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Old 05-22-2018, 08:28 PM   #1
SoCalSlaughter
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Intake Manifold gasket question

So I have a 1990 Suburban v2500 5.7. The truck sits alot. I took the truck out to get its smog taken care of. The next day I noticed some oil dripping on the ground. I popped the hood and saw the front of the intake manifold was leaking some oil. While I had the hood open, I checked the oil level and noticed a small amount of milkshake on the end of the dip stick. I thought.. great head gasket time. Once I got the truck home I removed the oil fill cap and there was no sign of milkshake. With the truck running there was no bubbles in coolant. Removed all spark plugs and none where fouled or irregular from one another. I removed the intake manifold (Edlebrock performer), removed the thermostat and noticed it was a 190. I live in Southern Cali, seemed abit weird to have such a high temp. And noticed the intake manifold gaskets had the rear coolant ports blocked with the alittle metal block plate. But the intake manifold has the rear cooling passage. Im thinking the cooling system built up to much pressure and blew the gasket causing some coolant to get into the crank. Also, when removing breather hose from valve cover to TBI, the hose has some milkshake inside of it, just a film of it. The truck doesnt put out white smoke while it runs, it just passed it smog with flying colors, no miss at idle or anything
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Old 05-22-2018, 10:27 PM   #2
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Re: Intake Manifold gasket question

When driven, short trips or long? Could be just normal blow by moisture not having a chance to evaporate. Double check the PCV system as that is what is supposed to remove blow by bad stuff.
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Old 05-23-2018, 12:33 AM   #3
SoCalSlaughter
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Re: Intake Manifold gasket question

Usually its short trips, takes me 15 min to get to work, usually leave around 6:30am. Also, about a year ago I moved close to the beach, less than a mile away, So Im sure that doesn't help. But I didnt think moisture would accumulate like that, none of my other vehicles show this.
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Old 05-23-2018, 08:56 AM   #4
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Re: Intake Manifold gasket question

Where did you get an intake with a rear cooling passage?
I’ve never seen one on a sbc
190 thermostat is about perfect too..
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Old 05-23-2018, 10:35 AM   #5
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Re: Intake Manifold gasket question

I am wondering the same thing about the intake manifold. Is it stock? I am looking for a manifold for a 1988 L98 Camaro Motor.
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Old 05-23-2018, 01:56 PM   #6
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Re: Intake Manifold gasket question

Some of the TBI engines have a heater hose attached to the rear of the intake manifold. That would explain the coolant passage.
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Old 05-23-2018, 07:52 PM   #7
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Re: Intake Manifold gasket question

The factory iron intake and the new EdelBrock intake both have the rear water passage, and heater hose fitting is in the back of the intake

Pic of both below VVV

https://scontent-sjc3-1.xx.fbcdn.net...fd&oe=5B9199D0
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Old 05-23-2018, 09:15 PM   #8
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Re: Intake Manifold gasket question

Like I said, I’ve never seen one with a rear passage.
And I still haven’t.
There’s no passage there, just a port for the heater hose. A passage runs from head to head. Those don’t have that.

If there was a passage the motor would run extremely hot with limited water flow in the heads.
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Old 05-23-2018, 09:20 PM   #9
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Re: Intake Manifold gasket question

My Air Gap has both rear passages plumbed to a plate beneath the thermostat. 406 small block and has never overheated.
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Old 05-23-2018, 09:23 PM   #10
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Re: Intake Manifold gasket question

Ok, here is a bottom shot of the intake. You can clearly see the coolant passages by the dizz hole in the rear of the intake, head to head.

https://scontent-sjc3-1.xx.fbcdn.net...a4&oe=5B840F2D
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Old 05-23-2018, 10:30 PM   #11
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Re: Intake Manifold gasket question

I stand corrected!
My apologies for doubting you!
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Old 05-29-2018, 08:09 PM   #12
SoCalSlaughter
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Re: Intake Manifold gasket question

So I finished replacing the intake manifold gaskets. Drove the truck about 18 miles today. Runs/drives great. I popped the hood when I got home and noticed the TBI unit was sweating/had condensation on it. It was cold to the touch. Removed the oil cap and it had a few tiny water droplets on the inside of it. Is this normal?
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Old 06-02-2018, 06:56 PM   #13
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Re: Intake Manifold gasket question

Quote:
Originally Posted by SoCalSlaughter View Post
So I finished replacing the intake manifold gaskets. Drove the truck about 18 miles today. Runs/drives great. I popped the hood when I got home and noticed the TBI unit was sweating/had condensation on it. It was cold to the touch. Removed the oil cap and it had a few tiny water droplets on the inside of it. Is this normal?
You're not getting any heat to the throttle body. The water passage in the TBI intake runs front to back (or back to front?) to warm the throttle body. See the photo.

What intake gaskets are you using? The ones with the rear coolant passage block-off? Are the heater hoses hooked up? Because the rear passage is blocked off except for a 3/32" hole in each gasket block-off, I think the coolant has to circulate through the heater hoses. (Just guessing on that though.)
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