Rear Main seal? / 3.1L V6

[strombony]

I own a 1995 Chev Lumina w/the 3.1L V6. When I purchased it in 2000 I had the rear main seal replaced as it was leaking. I now have 140k on it and my mechanic says he has noticed no visible leaks on the seal; however, I'm worried that it could be getting time to replace it again as it could leak from within and go into the oil. I religiously keep my antifreeze level in check. I top it off while the motor is cold and the other day I noticed the level was ever so slightly below the cold line, so I put a tiny bit of coolant back in to top it off. It barely took any to get it back to the cold line. Does this necessarily mean I have a main seal leak? Or, can some antifreeze evaporate over time? It has been about 8 months or so since I've topped it off.
And if it was leaking into the oil, would it hurt to wait until noticeably more coolant was missing?

I am changing my oil every 3 months, so if that small of an amount of water were getting to the oil, could it still cause any damage?

 

[Johnny]

Rear main seal has no connection to the water in you system. The only thing the rear main seal is for is to keep the oil from leaking out. If you have coolant entering you engine, it is either coming from a bad head gasket or intake gasket.

 

[c3po]

I think you need to worry about your head gasket not the rear main seal. Its your head gasket that can cause problems with oil and anti-freeze mixing, not the rear main seal.

 

[XS650]

A rear main seal has nothing to do with coolant.

The coolant loss you described isn't significant.

You can lose a small amount over time because the overflow tank breathes, sometimes hoses will have infinitesimal leaks you don't see, or it could be a small internal leak. At your loss rate, I wouldn't even bother with a used oil analysis, but you might want to for peace of mind.

You are doing the right thing by keeping an eye on it.

 

[strombony]

I meant the lower intake manifold gasket.....

 

[bobfather99]

A 3.1 Gm engine???

Been there, done that. (96 Monte Carlo and a 97 Lumina)
Intake gaskets. Id change em out with the Fel-Pro Problem Solver gaskets. The coolant youre "losing" is leaking internally into the combustion chamber and burning off. In extreme cases this can hydrolock the engine.

 

[XS650]

Originally Posted By: strombony
I meant the lower intake manifold gasket.....


That changes the equation a bit

If in doubt, get a used oil analysis to see if there is any coolant in your oil. Don't go swapping parts yet.

 

[strombony]

I would do a used oil analysis, but is there not a problem lately in interpreting them with all these oil companies using Sodium now as an additive?

 

[XS650]

Originally Posted By: strombony
I would do a used oil analysis, but is there not a problem lately in interpreting them with all these oil companies using Sodium now as an additive?


Search the archives for a VOA on your oil and post what oil you have. Then compare your used oil analysis with that. Someone here that know your oil might be able to tell you if that should even be a concern.

If you tempted to start changing parts, remember, automotive maintenance is like firing a weapon, the sequence is ready, aim fire, not ready fire, aim.

How much was the little bit of coolant you added? a cup, 1/2 cup, less ?

 

[Gary Allan]

Originally Posted By: strombony
I would do a used oil analysis, but is there not a problem lately in interpreting them with all these oil companies using Sodium now as an additive?


The additive level of sodium will be substantial when used with as an additive ..there will also be a potassium component to the coolant ingress .......and you see aggravating wear markers of Pb and other stuff that show the effects.

It's a fairly simple combination of stuff to read ..at least on seeing "something is unright here".

$22.50 is all it takes to see if your fears are warranted or not.

 

[strombony]

Someone tell me if this statement runs true.. My mechanic told me that typically an intatke gasket will show wear symptoms from the outside before you have internal leaks.

While I'm sure either could happen, is this true what he is telling me? Right now, the seal is dry from the outside.

 

[Gary Allan]

Originally Posted By: strombony
Someone tell me if this statement runs true.. My mechanic told me that typically an intatke gasket will show wear symptoms from the outside before you have internal leaks.

While I'm sure either could happen, is this true what he is telling me? Right now, the seal is dry from the outside.


I would say FALSE. While you'll surely know if it gets SEVERE ..and you're seeing obvious coolant in the oil (milky deposits through the oil cap and lining the PCV hose) the accelerated wear is astronomical compared to typical wear that it isn't even funny.

Now it could be argued that you may only be shortening the 300-400k life expectancy of this dandy engine to 200k ...but I don't see any published index by which to measure. I'm sure there are quite a few owners that skated through the whole thing without knowing any better ...but I know that there are plenty who suffered from the ignorance. The class action lawsuit is surely an indicator of the broad number of failures due to this condition.