Mystery coolant loss

[WalkGood]

2001 LeSabre Custom 3.8L

Losing coolant, but not finding a leak. The radiator was low too. Between radiator and overflow, almost 1 gal of 50/50 mix used to fill to hot FULL mark. Keeping an eye on it, topping off as needed, did hear air gurgle under dash when first starting engine and driving away. But stopped after topping off radiator twice.

Is there a "burping" port on engine to let out trapped air in cooling system?

Sometimes I do see a lot of water vapor fog from exhaust when first starting and driving away. It goes away after 20 seconds or so of driving.

Otherwise no issues. Except I did have a P0442 code but I think it was loose gas cap (truly it was wiggly). Just went thru that Artic vortex blast of 6°F here on Long Island NY. We'll see as I drive it a bunch after resetting the code.

 

[MelsRegal]

do a cooling system pressure test to start with. You could also do a hydrocarbon test of the coolant to detect a head gasket or other internal issue. Have you intake manifold gaskets ever been replaced?

 

[WalkGood]

do a cooling system pressure test to start with. You could also do a hydrocarbon test of the coolant to detect a head gasket or other internal issue. Have you intake manifold gaskets ever been replaced?

Don't know about intake mani gaskets, I got this used about 4 months ago. I texted former owner (relative who didn't drive it much last 3 yrs), just now.

I kinda doubt any combustion leak INTO the coolant - coolant not overheating. If anything the coolant might be leaving into the intake & out exhaust. Or directly into exhaust.

Or slow drip when engine hot that I cannot see & evaporates right away from engine heat.

 

[WalkGood]

Intake manifold gaskets have NOT been changed.

 

[HotZ28]

I would also be concerned about the EGR burn through in the UIM, behind the T/B, That is not an outside visible leak, but can wreck havoc on the engine in a short period of time.

 

[WalkGood]

I would also be concerned about the EGR burn through in the UIM, behind the T/B, That is not an outside visible leak, but can wreck havoc on the engine in a short period of time.

I'm not familiar with this engine - UIM? Upper Intake Manifold? What do u mean by "burn through"? Please explain in more detail & how to look for this problem. Thanks.

 

[Homer Jay]

Good info;
3800 Series II Vin K Upper Intake Information : Engine

 

[vermontcc]

I had an issue of mystery coolant loss. It was a cracked elbow inside the heater/AC box. It was exiting through the condensing pipe drain.

 

[W.Lasabre]

The coolant leaks into your oil bc the lower intake manifold gaskets are plasic and leak between the ports, when this happens the coolant washes your main bearings and they have known to spin em, so hurry up and fix this issue , or you can blown your bottom end out of the motor , engine is done

 

[WalkGood]

The coolant leaks into your oil bc the lower intake manifold gaskets are plasic and leak between the ports, when this happens the coolant washes your main bearings and they have known to spin em, so hurry up and fix this issue , or you can blown your bottom end out of the motor , engine is done

After almost a year, no evidence of any coolant in the oil.

 

[carlos&carlos]

I have had a similar problem with mysterious coolant vanishing without path marks. Until I finally found it. It was right under the manifold intake cover, in the corner, and was dripping over the engine surface and evaporating fast because the heat of the motor.

After replacing the two gaskets, I went the extra mile, at the manifold, and replaced the plastic cover I have had no more issues with low coolant.

Just drive normally and in your next stop don't turn the car off but open the hood and check if you smell burnt coolant, which is a smell different than oil and other fluids like brake or power steering fluids.

In case you can't feel any difference because you are not much familiar with car mechanical issues, then do the same with other(s) car(s) when you have the chance. If you car smells different than the others, then your car indeed has a leak somewhere. It is so small than only using the right tools you will detect it.

As long as the leak goes outside then you can drive your car always maintaining it at the proper level. It won't hurt anything but the smell of burning coolant might bother sometimes. The sensors won't catch up with such a leak as well.

However, as you were told right above, if the leak goes internally, then you have a problem. If not going directly to the engine, then it will affect your catalytic converter and eventually the O2 sensors, and etc. Get it fixed.

 

[Merkava_4]

I'm not familiar with this engine - UIM? Upper Intake Manifold? What do u mean by "burn through"? Please explain in more detail & how to look for this problem. Thanks.

The 3800 V6 has three known issues:
1. Original factory lower intake manifold gaskets not being steel reinforced.
2. Original factory upper intake manifold getting melted by the EGR riser tube.
3. Original factory coolant elbows breaking apart and leaking.

#1 is fixed by installing new and improved steel backed gaskets.
#2 is fixed by installing a smaller diameter EGR tube which comes with the lower intake manifold gasket kit.
#3 is fixed by installing new and improved GM plastic elbows or going with aftermarket aluminum elbows.

 

[WalkGood]

3. Original factory coolant elbows breaking apart and leaking.


#3 is fixed by installing new and improved GM plastic elbows or going with aftermarket aluminum elbows.

Where are the elbows located?

 

[squirrel]

sort of in the alternator bracket.

 

[WalkGood]

sort of in the alternator bracket.

Same for 2001 Era?

 

[Homer Jay]

Part of the belt tensioner assembly.

 

[BK3]

I replaced the elbows in my 3800 last spring. I bought the aluminum ones. It was fairly easy to make the repair.

 

[W.Lasabre]

I replaced my elbows last summer and the o rings dont hold up, just make sure you use blue rtv.

 

[Waiex191]

I documented my replacement of the lower intake manifold gasket in my '00 Century. That has a 3.1 motor. Starts at post 36.
Another new member with a 2000 Century

The failed gasket can be seen in this post:
Another new member with a 2000 Century

 

[Merkava_4]

Where are the elbows located?

There are two. One goes from the alternator support bracket the the water pump --- and the other goes from the alternator support bracket to the lower intake manifold manifold. They are fed by the heater hoses. It was an ingenious idea to route the coolant through the support bracket without going around the support bracket with additional hoses.