98 Bonneville SE

Okay, the factory manual says if you have to add Dex-Cool in to the overflow
container more than four times a year, have the car looked at.

I recently noticed that the antifreeze level in the overflow container is dropping
about an inch or two every two weeks and I have had to add more. The odd
thing is that I've been trying to see where the leak is and there is no
obvious water dripping or leaking out of the radiator or hoses nor is there
moisture around the water pump. There is no water accumulation anywhere visible.

We all know the weather in the east has been horrendous. Could this
simply be an artifact of extremely cold weather? Geez, I don't want to
get nickeled and dimed at my dealership. They're notorious for that.

Suggestions appreciated!

puppet

I hate to say it but the 3800 NA engines are known for leaking upper intakes, they're plastic. My initial guess is that it is leaking internal to the engine and getting burned off which is really bad for the engine and could cause some serious engine problems down the road. Not trying to frighten you but if this is the case I would definetly get it looked at and fixed as fast as possible before you have permanent damage.

I just picked up my 96SE yesterday. Was leaking dexcool around intake. replaced both intake and gasket. I did notice that the mechanic flushed the dexcool (that I had just replaced back in october) with the older type coolant. Intresting. I've been on line all day trying to figure out what the problem is. sounds like some folks are blaming it on the Dexcool coolant, and others are blaming it on the gasket material, or the combination of the way the plastic intake manifold is bolted down. I just found it intresting that my mechanic choose the old type antifreeze. My brother had the same thing happen on his 97 Z71 chevy truck. 350 V8, 55,000 miles. Back to my deal, I didn't have one problem with this till I flushed my system and installed new Dexcool. Hope you get your bonny fixed up, Good Luck !

I agree with SSEi95.

These plastic intakes are known for cracking. There are a few things you should know. If you continue to drive the car as is, you take the risk of hydrolocking the engine. In the worst case scenario, this means a new engine as potential bent rods and valves make for a nasty repair--not to mention the scoring that may occur in your cylendar walls.

Have it replaced (but keep in mind that it may be covered under your warrenty--it it hasn't already expired). This is usually a very costly repair if you don't do it yourself.

To help avoid this in the future, change your T-stat out to a 180 degree unit. they are $10-$15 and can help keep that plastic intake cooler, and thus less prone to cracking around the EGR valve. This is the one piece on the L36 engine that is poorly engineered. It was designed to be light weight and economical to produce, while giving increased hp, but just doesn't hold up to the heat.

Good luck, keep us posted!

Nothing pisses me off more than some people out there blaming DexCool for all their problems! It'* the Gaskets at fault! GM now realizes it mistake & has put out a redesigned gasket to replace the original ones. Here'* what needed to fix the problem: http://www.friedpoodle.com/ba/forum/viewtopic.php?t=360 & here'* the GM TSB on the problem! http://www.friedpoodle.com/ba/forum/viewtopic.php?t=297 Anymore questions?

No Prob! DexCool is actually beter at thermal cooling the engine than conventional antifreeze anyhow! That'* why it'* being used now too! In "lawmen'* terms" I mean, it takes the heat away from the engine faster & better than regular antifreeze does!

Let'* not forget the L27 has this problem too. Remember Jseabert just went through this. Gasket failure of the upper intake, but the intake was intact.

Thanks you guys! I'll have this looked at instantly.

Do any of you think this is related to my complaint
post (page 7 here) My Bonnie Hates Rain! Could
this be the moisture causing the Check Motor
Sensor to go off (which it hasn't done, incidentally
for a month now since I added injection
cleaner to the last 3 tanks of gas.)

(Obviously, not a mechanic, eh? )

Hi all--

New visitor to the forum here. I've been having the same problem you all described here, except that my radiator now will not hold any coolant. Now, when I run the engine and fill the radiator, I can see coolant leaking from what I believe is theupper intake area. I first noticed this one night after driving the car pretty hard; there was coolant sprayed over the left side of the engine block, on the alternator and on the serpentine belt. Prior to this I had noticed some coolant loss but hadn't been able to observe a leak.

My questions are: do you think I did permanent engine damage, and if not, how much should it cost to have the upper intake replaced (I dont want to get taken)?

Your help is much appreciated!

BTW, I have a '92 SE with about 162K miles on it; pertinent info--I've had to replace a radiator tank and the transmission cooling lines in the past couple years.

Hmmm....exactly the same place as Jseabert'* leak. #3 runner of the upper intake. First of all, I'd be surprised if your intake is cracked. I'm betting just a coolant passage seal or the intake seal itself. I'd bet your'e talking about 300 bucks if the seals are bad. Less than 100 to do it yourself. Probably less than 50. If it'* the upper intake, double the first estimate.

You have the EGR-less 92......after we get you through this coolant thing, we'll have some warnings and advice for lengthening the life of that car. 92 was an oddball in this regard. Still a damn good car though.

Welcome to the forum!