PontiacBonnevilleClub.com

Ok guys so I've been a long time lurker , this forum has helped out alot with maitnence and general info.

I have a 1998 bonneville SE And it recently started going through anti freeze like crazy. On Friday I started it and it was knocking loud so I checked it and it was out of coolant both overflow and the radiator, so I filled it up and got it home. On the way home the Check Engine light started flashing and it was running slightly rough at idle while at stops. The next day I started it up to give a buddy a jump, turned it off after that. I went to start it about 30 minutes later and it won't start at all. It cranks and cranks and cranks but will not turn over.

Now my question is , I'm thinking of tearing it down and replacing the LIM and UIM gaskets, do you guys think that will solve the issue? Or do you guys think the motor is ruined ? It sounds as If it may be hydrolocked.

Any input is very much appreciated, thanks guys!


Edit: after I filled it up and drove it home (25 min drive) it was yet again empty. No visible leaks under the hood. Exhaust is white-ish and sweet so I know it's burning anti freeze.

Check the oil level. If it is high, or if there is brown/yellow gunk under the oil fill cap after it's been sitting and cooled off, I would drain the oil. Immediately. Refill the oil with cheap stuff. Run it with the coolant drained for maybe 15-30 seconds. Kill it. Drain the oil again. That will maybe flush any water out of the bearings.

If the oil looks fine, i think it's more likely that the UIM failed by the EGR passage then it is that the LIM gaskets failed. But replace them anyway.

It has not been uncommon for the engine to spin/munch a bearing a little while after fixing either of these failures if water got into the oil. So, hopefully the coolant/water is just getting burned.

I just checked the oil cap and it has a tiny bit of yellowish cream on it. Would someone mind linking me to the replacement parts ? And how hard of a job is is the UIM and LIM ? This will be my first tear down basically, but it seems pretty straight forward. Thanks !

Upper plenum

It's easy

There's a really good article in techinfo on replacing the UIM/LIM gaskets that helped me do them my first time. I literally had only changed my oil/changed my battery before doing my gaskets, I just took my time and bagged/tagged every bolt and fastener. Now it takes me about 30 minutes to do the UIM gaskets on these motors.

The big thing to look for when you're getting you parts is to get a sleeved upper intake. This adds a metal bushing around the egr tube to prevent the intake from failing there. I got mine from ineedparts.com about 5 years ago, so I'm not sure if they're still a good source. Also, make sure to get metal lower intake gaskets. Either GM gaskets or felpro work just fine, as long as they're the metal framed ones. Hopefully like John said it's just burning coolant, but if you were hearing knocking, that's definitely something to keep your eye on.

Jfridge92 wrote:There's a really good article in techinfo on replacing the UIM/LIM gaskets that helped me do them my first time. I literally had only changed my oil/changed my battery before doing my gaskets, I just took my time and bagged/tagged every bolt and fastener. Now it takes me about 30 minutes to do the UIM gaskets on these motors.

The big thing to look for when you're getting you parts is to get a sleeved upper intake. This adds a metal bushing around the egr tube to prevent the intake from failing there. I got mine from ineedparts.com about 5 years ago, so I'm not sure if they're still a good source. Also, make sure to get metal lower intake gaskets. Either GM gaskets or felpro work just fine, as long as they're the metal framed ones. Hopefully like John said it's just burning coolant, but if you were hearing knocking, that's definitely something to keep your eye on.

It was knocking when I first realized what was going on but it would only knock until it warmed up a tiny bit I guess we'll see .

I kmow when Nos4bloods UIM failed, I believe he had a pretty bad knocking noise that turned out to be the lifters ticking from all the lack of lubrication since the coolant was diluting the oil (don't quote me on that lol, he can chime in to correct or verify). But hopefully you'll be lucky and it's just that. I know we've seen some pretty crazy comebacks from these motors with UIM/LIM failures before. It's pretty clear when a bearing goes though, just look for sparkles on the dipstick if you hold a flashlight up to it.

Well the bad news is the car is buried in snow right now so I can't get to it . Perfect

Redbonne1998 wrote:Well the bad news is the car is buried in snow right now so I can't get to it . Perfect

Snow? What's that? :p

Hope the weather clears up for you soon so you can get back on the road

Any other parts I should order along with the uim and LIM parts for while I'm in there?

