1991 Buick Park Avenue...eating coolant? {PICS}

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My brothers 1991 Buick Park Avenue has been losing coolant for some time. We noticed the reservoir kept getting low at first so he just keep topping it off, but recently he hasn't kept up with keeping it topped off. I checked the radiator today and its a smidge low, but also has some floaties in it. We are hoping its not engine oil as that would spell bad news. I checked the oil and there was no milkiness on the dip stick or in the cap. What do you guys think? Here are some pics....
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Originally Posted By: ejes
Lower intake manifold gasket most likely, or could be upper intake. Just had the same issue on a 97 Buick LeSabre with the 3800. Common issue. Upper intake plenum might be warped as well. I replaced both at the same time since I was there. Cured the problem. Spring for the aluminum LIM gaskets and save yourself having to ever go back in there for that.


This has the early model with metal gaskets..this I know to be true. I am just curious if anybody can confirm that that is what oil looks like in coolant. Its gone through a more than an entire reservoir full of coolant, and if it were all going into the engine I would think it would have been fried by now.
 
What about putting some of those cheap $4 coolant tablets in there? They're supposed to work very well, avail at the GM dealer and cheap.
 
Cooling system tabs won't help; don't ask how
I know. In my early years at my job, I have dos/done more than 50 of the LIM gaskets
 
Didn't say it didn't already have the metal LIM gaskets, just that you should spring for them if you replace them. That year probably doesn't have a plastic upper either, so likely not that. If you can't find any leaks, metal or not, it is probably still the the LIM gaskets. It looks like you have a little oil in there, but not much. It'll eventually get worse as it goes and you'll get the orangish jelly type goo.
 
I think you'd be able to rent one of those radiator pressure testers at the auto parts store for free. Screw onto where the radiator cap goes and pump it up. It has a gauge on it and you can see if it holds pressure. If not, you're usually able to see where it's leaking.
 
Well hopefully its nothing serious because he doesn't have the money for any major repairs. Is this something that you can limp along with frequent oil changes (3 months)?
 
A 91 should be an early 3800 with the metal intake manifolds and not the later troublesome plastic ones. Being an iron block/iron head engine, it is rare to knock the gaskets out of them.
 
Get out a drain pan and drain the radiator and refill with coolant, that way if there's oil in there you'd be kind of cleaning it up and limping it along. About $10 for a jug of coolant. There might be a petcock on the radiator to drain, otherwise just pop off the lower hose.
 
Originally Posted By: gregk24
Well hopefully its nothing serious because he doesn't have the money for any major repairs. Is this something that you can limp along with frequent oil changes (3 months)?


If there is coolant in the oil, it will kill the bearings in short order. There is no real way to limp along with coolant intrusion in the oil that does not end with a rod bearing going out.
 
Originally Posted By: Robenstein
A 91 should be an early 3800 with the metal intake manifolds and not the later troublesome plastic ones. Being an iron block/iron head engine, it is rare to knock the gaskets out of them.


LIM Gasket Problems: Engines affected: 3.8L V6, 3.8L V6 Supercharged, 4.2L 6 Cylinder
15 model years affected: 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

LIM gaskets installed on model year 1991-1999 3.8l's used carrier plates made of Nylon-66 plastic, and have the highest failure rate when used with DexCool coolant. Gaskets installed on 2000-2005 model year cars with Series II engines use carrier plates made of a different plastic that is more resistant to DexCool; but still fail.
 
Originally Posted By: ejes
Originally Posted By: Robenstein
A 91 should be an early 3800 with the metal intake manifolds and not the later troublesome plastic ones. Being an iron block/iron head engine, it is rare to knock the gaskets out of them.


LIM Gasket Problems: Engines affected: 3.8L V6, 3.8L V6 Supercharged, 4.2L 6 Cylinder
15 model years affected: 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005

LIM gaskets installed on model year 1991-1999 3.8l's used carrier plates made of Nylon-66 plastic, and have the highest failure rate when used with DexCool coolant. Gaskets installed on 2000-2005 model year cars with Series II engines use carrier plates made of a different plastic that is more resistant to DexCool; but still fail.


Sorry, but it's 1996 and newer, with the start of the series II engine. Also the 3.1 and 3.4.
 
Dex Cool came out in 96 so it wouldn't be an issue in any gasket failure on a 91 unless someone switched it over. I had a 92 and it had the alloy intake manifolds and it never went out once in over 230k miles of driving. But it only ever had the good old green antifreeze in it.
 
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Transmission cooler sprung a leak inside the radiator? Pull that dipstick and see if there's milkshake in the transmission. And pressure test the radiator cap if you can. That's another common issue.

Back when I had my 1999 LeSabre, the radiator cap didn't hold pressure. It was eating coolant from the reservoir and MPG was horrid. A $10 cap later and the issues were fixed.

This is likely something simple. The Series I wasn't known for eating LIM gaskets. My bet is the radiator cap. Just buy a new one since it's cheap on that car.
 
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