Head or head gasket ?

[MrMarty51]

1991 Oldsmobile 3.8 V6. Labeled as a 3800.
Heater not putting out hot air.
Thermostat removed.

Pull both heads or just rearward unit ?

 

[MrMarty51]

Dismantling process.


I see nothing real obvious. I’m not good at determining where a leakage has occured.

 

[MrMarty51]

Heads are at the block and heads shop.
He looked over the heads and said these heads dont crack in such a way to cause compression to pass to the cooling system.
He did mention that the valve seats are in pretty rough condition but said He would give them a once over so they’ll be better than they now are.
Said it’ll be about three or four days before they are done.
$100.00 seems reasonable to Me.

 

[dbrannon79]

from what I recall these 3800 engines are hard to "burp" and get the heater working. the bubbles I saw in your video were to me just a little air pockets working their way out as the engine began to heat. I'm assuming you didn't have the belt on where the pump was turning with the stat off the intake.

there should be a bleeder on the t-stat housing or some had one on the little steel pipe near the water pump that you have to use to get the air out of the system. when there is enough air even with the pump turning it won't pump coolant. it will cavitate until it catches coolant and pushes it though.

others please correct me if I am wrong here.

 

[dbrannon79]

Are those cast iron heads or aluminum? the ones I am used to working on all had aluminum heads. the 3800's, 3100's and the 2800's were tough little animals and would run in the worst of conditions!

 

[WarWagon]

or just rearward unit ?

Clearly you have a problem in the rear head area or block. Pictures you posted do not help. You need the entire rear head gasket examined both sides. If you don't see where coolant or carbon was tracking, yes, look for cracks. Including cracks past the valve seat into the runners on the head. Possible you cracked a cylinder too. Just because the generally don't crack doesn't mean "never". After all weak antifreeze will crack anything!

I would put the rear head back on the front of the engine in case they miss a crack. If the bubbles follow the head otherwise it's the block.

 

[MrMarty51]

These heads are cast iron as well as the block.
The head gaskets was some kind of a silver graphite sort of stuff. They really ripped apart when the heads were rocked free.
I did take them to an independent shop where He deals with such as this more often then I do.
He pointed out one spot where He thought it looked like the gasket had been leaking.
That is a good plan @WarWagon to install the rearwards head onto the front of the block, just in case there is a head problem. I did stamp them F and B.
There is no screw to burp this particular engine of air when filling it with coolant.
On the forwards of the engine there is a smaller diameter by pass hose.
When I filled the engine with coolant after replacing the intake manifold gaskets, I left the upper side of that connection disconnected, intake manifold side, and kept the hose elevated, filled the radiator until coolant was freely flowing from that nipple then shoved on the bypass hose.
I have heard of horror stories about getting the air burped from some of these different cooling systems but thought I had it pretty well covered with the method I used in refilling the radiator.
When I had the thermostat removed, and the serpentine belt, with the engine running, I thought about the trapped air syndrome but if it was trapped air I figured the air would have been coming from the front of the block at about an equal pace. That also is why I done a two minute test. If it had been just trapped air it most likely would have been a series of maybe two burps then done. The bubbles kept coming at about an even pace throughout the test run.
Moving those heads around is an excellent idea.
I do have a new thermostat that will be getting installed.
I am going to attempt to drill a hole through the wide flange of the thermostat so that after the engine is filled through the thermostat mounting hole and the thermostat is sealed into its position, if there is any trapped residual air it should be able to escape to the upper radiator hose and end that problem.
After the heads are installed and all the components are attached, before installing the thermostat I do plan on running the engine and checking for bubbles once again.
I figure a two minute run time should not damage gaskets or cast iron.

 

[MrMarty51]

Another thought.
When I do refill this cooling system, going to remove the upper heater hose and elevate it higher than the heater.
Using a small funnel and fill the coolant through that elevated hose until coolant flows from the upper heater core hose nipple.
That should eliminate any possibility of air being trapped in the heater core.
Just a thought.

 

[Will L.]

Don’t be afraid to add a bleeder valve somewhere, or like hummers in a couple places. But even with that some systems simply are a mess to bleed. Some cars simply can not be bled and require a vacuum/fill system.

I bought the mightyvac mv4525. At $300 nowadays that’s painful but a complete kit for vacuum filling, pressure testing system and radiator caps if you get the adapter. Also thermometer test while system is pressurized.
But you could just get a similar device or the few components and diy one.

Basically after assembling the system to the point you would normally fill with coolant you attach the radiator (or surge tank) cap which has a valve on it. Use shop air (or if diy rigged set up your hvac vacuum) to pull the coolant system into a vacuum. Then close the valve and wait. It should hold a vacuum, if it looses vacuum there is a leak somewhere to find. Most guys listen and find it, if not they dump the vacuum, pressurize with the pressure tester and use soapy water to spray for bubbles.
Pull back into vacuum and wait again, it holds vacuum Then you drop the hose into your coolant open valve and the vacuum draws the coolant into your system filling everything 100% eliminating the need to bleed air. It is best to dump all your coolant into a 5 gallon bucket before beginning. You don’t want to keep opening and closing valve to move hose from bottle after bottle if you can avoid it.
On hummers/hmmwv they hold 6.5 gallons of coolant stock, more for 4 core radiators so I just pour in the other bottles as it is drawing in the coolant.
It will draw in coolant until the system is completely full. So long as the hose was kept submerged the entire time there will be no air in the system.

