1995- 2004, 3800 Intake Manifold Coolant Leak Cheap Fix!

drvettedrvette Member Posts: 99
1995- 2004, 3800 Intake Manifold Coolant Leak Cheap Fix!

V6 Engine (VIN K - RPO L36) 3800 Series II
w/ Plastic Intake Manifold

IF your problem is coolant going directly into the engine,
by ANY the indicators below.

· White exhaust steam / smoke
· Losing Coolant and engine running poorly, with No visible leaks
· Coolant flooding the plugs & stalling the engine
· Hydro-Locked engine, is locked down from a cylinder full of coolant

Your intake manifold is by far the most likely the culprit.
Leaking coolant into the engines combustion chambers from a leaking EGR cooling port.
GM calls it the “EGR stove pipe”

The wall is very thin on that part of the intake manifold..
EGR coolant flow washes a hole into the vacuum side of the manifold.

* Note, for external leaks or leaks into the oil there are other causes !

DO NOT Take it to GM for this “EGR stove pipe leak” anyone can do this!!

*EASY Fix for these plastic intakes w/coolant leak, save the High Cost. Of a New one

#1 - they are real easy for any backyard mechanic to get off.
#2 - they are real easy to Repair!

Remove Manifold;
On the bottom of the intake, at the front, is a hole about 7/8~" in diameter,
Inspect closely and you'll see a washed out section on the SIDE of that hole.
There is only one hole that size anywhere on the intake.
[It’s at the front of the intake, beneath the throttle]

Here’s a picture showing the location, [older version [95-98] of the same problem] http://www.dslreports.com/r0/download/1474193~b8723533681b41ca0b2534e7002fd258/t- sb_01-06-01-007a.pdf

A old post w/more detail, but only up to year “98 [issue goes to 2004]

Tools Needed.
1. Wrenches to remove intake
2. 6” or less ¾” CPVC [not PVC] pipe It has an Orange Stripe down the side
3. JB Weld, Belzona E-Metal or equivalent adhesive that is temperature resistant and will withstand constant submersion in coolant [RTV will NOT work]
4. Fingernail Polish remover [Acetone] or Lacquer Thinner.
5. Torque wrench and/or former expertise in proper bolt tension & sequence.

¾” CPVC should measure 7/8”~ O.D. on a ruler or 0.875” on a dial caliper.

#1- See if the ¾” CPVC will fit in the hole, if not, enlarge slightly with knife.
#2 –Cut a piece about ¾”+ [make sure it’s flush on the Bottom of the intake]
#2a - *The hole is not “Blind” but open all the way through.
#2b - Cut enough to extend into the intake air flow a little bit, or if you’re picky, you can “Bevel” the part sticking into the manifold airflow a bit just to “look pretty”
#2c again [make sure it’s flush on the bottom of the manifold, the top doesn’t matter]
#3 – Using the Acetone or Thinner, clean the inside of the fit and outside of the CPVC and glue the CPVC into place using JB Weld, Belzona E-Metal or equiv.
#3a – * Apply a thin coat of adhesive to BOTH sides, of the fit
#4 – * You “may be able to reuse the factory manifold gasket if it’s got the Orange O-Rings, but not recommended by GM
#5 – Other applications that require the usage of RTV on the ends of intake manifolds, make sure it is marked OXYGEN SENSOR SAFE, I like Gold RTV

Though tedious to read, this is a EASY & Permanent Fix for THIS problem.

TSB [Technical Service Bulletin] Num : 040601017
TSB Technical Bulletin 04-06-01-017
NHTSA Item Number: 10008471

There “was” a short window on “GM recall #03034 ” engine coolant leak, long gone now.

Links to GM Forum

Rusty Wrench
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