Why does my 1999 Suburban consume coolant?

My 1999 Suburban has a 5.7L engine with 103,000 miles on it. Lately I noticed it has been consuming green anti-freeze but there are no external leaks, the oil was just changed with no signs of water contamination and there is no sweet smell or steam discharging from the tail pipe. However, when I removed the oil filler tube cap I saw a light brown residue along the walls of the tube and inside the cap. Also while running the engine it looks like steam coming out of the fill tube when the cap is removed. The coolant system will not pressurize and the temp seems to fluctuate on my dashboard gauge from 195 to about 170. The intake manifold gasket was professionally replaced a few years ago because the factory one started to leak at about 69K miles.

Is there a way to determine without dismantling the engine, if its a head gasket or cylinder head crack? Is it possible that its even an intake gasket? I'm prepared to get a new engine all together but I need to know for sure what is the cause before this type of investment.

Yes they make a chemical block check that ckeck for exhaust gas in coolant system.
But head gasket problems is unusall on that mileage.
First pressure test rad coolant system cold and warm and hot and see if you can spot any leaks.
Also they make coolant dye for coolant system to find the HARD TO FIND LEAKS.

In addition to what "MT_2500" says, I would pull all the spark plugs and check each one for coolant contamination. When doing this you need to pay attention to matching the plugs to each cylinder. If there is contamination on some plugs it would point you as to which cylinders may be sucking the coolant in.

If the intake manifold gasket is leaking again, is it possible for the coolant system to not pressurize? Right now my system will not pressurize. Of all the scenarios I can think of it should be either have a cracked cylinder head or leaking head gasket. Am I right? Today it is scheduled for a diagnostic and I will report back my findings.

Latest word from the pros is that they cannot figure out where the pressure and coolant is going. They have tested now since 8 am this morning and now its afternoon. It doesn't look good.

If it is leaking coolant it has to be going someplace.
If they can not find it ask them to put some leak dye in the coolant.
Always check cold and warm and hot and afte it has set overnight.

If any coolant is getting into the oil the leak dy will show up in the engine oil.
And as said pull the spark plugs after it has set overnight.

And last but not least run a chemical block test on coolant for exhaust gas in rad.
To show head gasket leakage.

They did a hydrocarbon test and the coolant showed negative for HC's. So this negates the head gasket having a problem.

Good
Sounds like they know what they are doing.
And should know how to test for leaks.
But
Tips on finding leaks.
Watch the engine oil for coolant.
Start with pressure testing the engine cold.
Then check it warm .
Then check it hot.
Always look on the underside of engine and water pump and rad and heater core and heater hoses and back and front of intake for leaks.
And for the hard to find leaks add leak dye to coolant and drive it and then check it again.
The leak dye will show where it has leaked.
Even into the engine oil.
Sometinmes water pumps weep and the quit and then leak again.
Good Luck
And let us know how it goes.

Here is the final word. The mechanic worked and tested the vehicle from morning until 5pm today and found nothing wrong. All tests were negative. System held pressure and no external leaks. It was tested cold, warm and hot. No HC's in the coolant either as stated before. However, something very bizzare was noted. They told me that the oil was 3 quarts too high. I told him I just changed the oil yesterday and only added 5 quarts after draining along with a new filter. How the heck it was 3 quarts too high I will never know. I didn't buy that much oil. Tonight I drained the oil with a dipstick pump to the proper level. The oil looked normal. According to the mechanic my oil filler tube looked normal this time of year with the cold temps and limited driving I do. He said condensation like what we see will form on the inside. But the question still remains...where did the extra oil come from and why did I have to add a gallon of coolant this week. Maybe I went too far long without checking my overflow tank. I hadn't checked since summertime. Anyhow, I am going to drain the oil again and change the filter one more time and keep tabs on everything daily.

Here is the final word. The mechanic worked and tested the vehicle from morning until 5pm today and found nothing wrong. All tests were negative. System held pressure and no external leaks. It was tested cold, warm and hot. No HC's in the coolant either as stated before. However, something very bizzare was noted. They told me that the oil was 3 quarts too high. I told him I just changed the oil yesterday and only added 5 quarts after draining along with a new filter. How the heck it was 3 quarts too high I will never know. I didn't buy that much oil. Tonight I drained the oil with a dipstick pump to the proper level. The oil looked normal. According to the mechanic my oil filler tube looked normal this time of year with the cold temps and limited driving I do. He said condensation like what we see will form on the inside. But the question still remains...where did the extra oil come from and why did I have to add a gallon of coolant this week. Maybe I went too far long without checking my overflow tank. I hadn't checked since summertime. Anyhow, I am going to drain the oil again and change the filter one more time and keep tabs on everything daily.

