GM 3800 Series II Supercharged Intake Manifold Leaks

[frosty9595]

Iv had my 01 grand prix for 11 years and 150,000 miles and if you treat the motor right, change the coolant regularly , warm it up before beating on it, and change the oil regularly and you will be totally ok

[Blahbevava]

I've had this Happen 3 different times with 2 different cars!! I finally learned from a Good and Honest Mechanic that GM DEX-COOL IS THE PROBLEM!! IT Erodes the Seals and Gaskets!! I Really Hate GM!!! It's Crap like this why I will Never Buy From GM Again!! Bunch of Liars!! The 3800 series 2 is a great motor though too bad they replaced it now in their newer models with a less efficient, less HP, less Torque, More complicated design!! GM sucks!!

[PeterCRissKISSgod]

i have a 00 camaro v6 with the 3800. Coolant is leaking out the intake manifold. replacing the lower gasket tomorrow. is it possible that it leaked into the oil as well? will i have to change the oil and filter? i just did it about 3 weeks ago.

[moldymac]

@PeterCRissKISSgod Just to be on the safe side I would. Oil and a filter is cheap compared to an engine overhaul.

[AndrewPify]

@moldymac theres the turbines?? lol try rotors. @masterhwoarang5 its pretty simple it took me 1hr and 45mins to take 1 apart and about 2hrs to put back together

[masterhwoarang5]

hey quick question if anyone is out there. I have to do this job for my mom on a 98 bonneville with a super charger. A shop wants 900 but new gaskets are only like 90 bucks from oreillys, is it really that much of a pain in the ass? how long do you figure itll take, it cant be that hard to get the LIM off can it? Engine will stay in the car.

[moldymac]

@masterhwoarang5 Its not that the job is hard, just time consuming. There's a lot of parts in the way that have to be removed to get to the LIM gaskets. Take your time and make sure you have a service manual to guide you.

[drhemi88]

Info is awesome. Thanks

[TheTuber124]

I have a 99 gmc sonoma. I flushed the dex cool out as soon as I bought it. I have had Peak global in it since. It just so happens that peak global is also Organic acid technology. I have had peak global in it for 7 years now. I did a flush after about 5 years cause I felt bad and never had any problems ( laughs). I put Peak global back in and have been good since. I personally think dex cool is just a bad product. My mom's Olds alero had intakes done at 45,000, and had never been touched. :(

[WWBZT1]

when GM owned EMD they made locomotives that had 2 cycle diesels engines with a roots type blower, like they had on vette's.

[WWBZT1]

I thought the fel-pro were rubber like with copper in the center

[247Countryboy1]

Ha, and Ram had the plenum leak. Guess both companies learned their cheap gaskets where not made for these high out put motors.

[aleon1018]

I just took my Regal into a shop for this. They gave me an estimate of $900.00 for the new upper manifold, the valve covers and oil pan leaks and supposedly including fluids and all parts. I thought this was a better deal than others and won't do it myself because it has a warranty and I don't. They called this morning and I asked about which intake gasket if it was steel or aluminum and he wouldn't say, which kinda irked me. He just said: we know what we're doing. WTF kind of answer is that?

[moldymac]

@aleon1018 Sounds like a decent price for the work, but it also sounds like they put the junk gaskets in there with a response like that. The dealer I got my parts from only had the crap plastic ones listed for my car, had to go by either a Bonneville or a Grand Prix to get the aluminum ones.

[aleon1018]

@moldymac When I asked the owners son, he said the dealers don't sell anything but the plastic ones. These are supposed to be the steel Felpro. I guess these guys don't like the aluminum set or they only deal with the one parts store like Napa? They also made some claim my MAP sensor was broken and glued so they replaced it. .um, ok I guess. But then later that night, I pulled my dipstick and that too was broken by the small O ring seal. But I fixed it with shrink tubing...for now.

[aleon1018]

@moldymac I told them I had Mobil One extended performance I'd just put in and they said they would drain it and put it back in since they also were changing the oil pan gasket. ( which isn't typical) But it looks fresh, so I don't know what's in there now since I run it 5,000+ miles. So, I wondered about the antifreeze. Found a video about using a meter to check the PH and the coolant was apparently more acidic. Now I have to find a shop to test it like Sears. So, I doubt they flushed it.

[gooeyzx6rr]

Your garage is a nightmare. How do you people work in that filth.

[bowtie4ever96]

its not even broke in yet ive never had these problems with mine but mine was rebuild cause it spun a rod bearing aND THE CRANK WAS NEVER HARMED

[bowtie4ever96]

its not even broke in yea

[vitothesaint]

Dex cool plays a nasty part in these going bad also

[arealscorpio1]

The berrings inside the supercharger would rubb together?? I keep haveing missfire issues, and I've changed the spark plugs, wires, and ignition coils, but still the same issue. no knocking, but just an obvious small shake when the engine is on, and missfire codes....what else am I looking past!?? It's driveing me nuts! I been in the house for 3days waiting on the coils to get here because I had to order them, and STILL the same issue....PLEASE HELP. I have an 04 GTP w/105,000...

