Cooling system issues

[grizzlebar]

Background - during the Vintage, my 2002 would trend towards overheating on city driving. Highways around Asheville wasn’t much of an issue, but outside of that it would climb and at around 215-220 I’d pull over and cool off for a half hour or so before driving off until it did it again.

 

I figured the thermostat was shot, so I ordered one which I finally got around to putting in today. The heater core is bypassed because of a leaking valve so I have the HC supply hose ducted to the HC return hose.

 

Flushed the system with a garden hose, with nothing of note to really say. Replaced the fluid with blue stuff. Radiator is at least 8 years old and is a “Ron Davis” aluminum one that looks pretty good.

 

Started it up but the temp continues to rise past 210 and the lower radiator hose is cold.

 

About to dive into the faq and my other books on hand but was wondering if you guys had thoughts to keep me on track.

[golf02]

What is the condition of the water pump? Any signs of weeping? Is your ignition and carb mixture good? An old water pump can get out of spec, the clearances of the impeller effect flow rates, a lean engine causes high temps. 

[grizzlebar]

What is the condition of the water pump? Any signs of weeping? Is your ignition and carb mixture good? An old water pump can get out of spec, the clearances of the impeller effect flow rates, a lean engine causes high temps. 

No weeping as far as I can see. Could be the original WP for all I know. Everything worked fine two years ago before I dove into the restoration. No idea when carbs were last rebuilt but the car drives great, overheating aside.

[golf02]

Test the sender for the gauge, measure the temp of the water, check the grounds on your instrument panel. Maybe you are not overheating?

[grizzlebar]

Test the sender for the gauge, measure the temp of the water, check the grounds on your instrument panel. Maybe you are not overheating?

Running a speedhut gauge with a new sensor showing the actual numerical temp

[Healey3000]

Is the lower hose cold or just comfortably warm?  If cold, there mustn't be any circulation.

[dlacey]

Ignition timing has quite an effect on running temperature, as the points wear and close-up the ignition retards and running temperature increases. Try reseting points and timing. If you have some electronic ignition then check the timing. 

[zambo]

Not sure if this is a cause of your issue or may add to it, but there have been threads on faq that suggest routing the heater core supply to the return isn’t the best option when you take the heater core out of commission for whatever reason - i.e. valve or core leak, removal of heater system for overhaul, etc.

Rather the suggestion is that you simply block off the hoses with a 1/2” plug or similar (which I did recently).

The rationale behind this I don’t recall off the top of my head, but I thought it had something to do with not adding potential heat to the cooling system when you simply re-route.

Perhaps others more knowledgeable can chime in on this as a possible cause/effect or discount it.

[golf02]

Yup look at the water pump, loosen the belt see if the bearing feels good, look for end play etc

[02Pilot]

45 minutes ago, Healey3000 said:

Is the lower hose cold or just comfortably warm?  If cold, there mustn't be any circulation.

 

This. If the condition of the water pump is unknown I'd suggest you simply replace it.

[grizzlebar]

Lower hose didn’t feel internally warm.

[Healey3000]

23 minutes ago, grizzlebar said:

Lower hose didn’t feel internally warm.

Sounds like a circulation problem.  Thermostat, water pump, radiator - I think it's just these three in the path.  Since the thermostat is new, it could be a bad water pump or a choked radiator.  When you flushed it with a hose, I assume you also opened the drain cock (if present) and let it run?

[grizzlebar]

Plan tomorrow is to get pyrometer temps on everything then drain and pull the thermostat. Will pull the radiator to have it professionally flushed while I’m at it. Also ordered a new water pump just because.

[lowniss37]

During any type of restoration performed was there any type of tape or caps placed on any hose connections where the hose was pushed over it and the tape/cap not removed? Sounds dumb but just a thought. 

[OriginalOwner]

grizzle,

 

Simple "fix" ...... you have a new thermostat, so remove it, dunk it in hot water and make sure it is actually opening.  Just because it's new doesn't mean it works.  If it isn't working, the lower radiator hose will be "cold."  Hopefully the "fix" is as simple as a bad thermostat.

 

Something else to observe.  With the engine cold, remove the radiator cap.  Start the engine.  When the engine gets to operating temp, and if the radiator isn't 100% plugged, you'll see & feel hot coolant coming into the top of the radiator as it flows in from the head.

      Theory:  with the lower hose being cold, there's no flow through the radiator.  Thus by removing the radiator cap, you'll now get flow up and out of the radiator fill spout since the spout becomes an exit location as the water pump pushes it.  This is also a check on the water pump to see if it works.

 

Depending on the above, the cold lower radiator hose tells me the radiator itself is "sufficiently" blocked and is the problem (this assumes the thermostat is OK).

     My thinking tells me the water pump is working to some level to circulate coolant because if coolant wasn't circulating at all, coolant just "sits there" and very quickly gets to boiling and beyond.  And thus being a closed system (i.e., coolant circulating only in block and head), it reaches some sort of equilibrium at a very high temp, in this case too high for safe driving.

 

My thought:  remove the radiator and backflush to check "blockage factor:"  garden hose taped/sealed into the lower outlet and full-blast with the hose, with radiator fill spout pointing at the ground.  You'll know soon enough what the blockage level is (if any).

 

In my '74tii I use the original radiator design, and years ago I found a 3-row core (original issue is 2-row).  A local radiator shop installed it using the original upper & lower tanks.  After that, no more heating concerns with 3 rows.

     SO, maybe you can find a "bigger" radiator with more rows ??

 

Cheers,

 

Carl

 

 

Edited August 18, 2019 by OriginalOwner