You have a internal leak on the intake gaskets.
You had better replace the intake manifold gasket.
Berfore the coolant in the oil takes out main and rod bearings.


Did the oil have a strange color?
If you add leak dye to coolant and the intake is leaking coolant into the oil it will get the dye in it and show up on the test light for coolant dye.

You have a internal leak on the intake gaskets.
You had better replace the intake manifold gasket.
Berfore the coolant in the oil takes out main and rod bearings.


Did the oil have a strange color?
If you add leak dye to coolant and the intake is leaking coolant into the oil it will get the dye in it and show up on the test light for coolant dye.

I just went out to the truck this morning to drain the oil and crack the bolt loose I saw coolant draining out! That damn shop pumped 3 to 4 quarts of coolant into my crankcase and I drove it that way home! What a bunch of idiots!

I'm draining the oil/coolant now and refilling it plus replacing the filter. I tried to locate some dye but no one has any around here. They the kind that goes into the oil but not the coolant. I am so upset about that shop. I probably scored the main bearings already driving it home last night. I'm seriously thinking of sueing them.

I just went out to the truck this morning to drain the oil and crack the bolt loose I saw coolant draining out! That damn shop pumped 3 to 4 quarts of coolant into my crankcase and I drove it that way home! What a bunch of idiots!

I'm draining the oil/coolant now and refilling it plus replacing the filter. I tried to locate some dye but no one has any around here. They the kind that goes into the oil but not the coolant. I am so upset about that shop. I probably scored the main bearings already driving it home last night. I'm seriously thinking of sueing them.


I just went out to the truck this morning to drain the oil and crack the bolt loose I saw coolant draining out! That damn shop pumped 3 to 4 quarts of coolant into my crankcase and I drove it that way home! What a bunch of idiots!

I'm draining the oil/coolant now and refilling it plus replacing the filter. I tried to locate some dye but no one has any around here. They have the kind that goes into the oil but not the coolant. I am so upset about that shop. I probably scored the main bearings already driving it home last night. I'm seriously thinking of sueing them now. And to think the shop has another shop come out and confirm everything was okay. I am so pissed right now my blood pressure is through the roof.

If it is that bad.
Relace the intake manifold gaskets before you blow the engine.

Prsts place can oder the dye for coolant.

Also aanother test is a pressure tester on rad with drain plug out and watch for coolant running out the drain plug.

If it is that bad.
Relace the intake manifold gaskets before you blow the engine.

Prsts place can oder the dye for coolant.

Also aanother test is a pressure tester on rad with drain plug out and watch for coolant running out the drain plug.

Is there anyway to know for sure it's the intake gasket without tearing down the engine? I only question if its the intake gasket because it was replaced with a new Fel-Pro gasket about 4 years ago by a great shop (not the coolant people that messed me up).

There is no for sure test or way to be for sure.
Only 99 times out of hundred it is the intake gasket if it is getting coolant into the oil.
The leak dye helps show where the leak is after intake is removed.
And for coolant in the oil before pulling intake.
Good Luck

I had the same problem 2 years ago. It turns out that after having a "Mechanic" replace the manifold gasket, the problem appeared again. When my engine was hot, it would seep and boil off on the hot engine. That made it almost undetectable. Almost. I have a really large nose and it served me well. Not with the ladies so much, but I could open the hood when hot and catch just a slight hint of anti freeze when I stuck my beek over the engine on the drivers side. Change the manifold gasket again. pay attention to proper torque and keep your nose clean. Alittle nose spray and kleenex could be your best tool.If it is a slow seep rather than a true leak it's a booger. Sorry, poor choice of words. Good Luck!!

[quote=jberenyi]My 1999 Suburban has a 5.7L engine with 103,000 miles on it. Lately I noticed it has been consuming green anti-freeze ...[QUOTE]

I believe your problems may have been caused by use of non dexcool GM approved coolant....100,000 miles is too soon to have all these issues...

also if you see rust color your coolant system is corroding from improper maintainence...make sure different coolants are not mixed ...If you or someone else changed from dexcool it is very important to completely flush out the entire system...this is rarely done professionally as it is too time consuming..

good luck your gonna need it...

