'98 gmc intake leak


Old 03-24-04, 04:18 PM
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'98 gmc intake leak

Ok, been awhile since I've asked for your help--so here it is. My 1998 GMC truck 5.7L has had a slight intake coolant leak for about 2 years now, it just recently got worse. It is the lower intake, the aluminum part, (very common from what I understand). I got the parts and can tackle the job no problem, but have been reading that it is possible for the coolant to get into the crankcase and cause bearing problems. Is this possible? How does it get into the crankcase? I can not see any signs of coolant in the oil, but the oil filler cap had some hardened junk in it, I scraped it out and it looked red. I have about 80k on the truck and always used mobil1 and changed it every 4k. None of my other vehicles has this gunk in the oil filler cap and they all get mobil 1. Am I looking at early bearing failure (cam or main)? If so, I will trade it in, already got a hell of a deal on a new duramax and they are giving me 11k for the truck--if the engine goes I ain't gonna get 11k! What do you think?
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Old 03-24-04, 06:54 PM
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The red tinge could be Dexcool. I wouldn't be too concered unless you find more than a quart in there. The oil will get contaminated when you lift off the intake anyway so just change it then and you'll be fine.
Old 03-24-04, 07:49 PM
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So it is open under the intake? That is how coolent can get into oil? This may sound odd, but I have never had the intake off a SBC. I have rebuilt pontiac v8's and they have a valley pan under the intake--if you have a coolent leak it does not get into the oil! So what your saying a little coolent in the oil (if it is indeed getting there) won't hurt anything even over two years?
Old 03-25-04, 05:25 AM
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a little coolant will be...

...boiled and turn to steam and be taken out thru the crankcase vent system...altho it does leave behind some stuff that doesn't boil. you have been on borrowed time and should have fixed it a long time ago...i've seen them dump the coolant into the oil while driving and then it's a short while til the engine seizes. sounds like you dodged a bullet here....when you pull the intake off, you'll see exactly how the coolant can get into the oil.

they say water and oil don't mix....think again...if you beat them hard enough, thay will most definately mix...and the crankshaft is a great beater!!

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