Combustion Gasses and Engine Coolant Violence

[Richard M.]

For those that have followed my thread HERE, related to the engine problems I've encountered, we have been trying to figure something out. I'd like your opinions as to what may be causing this unusual effect when the engine reaches it's "coolant expulsion" state. We cannot come up with a answer.

The horse is dead but we're eventually doing an autopsy before this block becomes a marine reef. This is alike rearranging deck chairs on the Titanic, but want to try to understand it as a learning experience.

This engine has NEVER reached a temperature overheat condition. Maximum temperature ever recorded in all (10 or so) "over/out flow" running tests has been about 195*.

As a refresher, here is the short clip of what happens when the diagnosed combustion gasses have pressurized the cooling system when NO radiator cap is present. After reaching apx 180* IR gun temp at the thermo housing this is what happens.....

http://www.youtube.com/watch?v=UQ_6vhfu0Ts&list=UUX13k501TPEFWCCwezJaoXQ

Now the following is what we all cannot understand.....

When a 13lb radiator cap is present (pressure tested pass), when the engine reaches apx 180*, a violent burst of the lower radiator hose blows it clear off the water pump loosing the coolant. BTW we've used water for all tests. This cooling system is brand new with Dewitts Top Tank rad, all new hoses etc. Take note that the lower radiator hose is attached to the water pump with a stainless steel WORM CLAMP. This after my thinking the Corbin clamp was defective. It wasn't.

We cannot understand why this happens. Imagine the huge air bubble growing inside the cooling system from the combustion pressure building up. The water pump(rebuilt original) hose nipple does not include a ridge at the edge. It is a smooth pipe at attachment. Most pumps are built this way as I have seen.

Is it possible that this is just due to expansion, the pressure being below 13lbs and has no where to go? As it increases I would think that it would gradually open the radiator cap pressure relief to release pressure into the overflow tank and out the overflow hose.

It appears the hose connection at the WP is the weakest junction in the cooling system and that's the release point. I'm glad it wasn't the heater core or valve, or the radiator itself. It's acting like a pressure cooker, and the temerature rises rapidly before it explodes.

Rich

[Rob M.]

Re: Combustion Gasses and Engine Coolant Violence

For those that have followed my thread HERE, related to the engine problems I've encountered, we have been trying to figure something out. I'd like your opinions as to what may be causing this unusual effect when the engine reaches it's "coolant expulsion" state. We cannot come up with a answer.

The horse is dead but we're eventually doing an autopsy before this block becomes a marine reef. This is alike rearranging deck chairs on the Titanic, but want to try to understand it as a learning experience.

This engine has NEVER reached a temperature overheat condition. Maximum temperature ever recorded in all (10 or so) "over/out flow" running tests has been about 195*.

As a refresher, here is the short clip of what happens when the diagnosed combustion gasses have pressurized the cooling system when NO radiator cap is present. After reaching apx 180* IR gun temp at the thermo housing this is what happens.....

http://www.youtube.com/watch?v=UQ_6vhfu0Ts&list=UUX13k501TPEFWCCwezJaoXQ

Now the following is what we all cannot understand.....

When a 13lb radiator cap is present (pressure tested pass), when the engine reaches apx 180*, a violent burst of the lower radiator hose blows it clear off the water pump loosing the coolant. BTW we've used water for all tests. This cooling system is brand new with Dewitts Top Tank rad, all new hoses etc. Take note that the lower radiator hose is attached to the water pump with a stainless steel WORM CLAMP. This after my thinking the Corbin clamp was defective. It wasn't.

We cannot understand why this happens. Imagine the huge air bubble growing inside the cooling system from the combustion pressure building up. The water pump(rebuilt original) hose nipple does not include a ridge at the edge. It is a smooth pipe at attachment. Most pumps are built this way as I have seen.

Is it possible that this is just due to expansion, the pressure being below 13lbs and has no where to go? As it increases I would think that it would gradually open the radiator cap pressure relief to release pressure into the overflow tank and out the overflow hose.

It appears the hose connection at the WP is the weakest junction in the cooling system and that's the release point. I'm glad it wasn't the heater core or valve, or the radiator itself. It's acting like a pressure cooker, and the temerature rises rapidly before it explodes.

Rich

Surely sounds like your combustion is building up the pressure instead of the hot water expanding resulting in this kind of behaviour. You still need to figure out how the combustion pressure gets to the coolant area....

