Coolant reservoir has engine oil in it - dipstick has no antifreeze in the oil. Why?

[eeyore2123]

I have a 1994 Chevrolet C1500 pickup with a 5.7L 350 and automatic transmission. I bought this vehicle with 33k miles. It only has 97k miles now. This truck has been pampered like a baby since I bought it when it was 3 years old. It has never been abused, raced or neglected. I tend to do 90% of the maintenance myself (I am somewhat car savvy).

A few months ago, I had noticed that the coolant reservoir was consitantly empty of antifreeze. However, the engine was running fine, and it was not overheating and the gauge was normal. I thought that the reservoir bottle was faulty, so I replaced it with a brand new one. However, antifreeze was still disappearing. I noticed antifreeze sweating near the water pump, so I had that replaced.

Recently, I noticed that the heater was not getting hot even after allowing the truck to idle for over an hour. The heat gauge would not move from 100 degrees. But, when I drove the truck into town - about 1.5 miles, the heat gauge would move up to about 150 -- with still no real heater. So, thinking that the thermostat was failing, I had that replaced by the mechanic.

Now I am having the same heater trouble. Because it's so cold here in Kansas, I have to let the truck warm up before driving it (hopefully so it will be warm inside too!), but after an hour of idling with the heater on high, it's still cold inside. The heat gauge is at 100 degrees -- sometimes at 140 degrees. However, when I go ahead and drive into down (about 2 miles), the heat gauge will steadily climb up to about 230 degrees. Another mile or less down the road, the gauge drops to 150 and stay there. But now I also have engine oil in the coolant reservoir, but not on the dipstick. It seems that the oil is in the reservoir and some in the radiator, but I don't see or smell antifreeze in the oil.

What could be wrong?

I have heard everything from a cracked head, blown head gasket, failed radiator, bad intake manifold gasket or a bad oil pressure switch that has failed and allowing coolant to mix with the oil. The latter doesn't sound plausible to me...and the thought of a major engine tear down on my baby scares me.

Any help or suggestions would be greatly appreciated.

Thanks!

[discnik]

The oil in the resivoir is it brown sludge or the rainbow looking appearance.
Have you check the tranny fluid ? Remote but I have seen the tranny fluid cooler in the radiator deteriorate and allow coolant into the tranny.

Have you checked to see if your heater core is leaking or plugged ?

You may have a bad thermostat even though it was recently replaced. I have ran into this problem with after market parts.

Just some thoughts.

[sleddinskeeter]

I would say It needs top end gaskets or a cracked head either way massive teardown. Do the Radiator hoses get rock hard?

[j cAT]

sounds like you have many coolant system problems...thermostats need be of high quality many don't work...you need to do compression testing ,coolant pressure test,and removal of plugs for inspection of the combustion of antifreeze...

heater cores trap debris any contamination of the coolant will cause the heater core to plug up...removal of the engine mounted heater hoses and using a water hose or air pressure blow out /reverse blow until clean...

oil residue could be combustion residue in the coolant..see if the coolant bubbles when engine is hot....but if this were a severe head problem the vehicle should overheat under load..

intake gaskets ,,,,cracked intake is another possibility...

[eeyore2123]

Well, my dad took my truck to a very well respected ASE mechanic in town (30+ years experience).
He said a few different things:
1) Could be a blown head gasket
2) Cracked head
All though both of these seem unlikely, it could be possible somehow
3) Broken down antifreeze
Said there was really no way to know about the cracked head or head gasket part without tearing into it -- then you're already into it, so you gotta fix it. Makes sense, but makes my wallet poor.
Also talked to another mechanic I know (I work for a parts store as a commercial delivery driver, so I know all the mechanics). He said that the 350s (5.7L) do not get their oil pressure from oil galleys like the new engines - the oil pressure comes from the pushrods. So, in his mind, the only way oil could get into the coolant reservoir is though the passages down by the cam/bearings from a minor crack. I haven't researched any of this -- does this sound plausible?
My truck is schedule to go into the shop next Friday for compression, coolant pressure and a couple of other tests before we start ripping into the motor.
I just don't understand this!

