Trying to understand my coolant system pressure test results

mpk

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Im pretty sure shops dont heat up an engine before a compression test. The purpose is to find one or more cylinders that show a significantly lower reading.
There are other chemical tests that do not require a vacuum source, they use a rubber squeeze bulb.
It was in the instructions that came with the gauge. I believe that is due to a warm engine may expand the leak therefore show a lower reading which might not be seen when the engine is cold.

I tried a block test with the chemical using a turkey baster bulb to draw air through the chemical. It passed so I was going to test each cylinder to see if it is a head gasket leak.

The only other test I may have failed that may point to a head gasket leak is when I did the coolant pressure test with the engine on revving the engine. The gauge moved down fast when I stepped on the gas and then shot back up higher psi than before when I let off the gas. I saw a video of a guy on youtube doing a test that way and his gauge did not move. They then celebrated that it was not a head gasket leak. So I am thinking I do have a head gasket leak from that and coolant being forced out of the over flow.

But not sure since I never did any of this before. I do not want to waste $1200+ fixing the head gasket on top of all the money I spent already with crooked mechanics trying to troubleshoot this.
 

melsg5

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Might have already asked but you dont have a check engine light on?
I would expect a misfire code to pop if exhaust gas is leaking out a cylinder into the cooling system.
You also haven't said anything about white smoke out the exhaust.
The mechanics who worked on the car, what was their diagnosis?
Were these shops ASE certified?
What explanation did they have as to why their repair attempts were not successful?
 

mpk

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Might have already asked but you dont have a check engine light on?
I would expect a misfire code to pop if exhaust gas is leaking out a cylinder into the cooling system.
You also haven't said anything about white smoke out the exhaust.
The mechanics who worked on the car, what was their diagnosis?
Were these shops ASE certified?
What explanation did they have as to why their repair attempts were not successful?
At one point I did have a code and misfire. I have not seen that for awhile now. I do not see any white smoke. The oil stick and oil cap look normal.

I had my car in for rear rotors/brakes. I told him that I have had the anti-freeze flushed/replaced professionally and by myself but it is still pushing coolant out/over heating. I asked him to do all three tests. Coolant system pressure test, compression test and chemical test. The charge was $700 combined with brakes. I go to pick it up and he says the cause was that I did not flush the air out properly and probably needed a new cap, so he replaced the cap. I asked the result of the tests and he said it was not necessary. He says no chance and adamantly said it is not the head gasket or cracked block.

I leave and the same thing happened. Overheated and pushed coolant out overflow.

I go back to him and he says that it is time to junk the car and get a new one. That it is probably the head gasket, or cracked block or bad engine. I asked about the tests and he said it was not worth it saying he would have to take the engine apart to figure it out if the engine is bad. Obviously he cannot be trusted. (several years ago he replaced the lower intake manifold due to overheating. A year later temp sensor/pig tails. Then I had the radiator replaced by another mechanic who thought it might be the head gasket but was not sure)

So here I am doing all the tests I asked him to do myself because I am sick of paying to get ripped off by him and others unable to find the cause or just guessing. I have also replaced the thermostat myself and also ran without one for awhile just to rule it out. I also took a garden hose to every hose, radiator and heater core to be sure there is no blockage and replaced the coolant cap. (since the new one the mechanic just replaced tested bad)
 
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melsg5

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You are sure there is no sign of leakage at the water pump?
Total long shot since it's something you havent done and I can find no evidence of it happening on other 3.4's , could the impeller on the water pump have failed?
When the engine reaches normal operating temperature and the thermostat opens do the top and bottom hoses feel they are roughly the same temperature which would indicate coolant is flowing through the radiator? A rental IR gun would be a better tool to use.
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mpk

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You are sure there is no sign of leakage at the water pump?
Total long shot since it's something you havent done and I can find no evidence of it happening on other 3.4's , could the impeller on the water pump have failed?
When the engine reaches normal operating temperature and the thermostat opens do the top and bottom hoses feel they are roughly the same temperature which would indicate coolant is flowing through the radiator? A rental IR gun would be a better tool to use.
As far as leaks I used tracer die but did not see anything. Although I do see old oil all over the bottom of the water pump.

I noticed the top hose is more frequently hotter and more firm than the bottom. Sometimes feels like there is nothing in the bottom. However there must be some movement since whenever I give it gas while bleeding it the coolant reservoir is all foamy from all the tiny bubbles. It settles down eventually at idle and regular bubbles come out. There are always tiny bubbles in the res if I step on the gas when bleeding.

