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How I changed the oil pan gasket on a 2008 3.5. It's easy
2008 Impala 3.5L the sub frame does not need to be pulled nor the driver side wheel. Pull passenger wheel and wheel well engine cover. Remove A/C Comp set aside, just put it on top of engine frame, engine to tranny bracket on passenger side. Remove front engine mount to frame nuts, engine roll brackets. Raise engine (about 6 to 8 inches or farther until alternator hits firewall) hold engine using engine support. You can raise engine with jack underneath oil pan. Now remove starter and the bracket, proceed to oil filter housing (you'll have access to all three bolts). Remove front engine mount. Remove drive plate plastic cover, transmission oil pan to gain access to rear and side pan bolts. Now you have access to all oil pan bolts. Practice getting a socket to the rear oil pan bolt by the transmission oil pan (use a 1/4 in drive short socket on a long extension). You do not need any special tools, for side bolts I was able to take them out with a 3/8 sockets and long ratchet. All oil pan bolts are 13MM. Whack the oil pan a few times on the side with a 2X4 and use a 1X4 from the frame to the pan to provide side force and loosen it up. It will fall right out then wiggle it out of the car. Clean it up, be liberal with black Permatex (grooves at ends and a bead around the inner flange to gasket , install new gasket and install oil pan. Assemble in reverse order, oil housing first, ect. Service tranny while a it. Let Permatex let dry for 24 hours. Then add oil. I did it in 4 hours, I'm an old guy with no help or lift. Total cost not counting tranny service (new oil and filter) $30. Enjoy
 

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It's easy
My 2008 LT 3.5L oil pan is leaking to the point that oil drips are visible (but no drops on the ground yet). Yesterday I jacked up my car, removing the passenger wheel and wheel well cover to see how difficult the job is going to be.

The engine mount is the easy and there is no obstruction to the bolts. All the bolts in the front are easy and accessible. I can't reach 2 pan bolts on the tranny side. 1 bolt tucked behind a metal bracket that holds the tranny and engine/pan. I think I can remove the bracket from the passenger wheel well to reach the bolt.

That the last remaining bolt (on the back side next to the fly wheel). I tried 3/8 and 1/4 sockets with extension, none can reach because of the slight angel. Dropping the tranny pan will gain me extra 2-3mm of room, still no convinced if I can get to it. Will a 1/4 socket with straight extension fit????

I don't have an engine hoist. So I need to invest on one. What did you use to hoist up the engine?

Thanks,
 

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How I changed the oil pan gasket on a 2008 3.5. It's easy
2008 Impala 3.5L the sub frame does not need to be pulled nor the driver side wheel. Pull passenger wheel and wheel well engine cover. Remove A/C Comp set aside, just put it on top of engine frame, engine to tranny bracket on passenger side. Remove front engine mount to frame nuts, engine roll brackets. Raise engine (about 6 to 8 inches or farther until alternator hits firewall) hold engine using engine support. You can raise engine with jack underneath oil pan. Now remove starter and the bracket, proceed to oil filter housing (you'll have access to all three bolts). Remove front engine mount. Remove drive plate plastic cover, transmission oil pan to gain access to rear and side pan bolts. Now you have access to all oil pan bolts. Practice getting a socket to the rear oil pan bolt by the transmission oil pan (use a 1/4 in drive short socket on a long extension). You do not need any special tools, for side bolts I was able to take them out with a 3/8 sockets and long ratchet. All oil pan bolts are 13MM. Whack the oil pan a few times on the side with a 2X4 and use a 1X4 from the frame to the pan to provide side force and loosen it up. It will fall right out then wiggle it out of the car. Clean it up, be liberal with black Permatex (grooves at ends and a bead around the inner flange to gasket , install new gasket and install oil pan. Assemble in reverse order, oil housing first, ect. Service tranny while a it. Let Permatex let dry for 24 hours. Then add oil. I did it in 4 hours, I'm an old guy with no help or lift. Total cost not counting tranny service (new oil and filter) $30. Enjoy
Hi looking for your input. 2008 with a 3.9+ engine. Changed leaking pan gasket about a month ago. After about a week I had a leak appear. Coming from oil pan under the rear main seal and running down pan. Pulled the pan again tonight thinking I messed up the gasket putting it in. Had a very hard time keeping the gasket in place for installation. The Felpro gasket I used did not press down into the groves under the main seals very well and kept wanting to pop out. Got the pan off tonight and I cannot really see any damage. Did look like by the line on the block under the rear main that the gasket may have been slightly out of place. Noticed that the groove under the gasket has oil in it which puzzled me. Noted in your post you talked about putting a lot of Permatex on. Not sure where you are talking about putting the Permatex. The only Permatex I applied was at the block to main seal housing transition on either side of the front and rear seal housings. I also pulled out my old pan gasket from the trash(factory gasket) and the portion of the gasket that the went under the main seals fit nicely into the groove on the pan and filled the space. Also noted it had a flat surface that went against the rounded area under main seals. The gasket I installed has a double lip type design that goes against the main seal area. Thinking the gasket I used might be the issue. What are your thoughts? Do not want to do this again.
 

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Quick Note about small bolt above corner of transmision. I struggle for hours with flex universal etc.'. Finally I just bought set of 1/4" wobble extension from Menards. It came off in seconds .. Buy the extension. Set comes with 3/8 and 1/2" also .
 

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I wonder if the 3.9 engine oil pan gasket would be so easy to change - the published procedure in the Haynes manual involves dropping the subframe, removing the catalytic converter, etc.

I have an oil leak on my 2009 Impala LTZ with the 3.9 liter V6 and almost 180k miles, but I am not sure if it is coming from the oil pan gasket. It could be the rear main seal leak.
 

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Parts list?

Besides the obvious oil pan gasket what else do I need on hand to do this? So far I've read Permatex, it looks like the oil filter adapter needs to come off, so there's another gasket.

What else?

I replaced the adapter gasket a few years ago. I noticed the bolts seemed to be lightly torqued on removal but a new gasket didn't change the relatively minor leak.
 

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Is everybody reasonable sure that all oil leaks are caused by leaky oil pan gaskets, not by leaky rear main seal? How likely are rear main seals to leak on these cars?
 

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Is everybody reasonable sure that all oil leaks are caused by leaky oil pan gaskets, not by leaky rear main seal? How likely are rear main seals to leak on these cars?
I was told by a shop that my Pontiac 3.5's rear seal was leaking, but I pulled off the inspection cover on the bottom of the bell-housing, and didn't see any sign of oil there. So I ruled that out and put a new oil pan gasket on it instead.

My 3.5 was the cut down version of the 3.9. As you mentioned, I had to drop the sub frame and front cat to get the pan off, as well as loosen the bell-housing and separate it a quarter or three-eighths of an inch, as I recall. In the G6 instructions, it's possible to swap the pan without fully removing the sub frame, but it involves jacking the engine up, and my home made engine holder lacks that feature :) So dropping the sub frame was the alternative for me.

Anyway, I get the impression that the rear main seals are pretty good across the board on these Impalas. But Chevy makes up for that by having a bunch of leaks elsewhere :)

Doug

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I just checked with the local GM dealer on labor costs to replace the oil pan gasket on my 2009 Impala LTZ. I was quoted $750 for labor alone, the cost of the gasket itself is about $ 30 from GM. They claim that the subframe must be dropped for this job.
 
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