At this point I've had the car for nearly a week and have put close to 300 miles on it. Here'* what I have discovered in my short time with it...

(+)
- At least through First, this car'* pickup will surprise you. The blower cars must really be something else!

- Great seats. Great, great, great seats. Interior layout is nice,. and I'm spoiled on the head-up unit. I rarely look down while driving.

- Overall this car is really a smooth operator, I enjoy tooling around in it and this has to be the best automatic trans I've had. You can't feel it shift.

(-)

- It has the dreaded upper intake problem. Pulled the engine cover getting ready for an oil change (I know it'* not necessary, just wanted to look) and I saw oil and antifreeze- puddled even, in one place. Amazingly, at 142K this car still has the original UIM (verified by date code on the unit). Time for a change. Real soon. Like, ASAP. Last thing I want is this thing spinning bearings or hydrolocking. Contemplating the Dorman kit but I just read up on the member who plugs the coolant passages near the EGR pipe. So I'm considering that, too. Valve cover gaskets need to be replaced (they're leaking), going to a 180º T-stat.

- Rear end feels pretty mushy in turns, I'm thinking struts or endlinks. It'* out of synch with the front, feels like it'* a half step behind. (Other than that it corners nice and flat)

- Looked at the brake lines under the hood today. OMG the rust... No leaks but looks like they might need to be replaced. Amazing in light of the fact that there'* otherwise very little rust under the car.

-Air bag light is always on. Fuse under the dash is ok, moving to the sensor under the pass seat next. I saw the post about the member whose bags went off at a red light. Don't want that to be me One more thing, is there a fuse in the mega block under the hood to check? I have searched this too but my head started spinning about a half hour into the search.

So, this is pretty standard Bonneville stuff, eh? I like this car a lot overall, but seeing that UIM today gave me pause big-time. I know it'* not a huge deal, it'* just a bullet I was hoping I dodged.

You've got a great Bonneville. I checked out the pics in "Your Ride" forum. It is recommended that the lower intake manifold gaskets be replaced while replacing the upper intake. Replace the LIM gaskets with the newer GM gaskets. There should be some more veterans & GH'* chiming in to help you out. Good luck with the job.

Definitely planning on the LIM gaskets, makes sense to just git 'r dun all at once than have to go back later. Thanks for the vote of confidence on my car

Within the next 2 weeks I'm hoping ot have this done, 'til then, I'll just drive it as gently and as little as possible.

oh and one more thing... Has anyone used the UIM overhaul kits from that famous auction site? If so- thumbs up or thumbs down?

Must reading for all L-36 owners (and especially those who have squeaked out 140K without poppin' somethin!):
http://www.bonnevilleclub.com/forum/...e=article&k=38

Re overhaul kits, here is some background on repair and replacement methods that retain factory coolant flows through the UIM and throttle body. Some of us here on BC built on the concept developed by Ken Spragg who first marketed an overhaul kit for L36 UIMs. The KenCo kit comprised a sleeve to epoxy into the (often perforated) EGR passage and a reduced diameter stovepipe both of mild steel. It used to sell for $80, and more recently for $70 or less. Ken'* idea was great - provide a heat shield in the most vulnerable area of the plastic UIM, the EGR bore, and reduce the diameter of the EGR stovepipe from .750 to .500 providing a .125 insulating gap between the hot pipe and the heat shield. Properly done, this is a very good fix. However, it takes skill and patience to center the repair sleeve in the EGR bore and to keep it properly aligned.

Everybody copied Ken'* concept - or, parts of it. GM increased the gap between the stovepipe and the plastic from practically nothing in 95-98 to about .065 in the 99+ models. They accomplished this by changing the EGR bore diameter in the LIM from .750 to .625, and by changing the stovepipe from a straight piece of .750 stainless to a straight piece of .625 stainless. That extra gap gave the plastic a longer expected life, but still did not prevent eventual deterioration of the plastic from heat. GM did not add a heat shield like Ken did or we would not still be dealing with the problem of perforated UIMs.

We liked Ken'* kit, but not the $80 price tag, or the use of mild steel, so, with some help from Bob Dillon, who recommended off-the-shelf 7/8" tubing for a sleeve instead of more expensive custom sizes, a low-cost stainless steel repair kit was eventually developed. For 95-98 engines, this included a .625 reduced diameter pipe and a thin-wall heat shield that together provide an insulating gap of about .090" and which was made available to BC do-it-yourselfers for $15. So, with $5 in JB weld and $15 in parts, you could repair your own UIM. For 99+ , only the sleeve and JB were needed -$10!

The problem is that perforation around the EGR is not the only problem with the plastic UIMs. They also can warp out of plane on the lower sealing surfaces around the EGR and coolant bores, and the sealing surface for the throttle body gasket often begins to gap open over time. So, a new UIM is often a good choice.

Most guys don't want to wait for mail-order parts, and just buy the widely marketed Dorman UIM replacement kit. Recently, Dorman has provided a reduced diameter (.625 x .510) aluminum stovepipe that will fit right into the LIM bore of 99+ L36s. This bettered GM'* '99 improvement by further increasing the gap between the hot stovepipe and the plastic to about .123. But still no heat shield.

For 95-98 guys who want to use the Dorman with a heat shield, a ring can be pressed onto the Dorman pipe to adapt it for the .750 LIM bores, and a .750 x .710 piece of stainless can be driven into the LIM bore to shield the plastic and provide a .100 gap for $10 in parts. 99+ guys with the smaller LIM bores need to apply some hi temp copper silicone to hold the shield in place.

The KenCo kit (unless they have changed it recently) stovepipe has a .750 shoulder to fit into the LIM of 95 - 98 L36s. The KenCo pipe could easily be turned to fit into a .625 99+ LIM bore and so achieve a .125 gap with a heat shield.

The new APN upper is really the best off-the-shelf fix we have seen for the UIM. It comes with a reduced diameter .500 pipe with a .750 shoulder, and a factory- sleeved EGR bore. The shoulder of the pipe will need to be turned to .625 for 99+. The APN upper can be purchased mail order for about $125 including shipping which makes the APN less expensive than the unsleeved Dorman. A little patience waiting for the mailman not only saves you money, but gets you a better design.

If you are still thinking of repairing your own UIM, remember to calculate the value of the new UIM gasket that both APN and Dorman provide. When you add that to the cost of a KenCo kit, it is pretty hard to justify compared to a new APN upper. If you have skill and time, and are inclined to do so, and your old upper is not too badly warped, you can save $100 and still get a very good fix by sleeving it yourself. If you want to repair your own in stainless and need any help or any of the parts described above , PM me.

Hey Steve, where in NY are you? I might be able to lend a hand.

Buttermore, I love your clear explanations when it comes to technical issues. You clearly lay out the possibilities, then identify the solution that seems best. Thanks for taking the time to explain everything to newer members and making this once-troublesome issue a walk in the park

^^What he said. Thanks a ton, Bill.

popatim I'm in Orange County- about an hour north of the city. .

***update***

With a huge amount of help from my dad the intake was removed today. At this point, we're collecting all the parts for reassembly, and it should all be back together I'm hoping by midweek. Sprang for a new water pump since we had it all apart anyway, with 143K on the clock and knowing the coolant system needs a good flush why chance an old unit. For $40 it'* cheap insurance.

So far so good, and thanks to the good people at this very site for all the info.

Steve, Progress sounds good. Replace the coolant elbow (with one made out of steel) while you're doing this job. It'* also good insurance like the water pump replacement.

Sounds great Steve..

You'll be good to go with that piece of mind out of the way.

Which seats do you have in the car.. switches in the center console (AL7) or switches on the seats (6way)