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Anyone know where i can look up the port size for a lower intake manifold on a 2003 buick century 3.1 sfi?
Took to mechanic for head gasket issue. Mechanic showed me lower intake manifold that had cracks in it. Said he couldn't find a new one in town so I ordered a dorman lower intake manifold from partsgeek and had it sent to his shop. Repairs done but now has a check engine light that says it'* getting too much air. Blames the part i ordered by saying the port sizes are too large and are allowing it to get more air. Says a year older or newer MAF sensor may fix the problem. I found the port size on the dorman (51 mm ; 33 mm) and i want to check those numbers against the oem specs to see if he'* accurate in his assessment or if he'* covering for a goof that may have been made.
If anyone can point me in the right direction of where to look, I haven't had much luck on google.
If Dorman said it is an OEM replacement for that year/make/model/engine then it was an OEM replacement. They are pretty good about dimensions. Also, If they did design it with really big ports, that wouldn't matter because the intake ports on the heads would still be normal size.
I'm curious:
Was the mechanic unable to find one at all? . . . or just unable to find one in town?
Was the mechanic willing to order one from out of town? . . . and is his nose bent out of shape because you brought your own part?
What was the specific part number etc. at Partsgeek?
I'm not there, but the idea that an OEM style replacement intake manifold of any sort would cause it to get too much air is suspect to me. Air is metered by the throttle plate and the IAC valve, and measured by the MAF sensor. If the air went through the throttle plate and/or IAC and the MAF, and then through a (sealed and) clean dumpster and then through the intake it would still be metered at the throttle plate and IAC, and measured by the MAF.
Speaking of which: Is the IAC sealed and connected properly?
What codes is it showing?
Are we sure there isn't a loose hose like the one to the vacuum booster?
Last edited by CathedralCub; 04-15-2023 at 01:05 AM.
If Dorman said it is an OEM replacement for that year/make/model/engine then it was an OEM replacement. They are pretty good about dimensions. Also, If they did design it with really big ports, that wouldn't matter because the intake ports on the heads would still be normal size.
I'm curious:
Was the mechanic unable to find one at all? . . . or just unable to find one in town?
Was the mechanic willing to order one from out of town? . . . and is his nose bent out of shape because you brought your own part?
What was the specific part number etc. at Partsgeek?
I'm not there, but the idea that an OEM style replacement intake manifold of any sort would cause it to get too much air is suspect to me. Air is metered by the throttle plate and the IAC valve, and measured by the MAF sensor. If the air went through the throttle plate and/or IAC and the MAF, and then through a (sealed and) clean dumpster and then through the intake it would still be metered at the throttle plate and IAC, and measured by the MAF.
Speaking of which: Is the IAC sealed and connected properly?
What codes is it showing?
Are we sure there isn't a loose hose like the one to the vacuum booster?
Mechanic was unable to locate one in town.
No he was happy that i ordered one and saved him the headache of having to locate one. I told him i found a dorman on line and could have it shipped to his shop. He seemed happy about all that.
part number was W0133-3552977
no I'm not sure. I wish i was. Cars been there a couple weeks (other repair done as well). But i was hoping to find the oe port outlet size so we could rule that out and maybe stop chasing a problem that isn't there.
Port size will not cause your problem. It can only pull in as much air as the cylinders will draw on their intake stroke. A big port only makes it easier to breath it will not make it take more than it wants.
What codes are you getting.
Last edited by carfixer007; 04-15-2023 at 01:39 PM.
No he was happy that i ordered one and saved him the headache of having to locate one. I told him i found a dorman on line and could have it shipped to his shop. He seemed happy about all that.
Okay cool. Many are sensitive about using customer-provided parts.
Originally Posted by Dehaka
part number was W0133-3552977
That'* the correct part. Going one year higher or lower won't change anything. It concerns me that your mechanic is thinking that there would be differences from one year to the other on this generation of engine.
Originally Posted by Dehaka
no I'm not sure. I wish i was. Cars been there a couple weeks (other repair done as well). But i was hoping to find the oe port outlet size so we could rule that out and maybe stop chasing a problem that isn't there.
