Don Terrill’s Speed-Talk

pamotorman wrote: ↑Wed Oct 18, 2017 10:46 pm there is a chemical reaction going on in the coolant causing a pressure build up. happens with apple cider after a setting few weeks

Back in the 60s my dad knew these two guys who were on the last leg of a long trip home hauling a load with this International 6 cyl petrol powered semi truck. The thing boiled over on a hill and all they had available to refill it with was a dozen bottles of beer. Not to far down the road it became a very fizzy drink episode.

Drain the system and refill with distilled water. I'll bet the "problem" goes away.

GRTfast wrote: ↑Wed Oct 18, 2017 9:41 pm

So you’re suggesting it is a leaking head gasket, and the water has so much co2 in it that after 8-9 hours cold with no radiator cap, it still could build a bunch of pressure up once the cap was reinstalled the next day, without ever running the engine? Honestly at this point, that is just as plausible as the outgassing coolant additive reaction. I’m gonna keep driving it since I’m not losing coolant, and it’s not overheating. We’ll see what happens.

Problems fixed early are easy and cheap and convenient.

If you leave them then"Murphy's law" will get you.

It'll leave you stranded in the wrong place at the wrong time and it'll cost you lots of $$$$$$.


What happens next is you'll pop a hose, then another one, then maybe the radiator........but you'll still be in denial.


I'm guessing this is the same rat rod that's got too much crankcase pressure ?
That needs fixing too.

Check oil, check plugs and check cylinders with a probe. If it checks out, and it does not lose or no contaminant coolant no worries.

YES A CLOSED SYSTEM CAN HOLD PRESSURE OVERNIGHT.

It's not always headgasket. I've seen guys fix it by flushing the system, filling with the correct ratio of distilled water/coolant many times.

Here's just 1 example. Seems like tap water is the common theme between them.

http://www.yellowbullet.com/forum/showt ... zinc+anode

And 1 more

http://www.yellowbullet.com/forum/showt ... ?t=1838450

It's because coolant (antifreeze) has special stuff in it which fixes small leaks....sodium silicate.

A proper modern cooling system will start off at zero pressure and full to the top.
As it warms up to the correct temp, the coolant expands (the cap vents at it's rated pressure) and flows into the expansion bottle.
When it cools, the pressure drops and a different valve opens so that the cooling system sucks coolant back out of the expansion tank and into the radiator.
If there's a loss of coolant from the radiator or if there's residual pressure, it's broken.
Problems always get worse before they get better.
Most owners / drivers wouldn't know.

joe 90 wrote: ↑Thu Oct 19, 2017 12:26 am

GRTfast wrote: ↑Wed Oct 18, 2017 9:41 pm

So you’re suggesting it is a leaking head gasket, and the water has so much co2 in it that after 8-9 hours cold with no radiator cap, it still could build a bunch of pressure up once the cap was reinstalled the next day, without ever running the engine? Honestly at this point, that is just as plausible as the outgassing coolant additive reaction. I’m gonna keep driving it since I’m not losing coolant, and it’s not overheating. We’ll see what happens.

Problems fixed early are easy and cheap and convenient.

If you leave them then"Murphy's law" will get you.

It'll leave you stranded in the wrong place at the wrong time and it'll cost you lots of $$$$$$.


What happens next is you'll pop a hose, then another one, then maybe the radiator........but you'll still be in denial.


I'm guessing this is the same rat rod that's got too much crankcase pressure ?
That needs fixing too.

Crankcase pressure issue is fixed. Oddly enough, it seemed to be worn exhaust valve guides. I got the guides done and viola, zero issue. I had it up to 140mph wide open with no oil coming out of the dipstick or breathers.

Regarding this issue, if I’m not losing coolant or over heating, or blowing coolant out of the overflow, I’m hesitant to tear it down.

