While punching out my response to bill buttermore in the 'Intake plenum still usefull??' thread (http://www.bonnevilleclub.com/forum/...ic.php?t=86576), I started looking for part prints to verify the distance between the EGR passage and the coolant passages in the UIM. I didn't have much in the way of luck in my quick search (long story), but I did stumble on to something I did not expect to see.

I pulled up the first LIM drawing I could open (long story again), an assembly drawing, showing the LIM and a few other parts (like the EGR stovepipe and bypass fittings).

It was missing something.

Something quite important. Or not, as it were.

There'* no coolant flow to the upper intake! None. Nada. No holes.

Talk about the easiest solution for fixing UIM failures, eh?

Now, that said, I'm not going to provide the P/N at this time, because I don't have access at the moment to the non-assembly drawing - the one with all of the details - things like - have they moved anything else that'* important to us?

I want to purchase one and have it in my hands (and do a test fit) before I have anyone else go out and spend money on this. The good news is that they're available in SPO right now (meaning a dealer can get a hold of it, as can GMPD). Cost to dealers is around $190.

Just checked GMPD, with their super-ridiculous way of calculating shipping based on the most expensive item in your cart, and the total will come to 240 if you do it through them. So it'll still cost more than a sleeved UIM, but it would deff. be the end of our UIM failures.

And based on the dates on the drawings, current production is running this - so if you can find a 3800 made w/in the last few months, you can find this LIM...

Any chance people want to pool together some $$ to pick one of these up to verify fit? I don't have a spare $200 laying around in the budget (especially since I don't actually own a 3800 any more), but I do have access to a) SPO pricing, b) a dead 3800 (my mom'*) in need of a fix, and c) another 3800 owned by a relative that could be used instead...

Matt..are you saying that they essentially blocked the coolant passages (by not machining them) or redesigned the manifold enough to change the coolant flow and didn't machine them in?

Right now it looks like they've blocked the old coolant ports by not even including them in the casting... i.e. there are no coolant ports for coolant to enter the UIM. The rest of the cooling circuit appears to be in place. This would be akin to the plugging of the LIM, without the air gap worries.

I'm trying to arrange a quick tour of Plant 36 at Flint North for this afternoon for me to get a closer look, so I can provide a better answer as to what all they've done. With only the assembly drawing, I can't tell if they've changed any other portion of the cooling system.

<edit> and it'* matt

Dunno what you are talking about. :P (Fixed!)

That is what I thought it might mean. Merely blocking the ports. interesting.

I'll be interested to see where the bypass is located...and if there were other outlets for throttle body heat. I wonder if it might have been a design to replace the LIM with something they knew would not allow the upper to puke coolant?

If no change other than the coolant bores missing, Bob Dillon'* $5 fix starts to look pretty durned good compared to $250!

I haven't had the chance to peek at the upper (half of the drawings for this redesign aren't in the system right now, which makes it very difficult to get useful information), so I can't speak to if they've changed that at all.

With the e-TB on the S3, I'd imaging the whole 'icing of the TB' can be taken care of programatically - those things have some crazy gearing on them, so a nice pulse from the PCM to loosen up the blade seems to be a reasonable solution, compared to routing the coolant through the upper.


What really confuses me though is this - if they're only building S3'* now - why the change? You've already got the aluminum upper, and the engine is only in production for some 9 more months. Why spend the money to change the lower intake - more than likely a new casting, as well as removing an op from the manufacturing process. It just doesn't make sense...

Either way, yes, the plugging (combined with a bleed point) of the lower looks very tempting right now, especially as my mum is about to throw $150 towards a new intake tomorrow.

Decisions, decisions.

It makes me wonder two things though:

1) Is this new LIM designed that way because the aluminum upper needs no coolant flow to keep from melting/degrading/etc.? Controversial topic, I know...

2) Is this THE new replacement for all Series II and III engines, or will they still produce the "old style" for the Series II? If this is THE new part, and the old one is no longer produced, then it seems like GM must have figured that it will work for the Series II engines too, as replacements are needed.

Is there still a passage through that part of the LIM going from one cylinder head to the other, or is it completely blocked off at the head now (I can't imagine them doing that, but I have to ask)?

I can't wait to see this new design, as it compares to the old. At first mental glance, it seems like it could be something that we could duplicate on our existing manifolds for much cheaper, if desired. Time will tell, I guess.

On that point, I can assure you that the coolant flow in the S2 upper was for the purpose of heating the TB. If they had really wanted to cool the EGR area, they would have done it with more than a supply and return to the TB, and they would have done it uniformly around the bore.

As far as I know, the S2 is out of production - and the old UIM was purchased. I.E., as far as GM is concerned, they're done with it, and if more replacements are needed in the future to fill SPO (they're required to have service parts for some 9 years after a vehicle is sold), they just purchase them. So I'll see what I can dig up, as far as current usage for the old LIM, but I don't know what I'll be able to find.

All I can tell from the assembly drawing that I have at the moment is that there are no ports for the TB coolant anymore - any other changes would have to be seen on the actual part print.

I'm very seriously contemplating doing just this for this weekend - picking up a spare at a boneyard, and seeing if I can throw together something I'm convinced will have a good amount of longevity, as well as removing any air bubbles in the system. I'm gonna give you a call once you're awake today...

While not an L36, I'd like to toss in my 5 cents about air bubbles etc.

I had an air bound issue once after a t stat replacement. It'* the one time that I did. My coolant gets drained on any whim and there are a lot of bonne'* that roll through here for coolant draining items. To date, my one time and once that Tony got air bound were the only two out of say around a hundred times.

Also.. PDXGTP and MV Bob provided me with a $. 0.20 mod to block off the passages. On the L67 lower (Not sure on the L36 lower) there are two indented areas for the coolant o rings, you merely file a little of the edge off two dimes and tap them into the bores. Blocked.

As well.. I've run two blocked off superchargers to date for over a year and a half now. There doesn't appear to be any need that I can find to be concerned about a bleeder valve being installed. While it may be a nice thing to have, it is not necessary from my findings.

Blocking a lower intake that has a metal upper is one thing, but blocking off a plastic intake IMO is looking for trouble with the heat and expansion extremes and cold climates in the northern states.
I'm still running the original EGR pipe touching the plastic with no issues. I simply modified the lower support braket to provide air flow to the egr flex pipe.
Should it go I will install a sleeved upper and reduced dia EGR pipe.