PontiacBonnevilleClub.com

Hello from Alberta Canada. I have had a thing for W-Body cars and of course H-Body cars for quite some time. I first looked for a good, W-Body, was hoping for a Regal, in 2014/15, but ended up buying a Ford out of necessity. I kept my eyes open, considered some H-Body cars (I think the 92-98 Bonneville SSEi's look amazing) but I could never find one that wasn't trashed. I stopped looking, but the project car itch was still around. I ended up buying a 78 Pontiac Grand Prix, saving it from the wrecker and getting it running and driving safe enough that I sold it a year later. I swore off more projects at that point because of space issues, which meant I bought a 1990 Caprice as one does, saving it from the wrecker too. I am selling that car, since I decided that what I really want, is a tenth gen oldsmobile 88. Not quite a bonneville, but my late grandmother had one so it had a bit more emotional impact if I could find one.

Well, find one I did. I found a 55k mile, 1998 Oldsmobile 88 that has been garage kept its entire life and according to the complete service history I have (outside of oil changes and I am guessing tires) it was only doing 3700 miles a year, until it sat for around 11 years and was bought by the person I got the car from. They had put only 800-1000 miles on it, before the UIM on the 3800 series 2 motor decided the cylinders needed large amounts of coolant, hydrolocking it. The owner knew the car was special, so hauled it home and replaced the motor, which on start up, dumped coolant out the spark plug holes. Shop claimed it was a headgasket or maybe a cracked head/cylinder. They started the hunt for a living donor car or a good block, which was estimated at over $4000.... They ended up selling the car to me. 30 minutes with a socket wrench and the upper intake is off, with all the coolant sitting on top of the lower intake manifold and the upper warped/damaged in the typical spot. Currently in the process of swapping an L26 aluminum upper and lower intake onto the car and I have the ZZP adapter so that I can run the L36 TB on the car... and eventually an L67 TB when I turbo it. Hoping right now that the only issue is the failed UIM, and that this shop didn't ruin the block, but when I go to replace the head gaskets and clean everything I will know more, since I absolutely do not trust that shops "opinion". They saw an easy mark and took them for a ride. I honestly don't even know if they swapped the engine out in the first place anyways.

Welcome to the club!

Nice pick up.

There are a few different ways to go with the UIM. The cheapest/easiest is to fill the water jackets on the failed unit with JB Weld. I ran one like that for years. The revised aftermarket UIM kit options all have skinnier stove pipes to make sure the UIM plastic doesn't melt to the coolant ports. Drilling and tapping the LIM coolant holes is also an option (L26 and L36 LIMs are identical). I eventually went this route.

IMO any of those options fix the L36 UIM issue and are better than swapping to the L26. Adapting the L36 TB to a L26 UIM will not allow for a smooth transition due to the different mating surface shape. The L26 also bottlenecks down substantially smaller at the entrance to the plenum. (You trade volume for air velocity here) You also either lose the PCV system and have to deal with un-metered air, or you have to cobble something together to re-plumb it.

95naSTA wrote:Nice pick up.

There are a few different ways to go with the UIM. The cheapest/easiest is to fill the water jackets on the failed unit with JB Weld. I ran one like that for years. The revised aftermarket UIM kit options all have skinnier stove pipes to make sure the UIM plastic doesn't melt to the coolant ports. Drilling and tapping the LIM coolant holes is also an option (L26 and L36 LIMs are identical). I eventually went this route.

IMO any of those options fix the L36 UIM issue and are better than swapping to the L26. Adapting the L36 TB to a L26 UIM will not allow for a smooth transition due to the different mating surface shape. The L26 also bottlenecks down substantially smaller at the entrance to the plenum. (You trade volume for air velocity here) You also either lose the PCV system and have to deal with un-metered air, or you have to cobble something together to re-plumb it.

Well, my goal once I get the car running is to turbo it. I would also like to run the ZZP Equalizer kit, but they said they installed it in a Bonneville back in 2022 and the stock intake tube contacts the crossover, so I might contact them and get details on that. I might just go and grab a junk yard L36 UIM, since it is a pretty cheap pick up (like 50 W/H Body cars at the two yards I use) and do the quick and dirty fix, since ZZP still hasn't shipped my order from Monday. Like I mentioned though, I plan on going turbo in the future, more for the street, so I assume the L26 UIM isn't needed for that, but I did get both the upper and lower, since from what I am reading the Lower is a better casting, so if I go L36 UIM I will still likely use the L26 lower.

I am super happy you responded though. I have lurked this forum and other 3800 powered car forums for years, and your Bonneville was the reason I got interested in trying to find an SSEi in the first place. Before I was hoping I could get my hands on either a GP GTP or preferably a Buick Regal with the l67 in it. I am keeping my eyes out for those spoke, BBS style rims you have, but I think they look awesome too.

Back to the L26 UIM, because I am in Canada, the exchange rate ($1 usd = $0.70 cad) along with shipping (the adapter and the complete gasket set from ZZP was $88 USD shipping) is a real killer. Some places don't even ship to Canada, because of the costs associated with it. I figured that if my goal is turbo, having the adapter so I can run an L67 TB later and the l36 now, on the L26 UIM would be the best move. That way I can start working on the air intake solution, since ZZP doesn't have a CAI in stock and from my reading, a fenderwell intake is the play. Maybe the whole thing was a waste and i just go L36 for now/future, to get the car up and running asap, but I still need to wait for the parts from ZZP because I know 100% that coolant got in the oil and cylinders, and since the previous shop said that it was a headgasket, and that they replaced it (I believe them I can see RTV squishing out in spots) I need to pull the motor apart anyways to make sure it was done correctly, which I doubt. The end goal of all this is a bad ass, street/daily driven Olds 88 that makes some turbo noises and sounds cool.

Thank you. I appreciate it.

I would go the route you're thinking and do the L36 UIM for now then go L26 UIM plus L67 TB for the turbo setup. Unless you want to try the 97/98 non-DBW F-body 3800 UIM/LIM setup. It requires some more work but would simplify cold side pipe routing.