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intake manifold differences between 95 and 98?

chatbreaker

chatbreaker

New member
Did an engine swap in my car due to a rod knock, the donor engine came from a 95 bonneville, my car is a 98 grand prix. I had to swap over quite a few parts, including the upper intake manifold and plenum gasket (dorman intake was on the old engine). I also swapped over the EGR tube, which was significantly smaller on the 98 engine than it was on the 95 engine.

I'm looking up gaskets online because I plan to do a head gasket/top end rebuild in the end of may, and I was wondering:

Why are the gasket sets for the 1995 3800 series ii engines different than the 1998 series 2 3800?

Everything seemed to swap over just fine, the intake plenums looked identical, and even the LIM gaskets look identical in the pictures. Should I buy the gasket set labelled 1st design, or 2nd design, considering I swapped the upper intakes? The Dorman one is the upgraded version from stock, so I would imagine that it's the 2nd design?

Any insight would be great, I'd like to get this figured out ASAP, I found a gasket set for less than $100 and if I can buy it soon, I might just do it next weekend. Thanks.
 


Here's the answer to your first vs second design question. 95-97 is first design, 98+ is second. Reality is.. you can use the 2nd design end seals on either.
http://www.grandprixforums.net/threads/39522-LIM-Gaskets-First-and-Second-Design?highlight=design

The reason the stove pipe was smaller is that GM started to realize the heat from the stovepipe and heat cycles were cracking the upper intakes and coolant was filling the intake of the engine. Next time you have the upper off, I'd suggest plugging the coolant ports (search on "e asy" without a space and my name for the how to mod a lim thread) and you'll never have an issue.
 


lol scotty, if it's not the same engine, it wouldn't have swapped into my 98 as easy as it did.

So bill, you're saying the only difference is the locating pins on the lim? the 98+ gasket set should work on 95 and older, right?
 
Yup bill is correct, the 95 Bonneville and iirc the Park Ave both have the series 2 engine in them. The difference between the first design and the second design blocks is there are holes on the end of the block for lining up the end seals on the lim gasket.

Sent from A Galaxy Far Far Away........
 
so can I buy a 2nd design gasket set? it has a dorman intake on it btw, not sure if that'll affect the swap or if an OE 2nd design gasket will fit that. I found a full gasket kit on ebay for cheap (good reviews too) so I'm gonna give it a shot, only problem is it says 97 and newer (second design). Everything looks identical, and I'll be buying steel LIM gaskets anyways so I guess it doesn't matter too much.

Are the rest of the gaskets the same? valve cover, tb, head, water pump, etc.? Gotta go to work, but I'll check in on lunch. Thanks.
 
Why bother the head gaskets? They rarely go even on high boost applications, and you will need new head bolts if you go that route as the stock ones are TTY bolts and not reuseable. I'd stick w/ the LIM/UIM/valve cover change and leave it be, that is of course after plugging the coolant ports on the LIM as Bill suggested.

I recommend the Fel-Pro valve cover gaskets and bolt grommets. I've put these in both my Series II cars (95 Bonne and 00 GP GT) and they still have yet to leak.
 


lol. I just want to go through and clean up the top end, there was quite a bit of sludge in the heads when I pulled the valve covers (already did the valve cover gaskets on the new engine) plus the valve seals are going bad, the thing smokes like a mother on a cold startup. There's also a rattle inside the engine, I drove it pretty hard today and it seems to have stopped so maybe it was a plugged lifter? but I'd like to check for play on the balance shaft, even though they rarely go out I think I may have a bad bearing in there. It could also be a water pump, idk.

Mostly I need to do the valve seals, and maybe put some 105# springs in there, and clean out some sludge since 2 oil changes in 120 miles hasn't done much to help with that. And although unnecessary, I want to grind the valves with some compound and just do some general cleanup inside the engine, to make sure it lasts a while. I plan on driving this car for at least 2 years, or maybe longer. Oh, and I need to clean the coolant journals, they're pretty gunked up from the dex-kill.

Also, what do you mean by plugging the coolant ports - the ones that go to the TB? I guess I'll search for that thread and see what you're talking about.
 
I searched but I couldn't find the thread, does anyone have it bookmarked? are you talking about the coolant journals by the egr stovepipe?
 


That makes sense. I'll have to do that, I don't like having coolant running that close to the TB, and it will prevent future leaks from there.

Don't think my other question has been answered, will I have to buy a dorman-specific plenum gasket, or will the one in the kit for the 2nd design work fine? I've pretty much got my mind set on the 2nd design gasket set at this point, just hope it works.
 
2nd design will work fine. I've used 2nd on a 1st w/o a problem, just be super aware of the end seals before you bolt it down.
 
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