Intake manifold gasket

russ3654 · #1 11-13-2009, 10:12 AM

I recently had front tires put on at Tires Plus, as usual they look the car over to find more work. They told me my intake manifold gasket is leaking anti-freeze, and needs to be replaced. I noticed I'm losing some anti-freeze, could it be the intake manifold gasket, and how hard is it to replace on the 94' , 3.8,buick lesabre?

HotZ28 · #2 11-13-2009, 10:27 AM

What year?

Airjer_ · #3 11-13-2009, 11:24 AM

What engine?

HotZ28 · #4 11-13-2009, 03:32 PM

Try a bottle of Bars Leak Part number R6 (5.5 oz) and watch the leak stop!

Jrs3800 · #5 11-13-2009, 06:15 PM

Chances are you have a bad intake gasket.. Just worked on one with the same issues as you are having..

You will have a 3800 Tuned Port Fuel Injection( L27 )... Chances are the intake gasket has cracked or deformed.. with age and mileage this is common.. In this pic you will notice the cracks, take a look at the nasty intake port near the coolant port... On this engine the coolant was wicking over to the cylinder 5 intake port... Car was using more than 1 quart per week... This is what I saw...

The gaskets for this motor are roughly $23... The charge to install them is another story.. The owner of the car was a good friend so I did his for free..

dpalomaki · #6 11-14-2009, 06:11 AM

Failing lower intake manifold gaskets were a common issue with the 3.1 L V6 used on a number of GM models including the Malibu. Apparently the plastic material used in the gasket frame did not agree with Dexcool in the long run, and the failure usually hits around 70-80K miles/6-7 years or so. Not so much a common problem with the 3800 engine from what I've read, but that does not mean it cannot happen.

There are many other possible sources of slow coolant loss, such as weaping water pump shaft seals or loose hose clamp.

If it is the gasket, bars leak type products are at best a temporary fix, and some may cause additional issues like clogged heater cores and radiator passages. Best to find and fix the leak.

Are you finding evidence of coolant in the oil. Might appear as the oil lever increasing ove time rather than holding steady or slowly decreasing. Or evidence of oil in the coolant? Might see evidence of coolant pooled under the valve covers.

Jrs3800 · #7 11-14-2009, 02:34 PM

I completely disagree... This is a common failure on the 3800's... The failure rate on a 3800 series II is much higher than a series I, But the series Ones will fail in due time.. Even if the gaskets on a series one don't fail they will be very badly deformed in most cases..

With the 3100 M, 3100 J, 3400 E, much like the 3800's the plastic gaskets would fail.. I will say the 3100-3400 was one of the worst gasket designs ever..

But GM did design a set of aluminum gaskets for the Series III 3800, these can be used for all series II engines as well, and its the replacement that we use in all 3800 series II's we work on..

The 3100-3400, Fel Pro actually has an aluminum set for these engines, and I do recommend them when doing the gasket replacement..

wafrederick · #8 11-14-2009, 07:17 PM

Dorman has the better set with new intake bolts for the 3100 and 3400 engines which is complete with all you need for the job and is cheaper than Fel Pro.GM says to use new intake bolts for the 3100 and 3400s when replacing the intake gaskets.I have seen one series 1 3800 with a bad upper intake.

HotZ28 · #9 11-14-2009, 09:55 PM

Quote:

Originally Posted by dpalomaki

If it is the gasket, bars leak type products are at best a temporary fix, and some may cause additional issues like clogged heater cores and radiator passages. Best to find and fix the leak.

GM uses a stop leak from the factory, if you flush & change the coolant without adding sealant, more than likely it will develop a leak somewhere. I had the same problem about 5-yrs years ago on my 94-LeSabre after a cooling system flush and added about 1/2 bottle or Bars Leak alumina seal, and have never had a problem since. (Engine runs cool in 105 deg heat) Do not use the rat pellets, they will restrict the coolant flow.

dpalomaki · #10 11-15-2009, 07:04 PM

I believe what GM used on a variety of their models was was a ginger root compound, a very specific product, and not the run of the mill stop leak sold to unsuspecting folks. Teh ginger root leak stop is OK, but probably will not take care of a failing gasket on a long term basis.

Jrs3800 · #11 11-15-2009, 07:23 PM

Never heard of GM using Stop leak on any Series I 3800 Engines.. I have heard of the dealers using the stop leak pellets on 3800 series II's to help seal the throttle body... But that was not a cure so much as it was a bandaid..

I know a lot of the Caddies used the stop leak from the factory and it was required when you replaced the water pump or gaskets.. The 4.6 N* also used the pellets from the factory..

I Could be wrong... But when I do anything to 3800 series engines I never use the pellets.. I have yet to have any issues with any 3800 using coolant after gasket replacement.. I haven't added anything to my 95 Bonneville in 6 months as far as coolant goes.. I have 3000 miles on my Vans powertrain now, and I do need to add a little coolant, but I caused that as I had to replace the Temp sending unit...

am just not a fan of stop leak additives.. In a pinch it'll work, but if I can avoid it I do..

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