1970 IIA 88" 2.25 Gas, Cooling system air bubble?

[NC_Mule]

Wrapping up the install on a new radiator, water pump, ft main seal, T-stat, temp sender and hoses.
The book doesn't give many hints in getting air bubbles out of the system. Before my repairs I drained the block via the block drain on the left side of the engine. I forgot to close my heater core valve, not sure how much of that system I drained. My upper radiator hose is hot but the lower is cold/warm. I let the truck warm up till the guage was about to red then I shut it off to cool.
I opened up the T stat cover and tested my new one and old one in hot water on the stove. The old one opened up at 180 and the new one opened up closer to 190. Old one was working fine before the repair so I put it back in.
Refilled the little water I had to drain to change the stat and started the truck again. Ran the truck up to red on the guage and still luke warm lower hose.

Any advise for me? Would air in the heater core cause a air bubble in the block?

Thanks pb

[artpeck]

A question or two then a couple of thoughts. Did you do anything with the electrical side of the equation ie the wiring from the voltage regulator etc? I wrestled with an equivalent issue for awhile to finally discover it was a ground issue. I also had a bubble and dealt with it by raising the front end and burping the system. Did this by in my case by driving up the lip of my driveway and road. All was good after that. Also you may want to fill from the thermostat cover and or the drain cock. This helped me also get air out. Last are you sure the pump is working? Good luck.

[NC_Mule]

I have not touched the electrical side other then installing a new temp sensor. When I ran it up to red the engine smelled hot so I'm pretty sure it's getting hot. That being said problems caused by bad ground pop up so I'll clean them.
I left the radiator cap off last night and the water was down this morning so a little burped out. I agree getting the front up is a good next step. I tried to jack up the front with my High lift and you guys are right the front bumper is very thin. As soon as the front started to rise I noticed I was bending the bumper. Note to self, find a stronger bumper. It will be handy in the future to raise the front with the High lift.
Thought about pulling the stat out so I can use the truck this weekend but I don't think that's going to do anything. I remember seeing a bleed hole in the stat so the bubble of air is in the block and/or hoses.

Going to try incline. If that doesn't work I'll drain the whole system and fill the block from the T stat cover with the block drain open. Once the block drain stats flowing I'll shut it and continue till the head is full then top off at the radiator. Or if the block drain is the lowest place I'll pop off one of the heater hoses on the head so air can escape.

Thanks for the thoughts. I'll report back.

[SafeAirOne]

Not sure where the temp sender is located on your engine. On mine its on the top rear of the head on the left side.

Whenever I fully refill the system, I leave the temp sender out and fill through the radiator till the coolant starts coming out of the sender hole, then quickly slap the sender in, tighten it down then finish topping up the system.

Haven't had any air bubble issues since I started doing it this way.

[artpeck]

Forgot to mention that owning a cheap infrared thermometer is a good thing. I bought one and at least convinced myself the engine wasn't hot until I found the ground issue and fixed. They aren't expensive and worth having in the tool box. To burp it you could also drive it cold and stop and start suddenly a few times before the engine gets hot. And yep, learned the same leasion with the hi lift. Don't go there.
Last thing to try is they sell an additive at napa or wherever that makes the coolant more "slippery" and helps the efficiently of the system.

[NC_Mule]

Yes, my temp sensor is at the top of the head. In researching my problem I realized I need to flush my heater core so draining and refilling was on the list anyway. I'll flush the core and refill with the temp sensor out. I've been thinking about buying a laser type temp gun. I'm a motorcycle mechanic and you can use those to check exhaust temp on multiple carbed bikes to see if one carb is running leaner then the others.
Have guests visiting so I will not be able to work on the Mule till Monday. Will report then.
Thanks for the good ideas
pb

[NC_Mule]

Update:
I flushed the heater core and decided to refill the block at the heater valve at the back of the head. I removed the top radiator hose and filled till the T stat housing was full of coolant. Reinstalled the heater hose and top radiator hose and filled the remainder of the system via the radiator neck. Before my refill I primed the heater core with water. I ended up with the method because I misread Safeairone's suggestion and thought he filled the block from the temp sensor at the back of the head. My temp sensor is at the front.

Guage still registered a hair under red after filling and burping on a incline.

So I drained it again and refilled where the front heater hose goes in the T stat housing. Since the front heater hose was unhooked I placed it into T stat housing where the top radiator hose is located. Filled the block till I had coolant coming out of the heater hose and the T stat housing was also full.

Guage still ran just under red after burping on a incline.

As a stab in the dark I took a thermometer with a sharp point and stabbed thru the return heater hose that dumps back into the head just to the left of the t stat housing (when looking at the engine from the front). The guage was a hair under red but the thermometer registered 160F. So my thought was o.k it's something in the gauge system. Found a chart safeairone created correlating Ohms at the temp sensor to degrees in F.
Chart http://siteground237.com/~gunsandr/showthread.php?1871-Temp-Sender-Ohm-Values-vs-Coolant-Temperature

My results are:
Gauge in the horizontal position (normal) 87ohms 180F
Gauge getting close to red 69 ohms 194F
Gauge just under red 64 ohms 200F

So this seems to indicate that I am running hot.

