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Post Info TOPIC: 3800 V6 3.8 GM Series II Intake Manifold coolant leak causing hydro lock.


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3800 V6 3.8 GM Series II Intake Manifold coolant leak causing hydro lock.


Well it would seem that 3800 come in pairs... After my last 03 Impala with the Series II 3800 engine leaking coolant out of the elbows I had a 1999 Buick Lesaber come in with complaints about sweeping engine tempratures and loss of heat during said sweeps.

First thing I do is check out the coolant level and sure as $hit, it's low. I topped off the system with DexCool and heat returned but engine tempratures were still sweeping. 

Since it was cheap enough I decided to install a thermostat figuring the spring was at fault as there really was no pressure build up.

Then what happend is for the history books... Upon restarting the vehice and refilling the coolant the engine began to run funny and sucked the entire contents of the coolant bottle into the radiator! The engine ran a little funny as the computer spit out a code for cylinder misfire in cylinder #5! Upon trying to re-start the vehicle it would no longer start! Seemed like it was locked up! So I pulled cylinder #5 and antifreeze come pouring out! At first thought it was a head gasket but I had never had anything like that happen. Next step was to start tearing it down, as I would soon learn about the dreaded 3800 Series II plastic intake weakness...

First on the docket was the upper intake manifold...

And look at that! FULL OF DexCool! To the brim! LOL

So here is what causes this problem, and trust me when I say many web sites give little information on the problem

As you can see the EGR port heats up the plastic intake that also carries coolant into the throttle body. This area disinigrates and it literally sucks coolant into the intake track. Some people get by for a long time with low coolant, but there was reports of the customer thinking he smelt antifreeze in the past. Anyway, to make a long story short, if you have a 3800 engine that is sucking in antifreeze into the engine it's a good chance the intake manifold needs to be replaced. In the event the engine hydro-locks I would suggest doing the head gaskets to clean things up and ensure everything is in order.

Here is a look at the tube on the intake from the factory that slides into the intake manifold.

And this is the new one that gets installed with the new intake kit shown below offered by Dorman



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So now, since it's hydro-locked I am stuck pulling off the heads to ensure she is worth putting the money into...

So here above you can see how the intake manifold gasket is also a problem area... They do sell these made out of aluminum but I have yet to see anyone local that stocks them. Most of the problem comes from the intake, but if you have a supercharged version of this engine I would go the performance route due to boost factors.

Here you can see the nastyness as I call DexCool! I tell you this stuff gets toxic because people forget it's 100,000 or 5 years... So they go 15 years before they get to 100,000 miles and well... This is what you get.



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So with my trusty Rol-Loc pad and die grinder in hand I work some "Magic" and bring them nasty looking heads, block and manifold back to life.

Ohhh.... Ahhhhh... So clean! PowerStroker would be jealous to know I did this by hand!

Now it's up and running like a champ! Heat is awesome, like a LeSauna in there! LOL!  Runs at a steady 190 as it should and everything on the lower end was happy.

Now it's time to put the Auto-Trend "glow" on it...

All DONE!



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FAR BEYOND DRIVEN

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By "auto trend glow" I take it you hose the engine down with a thick coat of n%##@r gel?

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Whale sperm... lol j/k

No it's a silicone based product. Good for the ruber and plastic parts.



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SOUNDS LIKE A UMNEY HOMEMADE VERSION OF DA KY JELLY!!!!!!!!!!!!!!!!!!!! AHAHAHAHHAHAHAHAHHAHAHAHAHAHHAHAHAHHAHA!!!!!!!!!!!!!!!!!!!!!!!!!!

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I wonder if using green coolant would have prevented that problem? I've heard nothing but bad things about Dex Cool.

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I think DexCool, changed at regular "green" coolant intervals would prevent this problem.

I have found that 10 year old DexCool is the most corrosive coolant I have ever seen. I have heard stories that GM was sued over DexCool, however in almost every case where DexCool becomes corrosive it's because people try and get over 5 years out of it.

Still, the fault is mostly with the intake manifold in this case. The design with the EGR being pumped into a plastic intake, followed by coolant circulation around the area is what really causes these things to "pop". In this case.

In other cases of the Vortec v8's with high miles, I see DexCool eats pits in aluminum manifolds and such all the time. Then again this has happend with Green coolant in days past with cast iron.  



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Here how you fix this leak problem forever by blocking the lower intake holes!!! it is cheep fix, i did that in my car and it is working perfect, i am not worry about any crack in the upper plastic intake.



-- Edited by 3800_fix on Thursday 22nd of February 2018 01:41:17 PM



-- Edited by 3800_fix on Thursday 22nd of February 2018 01:41:45 PM



-- Edited by 3800_fix on Thursday 22nd of February 2018 01:42:28 PM

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I guess if someone was strapped for cash and had some mechanical skills that could be a fix, but a dangerous one if they lived in cold climates like Michigan since the coolant ports you are plugging are there to heat the throttle body in cold weather to prevent any sticking. 

Looking at your photos I can only wonder how the upper intake manifold would fit back onto the lower without modifications to both the gasket and the plastic upper intake itself. Are you hogging out the gasket and intake to allow clearance? Has this repair been completed yet? If so, how long has it been working? I am sure people looking to save a few hundred bucks on an older 3800 engine would be interested but as a mechanic I could never sell that to a customer, that's one of them DYI only deals right there.



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I modified the upper intake by drilling in the coolant holes just to make them wider diameter so the nuts that are coming from the lower intake will fit there, and I cut the old upper intake gasket as showed in the photo because it will not seal anything now and need to be cut so the upper intake will seat perfect.

The repair has been completed one month ago and I put 3000 miles on the car after the repair without any problems, no coolant leak or even any cold start problems, the temperature was low as 22F here, no check engine, this repair did not make any deferent except that it protects the engine from future internal leak.

I came with this idea after I saw your repair photos, but as you say it is old car and I do not want to spend money on it. All it coast me is 5 dollars for the nuts and bolts from home depot!



-- Edited by 3800_fix on Friday 23rd of February 2018 01:29:40 PM

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Hmm,

At least make sure that you have the correct amount of coolant & demineralized water in there...

Ensure that your battery, & its earth-points are clean & conductive. Electrolosis may prove a corrosive phenonema, that will make your nuts & bolts disappear, & allow for a new leak to form.

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After this repair, and replacing the lower intake gaskets that already torn out from the DEX-KILL!, I used the aluminum gaskets then flushed the system with water and radiator flush, after that, I was changing the water every day for a whole week to make sure that the red stuff is completely out. then I used the green 50/50 antifreeze. And everything seems to work fine.

DEX-KILL is eating the gasket material and aluminum, by going green you bring life back to your engine!





-- Edited by 3800_fix on Friday 23rd of February 2018 07:03:30 PM

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OUT-OF-HAND

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Well it looks like you had some fun and saved some money! 

Wished I had known as I got a good (used) intake from an impala we cut up I could have given you for $20 and postage.

All is well that ends well!



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