The Oldsmobile Connection

[andrewk]

Hey all-

I was doing my normal 3000 mile service to my Lumina tonite (Oil/Filter change, check all fluid levels, refill washer fluid, grease the undercarriage, check tire pressure, check brakes, etc, etc) and I noticed the coolant was low. I have had a finicky low coolant sensor for awhile now, so I have sort of learned to ignore it, as I keep an eye on my gauges. Looks like it was telling me the truth this time. Anyway, I can't find the leak- My fluids (Engine and Transmission) are clean, there is no presence of moisture. I checked the plugs and they all look great, no signs of burning coolant. So I believe that leaves me with some sort of external leak. A friend of mine has borrowed my pressure tester, so I can't hook it up at the moment, but the car passed a pressure check when I did the engine mounts earlier this fall. The radiator is dry- no signs of leakage where the plastic meets the metal, and the coolant tank is holding coolant. All hoses are dry, and in good shape. The water pump is old, but it is not leaking.

I don't think there are many 3.1 guys here, but anyone got any ideas? Is there anything these engines are known for that I could be missing?

I'll update if I find anything, and thanks in advance for any replies-

Andrew

[91parkave]

im not sure about 3.1's but i know 3800's have problems wherere the UIM and TB meet. the gaskets can deteroiate overtime letting small amounts of coolant get sucked in the intake, Id check to see if your engine has a TB coolant circulation and try a new gasket there hopefully your problem is as simple as that. best of luck

[88 Coupe]

andrewk wrote: ........ I have had a finicky low coolant sensor ........
How long since you tested your coolant?

Quote: ........ I can't find the leak ........
Test the radiator cap.

Quote: ........ I don't think there are many 3.1 guys here ........
Is your cooling system different than any of mine?

If it is, you can do as 91buickman suggests, and start changing parts until you find the problem.

Norm

[andrewk]

88 Coupe wrote: andrewk wrote: ........ I have had a finicky low coolant sensor ........
How long since you tested your coolant?

Tested it late in the summer- was good for 20 below 0. The coolant in it is clean, but I can't recall when the last time I flushed the system was.

88Coupe wrote: Quote: ........ I can't find the leak ........
Test the radiator cap.

I should do it again, but I replaced the cap late this summer when my low coolant light first came on. I tested it when I first installed it, but that doesn't mean that it couldn't be bad now.

Quote: Quote: ........ I don't think there are many 3.1 guys here ........
Is your cooling system different than any of mine?

No, other than the physical construction/design of the parts. I didn't and don't know of any design flaws with the 3.1, but that doesn't mean there aren't any. However, any correct diagnostic procedure will yield the bad part, regardless of design.

I'll do some checking and report back.

Andrew

Edited to correct bad code-

[andrewk]

91parkave wrote: im not sure about 3.1's but i know 3800's have problems wherere the UIM and TB meet. the gaskets can deteroiate overtime letting small amounts of coolant get sucked in the intake, Id check to see if your engine has a TB coolant circulation and try a new gasket there hopefully your problem is as simple as that. best of luck

I don't know if I have coolant circulation in my throttle body, but I did injectors about 2 months ago, and I replaced the gasket where the throttle body and the intake plenum meet. One thing I did do was take some carb cleaner and check the throttle body for vacuum leaks, as I thought I heard one while I was warming the car up for service, but the test proved that it was my IAC gasket leaking, so I think I am good on the TB gasket.

The other reason I would displace this theory is the plug condition. While small amounts of coolant may not register, my plugs should have shown signs of this when I pulled them for how much coolant was gone. Since they were clean, and normal looking, I displaced that I was burning coolant.

[andrewk]

Sorry for the multiple replies, I have begun my holiday travels, and am stuck on dial up...

I just drove about 110 miles tonight, and the car ran really good, just like normal. When I got to my destination, I checked the oil. I didn't find the "milkshake" associated with coolant in the oil, but there was a small streak on one side of the dipstick that was pretty milky looking compared to the rest of the (new) oil.

If I was leaking coolant into the oil, it would not streak, correct? I think I know the answer to that question, but seeing that made me a little frantic and I am typing this in the "heat of the moment".

Is there a way to test my radiator cap without a pressure tester similar to how you test a thermostat with a pot of hot water and a thermometer?

Thanks all,
Andrew

[91parkave]

oh well, hopefully the pressure test will reveal the leak, then, also have you cheked where the heater hoses meet the engine?

[88 Coupe]

andrewk wrote: ........ was good for 20 below 0 .........
OK. We can assume your system will not "freeze" this winter.

What was the acid content?

Quote: ........ The coolant in it is clean ........
That's a good sign.

