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Gaskets on 3800 II Update: need advice


Nick1234

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i just did this 3 months ago. http://www.w-body.com/forum/index.php/topic,56428.0.html

 

first, get this kit. http://www.autopn.com/store/pc/viewPrd.asp?idproduct=229679 its the best upper intake on the market, AND it includes a smaller EGR stovepipe to help reduce manifold and gasket failure.

 

second, go to gmpartsdirect and get the aluminum frame LIM gaskets. they are the best you can get. GM Aluminum Frame Lower Intake Manifold Gasket set: GM PN# 89017816

 

third, go to your autoparts store and get a new coolant elbow. i would also change the fuel pressure regulator since they are prone to failure and cause fires!! i would also replace your injector o-rings. they are only a few bucks so why not?

 

if you have another $200 to throw down, this is a perfect opportunity to get the intake insert from ZZP.

 

this took me about 7 hours. you will prolly need a second set of hands to take the lower out and put it back in. sure made it alot easier for me.

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i just did this 3 months ago. http://www.w-body.com/forum/index.php/topic,56428.0.html

 

first, get this kit. http://www.autopn.com/store/pc/viewPrd.asp?idproduct=229679 its the best upper intake on the market, AND it includes a smaller EGR stovepipe to help reduce manifold and gasket failure.

 

second, go to gmpartsdirect and get the aluminum frame LIM gaskets. they are the best you can get. GM Aluminum Frame Lower Intake Manifold Gasket set: GM PN# 89017816

 

third, go to your autoparts store and get a new coolant elbow. i would also change the fuel pressure regulator since they are prone to failure and cause fires!! i would also replace your injector o-rings. they are only a few bucks so why not?

 

if you have another $200 to throw down, this is a perfect opportunity to get the intake insert from ZZP.

 

 

 

this took me about 7 hours. you will prolly need a second set of hands to take the lower out and put it back in. sure made it alot easier for me.

 

so you recommend all of this over just felpro gaskets? And i get a new manifold? is the stock one bad? for $100 including the gaskets

 

And since i haven't dug into this where is the coolant elbow?

 

my friend put the insert in from zzp and it didn't do much of anything for him.

 

thanks for you help. im looking into it right now.

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Yeah I've heard that the stock manifolds are cheaply made and are part of the reason the gaskets fail? I think it's because they warp over time, and can lead to coolant leaks...hence gasket failures. ZZP sells "reinforced" intakes that are made better I guess.

 

 

Although, I've never heard of the upper intakes warping on our cars though?

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How did you guys tell that your intake seal finally went?

 

Nothing on mine, however my dad's old 98 LeSabre was losing coolant but there were no exterior leaks to the ground, for instance. That could be one, I can't remember any others.

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mine isn't a coolant issue. i have oil sitting in the LIM and can smell it burning. Valve cover gaskets have already been replaced but im going to have to do them again. I am assuming i have to get those seperate as well. and loose about 1/2 quart ever 3k miles.

 

 

 

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there is supposed to be oil in the LIM. its probably the LIM's that are bad, thats why you are burning oil. is your oil milky at all?

 

i guess if your upper manifold isnt warped yet around the EGR stovepipe, you would be fine just replacing the upper gasket and getting the smaller pipe. :cough buy mine:

 

the coolant elbow is on the belt side, it literally is a 90deg elbow, 2" out from the manifold, 2" back into the belt tensioner. (the tensioner is also a coolant passage, there are 2 hoses off that back of it that go to your heater) my elbow was severely deteriorated when i replaced mine. i still have no idea why it didnt leak.

 

oh yeah its recommended to drain 2 gallons of coolant before pulling the LIM. i didnt and made a bit of a mess, not too bad though.

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i shall rephrase. there is oil ontop of the LIM. in puddles. in the valleys. Oil is clean. Coolant seems fine.

yeah there was on mine too. i figured this is normal.
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well i dunno what to tell you as far as your problem goes. compression check maybe?

 

oh yeah i forgot to say, that intake insert didnt make any noticeable seat-o-pants performance for me either.

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This is a picture of the 3800 II lower intake manifold showing the torque sequence.

 

When the lower gasket goes bad coolant can travel up bolts # 1,2,3,and 4 and pool on the lower manifold.

These bolts are directly above the coolant ports in the manifold.

On my car you could see the stains on the aluminum where the coolant was seeping from under the bolt head.

I had to replace these 4 bolts because the Dex-cool had corroded them just under the bolt head.

 

When I removed the lower intake manifold gaskets they looked and felt like they had been soaked in a mixture of motor oil and Dex-cool.

 

Lowernumbers.jpg

 

 

Like mentioned above use the GM aluminum lower gaskets.

 

ALUMINUMLIM.jpg

 

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ill have to look more closely, but i don't think i have any coolant issues. There is a good amount of oil sitting in the LIM right by the valve covers though.

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If coolant can come up bolts 1,2,3and 4 i guess oil could come up 5 and 7.

The only thing is that there is no oil pressure underneath only manifold vacuum on the heads of these two bolts.

 

“The two bolts in the holes (hidden bolts) # 5 and # 7 are covered with oil that traveled through the PCV system.â€Â

That is what I have read so I will go along with that explanation for now.

 

I have only taken the lower intake manifolds off of 4 cars so far so my knowledge is limited.

A 95 Bonneville, 2, 96 Regals and a 98 LTZ and they all had about half a cup of oil covering bolts 5 and 7.

On every motor bolts 5 and 7 look like new when removed and the heads wiped off.

So far the threads on every lower intake manifold bolt has been coated with thread-locking compound. This compound is hard and smells fishy.

 

If I ever replace L36 lower intake manifold gaskets again (hope not) I will try and buy new bolts from the dealership.

Wonder what the part # is for those bolts?

 

PS: Strange thing the lower manifold bolts are not metric but have 5/16†x 18 threads per inch threads.

 

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  • 1 month later...

Okay so i started on the gaskets friday afternoon. tore everything down. when i removed the UIM i found oil pooled up to the top of the LIM where the 2 bolts are for the LIM. im thinking i had a bad PCV valve or something. everything was caked with dirt and oil. cleaned everything. new plugs and wires. put it all back together, starts right up. idles fine. look over by the coolant elbow coming out of the LIM that i replaced, and i see coolant. open the throttle a little and i see it shoot out. WTF?

 

is there some secret to installing these stupid elbows. they hardly even hold in place at all. you can push it all the way into the LIM? how stupid. i took the alternator off and the idler bracket that has all the coolant running thru it, and removed the elbow. must have be cocked a little bit. o-ring is kinda flat? anyone have some suggestions or anything that would help.

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Coat the o-rings on the elbows with RTV and slide them into the tensioner.

Then line the tensioner and elbows up and slide the elbow into the lower intake manifold.

Your 2001 will have an upper and lower plastic elbow.

 

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i got them in, but didn't coat them with rtv. i should of. then i really wouldn't have to worry. well easy fix if they leak. i aligned them up right and got everything placed right the second time, so i drove 50 miles with no issues. thanks ron. stupid design if you ask me.

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stupid design if you ask me.

Nick1234 you can say that again.

 

The plastic coolant elbows are the worst.

They need to be made out of aluminum or brass and have 2 o-rings on each end.

 

My 96 only has one plastic elbow but knowing that cheap piece of plastic is there bugs me.

 

One of these days some one that works in a machine shop will make metal elbows and sell them.

 

http://www.clubgp.com/newforum/tm.asp?m=3941125&appid=&p=&mpage=1&key=elbow&language=single&tmode=&smode=&s=#3941125

 

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