[j cAT]

If this mechanic is as you say very experienced in this he should be able to look at the coolant and quicly determine the problem...

this is a 1994 a very old vehicle spending a lot of money would be foolish....what are you gonna do when gas goes to 10.oo/gallon...

I would replace the coolant flush out the heater core see what the coolant system condition is ..if it looks like theres no corrosion replace coolant with new and use distilled water add a coolant stop leak like bars but only add 1/4 of the bottle and give it a go...if it is a small leak it will stop/slow down if its the heads/gaskets it will do nothing...

then if the heads need removal the cost will determine your decision to go forward with this vehicle ...a total assesment,,,, then see if buying another vehicle makes better sense..,

check for the proper amount of coolant in the system do you have enough coolant to protect fronm freezing...? do you replace the coolant when you maintain this since you bought it 3 years ago ...?

[eeyore2123]

Ok. First of all, yes this is an older vehicle -- but it is MY vehicle and I love it. It's not a clunker as you would imagine. Check out photos at http://students.jccc.edu/scheasbr/st...interests.html

And, it's paid for. Buy another car/truck right now makes no sense.

But, thanks for the imput. Sorry to be a little defensive, but you're talking about my baby here!

[j cAT]

Originally Posted by eeyore2123

Ok. First of all, yes this is an older vehicle -- but it is MY vehicle and I love it. It's not a clunker as you would imagine. Check out photos at http://students.jccc.edu/scheasbr/st...interests.html

And, it's paid for. Buy another car/truck right now makes no sense.

But, thanks for the imput. Sorry to be a little defensive, but you're talking about my baby here!

the reason I brought up the age factor is simply things break..this is not going to get better..as the vehicle ages you have to make logical course of actions ...head gasket/head failures when this old is not uncommon.

sure no debt is very good ...but if it gets too expensive you have to be cautious...when you have vehicles this old you must learn how to maintain/repair your vehicle, the costs will become excessive if you have to bring it to repair shops..

so what is your maintenance history of this vehicle ??

[eeyore2123]

The maintenance record is this vehicle is very detailed and I have been very critical about it. Working at a parts store allows me access to everythingI need (at a discount).

The oil has been changed every 3000 miles or 3 months whether it needed it or not. Transmission service, lubrication, tune ups, air filters, detailing (wax, wash, vacuum), etc., on the dot.

As I mentioned in my earlier posts, this vehicle has NEVER been abused or neglected. And, no one else drives it except for me. I am extremely picky who does any maintenance or mechanical work on it - I usually do it myself or I have one specific mechanic who will work on it.

[MT-2500]

Originally Posted by eeyore2123

Well, my dad took my truck to a very well respected ASE mechanic in town (30+ years experience).
He said a few different things:
1) Could be a blown head gasket
2) Cracked head
All though both of these seem unlikely, it could be possible somehow
3) Broken down antifreeze
Said there was really no way to know about the cracked head or head gasket part without tearing into it -- then you're already into it, so you gotta fix it. Makes sense, but makes my wallet poor.
Also talked to another mechanic I know (I work for a parts store as a commercial delivery driver, so I know all the mechanics). He said that the 350s (5.7L) do not get their oil pressure from oil galleys like the new engines - the oil pressure comes from the pushrods. So, in his mind, the only way oil could get into the coolant reservoir is though the passages down by the cam/bearings from a minor crack. I haven't researched any of this -- does this sound plausible?
My truck is schedule to go into the shop next Friday for compression, coolant pressure and a couple of other tests before we start ripping into the motor.
I just don't understand this!

Better find a good mechanic or repair shop that knows what they are doing.
There is several good fast tests for head gasket or cracked head or leaking intake gaskets.
As far as oily stuff in coolant tank a good coolant flush and coolant clean up may take care of that.
Has the coolant ever been serviced?
Proper testing before throwing parts you do not need or head gaskets at it.
Good Luck

[j cAT]

Originally Posted by j cAT

check for the proper amount of coolant in the system do you have enough coolant to protect fronm freezing...? do you replace the coolant when you maintain this since you bought it 3 years ago ...?

what about these questions ?