[Richard M.]

Re: Combustion Gasses and Engine Coolant Violence

Rob,

Yes that is the cause, but the confusion is as this pressure is building, why doesn't it release slowly at the radiator cap rated at 13lbs before it blows the hose off the WP? With a 7lb cap it releases through the overflow hose, violently, but does not blow the WP hose off. Somewhere between 7lbs & 13lbs is the break point. When it blows the hose off, it must be much more than 13lbs.

Rich

PB030017.jpg PB030019.jpg

[Edward J.]

Re: Combustion Gasses and Engine Coolant Violence

Rich, When a hose blows off the engine its generally as you say combustion entering the cooling system, ( Head gasket, cracked head, cylinder head or block deck not flat). One test you can do to locate is try removing the spark plugs and hook up a air hose to each cylinder and watch the radiator for air bubbles.

[Joe C.]

Re: Combustion Gasses and Engine Coolant Violence

For those that have followed my thread HERE, related to the engine problems I've encountered, we have been trying to figure something out. I'd like your opinions as to what may be causing this unusual effect when the engine reaches it's "coolant expulsion" state. We cannot come up with a answer.

The horse is dead but we're eventually doing an autopsy before this block becomes a marine reef. This is alike rearranging deck chairs on the Titanic, but want to try to understand it as a learning experience.

This engine has NEVER reached a temperature overheat condition. Maximum temperature ever recorded in all (10 or so) "over/out flow" running tests has been about 195*.

As a refresher, here is the short clip of what happens when the diagnosed combustion gasses have pressurized the cooling system when NO radiator cap is present. After reaching apx 180* IR gun temp at the thermo housing this is what happens.....

http://www.youtube.com/watch?v=UQ_6vhfu0Ts&list=UUX13k501TPEFWCCwezJaoXQ

Now the following is what we all cannot understand.....

When a 13lb radiator cap is present (pressure tested pass), when the engine reaches apx 180*, a violent burst of the lower radiator hose blows it clear off the water pump loosing the coolant. BTW we've used water for all tests. This cooling system is brand new with Dewitts Top Tank rad, all new hoses etc. Take note that the lower radiator hose is attached to the water pump with a stainless steel WORM CLAMP. This after my thinking the Corbin clamp was defective. It wasn't.

We cannot understand why this happens. Imagine the huge air bubble growing inside the cooling system from the combustion pressure building up. The water pump(rebuilt original) hose nipple does not include a ridge at the edge. It is a smooth pipe at attachment. Most pumps are built this way as I have seen.

Is it possible that this is just due to expansion, the pressure being below 13lbs and has no where to go? As it increases I would think that it would gradually open the radiator cap pressure relief to release pressure into the overflow tank and out the overflow hose.

It appears the hose connection at the WP is the weakest junction in the cooling system and that's the release point. I'm glad it wasn't the heater core or valve, or the radiator itself. It's acting like a pressure cooker, and the temerature rises rapidly before it explodes.

Rich

I'm sorry to hear of all your problems with this build. I assume that at some point, you've carefully examined and pressure tested the heads. A common problem would result from a poor job of installing hardened exhaust seats, if that was done at some point, or a crack at an exhaust valve. The block might have a casting flaw or hairline crack at the upper part of cylinder bore(s), which might cause pressurization on the compression stroke as well.

[Terry M.]

[Dan D.]

Re: Combustion Gasses and Engine Coolant Violence

Rich, I am not an expert on this by no means, but let me tell you about an experience I had a long time ago.

Back when I was first driving I had a flat head Ford that did a similar thing. First, the coolant would turn yucky brown very quickly and you could feel the turbulence in the top hoses if you grabbed hold of them. People smarter than me at the time thought it was cracked valve seats. I don't think it was any more than head gaskets, common with old flat heads, but I don't really know because I killed the horse and replaced the engine.

I know you have done extensive head work, but could it be anything as simple as a hairline crack in a seat or port? It would be a much more simple experiment if you just replaced the heads to try it. Would not have to be the final heads you use, just something you may have laying around to bolt on cheap and easy to try.

Anyhow, my two simple questions are 1. is the coolant turning brown and 2. can you feel turbulence in the hoses? But I don't know what this will do for you, as it is pretty clear it is combustion gasses, and appears to only open up when the engine reaches operating temperature. This would explain why it does not show up in any pressure testing by your machine shop.