Quote: ........ can't recall when the last time I flushed the system was ........
Not a good sign.

Quote: ........ that doesn't mean that it couldn't be bad now .........
One of the basic rules of troubleshooting. Never “assume” that a new part is not dumpster food.

Quote: ........ correct diagnostic procedure will yield the bad part, regardless of design ........
Another of the basics. Chasing “design flaws” is counterproductive.

Quote: ........ I replaced the gasket where the throttle body and the intake plenum meet ........
Its condition, and why it was replaced, might be part of the puzzle. Refer to my question about acid content.

Quote: ........ While small amounts of coolant may not register, my plugs should have shown signs of this when I pulled them ........
Not necessarily. Depends on the size of the leak.

From your opening post:
andrewk wrote: ........ I have had a finicky low coolant sensor for awhile now, so I have sort of learned to ignore it ........
Sounds like a small one.

Quote: ........ I didn't find the "milkshake" associated with coolant in the oil ........
I would not expect to find it in a running engine, unless it was making a lot of strange sounds.

Quote: ........ a small streak on one side of the dipstick ........
Ignore it, unless it happens again. If it does, make sure you get clear pix, and a complete description.

Quote: ........ Is there a way to test my radiator cap without a pressure tester ........
Not that I know about.

Norm

[andrewk]

88 Coupe wrote: andrewk wrote: ........ was good for 20 below 0 .........
OK. We can assume your system will not "freeze" this winter.

What was the acid content?

No idea. I just used the hydrometer to measure approximate specific gravity. I think this is probably a good place to start. Do those test strips work well?

Quote: Quote: ........ can't recall when the last time I flushed the system was ........
Not a good sign.

I have been digging through reciepts, and haven't found anything newer than 3 years. I swear I get it done at least once a year, but I can tell you that it is no older than 3 years, and either way, it could probably use it.

Quote: Quote: .... I replaced the gasket where the throttle body and the intake plenum meet ........
Its condition, and why it was replaced, might be part of the puzzle. Refer to my question about acid content.

I replaced it because the gasket came in the plenum gasket kit when I did the injectors. I did not notice any abnormalities in the gasket other than it looked like it was old.

Quote: Quote: ........ While small amounts of coolant may not register, my plugs should have shown signs of this when I pulled them ........
Not necessarily. Depends on the size of the leak.

What is a good way to check this?

Quote: Quote: ........ a small streak on one side of the dipstick ........
Ignore it, unless it happens again. If it does, make sure you get clear pix, and a complete description.

Will do.

Quote: Quote: ........ Is there a way to test my radiator cap without a pressure tester ........
Not that I know about.

That may have to wait then. Once I get to my parents house, I'll call my old friends and see if I can locate a tester-

Thanks for all the help thus far!

Regards,
Andrew

Edited to fix code, again... I really should preview my posts before I post them.

[91parkave]

Checking for design flaws is never counter productive and it never hurts..arent there some 3100 forums?? IIRC? besides that was your coolant disappearing before you had the injector problem? if it wasnt you might be looking at improper install of the gasket, also note that pressure test IME have never shown a coolant leak at the TB because in most cases the coolant will seep into the intake instead of dripping down to be visible, so when you do the pressure test open your throttle blade up and have someone apply pressure while you look, or listen for any"sounds in the intake.... hope this helps

[andrewk]

91parkave wrote: Checking for design flaws is never counter productive and it never hurts.

That is looking for a shortcut, which in the long run can hurt you more than it might help you in the short run. Let's take the 3800 for example- Just because they are known for lower intakes and gaskets going out doesn't mean that every one of them will, or when you have a coolant leak, that the lower intake is automatically to blame. If you were to assume this, and replace the gasket, you may or may not have fixed the problem. That is counter-productive.

In this case, you can certainly look at the lower intake area to see if its leaking, but you should find the leak before you go off replacing things.

Proper diagnostic procedure should tell you to first check the basics, then systematically eliminate things by testing and checking until you find the problem, not check things sporadically just because they have had service issues. It could very well be the common problem, but for all you know, it is just as likely that there is another problem.

The other thing that needs to happen is the problem needs to be replicated so that I (or the technician) can see what exactly is happening. For me, this means I need to find that leak. If I just replace something, I have altered the system, and it may or may not be fixed, and I may now have a new problem. By going through the whole system, I will find my leak, and any other precursors to future problems, as well as any supplementary problems.


Quote: arent there some 3100 forums??

Probably, but I am not a member, and I have more trust in this board.

Quote: besides that was your coolant disappearing before you had the injector problem?