[777stickman]

OK, time to get back to basics.

1. No coolant on the dip stick does not mean there is no coolant in the oil. Water is heavier than oil which means the water (coolant) will settle to the bottom of the pan and not show up on the dip stick.

2. I have not seen that you have pulled the spark plugs to check for coolant contamination on them (previously mentioned).

3. Head gasket, cracked heads, cracked blocks, etc can be found by "leak down tests" and performed by "experienced" auto mechanics without pulling the motor apart.

4. The doomsayer mention of $10.00 a gallon for gas may come true. But by that time most of us will be driving electric cars.

5. I'm totally with you on keeping what you have and fixing it. It just makes sense.

[j cAT]

Originally Posted by 777stickman

OK, time to get back to basics.

1. No coolant on the dip stick does not mean there is no coolant in the oil. Water is heavier than oil which means the water (coolant) will settle to the bottom of the pan and not show up on the dip stick.

2. I have not seen that you have pulled the spark plugs to check for coolant contamination on them (previously mentioned).

3. Head gasket, cracked heads, cracked blocks, etc can be found by "leak down tests" and performed by "experienced" auto mechanics without pulling the motor apart.

4. The doomsayer mention of $10.00 a gallon for gas may come true. But by that time most of us will be driving electric cars.

5. I'm totally with you on keeping what you have and fixing it. It just makes sense.

It appears that this vehicle owner does do a great job of keeping the vehicle clean and polished, but it does lack proper maintenance...
the answer to the coolant questions are not being addressed..

this vehicle would require the coolant replaced every 2 years,,,and if the coolant was not properly monitored the head gaskets will blow as well as the other problems,, that all go back to coolant issues...the owner needs to find a mechanic that is better at these maintaining proceedures,,,

the recording and tracking of the maintenance intervals need be evaluated so that , the vehicle will continue to operate reliably..

the price of fuel will not get to 10.oo/gallon IF they develop the battery....gm has developed the volt but still has no battery....

the cart is in front of the horse...this is backwards....until that battery shows up fuel will rise as it is now getting close to 2.oo/gal...

when we are driving the [new] battery vehicles, and the price is below $40,ooo then we are safe.....from this ...price rise..

[GMMerlin]

Originally Posted by eeyore2123

Well, my dad took my truck to a very well respected ASE mechanic in town (30+ years experience).
He said a few different things:
1) Could be a blown head gasket
2) Cracked head
All though both of these seem unlikely, it could be possible somehow
3) Broken down antifreeze
Said there was really no way to know about the cracked head or head gasket part without tearing into it -- then you're already into it, so you gotta fix it. Makes sense, but makes my wallet poor.
Also talked to another mechanic I know (I work for a parts store as a commercial delivery driver, so I know all the mechanics). He said that the 350s (5.7L) do not get their oil pressure from oil galleys like the new engines - the oil pressure comes from the pushrods. So, in his mind, the only way oil could get into the coolant reservoir is though the passages down by the cam/bearings from a minor crack. I haven't researched any of this -- does this sound plausible?
My truck is schedule to go into the shop next Friday for compression, coolant pressure and a couple of other tests before we start ripping into the motor.
I just don't understand this!

I LOVE posts like these.
Your well respected ASE 30+ mechanic wants your money...he is willing to tear your truck apart without doing any diagnosis.........hack
Your company mechanic doesn't know what he is talking about........
Oil sender causing oil and coolant to mix...


You say you are "car savy"...well you are not ( If you are offended TFB...I don't sugar coat things)
First thing when you saw the overflow was empty was to do a pressure test on the cooling system to determine the leak.
Without looking at the vehicle, I can't give you a definate answer, but if you have an oily substance in your overflow, I would suspect that the trans cooler is cracked and the oily residue is trans fluid...which means that your coolant is going into the trans.
You need to find a real AUTOMOTIVE TECHNICIAN who will look at your vehicle and DIAGNOSE your problem and give you a point on cause of failure here.
Since you are too far away to bring your vehicle to my shop, I would recommend finding someone who will diagnose your problem before tearing your truck apart.
Good Luck