1984 - 1985 intake manifold differences?

[Hot Air Beast]

Have been told that my 1984 GN has a hairline crack in the intake manifold near the thermostat and coolant leak is evident.
I have a 1985 GN intake manifold, but it doesn't look quite like the 84. The car is in the shop and the 85 intake is at home so I cannot stand beside the 84 and compare. Looks like a different turbo oil drain location.

I am about to search for part numbers as a start. Any comments will help me decide to try and use the 85 or buy one specific to the 84.

Phil Errett
Ottawa, Canada
currently Florida

 

[BRAD_PADGETT]

I would use the 85 intake. They are the same.

 

[dank GN]

http://www.gnttype.org/techarea/pictureguides/intakes/intakeguide.html

 

[Hot Air Beast]

Thank you both - you have put my mind at ease. I was thrown off because the turbo oil down pipe looks so different on the 85 intake manifold I have, from the one currently bolted to the turbo on my 84.

Now, I am going to start a search in the Fort Myers, Bonita Springs, Naples area for a shop that has blast capabilities using walnut shell grit. Second choice - glass or plastic beads.

Any thoughts on which would work best and ensure no damage to the aluminum intake??

 

[Hot Air Beast]

Thanks to both of you. Pictures really helpful dankGN. I am going to tear down the 85 I have and get it cleaned up.

Just a couple of more things for you to comment on if you have the time.

What media would be best to clean it up - walnut shell grit - glass beads - plastic beads?
Have you heard of any way to locate and repair a crack in the aluminum on an intake manifold?

Thanks again

Phil

 

[Jerryl]

It sounds like you are trying to do it right. Whatever you decide . . Make sure they do not blast inside . . Or let the media go inside the manifold . It is VERY difficult to get it all out of this manifold.

Welding works . . . But depending on how much and where, it can warp the surfaces, which is obviously a problem.

I have used JB weld on one of the ports and ran the intake to 27 psi without issue.

If building a stock motor . . . Port out number 4 and leave the rest alone. Read the stickies on top of this section for info.

Good luck.

 

[m2mtrsports]

Aluminum can also be soldered once cleaned up. Less heat to warp it.
If I had mine bare I would powder coat it also.

 

[WE2Regal]

I remember reading some flow bench numbers on the 25515926 manifold versus a later design 25523552 manifold. The later design flowed slightly better, especially in the #4 port. Is this correct or is the difference not enough to matter?

 

[Hot Air Beast]

This is why I was thrown off, and thinking that the 84 was different from an 85.
Here is what the oil drain pipe from the turbo looks like on the 85.
On my 84 the pipe is a solid piece and I have always had trouble getting the adapter and the oil drain pipe to line up at the same time. Looks like a good mod - maybe I'll try it when we put things back together.

 

[2sloUknow]

This is why I was thrown off, and thinking that the 84 was different from an 85.
Here is what the oil drain pipe from the turbo looks like on the 85.
On my 84 the pipe is a solid piece and I have always had trouble getting the adapter and the oil drain pipe to line up at the same time. Looks like a good mod - maybe I'll try it when we put things back together.

Did you ever try to replicate this? Is this a manufactured kit or a home brew mod? I would like to try this as well.

 

[Hot Air Beast]

Nope - just went with the stock down pipe off, of the 85. No problems so far.

 

[Hot Air Beast]

One more thing - GM switched the places for the idiot light temp sensor and the sensor for the coolant temp to computer. Apparently in the '84, the coolant temp sensor was not always completely cover (Vertical beside thermostat housing) so in the '85 they dropped it down to the horizontal sensor position.