There are many versions of this tool- this one eliminates all the problems of the cheaper ones, and is multiple tool kits in one. Search on YouTube “vacuum fill coolant system” and you can see many versions and how they work. You’ll see multiple guys have more than one tool, and some show a fill kit and a pressure test kit as separate units.
When I was a Mac tools distributor for a few years I sold many like the airlift and others. I haven’t done a video using one, but made the video below showing a couple guys the one I recommend- one guy who already owned a cheap version.
I almost never work on rigs anymore but when I do need to do anything inna coolant system again I will make a video demonstrating this one in use.
Here is me showing the tool alone. I forgot to show- it does not include the adapter to test radiator caps- those are specific to your cap but tons are available cheap online and all work.

 

[WarWagon]

Heater not putting out hot air.

You verified you have flow through the heater with a garden hose and the in/out was hot? Stop leak a PO used (or customer) clogging the core?

When I filled the engine with coolant after replacing the intake manifold gaskets

What exact problems did this engine/vehicle have before you started the repairs? Generally the intake leak is a problem by itself but low coolant could overheat things till head gaskets let go and heads crack.

You were looking for a blown head gasket, why?

He pointed out one spot where He thought it looked like the gasket had been leaking.

This is very good news! Odds are very good he is correct with experience.

There is no screw to burp this particular engine

Production changes to solve "problems" are very common. The 3.1L engines of this vintage had a bleeder screw on the T-Stat housing. What is the highest point in the system?

 

[MrMarty51]

Don’t be afraid to add a bleeder valve somewhere, or like hummers in a couple places. But even with that some systems simply are a mess to bleed. Some cars simply can not be bled and require a vacuum/fill system.

I bought the mightyvac mv4525. At $300 nowadays that’s painful but a complete kit for vacuum filling, pressure testing system and radiator caps if you get the adapter. Also thermometer test while system is pressurized.
But you could just get a similar device or the few components and diy one.

Basically after assembling the system to the point you would normally fill with coolant you attach the radiator (or surge tank) cap which has a valve on it. Use shop air (or if diy rigged set up your hvac vacuum) to pull the coolant system into a vacuum. Then close the valve and wait. It should hold a vacuum, if it looses vacuum there is a leak somewhere to find. Most guys listen and find it, if not they dump the vacuum, pressurize with the pressure tester and use soapy water to spray for bubbles.
Pull back into vacuum and wait again, it holds vacuum Then you drop the hose into your coolant open valve and the vacuum draws the coolant into your system filling everything 100% eliminating the need to bleed air. It is best to dump all your coolant into a 5 gallon bucket before beginning. You don’t want to keep opening and closing valve to move hose from bottle after bottle if you can avoid it.
On hummers/hmmwv they hold 6.5 gallons of coolant stock, more for 4 core radiators so I just pour in the other bottles as it is drawing in the coolant.
It will draw in coolant until the system is completely full. So long as the hose was kept submerged the entire time there will be no air in the system.

There are many versions of this tool- this one eliminates all the problems of the cheaper ones, and is multiple tool kits in one. Search on YouTube “vacuum fill coolant system” and you can see many versions and how they work. You’ll see multiple guys have more than one tool, and some show a fill kit and a pressure test kit as separate units.
When I was a Mac tools distributor for a few years I sold many like the airlift and others. I haven’t done a video using one, but made the video below showing a couple guys the one I recommend- one guy who already owned a cheap version.
I almost never work on rigs anymore but when I do need to do anything inna coolant system again I will make a video demonstrating this one in use.
Here is me showing the tool alone. I forgot to show- it does not include the adapter to test radiator caps- those are specific to your cap but tons are available cheap online and all work.

WOW, that is some excellent information and very educational, detailed as well.
I searched for the MV4525 and found them on Amazon for about $275.00.
After I get back to work on the weed killing sites I will be making this purchase.
I do have the radiator cap pressure tester with the cap adapter and it does get quite a bit of use.
Thank You for posting this.

 

[MrMarty51]

You verified you have flow through the heater with a garden hose and the in/out was hot? Stop leak a PO used (or customer) clogging the core?



What exact problems did this engine/vehicle have before you started the repairs? Generally the intake leak is a problem by itself but low coolant could overheat things till head gaskets let go and heads crack.

You were looking for a blown head gasket, why?



This is very good news! Odds are very good he is correct with experience.



Production changes to solve "problems" are very common. The 3.1L engines of this vintage had a bleeder screw on the T-Stat housing. What is the highest point in the system?

