93 GMC 350 intake

[sixteenacrewood]

Hi everyone
first time here with a question.

I have a 350 with 421,000 miles blowing white smoke and leaking coolant on top of the intake.

She uses about 16 oz of coolant per 200 mile round trip to a farmers market i work.

It has been doing this for about 8 years, but has been blowing a bit more smoke/steam this year

I want to get another year or so out of this motor so I am thinking about replacing the intake manifold and gaskets, well within my abilities.

My question
the motor has a fair amount of gunk and sludge build up i think, it has been mistreated through most of her life.

Do I run the risk of dislodging sludge and causing engine failure in the near future?

Should I not do the intake swap?

The truck drives like new, decent acceleration and will still pull a 6000 lb load

never been wreaked, 0 rust, no major dents, new transmission, front end, brakes.

If I decide to do the intake, do I clean out the sludge build up?

Thanks for any help / past experiences you can offer

Steve

 

[littlemlittle]

Cover the important stuff like electronics and such and the pressure wash and gunk engine degreaser before you start the tear down. You mentioned intake swap.. why swap and not just go back to oe since it pulls good now?


Also when you're in there. Just cover all of the holes for the head and such and get a small bristle brush and brake clean it, then after all is cleaned spray wd40 to keep it lubed (except gasket surfaces).


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[sixteenacrewood]

Actually I'm not sure why I have been planning on replacing the intake, I thought with 400k miles I was supposed to.
I imagine its cast iron. do these ever warp?

You think it would be safe to reuse the old intake?

 

[Eveready]

I would think it would be fine to do so. I haven't heard of many intakes wearing out. I expect new gaskets may help with the coolant leaking issue if that is where it is. Sounds like you have a pretty good old truck and with the lack of rust definitely worth keeping in the road.

 

[RawbDidIt]

While you're at it, I'd recommend replacing the head gasket as well. Wouldn't worry about replacing the intake unless you see signs of warping. Cast iron can take just about anything you throw at it. Just give everything a good cleaning like everybody else mentioned and inspect the mating surfaces for imperfections that might lead to gasket failure.

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[someotherguy]

The intake is cast aluminum. No need to replace it unless the leak has pitted the hell out of the gasket mating surfaces near the cooling passages. No need to clean any sludge out of the inside of the intake. Just replace the intake gaskets. You'll also need a throttle body gasket, EGR gasket, thermostat gasket (replace the thermostat too), and fuel line O-rings to complete the job.

I did my '94 years ago, and did a picture write-up of it: http://www.someotherplace.com/bb/proj/rh94intake.html

This will be the same as your '93 with exception of a couple very small details like your '93 doesn't have the purge solenoid.

Richard

 

[Schurkey]

Any chance the leak is just the heater-hose quick-connect fitting? The original ones are known for corroding and seeping. The aftermarket replacements were much more durable, at least when I bought mine twenty years ago. Ten bucks for a new quick-connect and an O-ring and you'd be set.

If you do pull the intake, be sure to use the correct gasket set. The TBI intake manifold takes a special TBI intake gasket set.

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