The Suburban is scheduled for an intake manifold gasket change at the Chevy Dealership. My friend works there and cut me a great deal. It still bugs me though, that and intake manifold gasket could be the culprit with it being changed out only 4 years ago to replace the defective original factory gasket. I've not heard anyone having an intake gasket issue again after replacing the flawed factory gasket.

The Suburban is scheduled for an intake manifold gasket change at the Chevy Dealership. My friend works there and cut me a great deal. It still bugs me though, that and intake manifold gasket could be the culprit with it being changed out only 4 years ago to replace the defective original factory gasket. I've not heard anyone having an intake gasket issue again after replacing the flawed factory gasket.


Are you sure it was replaced with the Felpro problem solver intake gasket?
Is the dealership going to install a problem solve intake gasket or OEM gasket?

I got the vehicle back today and I am a happy camper. It was the intake manifold gasket. The mechanic verified this and did a great job.

I got the vehicle back today and I am a happy camper. It was the intake manifold gasket. The mechanic verified this and did a great job.


Thanks for posting back how it went.
Glad you found the problem and got it fixed.

But was wondering if the gasket that was replaced a bout 4 years ago was the gm plastic one or the felpro problem solver?
Did they show or tell you what failed or what happened to it?

Did they put the Felpro solver problem solver gasket on it this time?

[quote=MT-2500]Thanks for posting back how it went.
Glad you found the problem and got it fixed.

But was wondering if the gasket that was replaced a bout 4 years ago was the gm plastic one or the felpro problem solver?
Did they show or tell you what failed or what happened to it?

quote]

It is quite possible that the gasket failed because of the corroded metal ....

Thanks for posting back how it went.
Glad you found the problem and got it fixed.

But was wondering if the gasket that was replaced a bout 4 years ago was the gm plastic one or the felpro problem solver?
Did they show or tell you what failed or what happened to it?

Did they put the Felpro solver problem solver gasket on it this time?

The gasket that was replaced 4 years ago was a factory original and it was replaced with a Felpro according to the mechanic that I just spoke with. They put the AC/Delco replacement in this time. Something to note that was mentioned by the mechanic is that when the GM one leaks it will most likely leak externally. If its a Felpro it will leak internally most of the time. The GM mechanic who worked on my vehicle is noted as the best anyone has ever seen or worked with. His reputation is also backed up by my friend as well who is a GM certified mechanic in the local area. I feel fortunate I was able to get him to fix my problem.

The gasket that was replaced 4 years ago was a factory original and it was replaced with a Felpro according to the mechanic that I just spoke with. They put the AC/Delco replacement in this time. Something to note that was mentioned by the mechanic is that when the GM one leaks it will most likely leak externally. If its a Felpro it will leak internally most of the time. The GM mechanic who worked on my vehicle is noted as the best anyone has ever seen or worked with. This statement is also back up by my friend as well who is a GM certified mechanic in the local area. I feel fortunate I was able to get him to fix my problem.


Glad you got it fixed.
Good Luck with it.

The gasket that was replaced 4 years ago was a factory original and it was replaced with a Felpro according to the mechanic that I just spoke with. They put the AC/Delco replacement in this time. Something to note that was mentioned by the mechanic is that when the GM one leaks it will most likely leak externally. If its a Felpro it will leak internally most of the time. The GM mechanic who worked on my vehicle is noted as the best anyone has ever seen or worked with. His reputation is also backed up by my friend as well who is a GM certified mechanic in the local area. I feel fortunate I was able to get him to fix my problem.


Not sure on that mechanics qualifications but I had both Fel-Pro and GM (old style) take a dump and leak internally. Sound like the guy was being a little self serving imo.

These are first design fel pros

http://img119.imageshack.us/img119/7834/8140397660lty8.jpg

http://img246.imageshack.us/img246/4551/8140768380lzh2.jpg

http://img246.imageshack.us/img246/9695/8140178883lgk3.jpg

Right on Mr Smith,
The old style felpro was not any better than and looks the same as the GM oem gaskets to me.

The Felpro problem solver rubber over steel is the way to go.

I said "most of the time" not all of the time. Now who's self serving. I gave Fel Pro a chance and it didn't last but 25Kmi so back to OEM GM I go. We'll see how long it lasts but for now I'm not convinced that Fel Pro is the save all 100% of the time. Have a nice day.

