Avoiding air lock when refilling rad and block

[NAM VET]

Am in the process of replacing my T Stat, repainted the housing, and will put it all back together tomorrow, using a 160 to replace my 180, for a cooler running motor. I drained the rad and block via the T outlets. Are there any special precautions or procedures when replacing the coolant to avoid air locks and hot spots? Thanks, hal

[NAM VET]

Always a good idea to re-read the applicable TM. it appears that just filling the radiator will then fill the engine via the lower hose, and fill up the block as the air bleeds out into the upper hose. The thermostat housing has a small air bleed hole to allow this, and I drilled another small hole in my aftermarket non-OEM T stat to ensure the air can escape. I am using Permatex sealant on the T state bolt threads. So I should be good to go, Be safe, Hal.

[sturmtyger380]

I fill the radiator and some of that makes it into the block. I don't like the engine getting really hot before the coolant starts flowing.

Here is what I do, I heat the coolant on a propane stove in a pot and pour it down the radiator hose to sit on top of the thermostat. Then when that opens it fills the engine.

[NAM VET]

good idea. But my top hose is a stiff racing hose, so I can't just pull it off. But will fill the rad with hot coolant. By the way, when Charles T re-did my engine several years ago, he added a coolant filter. When I drained my block and radiator, the coolant is crystal clear, not a bit of debris or crud, and NO evidence of oil contamination. Also the cast thermo neck has a small hole adjacent to the where the top rubber gasket fits, so as to allow air to bleed when the block fills from below. No need to drill the T Stat.

Oh, I need to remind myself to make checklists before disassembly, and especially for reassembly. So as to be sure the small details are completed. I just finished reinstalling my T Stat assembly, and then wondered if I had removed the cloth I had pushed down into the water pump outlet. When I was cleaning the old gasket and the threads, I put some rag down into both the head and the water pump outlet, so as to avoid debris falling down into the two parts.

So just as I finished up tightening the whole thing up, I wondered if I had removed the rag bit in the water pump hole. So..... Took it all off and of course, both the head and the water pump outlet were clear of any of my rag. If I had made up a checklist for reassembly I wouldn't have had to do it twice.

Many years ago, my dad and I rebuild my TR'4's engine, and I promptly drove the 1000miles back to Lincoln. But when I got there, I wondered if we had remembered to bend over the con rod bolt tabs. So.... went to a gas station, put the TR4 on a rack, dropped the pan, and of course, all was well.

Happens to pros too. A few years ago, had a BMW shop do some work on my really sweet 6 cy '90 BMW 325. But driving home, merging into traffic, I did not notice my engine was hot, and coolant spilled over the hood. The mechanic had forgotten to tighten all the hoses, and my BMW had a warped head. I had it flat bedded back, and told him I would pay for parts so he could do the repair. So he sourced a used head and the special bolts, and in a few days I was on the road, $400 poorer. I was afraid if I didi not pay for new one-time bolts, it wouldn't be done right.

Gotta remember to make checklists next time.

Hal

[ez8]

Couldn't you just use a coolant pressurization device? I use one on watercooled Porsches. Harbor Freight makes a reasonably priced one or you can borrow them from auto parts stores. Vent at the hole in the cast thermo vent and you're in high cotton.

[Cal_Gary]

VPW offers that you should drill a small hole in the thermostat to avoid air pockets:
https://16add72a-0e73-4942-9955-d76f2f0 ... index=true
Quick Tip 5:
Thermostat Installation
What do I need to know when installing a new thermostat?
In some cases you may want to drill a 1/32” hole in the top plunger (the piece that opens) of
the thermostat towards the outer lip. This allows for circulation before the thermostat opens,
reducing deposits in your cooling system and reducing the possibility of pressure build-up. This
also helps bleed air from the system, reducing the chance of air pockets which can create hot
spots in the engine. Don’t forget to replace the thermostat housing gasket.