Port outlet size doesn't matter in this context. It is the correct part, and if the ports were oversize, that doesn't change anything else in the intake tract including the MAF sensor'* readings . . . and where the ports mate with the ports on the head, the ports on the head are the correct size anyways. Dorman sells this exact part number W0133-3552977 for two different sizes of engine installed in 13 models from four branches of GM over six model years. GM makes less money if they change the design of parts from one year to the next. Dorman would have noticed by now if they were getting complaints on the core design of this part.
To get the answer to your original question: Where is the old one? Have him measure that, or give to you so you can measure it.
Similar to what I was saying above: If you have a giant sealed tank, and a straw feeds in and another straw feeds out, then the size of the tank is generally irrelevant. You are still restricted by the size of the straws.
Okay cool. Many are sensitive about using customer-provided parts.
That'* the correct part. Going one year higher or lower won't change anything. It concerns me that your mechanic is thinking that there would be differences from one year to the other on this generation of engine.
Port outlet size doesn't matter in this context. It is the correct part, and if the ports were oversize, that doesn't change anything else in the intake tract including the MAF sensor'* readings . . . and where the ports mate with the ports on the head, the ports on the head are the correct size anyways. Dorman sells this exact part number W0133-3552977 for two different sizes of engine installed in 13 models from four branches of GM over six model years. GM makes less money if they change the design of parts from one year to the next. Dorman would have noticed by now if they were getting complaints on the core design of this part.
To get the answer to your original question: Where is the old one? Have him measure that, or give to you so you can measure it.
Similar to what I was saying above: If you have a giant sealed tank, and a straw feeds in and another straw feeds out, then the size of the tank is generally irrelevant. You are still restricted by the size of the straws.
The old one is at his shop.
Yeah im not sure what to do. Suppose i could go down there with a micrometer.....was wondering if there was a way to look up the spec. Here is the dorman specs
Yeah im not sure what to do. Suppose i could go down there with a micrometer.....was wondering if there was a way to look up the spec.
Here is the dorman specs
You don't need a micrometer to measure ports. a measuring tape or ruler would do fine. If a port is off by a thousandth of an inch nothing would happen. Either way, it is extremely rare to find the kind of measurements that you are looking for. Partly this is because they don't generally publish their CAD drawings for their competitors to copy, partly because nobody asks as the dimension is dictated by the original design and doesn't change.
You're stuck in the impossible conundrum of proving a negative to an accuser while the accuser holds the evidence. The mechanic says the ports are too big. The mechanic has the old one. The mechanic is the only one who has access to both.
The mechanic, if they have much real experience in this profession, should already know all of what I pointed out above that disproves this strange theory.
I think I understand where you're coming from. The mechanic holds all of the cards. They have the experience in the profession, the old part, the new part, and your car while you're just the customer that they assume knows little about any of it. Here'* the thing. The mechanic holds most of the cards, not all of them. You're going to pay out the nose for more labor for this mechanic to keep doing strange stuff to your car. Order another W0133-3552977 and take it down there with you. Hold it up side by side with the original old unit. Get out a measuring tape, ruler, or micrometer if you insist, and go to town measuring everything.
Based on all of this silliness about the ports on the Dorman unit being too big, I'm going to stick with my suspicions of this mechanic.
In the meantime, I can't think of more different ways to explain away that the [port sizes are too large and are allowing it to get more air] theory doesn't add up.
Next steps that we could possibly help with would be to get us codes that are stored in the PCM.
I assume you have lean code(*). He'* blowing smoke if he say'* it'* because the ports are to large. We would polish the ports correcting casting issues and smoothing out the walls to get the best flow.
I did some prerry hard investigating and found that eventhough the dealer website lists the part as a fit for the 2003 Buick Century, the manufacturer website, Dorman only lists it for the 2005 Buick Century and not my 2003 https://www.dormanproducts.com/p-106...origin=keyword . It lists earlier model years of the 3.1 engine like on the chevy malibu all the way back to 2000. So now i guess i have to go with the mechanics idea of using a different MAF sensor or paying him to take the whole thing apart and redo with a used or reman lower intake manifold.
The 2003 Malibu 3.1 is the same LG8 engine as the 2003 Century 3.1. I bet Dorman has accidentally omitted a number of vehicles from their compatibility list.
04-14-2023, 11:31 PM
2003 Century 3.1 lower intake manifold port sizes