I get this feeling from your posts that you think I don’t want to work on it or something. I spent 3000 hours building this car, I have no issue tearing into it. I just want to make sure I understand what’s going on before I do. No sense in pulling it apart if I’m chasing a problem that isn’t there. I appreciate your insight, but there’s no need to be condescending.

kimosabi wrote: ↑Thu Oct 19, 2017 1:50 am Check oil, check plugs and check cylinders with a probe. If it checks out, and it does not lose or no contaminant coolant no worries.

YES A CLOSED SYSTEM CAN HOLD PRESSURE OVERNIGHT.

I did this with bore scope I bought for my iPhone. Everything looks normal. Plugs look good. Not losing coolant. I have a coolant contaminant kit coming from amazon, but another member here tells me it’s useless. We will see I guess.

midnightbluS10 wrote: ↑Thu Oct 19, 2017 2:55 am It's not always headgasket. I've seen guys fix it by flushing the system, filling with the correct ratio of distilled water/coolant many times.

Here's just 1 example. Seems like tap water is the common theme between them.

http://www.yellowbullet.com/forum/showt ... zinc+anode

And 1 more

http://www.yellowbullet.com/forum/showt ... ?t=1838450

That is really interesting, thanks for the information.

I have softened well water at my house. Last night I drained the system and refilled with my tap water (well water) and there was a little pressure in the system this morning (without running the car at all). I'm gonna pick up flushing kit, some distilled water, and some antifreeze today and do a full flush and refill with blend of the distilled water and antifreeze. If I'm still having issues after that, I'll pull the heads.

You might save some bucks , or atleast time by just switching right over to Evans waterless coolant!

You don't even have a problem.Seen many keep pressure for weeks without cranking. To the contrary it's a good thing. Means you're system is sealed up good and no leaks. Go to fooling with it and its all for nothing.

geraldtson wrote: ↑Thu Oct 19, 2017 8:21 am You don't even have a problem.Seen many keep pressure for weeks without cranking. To the contrary it's a good thing. Means you're system is sealed up good and no leaks. Go to fooling with it and its all for nothing.

I suspect this may be the case, but I'm trying to be proactive. I appreciate the feedback.

GRTfast wrote: ↑Thu Oct 19, 2017 7:27 am

midnightbluS10 wrote: ↑Thu Oct 19, 2017 2:55 am It's not always headgasket. I've seen guys fix it by flushing the system, filling with the correct ratio of distilled water/coolant many times.

Here's just 1 example. Seems like tap water is the common theme between them.

http://www.yellowbullet.com/forum/showt ... zinc+anode

And 1 more

http://www.yellowbullet.com/forum/showt ... ?t=1838450

That is really interesting, thanks for the information.

I have softened well water at my house. Last night I drained the system and refilled with my tap water (well water) and there was a little pressure in the system this morning (without running the car at all). I'm gonna pick up flushing kit, some distilled water, and some antifreeze today and do a full flush and refill with blend of the distilled water and antifreeze. If I'm still having issues after that, I'll pull the heads.

You already had the ideal water. Soft water is preferred over distilled .

If you can't just ignore this non-issue, how about either letting the soft water stand for a couple of days to out-gas before filling the system, or just leave the rad cap off and see if eventually no pressure build up occurs when it's installed?
Changing head gaskets at this point makes as much sense as swapping on the spare tire to see if radio reception improves.

MadBill wrote: ↑Thu Oct 19, 2017 2:08 pm If you can't just ignore this non-issue, how about either letting the soft water stand for a couple of days to out-gas before filling the system, or just leave the rad cap off and see if eventually no pressure build up occurs when it's installed?
Changing head gaskets at this point makes as much sense as swapping on the spare tire to see if radio reception improves.

That's not a bad idea. The reason I am still not taking the head gasket option off the table is due to some advice another member gave, which is that a blown head gasket could be diffusing CO2 from the exhaust into the coolant. Trust me though, I plan to exhaustively (hehe) pursue the other possibilities before I go down that path. It is my pursuit of happiness that drives me to understand the cause of things....