Exhaust leaks to coolant

Byron Warwick

Byron Warwick

Senior Member
I have not visited the site for some time.
My problem.
I am getting exhaust gases in my anti freeze. I have tried using Iron Tite but without success.
I believe the source is the helicoils that were put in and they allow the gasses to pass. I have replaced the head gaskets and torqued to 60 psi. I did not see any cracks in the block. It was magnifluxed before being built. It went on the road in 2009.
Hope someone has some answers.
Cheers, Byron
 
I you take the belt off the water pumps and take the top hose off with the coolant filled to the top of the neck start the engine.
Since left and right are separate the side making bubbles or continuously pushing out coolant will be the problem side.
after a few minutes localized hot spots may start making bubbles just before boiling.
even cranking with ignition off may be enough to tell which side has a problem.
 
Small leaks can be really difficult to locate. For starters you might pull the plugs and see if one of them looks shiny,but there probably won't be a shiny plug if there isn't any sign of a misfire yet. If there is, the coolant in the cylinder will wash the spark plug shiny new looking. That's a good sign that something in that cylinder is leaking coolant. Also check the oil for any signs of coolant. Check under the oil fill cap for condensation. Kurt has some good suggestions. You might also try blocking the lower hose off with an ABS pipe rubber pipe cap on the water pump and then remove the upper hose from a warmed-up motor. Then take a compression tester's adapter hose and hooked to an air compressor and pressurize it up one cylinder at a time. Look for air bubbles where the upper hose hooks onto the head. Unless an engine is losing coolant fairly quickly it can be really tuff to find a leak. One thing we used to do at work was take the hose from the smog machine and hold it over the radiator and check for exhaust gas readings. Any exhaust reading told us there was definitely a leak but not where it was at. We'd pull the heads and send them out. The Dodge 318 heads were notoriously bad for cracking. The shop welded them up and they lasted as long as they did originally. That proved to me that cast iron can be repaired if the right place is doing the work. Very few places are capable of doing it.
 
Last edited:
Any thoughts on using Iron Tite for these exhaust leaks?
I am thinking of going to only water in the cooling system, as there will be no foaming. I’ll add some antifreeze for lube etc.
Cheers, Byron
 
I would suggest getting to the root of the problem, rather than trying to "band-aid" it by changing coolant formulations. You may avoid a more serious problem down the road.
 
Hopefully the rebuilder did not use "HeliCoil". Good product, though not for this application. They hopefully used an Keensert or equal. How can exhaust gasses leak around a threaded mechanical connection in the block?
A few questions / comments
Have you measured the PPM of the exhaust gas at the radiator neck? Should be 0-5 PPM.
Did you and or the rebuilder use a flexible threaded sealant?
Were the head(s) resurfaced when you replaced the head gaskets?
What brand head gasket? Best, FelPro...
Did you copper coat the head gaskets?

Get the exhaust gas measured first, see how much is getting into the coolant. There is a block tester liquid that is available at NAPA, using a exhaust gas analyzer is preferred.
Be sure the engine is fully at operating temp when you check the exhaust gases.
I was in the 30PPM range and got it down 3-5 PPM.
Irontite is the best sealant available. The coolant system must be clean, and any traces of anti freeze must be cleaned out as well. You must follow the directions exactly as they are presented, otherwise, no good result. Irontite makes a statement regarding anti freeze.
I had similiar problems years ago, and as Tubman says, get to the root cause of the issue. Keep us informed.
 
Many thanks to those who posted help.
I am of the opinion that the exhaust leaks came only from: the four head bolts that go only into the centre exhaust line in the block. I therefore set about to change the head gaskets. I found no block cracks.
To help seal those four holes, I put form-a-gasket around the holes on both sides of the gasket and did the correct procedure of tightening the head bolts to a final 60 lbs torque.
I have not seen any evidence of the gasses in the coolant yet. I have not put many miles on the truck yet as I was also having a battery issue. I now have a second new Interstate 8 volt battery and am now starting to drive it again.
Thanks again. Byron.
 
Did you do the “re-torque “ after three successive heat/cool cycles? I didn’t see it specifically mentioned in previous posts……Mark
 
You must log in or register to reply here.
Back
Top