know theyre pretty comparable reliability wise with the 350, does anyone know anything i should do to keep up longevity ? Im very proactive with my repairs and change my oil every 3500 with synthetic 10w30 and check plugs and everything every few months but as far as upgrades go should i do anything other than the injectors? Like would replacing the oil pump be something that would be good?

 

[Joe Dirte]

Awesome thanks so much everyone!!!

yea alpinecrick odds are it probably was already replaced so I probably should just leave it alone because i might break more stuff then its worth

so my 5.0 is great and all and i know theyre pretty comparable reliability wise with the 350, does anyone know anything i should do to keep up longevity ? Im very proactive with my repairs and change my oil every 3500 with synthetic 10w30 and check plugs and everything every few months but as far as upgrades go should i do anything other than the injectors? Like would replacing the oil pump be something that would be good?

If ur pressure readin ok i wouldn't mess with it. Id try switchin to the recommended 5w30. I was runnin synthetic blend 5w30 in my 305 n never had any severe oil consumption issues. I lazily changed it "around" 5000 miles and always came out just a lil darker than it went in. Just keep the tires rotated, check the tread, check brakes since ull have tires off. Typical crap. Truck should last a while. I had a veat to death 4.3 years ago n though it was tbi and i was young n dumb i ran the dog snot outta it with 350k miles on original motor. Sold it with 375k n it never gave me any issues and maintenance wasnt a high priority for me on that truck. Now a days bein almost 20 yrs older, somethin seems "off" with a vehicle im checkin it immediately. Even when i ride with my folks since im their mechanic.

 

[alpinecrick]

I would switch to the recommended 5-30 too………