When the pressure tester is connected to the overflow and I step on the gas the needle on the gauge goes way down until I take my foot off the gas. Then it rises higher psi than what it was before I stepped on the gas.

It is regularly pushing anti-freeze out of the overflow after it heats up. If I bleed it, the level will eventually rise past the spill proof funnel which is like a foot higher than the overflow. After it spills all over everything it eventually goes back down and I need more anti-freeze.
 

melsg5

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when you did the chemical test, did you raise the engine rpm so that you created those bubbles you mention above?
did you use the bleed procedure shown in this video assuming you have the two bleed ports?
 

mpk

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when you did the chemical test, did you raise the engine rpm so that you created those bubbles you mention above?
did you use the bleed procedure shown in this video assuming you have the two bleed ports?
I used the bleeder so many different ways in the past to try to get the air out. Since the cap change I opened it at the beginning and anti-freeze came out, no air. Put it back and continued to burping through the overflow tank. The time before last bleed since the cap was replaced I opened it up in the middle to be sure there was no air and it was all anti-freeze. The chemical tests, tried multiple times. Next time will get someone to rev the engine while I am doing it.

I went to do the compression test today and I could not get the spark plug wires off (mechanics in the past had to cut them off and replace). Really odd, so I did not continue until I pickup a wire set since it looks like I may have to break them get them off or may break one of them.

As I was dealing with that I found something I thought unusual. I appear to be missing a bolt near the first spark plug wire. Cyl 2, 4, 6 are on this side so it is the next bolt near cyl 2. Is this a head gasket bolt? What would this missing bolt effect or is it supposed to be missing?








20200603_182142.jpg
 
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melsg5

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It sort of looks like where a head bolt would go . Find an image of a head gasket.
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mpk

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I just went through all this with a 2008 Torrent I recently purchased. It turned out to be the head gasket failure in the typical place between the #2 cylinder and the coolant passage. Get a "Block Tester Combustion Leak Test Kit" online. It tests the overflow tank for presence of exhaust gasses. It's not expensive - about $35. I replaced the gaskets myself. It's quite an involved job but if you're mechanically inclined it's not that bad a job. There are good videos showing exactly how to do it on YouTube. Good luck!
#2 looks like where my missing bolt is.

It sort of looks like where a head bolt would go . Find an image of a head gasket.
IDK, if you overlay #2 and #4 gasket in this picture in this link I think it might line up.
 

melsg5

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There are 8 head bolts on each head, 4 per side. There appears to be a head bolt to the left of the hole so they cannt be both head bolts. Look up head bolt torque sequence for GM 3.4.
 

mpk

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Look up head bolt torque sequence for GM 3.4.
Ok, I see it that 4 are head bolts. But then what are the extra they 2 (or 3 I think one more behind the oil stick), with one without a screw?

btw - here is what it looked like trying to bleed it at one point the other day.

 

melsg5

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That is a lot of bubbles for just air.
I cannt tell you if the empty holes are supposed to have anything in them.
You need a manual that has pictures of a 3.4, doesn't have to be a Torrent.
Could also try a salvage yard to see if they have an engine you can look at.
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Baliguy

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The heads go on either side. On the back side I think the mount for the coils go there. Those bolt holes would go right into the exhaust ports. I've had my heads off twice. This engine will "boil" a lot without the cap on and when there is not enough coolant flow. Generally, in the past with other cars, when the engine is very cold like in the morning, start the car and run and take the cap off. If it blows bubbles right away, it is defiantly a head gasket or crack. Still could be a bad head or gasket if it is heat dependent.

The bubbles are from somewhere. Some leak the the combustion chambers or it is boiling. Once I got away from dexcool, I've had no issues with getting the air out of the system.

Sometimes you can pinch off the bypass hose and force flow in the heater core to get a bit more air out. This engine has a self air purge system that works pretty well. Again, Dexcool is evil.


Need pictures? I can check mine for you, it looks exactly the same.
 

mpk

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The heads go on either side. On the back side I think the mount for the coils go there. Those bolt holes would go right into the exhaust ports. I've had my heads off twice. This engine will "boil" a lot without the cap on and when there is not enough coolant flow. Generally, in the past with other cars, when the engine is very cold like in the morning, start the car and run and take the cap off. If it blows bubbles right away, it is defiantly a head gasket or crack. Still could be a bad head or gasket if it is heat dependent.

