replacing intake manifold gaskets on LG3 3.8l V6 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 08-11-2007, 01:34 PM   #1
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Default replacing intake manifold gaskets on LG3 3.8l V6

Hello everyone. Im looking to replace the intake manifold gaskets on my 87 Buick Park Ave, as i have oil leaking into my coolant (but not vice versa thank god). I am assuming that this is the intake gaskets and not head gaskets.
Now, i seem to have lost my haynes manual, and was wondering if anyone had a writeup and or torque specs for this job

thanks
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Old 08-11-2007, 01:46 PM   #2
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You mean your Buick Electra Park Ave right? Park avenue was a trim until 1991 when Electra was discontinued.

When doing something like this, its very beneficial to have a FSM, have you looked on eBay etc for an FSM for ANY 1987 GM with the LG3?

Being that the LG3 was only used for one year, in our cars at least, maybe 2 in others, there is very limited knowledge on performing service on this engine.

If you want to get this done efficently without having to wait for someone to find it, you'll need an FSM.

However, as I have worked on the LG3 before, I do believe that the torque specs on the upper intake manifold to the heads would be the same as an LN3, or at least the same neighborhood, but before throwing out numbers, i'll need someone to confirm that.
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Old 08-11-2007, 01:55 PM   #3
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just throw me the torque specs for the LN3 and i should be OK.
Or, do you have the writeup for the LN3?? I dont know if it would be easier to remove the fuel rail....or try to leave it on??

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Old 08-11-2007, 01:58 PM   #4
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WHOA. WHOA..... The LG3 does not use the same LIM gaskets that the actual "3800s" use. They use a layer metal gasket with a valley pan, and tq specs are MUCH different I believe. If you can hold on a second, I have a FSM for '87 A-bodies and it has the TQ specs in it.
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Old 08-11-2007, 02:07 PM   #5
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Well I know it doesn't use the same gaskets, but its a VERY similar engine. sending a PM roman...
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Old 08-11-2007, 02:08 PM   #6
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Also according to the FSM, if you are using the metal type gaskets, apply RTV sealant to BOTH sides of the gaskets, and fit them into place. Also apply RTV to the ends of the manifold to block seals, and make sure the pointy ends of the seals fit snugly against the head and the block. ALSO make sure to change your oil if you got coolant down into the engine, which is very likely.

Use threadlocker, and Tighten them down to 32 ft/lbs in STAGES. Meaning 16 ft/lbs first all the way around, then tighten them again until the wrench reads 32 ft/lbs. Here is the tightening sequence -

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Old 08-11-2007, 02:11 PM   #7
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Also make sure that you get the bolts with the mounting studs back into the right places, otherwise you will have trouble.
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Old 08-11-2007, 02:54 PM   #8
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Here are the directions you requested -

Removal -

1. Relieve the fuel pressure to prevent spraying/fire.
2. Disconnect the Neg. battery cable.
3. Remove Mass air flow sensor and air intake tube.
4. Remove the EGR valve from the intake manifold.
5. Remove the PCV valve from intake manifold (replacement recommended if haven't been done).
6. Remove the throttle/cruise control cables from the manifold'* bracket.
7. Remove the transaxle TV cable from the manifold bracket.
8.IF it interferes with the manifold removal, remove the alternator and brackets.
9. Drain the cooling system into a container suitable to hold the coolant, so you can put it back in later.
10. Remove spark plug wires off the coils and set them aside so they don't interfere.
11. Disconnect the IGN module assembly and set it aside.
12. Disconnect the upper radiator hose, and hoses on the Throttle body.
13. Label and remove the vacuum and fuel lines.
14. Remove fuel rail and injectors (o-ring replacement strongly recommended)
15. Remove manifold bolts and please note where they go, some have ends on them that hold the fuel rail down. DO NOT pry the manifold off, just carefully wiggle it until it pops off. And there you go! Now follow the directions in the thread for the gasket installation, and reassemble using above steps in reverse. I will give you the TQ specs for the TB, EGR and such when you are ready to put them back on.
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Old 08-11-2007, 03:31 PM   #9
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thanks alot!!
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Old 08-11-2007, 04:01 PM   #10
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How do i go about removing the fuel rail and the injectors?? i was trying to pull them off, but i don't want to pull to hard and **** some **** up. should the injectors come out with the fuel rail? or should they com apart separately?

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