I also pulled my voltage stabilizer and cleaned the contacts. Didn't see a ground wire but I cleaned it's screws thinking is grounds to the chassis.

So which temp test is accurate the thermometer in the heater hose or the ohm readings at the temp sensor.

I have a laser type temp gun on order it will be here in a few days. May be that will give me some answers. Might replace the voltage stabilizer to rule it out.

Thoughts?
Thanks pb

[dunerunner]

So, I take it the T-Stat opens properly and the new pump is moving coolant through the new radiator at the proper rate and the fan is pulling air across the fins of the radiator and is removing engine heat from the coolant. Pressurized cap? Overflow reservoir? Something isn't right.... (scratching my head)

I'd pull the T-stat and test it in a pan of hot water....

[NC_Mule]

Stat has been tested on the stove and passed. I do have the overflow reservoir 1/2 full. You reminded me one thing I left out.
No pressure at the cap.
Even after running for 10-15 minutes or driving 5-6 miles. The temp runs up to just below red and stays put but no pressure at the cap. Lower hose feels warm but not as hot as the top. When I open the radiator cap I see a little flow not sure how much flow I should see.
Fan belt is on/tight and spinning the new water pump.
Scratching my head as well. May be I should remove the t stat, refill to see if I get pressure at the cap and a lower temp. I'll test the stat again to make sure I'm not missing something.
pb

[SafeAirOne]

I don't think an air bubble is your problem. Could also be a bad sender. Also note that temp readings will be different in different parts of the engine, so you should try to take a reading as close to the sender as possible (not sure where it is on your engine) when comparing a thermometer reading to the sender.

[ArlowCT]

You should be building pressure in the system. Sounds like a bad radiator cap too.

Good luck!

[NC_Mule]

My manual temp reading with the thermometer was taken a few inches from the temp sender. I took the trash to the dump last week so my old temp sender is gone. I'll go look and see if I have my old radiator cap. Going to pull the stat and reassemble to see if I can build pressure.
Thanks for the thoughts, I'm stumped and willing to try anything at this point.
pb

[printjunky]

I've had air trapped in the cooling system a couple of times. Took me FOREVER to figure out. The first clue I eventually clued into was that it was not taking NEARLY a normal amount of fluid to fill to the top of the rad. So after doing some searching and reading, I tried several things, including massaging the hoses (HAHAHA), filling through the rear heater hose connection, etc.

But what ended up working was draining the system, both the rad and the block, then pointing the nose as far up as possible (my driveway has a steepish apron) and filling it then. It allows the fluid to displace any air at the lower back of the engine, instead of trapping it there. Again, the biggest clue that something was different was that it took a normal amount of fluid (somewhere around 2.5 gallons) to fill.

Worked like a charm, but man was it a mystery for a while.

[NC_Mule]

The last few times I filled it I did keep track of the qty of fluid I poured in. I ended up putting in 2 gallons. Book says the capacity is 2.3ish. The block drain is not at the bottom of the block but may be it's at the bottom of the water passages. I haven't seen a bare block to know.
I started to do a partial drain so I could remove the stat but ended up draining the whole radiator so I could check a few things. I verified all the hoses are free and clear. I took a heavy wire and ran it up the water pump to verify the propeller is spinning, it is.

Put everything back together less the stat and ran it. The guage still ran up to red. With the cap removed I could see obvious coolant flow. I went on a 5-6 mile test drive came back and stuck a thermometer in the flowing coolant at the radiator cap. It registered 160 but the guage was a hair under red.
Think I'm going to order another temp sensor and a new voltage stabilizer. Going to hold off on reinstalling the stat till I get these installed.
The IIA temp sender is NLA so the offering is for a Series III. Any chance the SIII doesn't work with the IIA voltage stabilizer?
Might give RN tech a call tomorrow. All my parts are from out hosts.

One more note, I'm still not getting any pressure at the radiator cap. Is 160F coolant temp hot enough to create pressure?

pb

[SafeAirOne]

You'll be fine with the SIII sender.

The fact that it didn't build pressure is what lead me to believe that the sender is faulty. Cold water doesn't make steam. Hot water does.

[NC_Mule]

Mark, that temp/ Ohm chart is very cool. So is guns and rovers.
I have a new sender in now guess it's bad. Going to replace and report back.
Thanks for everyones help, it's nice to have the Rover back on the road, it drives me crazy to see the temp at red but I can cope for a few days till the parts come in.

[gwmaxhunter]

if there are bubbles in the cooling system it may be a leaky head gasket.

[sleam]

If it has a leaky head gasket, doesn't it lose the fluid pretty badly? Or the oil in the engine comes out weird when you check? I remember that from an old toyota. Mine, a 72 is having similar problems so i'm going to check the voltage grounding tomorrow and I cleaned the sender connection so we'll see. Thanks for everyone's input here.

[gwmaxhunter]

RE; head gasket leaks...... engine compression is say 150 psi when the plug fires i don't know how much pressure there is but a lot so a small compression leak can put gas into the coolant.... but a 15 psi rad cap may not put enough pressure to push a thick liquid into a cylinder....and a blown head gasket may be compression and coolant and not oil gallery......also it may be coolant and oil gallery and not compression ....a rover engine i seen had blown head gasket was compression to compression..so did not contaminate anything just ran on 2 cyl. making 10 HP.