34 coolant leak
 

Greetings. I have a 34 V8 with the water pumps located at the front of the head.
I can lose half gallon in 10 miles. I have checked the overflow, and it is not overwhelming the radiator.
I have used dye, removed the plugs, and pressurized the cooling system, with no leak. I did that for more than 2 weeks, changing the position of the pistons every other day.
It starts and runs fine. Nothing leaking anywhere. I have equal pressure in each cylinder.
When not running, I do not lose a drop.
I have changed the head gasket twice. No coolant is in the oil. The radiator tests positive for Monoxide. I just cannot find it. Any ideas?

Also, does anyone know of any cast heads available?
Thanks

Re: 34 coolant leak
 

Re: 34 coolant leak
 

When you removed the plugs ,were any of them exceptionally clean compared to the others? Any white smoke out the tailpipe?

Re: 34 coolant leak
 

Thanks, I connected a hose from the over flow to a bottle, I'm not loosing it there. If I run any distance, I continue to loose. 20 miles is one gallon, and it just continues.

Re: 34 coolant leak
 

I have had the head off twice. All cylinders are equal mild carbon. All the plugs are equal. I have changed the head gasket twice. I took the plugs out, put dye in the coolant, pressurized the cooling system for a week. Nothing.
No steam, nothing in the oil. A cylinders hold pressure.
Thanks, any other thoughts?

Re: 34 coolant leak
 

Gremlins??? You said you removed the head twice, and changed the gasket twice, speaking as if singular. Did you remove the other head as well?

Re: 34 coolant leak
 

That's a lot of water in a short time. Don't see how that wouldn't be pretty obvious. Not many places where it can get out. If it isn't being burned, it's either in the crankcase or leaking out.

Re: 34 coolant leak
 

I chased a coolant leak in the 33 for ages,could see no visible leaks,did the same as you,even changed the heads,turned out it was the pumps.
They leaked at road speed and it must have sprayed out ,I was only using water and it w as hard to see.
Lawrie

Re: 34 coolant leak
 

If there is no water in the oil or no water coming out of the exhaust pipe and no visible leak it has to be coming out the overflow. G.M.

Re: 34 coolant leak
 

Crack in engine block in one exhaust valve port. Water going straight out exhaust pipe maybe ?? Check the end of the exhaust pipe for moisture with engine well warmed up and some revs on. Regards, Kevin.

Re: 34 coolant leak
 

Please change "Head" to "Heads" and "Head Gasket" to "Head Gaskets".
I have changed them twice. I cannot find any weakness or evidence of bypass on either gasket, or on the block or heads.

I changed them the first time thinking for sure I knew the problem. I changed them the second time, when I realized that I had not found the problem, and needed much closer inspection.

Re: 34 coolant leak
 

Thank you for the input. I have inspected the pumps very closely. I have run the engine with the hood open, and close inspection. No leak.
Loosing a gallon, I should see it.

Re: 34 coolant leak
 

I have pressure tested the cooling system. I have also attached tubing from the overflow to a container. When starting on a full radiator I have the usual blow by. Then no further fluid.
The bottle level remained unchanged. The coolant system was down over a gallon after the test.

Thank you for your input, and please keep thinking.

Re: 34 coolant leak
 

This....

I would put some antifreeze in the system to make it a bit easier to see. this is one of those situations that it would seem so complex, when you find the answer it will already have been something you thought you inspected and dismissed.

i vote that you have a leak, and just haven't found it.

also consider the volume you are a talking about. that is significant, and again makes me think leak!

also as GM said it could be coming out of the overflow, which will could be very hard to find evidence of, after the fact.

drain the system of the water and put a antifreeze mix in it, and you will have residue somewhere that will tell you what is going on.

Re: 34 coolant leak
 

So far 4 of us have inspected this engine, and agree that your answer is most likely the issue. I have not removed the valves.
A cloth placed over the exhaust, and it had very mild moisture. I then compared it to another car, and there was no major difference.

Can you think of any test we can do to verify this?
All cylinders have equal compression, and hold the compression. But if the crack is below the valve, that would be the issue.

Do you know of any other test I could do with the heads off to verify this?
Thank you for your assistance.

Re: 34 coolant leak
 

Thank you. I verified the overflow by attaching tubing onto the overflow, to a container, no major loss via the overflow. Yet I was down about 1 gallon of coolant.
We all agree that there is a crack, I just can't find it.
I have tried antifreeze and marking dye, and still nothing.

Thank you for your input. Currently both heads are off, if you can think of any other test I can do please forward your ideas.

Re: 34 coolant leak
 

i saw where you put the dye in, but didn't see any mention of the antifreeze. most dies i have worked with don't leave much of a residue.

do you have dual exhaust or single? if it is what you are thinking and you have dual exhaust i would run the antifreeze exclusively. that would hopefully elminate one side of the engine.

again with the volumes you are describing, there would to be a telltale residue sign somewhere.....

Re: 34 coolant leak
 

Put a bottle of Bars stop leak per their instructions in it, why fight it. It is sure as heck not going to hurt anything and will probably stop the leak.

Re: 34 coolant leak
 

Well to bring you up to date, I did as suggested and went to the fire Dept and tested the radiator for Monoxide, and it went off the chart. Several cracks were found, along with pounds of rust and scale.
I now have the engine back in, but having some issues making it run smooth.
Here are some photos of the rebuild.
https://www.facebook.com/J-and-M-Mac...96175313829376

Re: 34 coolant leak
 

Well, the engine is looking good (now). Hard to believe how much stuff comes out of the block!! And it's normally not just rust, there is core sand and wire and whatever in there.