Yes, Low coolant light came on this fall, and the cap tested bad. I replaced the cap, pressure tested the system, it passed, so I went on my way. Didn't notice any problems since, until now.

Quote: if it wasnt you might be looking at improper install of the gasket,

I am almost certain that it is installed correctly, but I suppose anything is possible- If so, it will be discovered as I work my way through the system.

Quote: also note that pressure test IME have never shown a coolant leak at the TB because in most cases the coolant will seep into the intake instead of dripping down to be visible

If it were leaking, the gauge on the pressure tester wouldn't hold, and I would know there is a leak somewhere. If it holds pressure, there is no leak. If it fails a pressure test, I'll check that as a possiblility along with everything else.

Andrew

[andrewk]

I keep thinking of other things I have done that may be applicable, or not, but I like to provide as much info as possible.

Yesterday at work I cut apart my oil filter to see what, if anything was inside, and it looked very normal, with no signs of metal, coolant or anything in it other than a little grit that appears in all my filters.

This morning I checked my oil (I haven't driven the car since my post about that spot) and that spot was there on the same side of the dipstick, only much smaller. I don't have my camera here to take a picture, but I don't think it is coolant. I wiped the dipstick, and checked it again, and there was no light colored spot. Seems to me to be some sort of condensation, could that be normal?

This spot smells like oil, does not smell the least bit sweet, or smell like gas. It feels like oil, but maybe a little slimy, but not much different than the oil on the dipstick. There really isn't enough of it there to get a good sample to taste.

I can't think of anything else at the moment, but I will post if I do-

Andrew

[andrewk]

Went to the local NAPA parts store this morning, to look for a coolant ph test strip- Owner of the store said he hasn't seen them in about 5 years, nor did he know of anyone around that carried them anymore. I don't buy it, even though the guy knew exactly what I was talking about, and he seemed very knowledgable, but it looks like this test will wait until I am back home where there are more stores around.

I think litmus paper would work too (Isn't that all those tests strips are?), but there will be nowhere in rural IA that will probably carry that either-

And if you can't tell by all my posts, I am rather bored today at the in-laws...

Andrew

[88 Coupe]

andrewk wrote: ........ Do those test strips work well? ........
They do. Make sure the strip and the coolant come from the same manufacturer.

88 Coupe wrote: andrewk wrote: Depends on the size of the leak. What is a good way to check this?
You will lose more coolant, in a given time, with a bigger leak.

andrewk wrote: ........ that spot was there on the same side of the dipstick, only much smaller ........
Top or bottom?

Quote: ........ could that be normal? ........
Good question. If a few drops of coolant were to drop from the intake, fall into the crankcase, and settle on the dipstick, you would see it when you checked the oil. Or would you?

Now, if you did, what color/consistency would it be?

andrewk wrote: ........ Owner of the store said he hasn't seen them in about 5 years ........
Alternative is to flush and change once a year. Or two, if you feel lucky.

Norm

[andrewk]

88 Coupe wrote: andrewk wrote: What is a good way to check this?
You will lose more coolant, in a given time, with a bigger leak.

I should have phrased that better- If a small leak doesn't necessarily register on the plugs, is there a way to determine that I am burning coolant instead of leaking it somewhere?

Quote: andrewk wrote: ........ that spot was there on the same side of the dipstick, only much smaller ........
Top or bottom?

I would call it the top. It is the side that faces the engine when you insert the dipstick, and it sits higher in the oil than the side that faces you.

Quote: Quote: ........ could that be normal? ........
Good question. If a few drops of coolant were to drop from the intake, fall into the crankcase, and settle on the dipstick, you would see it when you checked the oil. Or would you?

I think you would, given that the two fluids are quite different, but it would have to settle on the dipstick somehow, and I am not sure if it could do that. IIRC, the specific gravity of oil is less than that of water, and glycol, so the coolant would settle in the bottom of the pan.

Quote: Now, if you did, what color/consistency would it be?

I would think it would be green, and not frothy or milky like I described, since the oil has not been churned up by the oil pump, and it is just dripping. If ran, those few drops would emulsify into the oil, (at least until you shut the engine off and allowed it to settle), and then you would see a consistant "mixture" throughout the oil on the dipstick.

Is that right, or even relatively close?

Quote: andrewk wrote: ........ Owner of the store said he hasn't seen them in about 5 years ........
Alternative is to flush and change once a year. Or two, if you feel lucky.

Yeah, I think its been at least two- I hope nothing is hurt by the probable acidity of my coolant-

Do you believe it would be wise to find the leak before I flush the system, or would I be better off to flush before and see if it still leaks?

Thanks-

Regards,
Andrew