[moldymac]

@arealscorpio1 You can try taking the belt off the supercharger. The engine will run fine with it disconnected, just won't have the power it should. There is a coupler in the SC that goes bad and can cause a knocking sound, but I don't think that is your issue. You may have low compression on one or more cylinders, start by disconnecting one wire at a time for each cylinder until you unplug one that makes no difference in how it runs. You an do a leak down test on the suspect cylinder.

[tank255320]

dex cool is what kills them they say that it helps lube the parts like the water pump, i think it is crap because i put the green coolant that is for every make and i have had good luck. dex cool is acidic what do you think is gonna happen it will eat the gaskets away.

[LAUTRAED09]

could the intake manifold leaks cause lose of boost and stallin at full throttle??

[Leacholopolis]

Nice Laptop

[hoth260]

Bars leaks baby,

[EmX3Ed]

is wear to god that GM purposely built these engines to have the intake gasket go out every 60,000 miles so they can keep their mechanics in business

[shadow281000]

Hey I did the same thing you did with my riviera.One question did you change the yellow orings on top of the intake manifold?

[moldymac]

@shadow281000 I changed those too. The felpro supercharger kit comes with them.

[homes24]

why would they use a plastic anything for an engine?

[moldymac]

@homes24 mostly cost cutting. GM loved to use plastics in 90's. On the non supercharged 3800's the whole intake is plastic, that warps and needs to be replaced.

[MrLazloe]

why does coolant leaking cause a knock?

[moldymac]

@MrLazloe It dillutes the oil which then doesn't lubricate well.  That causes the bearings to rub and damages them.

[voodoochild2006]

Another 3800 Ser 2 owner here. Mine just stalled one day and I tried diagnosing the fuel delivery out of ignorance. Now that I think about it I remember the coolant dropping mysteriously and intermittently and the smell before it happened. Now I'm just studying up to try to make the process easier. Thanks all for the great info! BTW - I wonder if it was one particular engineer that was responsible for the brilliant use of plastic? Or was it a whole team of idiots?

[moldymac]

@voodoochild2006 I bet a whole team, GM loved to used plastic where it didn't belong. The non supercharged Series II had a completely plastic intake plenum that would warp and could cause the same problem. At the minimum is caused air leaks and made the car run like crap, or not at all.

[tsmsom]

@voodoochild2006 i have the same problem right now, and I also smelled the coolant right before it sarted happening, Im going crazy hopeing it wasnt the transmission, but im hearing its the gaskets

[SuperSportSS]

The website for the below comment is dex (hyphen) cool (dot) net

[SuperSportSS]

The plastic gasket is not the problem. Its the dexcool that eats away the plastic. I found a website that shows the series 1 3.8 had perfect plastic gaskets at 125,000 miles. Thats when GM used green coolant. I just changed the intake gaskets on my L36 Grand Prix. Bought the aluminum gaskets, vc gaskets, plugs and wires for 150 bucks total, and had the gaskets changed in a day. I LOL at people who drop 800 bucks to have them changed for them...

[dantheman121983]

i would of gotten a engine stand and tore the whole thing down. then i would of shipped the block out for new cam bearings ect, and redid everything just to be sure. sometimes like in your case the JUNK in junkyard motors tend to bleed through, nicely done though

[apostlegato]

Thanks for the post, I don't know how many people told me my gtp needed a head gasket and many mechanics said it needed a plenum ( Which it don't even have). I pulled mine apart and gasket looked just like yours. It had just started missing real bad and started blowing white smelly smoke. I didn't run it anymore so it should be ok. Most of the coolant looked ok but some had some gooeyness . Should I flush the cooling system? And what else do u recommend doing to it?

[impalashotya5]

i just got mine replaced too now its badass man...like your vid im also rebuilding the valvtrain and putting in a comp cam i'll let u no when the vids in u got to see it

[moldymac]

Sound awesome, post a video response when you get it done.

[Ajaces]

Is there much to go wrong with a supercharger? I've heard of them needing rebuild from time to time.

[moldymac]

Most common is the plastic coupler goes bad. It makes a clunk sound, but still functions. I have heard of bearings goin in these, but not too much. The coupler is a consumable part.

[justin3zelda]

Looks like you could probably port that supercharger for some more flow.

[moldymac]

That can be done, putting a smaller pully on it does the job with less effort. But my exhaust is stock and wont handle the extra power too well.

[NRP1991]

GREAT video there really arnt much on here of the 3800 series engines but very well done KEEP THEEM COMING!!!! 5*!

[phill903]

GM dose that to save money.

[firehawk400]

I knew they used these s***y gaskets on the L36, but who in their right mind would use plastic gaskets with forced induction? Idiocy. They have been replaced with non-plastic ones on the Series III though, thank God.

[casebutler]

thats gm for ya using plastic

[moldymac]

The non supercharged ones have an all plastic intake manifold that warps from heat and would need to be replaced. Geniuses.

[99minerkc]

It would SURELY SUCK if the replacement is bad as you will be shit out of luck on the cost of gaskets etc! Thanks for keeping us updated!! :-)

5/5

[dangeroustoys56]

Great ideas to cut costs on production...plastic.

Plastic should only be used for intakes and shrouds.

How'd the oil look? it was probably just starting to go hopefully.

[moldymac]

The oil in the pan looked like used oil, not like that crap out of my old engine.

[terhhh87]

Is that M90 or M120 eaton supercharger?

[moldymac]

I believe its an Eaton M90