The bottom hose is inlet water to the engine, and why very high pressure would build up there instead of just venting out the top which is open to the environment is puzzling. It should just be able to push back up through the radiator.

Another bit of the puzzle it the fact that the engine had crud and metal fillings in it that apparently took out the bearings and crank. How in the world did this happen? I can't believe that any machine shop would ever put an engine together like this. Something had to have ground up in there after the engine was assembled. But my question is does this have any connection to the problem you are having now? It is just another symptom the engine is telling you why it is sick. Did the owner indicate that the engine was ever overheated at one time? Why did he have it rebuilt in the first place?

By the way, is this the same car you gave all the good advice to with the doors? From the photos that is one beautiful car. My 57 was originally black with silver coves and red interior. It is not black now, but will be going back to the original black; that color combination is just stunning.

-Dan.

[Richard M.]

Re: Combustion Gasses and Engine Coolant Violence

Terry, Edward & Joe,

Thanks, that other thread I linked has all of the history and diagnosis of the problem. It's long reading, and I understand painful to try to read it all and catch up, but the summary is the block is toast, likely from uneven decks and or crack(s). It was decked once, belt sanded on a flat table sander(obviously in error), observed to be out of tolerance(up to 0.008" in some places), then decked again to regain flatness. Heads were properly rebuilt after improper initial resurfacing(on a belt sander as well), and my tests proved we have a unrepairable situation. Engine is trash and I'm just trying to understand some diagnosis oddities.

The thermostat has had it's center plug removed to ensure there are no air pockets during all tests. This leaves about 1/2" diameter relief hole during fill and throughout operation. It just takes a little longer for engine temp to stabilize for the tests.

I did the cylinder pressurization on the 2 most recent suspect cylinders(#5 & #8), testing with the thermo housing removed and water up to the intake lip. Never saw a bubble at 120psi.

Without taking it apart again, which we are not going to do for a while due to other scheduled activities, I am quite sure #8 is the major cause, albeit either a crack in the bore near a water passage, or unevenness in the deck surface. This area had extensive variations in deck surface flatness before re-decking a second time.

The heads were pressure tested 3 times. Prior to 1st rebuild, after removal for diagnosis, then again during 2nd rebuild. mag'd all 3 times too. One note of interest, pressure testing a head on the bench is performed using shop air around 120 psi. From cooling passages to head chamber. Combustion pressure in the other direction is at 1500+psi peaked pressure and it may not be evident at those bench test pressures. I'm not expertly trained at these test methods but took a crash course trying to figure it out. Still much to learn but trying to understand for my own curiosity.

Thanks,
Rich

[Richard M.]

Re: Combustion Gasses and Engine Coolant Violence

Hi Dan, figured I'd just answer in bold print. Thanks for your suggestions and info.....Rich

Rich, I am not an expert on this by no means, but let me tell you about an experience I had a long time ago.

Back when I was first driving I had a flat head Ford that did a similar thing. First, the coolant would turn yucky brown very quickly and you could feel the turbulence in the top hoses if you grabbed hold of them. People smarter than me at the time thought it was cracked valve seats. I don't think it was any more than head gaskets, common with old flat heads, but I don't really know because I killed the horse and replaced the engine.

That's what the owner wants to do, just replace it. He's very frustrated. Too much time, money, and effort.

I know you have done extensive head work, but could it be anything as simple as a hairline crack in a seat or port? It would be a much more simple experiment if you just replaced the heads to try it. Would not have to be the final heads you use, just something you may have laying around to bolt on cheap and easy to try.

Yes that'd be a good idea and a friend suggested also but it's going to sit for now. Maybe future experiment.

Anyhow, my two simple questions are 1. is the coolant turning brown YES

and 2. can you feel turbulence in the hoses? YES, but feels normal to me.

But I don't know what this will do for you, as it is pretty clear it is combustion gasses, and appears to only open up when the engine reaches operating temperature. This would explain why it does not show up in any pressure testing by your machine shop.

Definitely combustion gasses proven by Block Dye Testing initially, then leakdown testing to isolate which cylinders.

The bottom hose is inlet water to the engine, and why very high pressure would build up there instead of just venting out the top which is open to the environment is puzzling. It should just be able to push back up through the radiator.