It'd be a good idea to order the two coolant elbows that go into the belt tensioner. They may come up on the parts siteas "heater hose" but make sure to get the aluminum elbows. The plastic ones crack easily or fail at the o rings, but we haven't seen any aluminum elbows fail so far since they were redesigned. Otherwise, now would be an easy time to change the serpentine belt while you're in there, as well as plugs and wires if they're needed since the wires have to come off anyways.

You'll also want to make sure to replace the fuel injector o-rings for peace of mind. The old o rings might be okay, but while the fuel rail is off, you may as well put new ones on that you'll know won't leak.

If you're looking to do any performance mods, now would be the time to port the lower intake manifold, but if you're just keeping things stock, that's about it

Thanks for the help ordered those as well. Started tearing everything apart today while the weather cleared got everything out of the way and off ready to get the fuel rail off and get to digging in once the parts get here tuesday.

Got the TB off and peeked inside the UIM it's full of coolant and a little muck but I've read it's a wet intake so I'm assuming that's normal idk I'm no motor wizard lol any inut or comments appreciated.

Will be updating periodically, and probably asking for tips and help if I run into any problems if that's cool

Anyone know the torque specs for the tensioner assembly? Can't find it . Thanks guys

I've never heard of a wet intake. Some oilyness isn't out of the ordinary. The coolant is. The UIM is definitely bad if it's not maybe just the TB gasket.

Got the LIM off today and low an behold the entire thing was filled to the brim with coolant. Cleaned the LIM and got the new gaskets in place replaced the elbow that goes from the tensioner assembly in to the LIM. GOT the lower intake manifold torqued back in and tensioner assembly In and realized I didn't do the other elbow cuz I never saw it. Also my kit came with a few metal sleeves dowhere do those go? Hoping to finish tomorrow before Temps start hitting near 0 degrees . Any other tips appreciated!

Yeah coolant in the UIM is definitely not something you want to see. More than likely, the passage in the UIM where the egr stovepipe goes (silver sleeve near the Throttle body that's pressed into the lower intake) has melted the inside of the UIM. You can't always see a failure there, but usually if you feel inside the UIM or poke the passage with a screwdriver you can see that the material is cracked and brittle.

Also, to answer the question of the sleeves, are they cylindrical sleeves about an inch or so long with a larger diameter base? If so, those are reduced diameter sleeves for the egr stovepipe mentioned above. You remove the one from your LIM, and install the smaller diameter one. The idea behind these is that with a smaller diameter stovepipe, it helps keep heat off of thr passage in the UIM to prevent future failures. Those, combined with the redesigned UIM that's sleeved itself, help eliminate that failure point. Hope the rest of the reinstall goes smoothly for you, and if it makes you feel better, I broke the new elbow off in the tensioner putting it back on the first time (this was before the aluminum elbows were out) haha

Got it put back together and went to start it and when I turn the key the lights dim it clicks but won't crank. Any ideas? Really frustrating, tried jumping it and I couldn't get jumper cables to spark when they touch the terminals , but the car lights come on so idk.

If you removed the alternator, did you reconnect the plug on the back of it? It's easy to miss when putting it back together and can cause voltage issues

Haha as a matter a fact that was the last plug I put in I almost did miss it. But I plugged that in any other ideas? Its snowing bad again so it's gonna sit at least its back together and fresh oil and coolant in the radiator and tank now just need to get that circulating through the engine by getting it started.

Really hope the engine isn't ruined with a bent rod or something maybe it's hydrolocked. I love this car.

Any other ideas? I'm going to check fuses as well.

As I recall when the no start issue started before the LIM uim replacement, it cranked a few times , then I tried later that day and it did what it's doing now , no crank no start just a quiet single click but the lights dash and radio came on and fuel pump. And lights dim when I try to start so Im pretty sure the sure the starter is pulling alot of power to try and start it but it just won't crank.

By the way merry xmas eve everyone

To rule out that it isn't hydrolocked, you can pull all of the spark plugs out and turn the engine over by hand a few times (or someone can crank it in the car, but any coolant will spray out that's in the cylinders). Usually if it is hydrolocked, the starter will click since it can't overcome the resistance of the water is the cylinders. Hopefully it's not that though