Rad Flush - antifreeze question

Got into it this morning and opened the rad cap, no room to add any more coolant. Let it warm up. And put it on a steeper incline to help with air bubbles. Turned the heater off and steam started coming off the rad and temp gauge shot up, so turned heater back on and this stopped steam and lowered temp gauge back to normal. Could have been a coincidence so waiting for it to cool again and will test with no heater. Took it around the block also and engine didnt die on me this time. Hoses are all hot but quite hard to squish. Dont know how pressurized they should be but concerned that they are under a lot of pressure.

Still quite concerned it's the thermostat or water pump not opening fully or slow flow (I should have tested the bloody tstat before installing.

I may just take it to the shop and have them diagnose it.

Yes it will overflow as the air bubble expands due to rise in temperature.
All you can do is attempt to catch the overflow. When the thermostat opens the radiator will seem to go empty. Keep topping off for 5 to 10 additional minutes.

I assume you have a coolant recovery bottle. This will chase any remaining air out of the system during the first few heating and cooling cycles.

I have always thought about drilling a 1/16" or 1/8" hole in the flange but have never tried it. Can't see that it would hurt much. Could go down and ask for a premium thermostat and see if it has the release hole. Or possibly remove the thermostat during the initial fill to that level. Still need to observe the thermostat open and verify the level before you roll.

No idea why it shut off.

Did you have the old thermostat in during chem clean? Probably had the release valve. Dig it out of the trash and inspect.

Yes, new tstat. No it did not.

Yeah I waited forever for the tstat to open when I did the initial fill but coolant started overflowing so I shut it off. Okay, hope it settles down once cool and will top up. Haynes only says to squeeze the upper rad hose to bleed but I've done that. How would an air pocket cause the engine to shut off while driving? As in what goes on inside the engine. It's a 1978 so I doubt it has much in the way of fail-safes.

Also I didnt have these problems when I filled it with just water and drove for a few days to do the chem clean.

MarkLDN wrote:
Right. Something has gone wrong.

I put a final topoff in the radiator, capped it and warmed up the engine. I then took it for a slow 20km/hr drive around the block and the engine died on me after about 300 meters. It restarted and after getting it back to the hose the temp gauge was past the midpoint and steam was coming out of the hood. It was coming from the radiator.

Classic air pocket in cooling system. Need to top off again with 50/50 mix. Let it idle until you see the coolant moving through the radiator.

I assume a new thermostat was installed... did it have the little air bypass valve?

See that little peg front center(below).



This one does not have the device:



Squeal could be coolant on the belt and will go away with time.

Right. Something has gone wrong.

I put a final topoff in the radiator, capped it and warmed up the engine. I then took it for a slow 20km/hr drive around the block and the engine died on me after about 300 meters. It restarted and after getting it back to the hose the temp gauge was past the midpoint and steam was coming out of the hood. It was coming from the radiator. Other symptoms are a new squealing sound (sounds very similar to a dying water pump on www.mycarmakesnoise.com). Also the hoses seemed abnormally hot to touch, but the bottom rad hose was just warm (which I guess makes sense). Also I noticed a tiny bit of coolant coming out of the plug fitting (see photo, plug is located between the heater hose and upper rad hose; it's not significant, just a little seepage. The dampness you see above it in the recess on the engine is just water collected from the flushing process).

It seems to indicate a dying water pump but the water pump was doing fine before all this. We drove 9000 miles and never overheated once. Temp gauge only approached midway when going up hill. My only other hunch is that the new thermostat is possibly failing and/or only opening up halfway.

Westend! What do you think?

MarkLDN wrote:
Wondering where best to place the hose to flush that part of the engine block out.

. What I do is remove the lower hose from the radiator, remove the thermostat and reinstall the housing then insert a garden hose into the lower hose and force water though the entire system. I made a section of hose that fits tightly into the radiator hose then clamp with a hose clamp. By removing the thermostat you allow water to pass through the block. I also set the dash to heat to flush out heater core. When I first did this after using the Prestone Flush I was amazed at how much more stuff came out of the system.

Great to hear I am on the right track! We bought this 1978 Dodge campervan to do a small tour of the western US and sadly now need to sell the van so I want it in tip top shape for the new owner. I had no knowledge of automotive maintenance and repair before this but these last few months have been an education! And I love it! So much satisfaction when you tighten that last bolt and the thing still starts!

Really appreciate all your time!

MarkLDN wrote:
Haha Complete Novice.

