Questions about Intake Manifold on 2005 LS V8

[BubbaMO]

I have 2 questions about my 2005 LS V8. Is the Intake Manifold cast or plastic? Is there a pattern of the manifold itself causing leaks or is it reasonable to presume that I can just replace the gaskets?

Background: Suddenly started running rough on cool weather startup and showing CEL and P0171 and P0174. Throttle response lags throttle, but gets better when warm. Dealer says that they sprayed carb cleaner near intake and idle came up, implying a leak. I trust them on that.

They wanted to sell me an entire intake manifold since they can't get two of the types of gaskets. I found the gasket thread here on LvsC, and have found on-line sources on ebay for each of the gaskets on the ends of the manifold and the eight that couple it to the "tune runner" (that's what the mechanic called the spacers below the manifold and above the block).

I was hoping y'all could clue me as to how much risk there is in there being an actual problem with the manifold itself. I have a coworker who has a deep hot rodding and mechanical engineering background and he warned me that there might be issues if the manifold is plastic or could even have issues if it is a cast manifold.

I'm a Ford guy through and through, have a '90 Mustang 5.0 Vert and a low, low mileage '96 F150. I work on those vehicles to a limited degree, but typically have the dealer work on my Lincoln.

 

[joegr]

It's both. The main part of it is plastic, and lower part at each side is metal. Anyway, it seems that the more common leak is the gaskets between the metal parts and the plastic part. The dealers were only ever meant to replace the whole manifold, so those gaskets are not available to them (the gaskets between the whole manifold and the heads are available). You choices are to (1) replace the whole manifold, (2) use the unofficial source of the internal gaskets, or (3) use RTV form-a-gasket.

As far as I know, as long as you use the correct torque and sequence for the bolts, the manifolds don't crack. There have been some gen I that blew the end cap off, but that seems to have been corrected on the gen II manifolds.

 

[BubbaMO]

It's both. The main part of it is plastic, and lower part at each side is metal. Anyway, it seems that the more common leak is the gaskets between the metal parts and the plastic part. The dealers were only ever meant to replace the whole manifold, so those gaskets are not available to them (the gaskets between the whole manifold and the heads are available). You choices are to (1) replace the whole manifold, (2) use the unofficial source of the internal gaskets, or (3) use RTV form-a-gasket.

As far as I know, as long as you use the correct torque and sequence for the bolts, the manifolds don't crack. There have been some gen I that blew the end cap off, but that seems to have been corrected on the gen II manifolds.

Thanks, I'm going to just replace the gaskets then. I much appreciate your input.

 

[DeviLSh]

Not sure if the resource you mentioned was my thread or not, but the "upper" 8 gaskets were available from LandRover for the Range rover V8 manifold, and I can confirm they fit my 06 LS manifold. Joe is right in that Ford only offers the lower gaskets (1x4) between spacers and cylinder head. I would pull yours apart first to confirm the type of gasket that is there before you decide on the "unofficial" part.

 

[BubbaMO]

Not sure if the resource you mentioned was my thread or not, but the "upper" 8 gaskets were available from LandRover for the Range rover V8 manifold, and I can confirm they fit my 06 LS manifold. Joe is right in that Ford only offers the lower gaskets (1x4) between spacers and cylinder head. I would pull yours apart first to confirm the type of gasket that is there before you decide on the "unofficial" part.

Thanks, DeviLSh. I did use your thread, but found the upper 8 gaskets on eBay, labeled as fitting the LS V8. I'm not planning on doing this myself, and the dealer said they would do the work for me with me supplying the gaskets. Here's the link for the upper intake set of 8: Lincoln ls 3.9 upper intake manifold gasket set (8 pieces ) | eBay

Thank you for your help, this site has been such a great resource for keeping my LS in top shape.

 

[DeviLSh]

You're welcome - beware, those gaskets list the 2005 but not the 2006. They are the ones I tried at first as well. ( i still have them lying around) They did not fit my gen2/'06. Unless Ford/Linc made a change for 2006 only, those look like gen1 gaskets.

Let me know if they work, because if they do I will update my gasket thread with year-by-year data.

 

[BubbaMO]

You're welcome - beware, those gaskets list the 2005 but not the 2006. They are the ones I tried at first as well. ( i still have them lying around) They did not fit my gen2/'06. Unless Ford/Linc made a change for 2006 only, those look like gen1 gaskets.

Let me know if they work, because if they do I will update my gasket thread with year-by-year data.

Thanks. My LS is a 2005, so I'm obviously hoping they'll fit. I'll post the outcome here when I take it in for repair. Waiting until after the holidays to take it in. I had read a thread here that the black bits just helped position them during assembly. I'll end up buying the Rover parts if need be, but hope it doesn't end up that way.

 

[Andrizzle]

Team RTV here. Mine is still running great.

 

[BubbaMO]

You're welcome - beware, those gaskets list the 2005 but not the 2006. They are the ones I tried at first as well. ( i still have them lying around) They did not fit my gen2/'06. Unless Ford/Linc made a change for 2006 only, those look like gen1 gaskets.

Let me know if they work, because if they do I will update my gasket thread with year-by-year data.

Those gaskets worked, as did the gaskets for both ends of the intake. I just had it repaired at the end of last week. No problems, other than the $662 for the work, which was listed on the bill without any mention of hours. I provided the parts, all bought on ebay.

 

[GreyWisent]

I'm left scratching my head a bit at this...

The eBay gaskets that you posted had those black rubber tabs on them, but the open manifold picture I've seen have no room for those tabs.
Did your dealer carve the tabs out OR did they just not install them? Those tabs don't like like they simply slide off...

(Credit DeviLSh)

 

[BubbaMO]

When I took my LS to the dealer for this work, I gave him a set of each of those gasket types. They weren't that expensive and I didn't want them to take it apart and then not have the correct gaskets in-hand. I was told that the mechanic said those blocks were left on and they were installed as-is. I asked out of curiosity, but that word came from the service writer... not from the mechanic.

So, don't know what to tell you...

My next task is replacing 2 rear door lock actuators.

 

[GreyWisent]

Hmm, my (big) gut tells me to think twice about trusting that service writer going forward... The lack of hour tracking just adds to that hunch.

Anyway, thank you for sharing. I'll tear mine apart and see.