3800 V6 3.8 GM Series II Intake Manifold coolant leak causing hydro lock. - Auto-Trend Repairs and Service Information Forums

SELLC · CERTIFIED POST WHORE

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

SELLC · CERTIFIED POST WHORE

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.

SELLC · CERTIFIED POST WHORE

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!

PowerStroker · UNSTOPPABLE!

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

SELLC · CERTIFIED POST WHORE

Whale sperm... lol j/k

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

stoma · Member

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

PowerStroker · UNSTOPPABLE!

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

SELLC · CERTIFIED POST WHORE

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.

3800_fix · Rookie

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

SELLC · CERTIFIED POST WHORE

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.

3800_fix · Rookie

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

Rastus · UNSTOPPABLE!

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.

3800_fix · Rookie

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

SELLC · CERTIFIED POST WHORE

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!

Rastus · UNSTOPPABLE!

Yo,

Here's a picture of our version of the 3.8 ltr V-6...And thankfully, the rear-wheel-drive version retains an all-aluminum intake manifold, & a few differing bits & pieces, though it's essentially the same thing. (I haven't cleaned anything or washed-her-down just yet, so some rocker-cover seal seepage is evident ).

Our biggest problem IMO is the heater-control-valve ( below the brake master cylinder assembly, you'll at least see its vacuum-cell in the photo ), where the plastic one-day decides to crack & split, loosing all your water...And then its head-gasket replacement time LOL.

It looks like we share all the same ancillaries that are driven by the serpentine belt too.

Interestingly, ours are rated at 147-KW, which is the same as the little MB 3.5 ltr V-8, though the V-8 makes its power at 5,800-rpm, compared to 5,200-rpm for the GM-V-6. The V-6 does edge-it-out with a further 20-Nm of torque at about 400-rpm less than the 3.5 V-8, at 3,600-rpm. I probably prefer the 4-speed auto too, than the high-stall 3-speed from MB.

Rastus · UNSTOPPABLE!

Yo,

I'm not suffering any coolant loss guys, but I do have a little bit of ( what I think is ) oil making its way into the coolant. It's not cherry colored milk, so the auto-cooler is fine...Anyhow, I changed the spark-plugs-out, & they were all fine, in good condition, & burning really well. Not a dud among them, & the car runs really well on all cylinders...So my question is...

Can the head-gaskets keep cylinder pressure, but fail where say an oil-gallery under pressure feeds into the cooling system on these motors ?...

I don't have an oil-feed-diagram, & would think that any oil-feed-hole through the heads is a drain, since the lifters & push-rods are what I'd guess provide the OHV lubrication. Having said this, I "should" have coolant leaking into the sump, & not oil leaking into the cooling system if the head-gasket has failed in this way. The rad-cap indicates good pressure in the system that holds well when hot, & sucks from the reservoir when cooling down.

There's not much oil by any means to be found in the coolant, & the level doesn't drop, but I think there may be a problem starting. ( Or it's just residue from a job long gone, but all the oil-seepage around the rocker-covers tell me they haven't been lifted in years )...Nothing around the motor looks to have been disturbed for a long while.

Cheers,

Rastus

SELLC · CERTIFIED POST WHORE

It is so cool to see what they do on the other side of the world with the same engine! I dont think I have ever seen anything like that in terms of the top end! And I think that is the first 3.8 (except for the Grand National engine) that I have seen mounted straight like that!

That is just really cool to see! Looks great Rastus! Looks like GM is doing Australia right with that design!

Rastus · UNSTOPPABLE!

LOL,

Yes, the tunnel-ram induction seems to work well ! As a regular day-to-day work-horse, it's perfectly fine, & even drinks a little-less fuel than the Mercedes too.

A few sustained high-speed blasts has seen the cat open-up, & the exhaust too, meaning I even get the pleasure of a subtle, near-V-8 induction noise lol, (though not the same).

Here in Oz, we did produce our own designed little V-8's, in 4.2 & 5.0 liter capacities under the GM banner, that saw production for over 30-years. Sadly, the 4.2 was retired in the mid-1980's, but the 5.0-ltr continued on into the early 2000's. These were great little motors, & I often wonder how an EFI 4.2 V-8 would have compared to the current V-6, especially since the 5.0ltr saw EFI in the late 1980's. I guess it was more economical to import the V-6, & there's no-doubt about the world-wide popularity of the V-6, with just about all the manufacturers offering a version.

Any how, simple maths reveals that you can make 4 V-6's to 3 V-8's when you count-up the pistons & rods etc needed.

I haven't converted results yet to your scale, but in metric, I'm using 10.74 liters of fuel per 100-k's traveled, combined hwy & city regular driving. ( The Merc drinks around 12-litres ).

Or if you rather, each 1 x liter of fuel, gets me about 9.31 kilometers. ( The Merc returns around 8.5 km ).