Is It True?
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13,378 Posts
all Gen III motors have a plastic resin intake, yes.
The Gen IV also have plastic intakes.
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2,426 Posts
I don't see how one could have fouled. There is not coolant running through them, so it's not like anything inside of them is under pressure. The only thing I could see is someone making smacking a wrech or something off of one of the runners or something and then cracking it.
Ford's modular motors also use the composite intake, but they do have coolant running through them. Some of their earlier designs had problems cracking (such as my buddy with a 96 GT). I'm not sure when they switched, but the newer style has a cast section that's under pressure so it's not going to leak.
If you are worrying about the life of the "plastic" intake, don't.
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13,378 Posts
fouled? I have heard of some problems with the gen III motors, but nothing to do with the Intake.
Only down part is that it cant be ported like an aluminum or other metal intakes. Dont get too worked up about it, nothing all that important.
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13,378 Posts
Melted eh? Man, they have more problems then a plastic intake to worry about.
GM has used plastic intakes for 10 years. Ford and Chysler use in on almost all their models. A lot of Foreign cars use them too. A few have had limited problems, but most if not all were production problems not design.
Engines that use plastic intakes:
GM
96+Vortec V8s
94+ GM 3800 (not series III or supercharged engines)
Northstar
3500 DOHC
Chryslers:
00?+ 3.3, 3.8
2.4
2.7,3.2,3.5
Hemi
Ford:
3.0
3.0 DOHC
4.0 SOHC
And lots more.
-T
Engines that use plastic intakes:
GM
96+Vortec V8s
94+ GM 3800 (not series III or supercharged engines)
Northstar
3500 DOHC
Chryslers:
00?+ 3.3, 3.8
2.4
2.7,3.2,3.5
Hemi
Ford:
3.0
3.0 DOHC
4.0 SOHC
And lots more.
-T
Plastic intakes have the advantages of giving a smooth surface to the ports and airways which decreases any turbulence. But the main advantage is that they cost less and are lighter.
I have heard that GM has had problems with these intakes particularly sealing. In fact, some motors will exhibit hydrostatic lock due to coolant loss into the cylinders.
Motor Magazine may have been the source.
The other possible problem related to sealing is torquing the screws to obtain a seal without cracking the unit. Hopefully, the part has been designed with this in mind.
My apprehension is that parts are now being designed with the warranty in mind. What happens to those customers that keep a vehicle for 5+ years-into the 100,000 mile range? Everybody applauds some gadget that performs well on a new car but will it hold up to fatigue induced by vibration and temperature variations?
I have heard that GM has had problems with these intakes particularly sealing. In fact, some motors will exhibit hydrostatic lock due to coolant loss into the cylinders.
Motor Magazine may have been the source.
The other possible problem related to sealing is torquing the screws to obtain a seal without cracking the unit. Hopefully, the part has been designed with this in mind.
My apprehension is that parts are now being designed with the warranty in mind. What happens to those customers that keep a vehicle for 5+ years-into the 100,000 mile range? Everybody applauds some gadget that performs well on a new car but will it hold up to fatigue induced by vibration and temperature variations?
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2,426 Posts
As I mentioned above, the Gen III do not have coolant flowing through them - just air.
Not everyone is referring to the LS1.
Basically, I have learnt to refer to the plastic upper intakes as
"expensive, cheap intake gaskets"
because that is basically what they are.
The major problem is with warpage, just think of the warpage difference
between steel and aluminum, and double it to see the difference between plastic and aluminum. Which is sad, because there are composites out there that could do a much better job, but aren't being used.
Basically, I have learnt to refer to the plastic upper intakes as
"expensive, cheap intake gaskets"
because that is basically what they are.
The major problem is with warpage, just think of the warpage difference
between steel and aluminum, and double it to see the difference between plastic and aluminum. Which is sad, because there are composites out there that could do a much better job, but aren't being used.
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1,037 Posts
Ford's had problems with them as well:
Consumer complaints in www.nhtsa.gov carries the info under "engine and engine cooling". Leaking of the intake manifold on 3.8L's.
What is the fix for these cases?
Except for a re-designed part, you are looking at recurring problems.
How I hate the methods of weight saving. In contrast, on my all cast iron Pontiac motor (400 cubes for my 73 Grand Prix), I had a hose blow while on the highway and before you knew it, the motor just ground to a halt. I let it cool, walked to a service station for a new hose and coolant and replaced the hose. Started it up and ran the car for another 5 years with no problems until I sold it. If you want to save weight, make the seats lighter.
And the transmission on that 73 was a real rock crusher.
An aluminum intake manifold would suit quite nicely.
Except for a re-designed part, you are looking at recurring problems.
How I hate the methods of weight saving. In contrast, on my all cast iron Pontiac motor (400 cubes for my 73 Grand Prix), I had a hose blow while on the highway and before you knew it, the motor just ground to a halt. I let it cool, walked to a service station for a new hose and coolant and replaced the hose. Started it up and ran the car for another 5 years with no problems until I sold it. If you want to save weight, make the seats lighter.
And the transmission on that 73 was a real rock crusher.
An aluminum intake manifold would suit quite nicely.
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