That is exactly my question, why at the INLET? All I can think of it's the weakest link attach point.

Another bit of the puzzle it the fact that the engine had crud and metal fillings in it that apparently took out the bearings and crank. How in the world did this happen? I can't believe that any machine shop would ever put an engine together like this. Something had to have ground up in there after the engine was assembled. But my question is does this have any connection to the problem you are having now? It is just another symptom the engine is telling you why it is sick. Did the owner indicate that the engine was ever overheated at one time? Why did he have it rebuilt in the first place?

Machine shop was chosen by others and I got to assemble it. It was doomed before I got it apparently.

By the way, is this the same car you gave all the good advice to with the doors? From the photos that is one beautiful car.

Yes, beautiful car but only works downhill at the moment.

My 57 was originally black with silver coves and red interior. It is not black now, but will be going back to the original black; that color combination is just stunning.

-Dan.

[Ken A.]

Re: Combustion Gasses and Engine Coolant Violence

Sounds like a crack in one or more of the block's cylinders. Only opens up when temp go up. Should have been sonic tested & magnafluxed for cracks.

[Edward J.]

Re: Combustion Gasses and Engine Coolant Violence

Rich, Once the engine was disassy'd did you ever find any evidence of pistons being washed? I all my years as a mech. I have never seen a cracked cylinder liner on a small block, I would still be leaning toward cylinder head.As the temp rises cracks do appear ,as the cylinder heads has a lot of small areas that do not receive direct coolant flow.The engine block has coolant flow around each cylinder.

Not to say a cracked block could not happen, its so rare. and I Also would say anti freeze should enter the cylinder once shutdown, and then out the tail pipe when restarted and cause rough running for a few seconds after start.

[Richard M.]

Re: Combustion Gasses and Engine Coolant Violence

Ken,
The block and heads were mag'd, not sonic tested. Please explain the sonic testing process.

Edward,
My suspicions are a crack low in the #8 and/or #7 cylinder wall, which pressurizes the cooling system on each stroke. Eventually a large air mass is formed and causes the coolant volcano. With the rad cap on, it blows the lower hose off the WP.

I removed the sparkplugs today. #7 & #8 show signs of being washed. Not as white porcelain as the first time run, but still evident. #5 looks normal. I suspect the high reading on the leakdown test on #5 was inconclusive. Leakdown test is only done at TDC. I may try leakdown testing at BDC with valve rocker arms released when I get time.

today....
#7
PB250007.jpg

#8
PB250008.jpg


When this was first diagnosed, plug #'s 5,6,7 had signs of washing. Porcelain was very white, electrodes shiny. The head chambers showed obvious clean surfaces and whitish exhaust valves as shown below. #8 also showed washing on its valve, but not the plug.

First run.
Right head
PA060038.jpg

Left head #7, #5 shows white on ex valve also.
PA060018.jpg

[Ken A.]

Re: Combustion Gasses and Engine Coolant Violence

[QUOTE=Richard Mozzetta (13499);685712]Ken,
The block and heads were mag'd, not sonic tested. Please explain the sonic testing process.

Sonic testing is used t o determine "core shift" to see if the cylinder walls are thick enough for overbore.
Most shops do not look for cracks in the cylinder walls, unless they're pros or instructed to do so.

[Edward J.]

Re: Combustion Gasses and Engine Coolant Violence

Richard, you are correct there are 3 cylinders washed out clearly in the pic.s, I still say cylinder head issue. To have 3 cylinders with cracked liners is far fetched, My advise is maybe to see if you can come up with a set of cylinder heads just for test reasons. I sure you must have a zipper on the engine by now. If your working with a original block it would be nice to keep. Also combustion happens when the piston is about 10 degrees before TDC, This likely mean the cracks would have to be high in the cylinders.

[Richard M.]

Re: Combustion Gasses and Engine Coolant Violence

Update.

Last week I did additional testing before removing the engine from the car. The thermostat housing was removed and water filled up to the top of the intake manifold thermostat mating surface. I released all rockers from the valves and set each cylinder at bottom dead center and pressurized each sequentially at 120 psi through the spark plug holes.

After 1 minute at each cylinder, we saw no bubbles rise in the water.

We pulled the engine, removed the heads, and see pistons 7 & 8 washed, mating head chambers washed, and 5 & 7 just slightly washed. The engine is being de-assembled completely again for analysis.

Rich