Hoo boy.
I failed to check the heater core for flow. For some reason that never entered my mind.
The ECM was throwing a code for a faulty CPS. While I was in to it that far the cam position sensor was right handy so I pulled it and discovered a scratch mar across the face, cam sprocket side, and then did some research to find that there is a magnet through a bore in the cam sprocket that if it falls apart it will scar the sensor and eventually when it totally comes apart the engine will not start, so, the entire timing chain/sprocket and that magnet device got changed out.
That fixed the CPS code from tripling and also, there was a cose for intake air temp sensor, installed a new sensor in the air filter housing and that code went away.
This wehicle has no gauges at all.
When out on test runs it did not seem to overheat, there was no boiling or blowing coolant, all seemed real good.
The pan gasket was leaking so after installing the timing cover I also installed a new pan gasket.
When I pulled the OP drain plug there was no coolant present when the plug was loosened then removed so that was a good sign.
The reason for pulling the intake manifold was for oil leaks.
There was no sign of coolant leaks from bad gaskets on the intake manifold.
The rocker covers also were leaking so those gaskets and grommets got Changed as well.
I seen no signs of any kinds of stop leak in the cooling system. There was no buildup around any of the ports after the intake manifold and heads was removed.
I had also pulled the block drains and there was no sign of stop leak in that drain.
After draining each device, the radiator, that coolant was poured into sealed containers to be discarded, then each engine block drain plug. That was the coolant that was in the system from the first drain down. No sign of bars leaks or Aluma Seal in those samples.
After assembling and refilling, then draining it all back down again, once more the radiator was drained, that coolant is in a sealed container, then the rear block drain, that coolant into the sealed comtainer, then the front block drain and that coolant into the sealed container.
I pour each drain point into a different container to keep oil and dirt from contaminating that new coolant. I have had that happen a couple of times then I learned, container and seal each drain point to preserve the integrity of the coolant.
When driving the car before any work was accomplished, the engine did not display any signs of bad habits.
The engine oil and transmission fluid were both right on the full marks and the engine ran real nice. Even on the idle and acceleration was great, set us right back in the seat.
One time when my son and I took it for the first run, we turned around about five miles out over the very trying Yellowstone Hill, when we stopped to make the turn around the engine died, we both said ohoh, into park with the shifter, twisted the key and the engine fired up without hesitation.
After all the work and the fluids was all topped up, no more SES lamp was ignited and it ran very nice.
It was the condition of no heat out of the heater that I suspected a head gasket. Nothing more.
The indy inspecting the heads before I cleaned them up and after the test for bubbles with the thermostat removed pretty much confirmed that it was head gasket problem.
I now will drag out the necessary amounts of garden hose and attempt to blow some water through the heater core.
More to come.

 

[MrMarty51]

One more note:
The highest accessible point on the cooling system, besides the heater core, is that bypass hose that I had removed upon filling the system. By having that hose disconnected then raised up, it burped several times before straight coolant began pouring out. I did let it burp to be sure that any air from within that area would be pushed out.
Then the prestone began pouring out of the nipple attached to the intake manifold. That nipple is near the same level as the thermostat bore in the manifold. I’ll have to give it a once over but I am going to make a guess at less than a 1/4 of an inch lower.
This next time I fill the coolant system, the T stat will be removed and when the coolant gets to that level I’ll install the T stat and cover along with the upper hose then continue filling through the radiator. When it dont take any more coolant there then I’ll fill through that upper heater hose, raised to a level above the heater core nipple and fill until coolant pours out of the core then plug in that hose.
Not having the proper check/refill equipment makes the refill process more painful but it can be accomplished through the process of elimination through certain steps.
I feel.

 

[dbrannon79]

Marty, Just out of curiosity, does this unit have a vacuum controlled heater valve? sometimes they can get sticky and ether stay full open flow or stuck shut blocking flow.

 

[Twisted Steel Performance]

Why not deck the heads, it's not expensive.

 

[MrMarty51]

Marty, Just out of curiosity, does this unit have a vacuum controlled heater valve? sometimes they can get sticky and ether stay full open flow or stuck shut blocking flow.

I’m not sure if they are vacuum or electronical controlled.
Maybe tomorrow I’ll crawl under the dash and take a peek at the heater box.

 

[MrMarty51]

Why not deck the heads, it's not expensive.

The machine shop owner checked them with a straight edge and declared them to be flat.
I’ll stop over to his shop and ask if he would do that. If it’d be $50.00 or some such I could probably manage that.
IDK how much that would be above the hundred but moneys mighty tight over here.

 

[dbrannon79]

I’m not sure if they are vacuum or electronical controlled.
Maybe tomorrow I’ll crawl under the dash and take a peek at the heater box.

just look along the heater hoses from the block to the firewall and see if there is some sort of valve inline with one of the heater hoses. if there is not, then its flowing coolant all the time. my thought was if it had a heater valve that it might be stuck and why you weren't getting heat from the heater.

 

[MrMarty51]

just look along the heater hoses from the block to the firewall and see if there is some sort of valve inline with one of the heater hoses. if there is not, then its flowing coolant all the time. my thought was if it had a heater valve that it might be stuck and why you weren't getting heat from the heater.

Nope. No inline heater valve. Just heater hoses and nipples. I like nipples.

 

[dbrannon79]

Mee too! lol

no valve so there's nothing to stop coolant flow into the heater! Once you have the engine back together everything will work perfectly and run like a new car!!