intake manifold gasket failure?

kelley13

I have a 1999 gmc c/2500 w/7.4 engine in which i have replaced the intake gaskets and 1 lifter. I have discussed this issue with GM but to no avail. Any suggestions? Also water pump and only 57000 miles.

                            Malcom E. Kelley

themailman1

Not long ago I posted something about this problem. I deliver mail to a repair shop for about 20 years and I saw a 99 silverado with the top of the engine off. I asked what was the problem and they said the dex-cool ate away the intake gasket. He advised me to drain and flush the dex-cool from my 01 Sierra [5.3] and replace it with good old Prestone. But first I have to find out if that voids the warranty. Keep me posted.

jtt3

The problem is created by bad maintenance by allowing the coolant level to drop below normal levels. Which in turn allows oxygen to enter the system and cause corrosion and over heating.
  
  This will dry out and overheat gaskets as well as lubricating the water pump.

  I disagree with leaving any fluid unchanged as long as they suggest. I would change and flush my cooling system probably 30,000 miles or 3 years. I would not hesitate to use dex-cool as it is probably a little advanced over older coolants.

slickracer

I had to have the intake gaskets replaced in my 99 S-10 4.3 and I can guarantee you the antifreeze level was never low. I always kept the level at the full hot mark when cold. I only had 37,000 miles at the time. The mechanic who fixed it is a good friend of mine and he did a complete flush and changeover to green antifreeze.

themailman1

Will changing to Prestone on my 2001 Sierra void the warranty?

dodgeram10

GM knows they have a problem with Dexcool but they are not willing to correct this problem by going back the green coolant that did not have any problems, & when the Dexcool eats away the intake or water pump gaskets allowing the cooling system to leak coolant & get low it will start caking up in the cooling system. Jtt3 per Gm dexcool is not due to be serviced until every 100k, I have look at some vehicle at 30k & the dexcool already looks really dirty, I would recommend having the cooling system completely flushed & have green coolant put in the vehicle, unless you like buying intake & water pump gaskets

markw8

My son recently replaced tke intake gasket on his 96 s-10 4.3. The truck was bought new by me in Sept. 96. The truck had 166,000 miles when it failed. Also it still has the original waterpump.It has never had anything but Dex-cool in it, and still does. The problem is with the composite manifold and the type of gasket with o
only about 15 inch pounds of torque. Mark

ryanbab

its not a dexcool problem

slickracer

I still trust my mechanic. He works on 'em everyday.

gator36

Basically Mark is right. There has been a TSB or two in the past referring to overtightening of the intake manifold, thus the resulting gasket leak.
A number of the mechanic's I have seen still try to bolt these intake's down by "feel" and fail to follow the manufacturer's guidelines. Most still try to torque the manifold in ft lbs not Inch lbs.

gmengineman1

Intake and exhaust manifold problems have plagued the GM big blocks for some time. The exhaust manifolds get so hot that they warp and have to be resurfaced. The intake manifold problem is present with either the red or green coolants. However there seems to be a problem with dexcool. GM has launched a suit against Dupont over that product and the costs that GM has incurred dealing with their use of the product. Both parties are now negotiating what will happen. Interestingly, GM is still using the product in their vehicle line today.

cspaulding

You can bet consumers will get the short end of the stick...just like the last suit for the gas tanks, a $ off voucher that you have to jump through hoops to get...my truck still has the original gas tank. But, to cease using the product would be to admit that there was a problem with it.