I said "most of the time" not all of the time. Now who's self serving. I gave Fel Pro a chance and it didn't last but 25Kmi so back to OEM GM I go. We'll see how long it lasts but for now I'm not convinced that Fel Pro is the save all 100% of the time. Have a nice day.

I find this problem interesting...It is strange how some have this repeating failure and others never have this problem...

maybe its because their using the wrong coolant....

I believe a 99 chevy engine that this has,,,, was designed to use dexcool...

I find this problem interesting...It is strange how some have this repeating failure and others never have this problem...

maybe its because their using the wrong coolant....

I believe a 99 chevy engine that this has,,,, was designed to use dexcool...

Both coolants will become corrosive if not flushed in the required time period. I personally don't see why we had to changed a good thing that's been around for eons. I'll stick with tried and true for now and go green.

Both coolants will become corrosive if not flushed in the required time period. I personally don't see why we had to changed a good thing that's been around for eons. I'll stick with tried and true for now and go green.

its your money.

its your money.

My feelings exactly!

My feelings exactly!

As J cat said it is your money and your truck.
From reading over your posts you have came from knowing nothing about it to an expert on it.
If you want to use the old green and the old style felpro or GM gasket and replace it every 3-4 years more power to you. Your money.
But
If you want to fix it right and not have not have any more problems get the felpro problem solver intake gasket.
Your money.
Good Luck

As J cat said it is your money and your truck.
From reading over your posts you have came from knowing nothing about it to an expert on it.
If you want to use the old green and the old style felpro or GM gasket and replace it every 3-4 years more power to you. Your money.
But
If you want to fix it right and not have not have any more problems get the felpro problem solver intake gasket.
Your money.
Good Luck

I am by far an expert. And if I was, I wouldn't have solicited any help from the forum members. Its amazing how what was once an informative helpful topic has run amiss. AC-Delco breaks in when Fel-Pro breaks down.

Ac-Delco - 70K mi
FelPro - 30K mi

See you all in another 70K miles.

I am by far an expert. And if I was, I wouldn't have solicited any help from the forum members. Its amazing how what was once an informative helpful topic has run amiss. AC-Delco breaks in when Fel-Pro breaks down.

Ac-Delco - 70K mi
FelPro - 30K mi

See you all in another 70K miles.


There is two different Felpro gaskets.
The old style felpro was just like the GM gasket.

As said if you want to fix it and not have any more problems us the Felpro problem solver gasket.

There is two different Felpro gaskets.
The old style felpro was just like the GM gasket.

As said if you want to fix it and not have any more problems us the Felpro problem solver gasket.


That's what I had when it was done last time and 30K life doesn't really impress me much. So I guess it comes down to replacing one at 30K or 70K. Hhmm, I think I'll go with the latter.

Any chance of posting the part # for the Fel-Pro problem solver gasket?

What I've found is two Fel-Pro part #s:

#1204 is the embossed steel laminate version, Ports are 1.23" x 1.99", 0.060" thick, crossover exhaust port is blocked.

#1205 is the composite with "Printoseal", ports are 1.28" x 2.09", 0.060" thick, exhaust port condition unknown.

I don't know if they are precisely for the Chevy truck 350, but that's what I've found so far...will update if I can.

What I've found is two Fel-Pro part #s:

#1204 is the embossed steel laminate version, Ports are 1.23" x 1.99", 0.060" thick, crossover exhaust port is blocked.

#1205 is the composite with "Printoseal", ports are 1.28" x 2.09", 0.060" thick, exhaust port condition unknown.

I don't know if they are precisely for the Chevy truck 350, but that's what I've found so far...will update if I can.


I get mine from O'riellys

Felpro part no MS98000T
Stell shell on lower intake /rubber backet gasket.
It comes with the upper gaskets and one valve cover.
Cost around 50$

They also have the oem plastic gasket part no MS90131

Checked with Carquest.
Carquest/victor gasket part no.

They show the OEM plastic intake lower Part no MS16167.

The lower steel/rubber lower intake part no MS16167P

Rock auto parts web site.
http://www.rockauto.com/catalog/raframecatalog.php?a=G-felpro
Under engine/intake gaskets.
Looks like Dorman may be in there to on problem solver gaskets.

That's what I had when it was done last time and 30K life doesn't really impress me much. So I guess it comes down to replacing one at 30K or 70K. Hhmm, I think I'll go with the latter.

remember you can use a platinum gasket and it will fail if the engines metal where the gasket sets is damaged from corrosion....

repeated failures here is a sign of incompetance...