I've done this mod and had no problems since.
Gary

[NAM VET]

My cast iron thermostat housing, the big hunk of iron that holds the T stat and bolts to the top of the cylinder head has a small hole, larger than 1/32 in the top circle where the top of the stat fits with the thick rubber gasket. It is outside the rim where it would be blocked by the gasket. So no need in my housing to drill the T stat itself. I checked the hole with a small piece of wire, it is a thru hole, to accomplish the air bleeding mission when refilling. It appears to me looking at the diagram of the coolant flow path, that the block fills from the radiator's lower hose. I may fill it and then drive my truck up onto some front wheel ramps to encourage the head to fully fill with coolant.

I let my permatex sit the suggested 24 hours and will go out in a in hour after more coffee to start filling it back up. The coolant Charles T put in is green. My drained coolant is crystal clear with no debris or oil traces.

Pretty day here in UpState SC, and this afternoon going to a state range to check the scopes on my 308 and my Weatherby 257 Mag rifle. A great 45 mile drive thru the back woods and hills to the range. My daily driver is an Alfa Romeo Guilia Quadrifoglio with a Ferrari designed 505 horsepower engine.

hal

[NAM VET]

Always something. With the 160 'T stat in, idled for awhile, but wouldn't t get hot enough to open the 160 stat. So went for a sort 5 mile drive and still not to 160, so put some cardboard in front of radiator, and then with more idling, it did get to 160 and the T stat opened and looking down in the cap neck lots of good flow.

so went out just to be sure without the cardboard, and going up a slight incline, truck stuttered and hesitated, so came back, idled fine, and supposed with low fuel level, accelerating up a hill, or for what passes here for a hill, tank pick up was uncovered, and inadequate fuel. Drove a mile to my nearby gas station where they have non-ethanol, and coming back, the stumble was worse. Made home and found my fuel pressure at my adjustable regular was only about 1 psi of gas. So either my 24 V Facet was not getting the full voltage, or the internal filter was plugged, or the one at my regular was plugged, (it looked ok), or my regular was bad, as no adjustments at the regular made any difference in my low pressure.

So removed the Facet's filter, easy as pie, and it was pretty plugged up. Put in a new one, takes five min to do that. Then replaced the WIX clear plastic one at the regular, and promptly my pressure went up to my usual 3.5 psi. Went for a drive, all well, good power, no stumble, idle pressure about 3+ psi.

Just a coincidence, but always interesting how working on one part of a vehicle, always seem to make some totally unrelated part act up. New wiper blades, turn signal out. Replace engine oil filter, lose first gear. Adjust brakes, radiator leaks. Recharge AC, driver seat's motor fails. New muffler, dome light out. And on and one...

NV

[greeno]

…get in running, now a frame off resto…

[Cal_Gary]

Indeed, Nam Vet-always something!
Gary

[sturmtyger380]

Not to mention - but - you are diving along and - what's that? A new noise!!! Then the game of finding it starts.

[NAM VET]

yeah, many decades ago, just started a thousand mile trip in my TR4, and just after my departure, I noted a faint "knock', and sure enough, soon had bad bearing noises, which was an epic adventure. When I start off in my my truck I am alert for any unusual, new "sounds", and only when nothing new, I then put in my ear plugs. There is a big difference in sounds you hear, and new things you feel. The latter is more ominous. When I went out yesterday to figure out my low fuel pressure, my wife asked "..now what" and my reply was "...its 70 years old, there is always something about to happen." Sort of like me.

Nowadays, modern cars are so complex an enthusiast owner really can't do anything to fix or upgrade their pride and joy other than a different set of wheels, or maybe a different exhaust. No need to carry any tools with you, not even a screwdriver. Me, I have a heavy tool kit in my truck. But then, I grew up with a TR4 and an MGB, so being prepared was essential 

By the way, having a fuel pressure gage, easy to install on my regulator gave me a headstart on deciding where to being my search for my stumbling. I knew right away it was fuel, not electrical.

I think being the one who restores, who rewires, who changes and modifies their truck is essential to being able to figure out why something is wrong. What fuse, what wire, what hose, what fastener iis acting up. For a "new" owner, trying to get one of these vintage vehicles to operate properly must be a frustrating experience.

Now heading out to a rifle range for some shooting. Hal