The Stupid Engine Questions Thread

[Erik the Awful]

Eric,
Only the upper half of the intake is plastic, and no coolant in the upper half. That plastic portion of the intake houses the FI spider.

Read carefully. I said intake manifold GASKET.

 

[alpinecrick]

I've changed or helped others change a half dozen Vortecs and a couple TBI's. My 91 K2500 started seeping a tiny bit at around 250K, when I sold it at 285k, it was still just a seep.

Most of them will leak at the rear of the intake, but some do leak at the front. Usually they leak to the outside, but on occasion will leak to the inside (my 96 G1500 did that) and eventually you'll get milky engine oil.

I bought my 97 K1500 from the original owner who worked in the parts dept at a GM dealership, and he was aware of the issues with GMT400's. He preemptively changed the intake gaskets at around 120K and they found it was just beginning to have a tiny, tiny seep that couldn't be seen or smelled. If you smell coolant when the truck is sitting there idling it's usually the intake leaking in my experience.

 

[alpinecrick]

Read carefully. I said intake manifold GASKET.

You are right, my bad. And I complain about others reading comprehension.......sheesh.

 

[evilunclegrimace]

Aside from normal parts lifespan, did the TBI 350s have the same failure issue with intake gaskets as the vortec?

I’m tentatively looking at a 95 Z71 for my son. It has 140k on it.

They fail after time, the failure is caused by the aluminum intake manifold expanding and contracting at a different rate than the cast iron cylinder heads. I would plan on changing the intake gaskets IF you by the '95 for your son. I would consider it good preventive maintenance.

 

[Awest623]

They fail after time, the failure is caused by the aluminum intake manifold expanding and contracting at a different rate than the cast iron cylinder heads. I would plan on changing the intake gaskets IF you by the '95 for your son. I would consider it good preventive maintenance.

That and it ain't hard at all. Most people think anything related to the engine is gonna put them way over their head. But honestly, engine work is 100x easier than those damn bushings in the front end. I'll admit I was hesistant when I first changed out my spider for mpfi. Not long after that I tore the thing down and put a cam and rockers in it. Now it has an 0411 that I've tuned and is fixing to get bigger injectors and a supercharger. If you ever get stuck, just ask on here. There's hundreds of years of experience with these trucks on this forum.

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[east302]

Thanks guys. The 95 fell through, but it looks like there’s less “stuff” in the way compared to my two 98’s.

I’ve done the intake on those and I agree - if you have a manual and tools, there really isn’t much to them. If some dude in Detroit could put it together then I figure I can take it apart.

 

[jeff1953]

My truck is a 1993 1/2 ton 4x4 with a 4.3 v6 it has developed a random knock its quiet at start up it mainly does it under light acceleration but its alot louder than a spark knock I have narrowed it down to the area of the flywheel inspection cover or the oil pan with a mechanics stethoscope.

Now I have heard these engines had a problem with the flywheel or flywheel bolt that give off a rod knock type sound does anybody here have any other ideas or have heard of this type issue with the flywheel?

I suppose it's possible could be a bolt or cracked flywheel would be better then a main or a rod, or toque converter.

 

[jeff1953]

Yes I have a stupid question just traded for a 1993 GMC sierra 3500 454 my first big block what is this tawanda 454 up to a plain 454.

 

[bigfutz]

I recently developed something new on my 95 350 TBI, I call it stumbling at idle. Mine seems to happen only when engine is warm, AC is on, and in Drive with the brakes on (at a traffic light for instance). It stumbles just briefly but randomly. I was thinking something with the Idle Air Control (IAC)? I don’t think I’ve done anything recently to cause it, unless putting in a new air filter WIX 42098 and fuel filter WIX 33481 counts.

 

[Donald Mitchell]

They fail after time, the failure is caused by the aluminum intake manifold expanding and contracting at a different rate than the cast iron cylinder heads. I would plan on changing the intake gaskets IF you by the '95 for your son. I would consider it good preventive maintenance.

Cast iron intakes were bad about leaks too.