I have my Haynes manual to hand and have consulted numerous forums (such as this one) on how to conduct a thorough flush. Though I get nervous when something doesn't go to plan, or something unexpected happens. The last thing I want to do is break something and have to take it to the shop. The whole reason I am doing it myself is to save on shop labour (currently off work so plenty of free time).

The reason for the flush is that I noticed a drop in my coolant level and saw indications of a leak. As I had to drain the system anyway I wanted to give it a proper flush/chem clean and put new coolant in. Replaced the thermostat while I was at it. So the answer is I am probably paranoid because nothing was wrong with the system before I took it all apart.

Putting new coolant in now very slowly. The reason I dont think the thermostat is opening is because I can normally see the coolant flow towards the upper rad hose (through the open cap) and feel the hose itself get hot. Only hoses that are getting hot are the heater core hoses at the moment.

I have topped it up with 3 gallons and currently letting it cool to try a final fill up before putting the cap on and taking it for a test drive.

Very much appreciate your words of wisdom and patience with my posts!

Mark

Mark,
I applaud your efforts to get the Haynes manual and work your way through the flush process. I have customers that want to maintain their equipment and vehicles. I tell every one of them to buy a Haynes manual and do some reading before breaking out the tools.

The manuals can be worded towards a more generic instruction set so some vehicles that have inherent air entrapment need to be treated differently than those with common cooling systems. I have a BMW, for instance, that is somewhat difficult to get the air out of the head and upper coolant plumbing. My Ford truck is totally different. Pour in antifreeze and go with the truck. Your van is probably more alike to the truck.

You may not feel the upper radiator hose getting extremely warm right away. You will definitely know with a test drive if your system is full and the thermostat is opening. Without a full system, the van engine will get very hot, even overheat. Don't worry about it if you have filled the radiator a couple of times. Any trapped air will be expunged by the water pump and your system should be full.

Good luck with your radiator.

Haha Complete Novice.

I have my Haynes manual to hand and have consulted numerous forums (such as this one) on how to conduct a thorough flush. Though I get nervous when something doesn't go to plan, or something unexpected happens. The last thing I want to do is break something and have to take it to the shop. The whole reason I am doing it myself is to save on shop labour (currently off work so plenty of free time).

The reason for the flush is that I noticed a drop in my coolant level and saw indications of a leak. As I had to drain the system anyway I wanted to give it a proper flush/chem clean and put new coolant in. Replaced the thermostat while I was at it. So the answer is I am probably paranoid because nothing was wrong with the system before I took it all apart.

Putting new coolant in now very slowly. The reason I dont think the thermostat is opening is because I can normally see the coolant flow towards the upper rad hose (through the open cap) and feel the hose itself get hot. Only hoses that are getting hot are the heater core hoses at the moment.

I have topped it up with 3 gallons and currently letting it cool to try a final fill up before putting the cap on and taking it for a test drive.

Very much appreciate your words of wisdom and patience with my posts!

Mark

MarkLDN wrote:

westend wrote:
Some vehicles will have a "T" in the upper heater hose to eliminate air. Some vehicles have an expansion reservoir that is plumbed into either the radiator cap or a fitting on top of the radiator. That plumbing to the reservoir acts as an air eliminator. Any opening on the top of the radiator will eliminate air in the cooling system. IOW, leave the cap loose.

Ah okay yeah it has a reservoir with a hose connected to the radiator cap.

I've done the hose squeeze after warming up, cap off, thermostat opened. However alarmed when I turned the engine off and water shot out of the radiator.

Let engine cool a bit and added more water. Warmed engine. This time thermostat didnt seem to want to open. Then water started shooting out again and I immediately shut the engine off. Seems quite hot. Steam was coming off exhaust manifold from splashes. Getting worried!

Stop and think about this for a minute. How did the water get hot while just sitting in the radiator or the connected hoses? It didn't.

It takes a running engine to heat the coolant and the coolant doesn't flow into the radiator until the thermostat opens. Opening temp is probably around 190f or better. That is just shy of boiling point and some of that coolant may be above that temperature.

I'd suggest that you now fill the system with antifreeze, start engine with cap on and allow to cool. Make sure any valves to heater core are open. Remove cap when radiator cap is cool enough to open and top off the system with antifreeze. Fill your reservoir to the correct level.

I don't know your level of experience but it sounds like there is a lot of over-thinking about this whole process. What is the reason behind all this flushing and filling?