The bubbles are from somewhere. Some leak the the combustion chambers or it is boiling. Once I got away from dexcool, I've had no issues with getting the air out of the system.

Sometimes you can pinch off the bypass hose and force flow in the heater core to get a bit more air out. This engine has a self air purge system that works pretty well. Again, Dexcool is evil.


Need pictures? I can check mine for you, it looks exactly the same.
If not enough coolant flow causing it to bubble and push out of the overflow, water pump issue?
 

Baliguy

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I doubt your water pump doesn't pump enough. It is very rare to lose a impeller or have it corrode away. A collapsed hose or plugged heater, radiator or passageway is more likely. If coolant doesn't move fast enough past a hot spot, it will boil. When my head gasket failed, tons of white smoke came out of the exhaust. I'm sure you would notice that.

Any of the above still could be possible. Maybe a one way leak in the head gasket. Generally that will get worse until it is more obvious.

I see you replaced the thermostat and briefly ran without it. What did it do then?

When I purge the air, I will pinch off the bypass briefly and the the heater hose briefly, alternating. I'll repeat both a few times. I will then pinch off the bypass an drive a few miles. that will get all the air out of the heater core.

Is it possible the small hoses got mixed up? I hate to add more to the list of possibilities. I'll see if I can find a diagram or make one up.
 

Baliguy

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If you don't want to take the intake and heads off (I don't blame you), you can take off the water pump, thermostat and all the hoses, the bleeder assembly and the tank. Really inspect all. The radiator won't cause the problem until the engine is hot. The heater core is bypassed mostly and won't stop flow. All the flow is in the block, heads, intake and bypass line when cold. Really check the bypass line with the garden hose both ways. It is a rubber hose starting from the bleeder and then a tube under the intake. If all of that is good, it is in the block, heads or intake. Ok, not the intake, which just leaks into the oil or outside to the ground.

I forgot to ask, do a lot of bubbles come out in the first minute when cold in the morning with the cap off?
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mpk

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I doubt your water pump doesn't pump enough. It is very rare to lose a impeller or have it corrode away. A collapsed hose or plugged heater, radiator or passageway is more likely. If coolant doesn't move fast enough past a hot spot, it will boil. When my head gasket failed, tons of white smoke came out of the exhaust. I'm sure you would notice that.

Any of the above still could be possible. Maybe a one way leak in the head gasket. Generally that will get worse until it is more obvious.

I see you replaced the thermostat and briefly ran without it. What did it do then?

When I purge the air, I will pinch off the bypass briefly and the the heater hose briefly, alternating. I'll repeat both a few times. I will then pinch off the bypass an drive a few miles. that will get all the air out of the heater core.

Is it possible the small hoses got mixed up? I hate to add more to the list of possibilities. I'll see if I can find a diagram or make one up.
No difference with thermostat out. No chance of mixing up hoses.


If you don't want to take the intake and heads off (I don't blame you), you can take off the water pump, thermostat and all the hoses, the bleeder assembly and the tank. Really inspect all. The radiator won't cause the problem until the engine is hot. The heater core is bypassed mostly and won't stop flow. All the flow is in the block, heads, intake and bypass line when cold. Really check the bypass line with the garden hose both ways. It is a rubber hose starting from the bleeder and then a tube under the intake. If all of that is good, it is in the block, heads or intake. Ok, not the intake, which just leaks into the oil or outside to the ground.

I forgot to ask, do a lot of bubbles come out in the first minute when cold in the morning with the cap off?
It passes a coolant pressure test. No pressure lost at 15psi. But I do remember seeing some bubbles in a minute with cap off.

I notice even after it warms up the bottom hose off the water pump is easier to squeeze then the top and is always cooler. Top one is always very hot and harder to squeeze.

Still no white smoke and oil looks good.
 

melsg5

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Do you you think testing the new thermostat is worth a try. Heat up some some water in a pot, suspend the thermostat in the water, and slowing bring up to a boil. By the time it gets to a boil it should be completely open.
 

mpk

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Do you you think testing the new thermostat is worth a try. Heat up some some water in a pot, suspend the thermostat in the water, and slowing bring up to a boil. By the time it gets to a boil it should be completely open.
Like I said I ran without the thermostat for a long time and no difference.
 
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