Subject: [TR] tr-3 lukewarm heater

From: Gary Nafziger <[email-masked]>
Date: Thu, 7 Nov 2013 11:25:09 -0800 (PST)

newly restored tr-3 has a Meradyne heater installed.  Temp guage shows 180-190
radiator temperature but very luke warm heat from the heater. 

I assumed an
air bubble in the heater core so tried to remove that by running engine with
radiator cap off until thermostat opened.  Then I loosened the inlet heater
hose at the firewall untill water seeped out and also did that at the firewall
for the outlet, attempting to bleed the air out.  Before I got everything
finished the car overheated and coolant boiled out.  

Shut everything down
and let it cool, added more coolant and installed cap and am gonna forget it
for now.  Oh, during this process I also had the front of the car jacked up
high.....hoping this would get the radiator resevoir above the heater
resevoir.  

Drove it around for 15 minutes and still lukewarm heat from the
heater.  Anyone have suggestions or more clear instructions on next move?  I
do have the skirted thermostat.

gary n.

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From: Randall <[email-masked]>
Date: Thu, 7 Nov 2013 21:00:12 +0000

> do have the skirted thermostat.

Assuming you made at least one pull up past 3000 rpm or so, I really doubt that an air bubble is the problem.  The TR pump produces plenty of head at higher rpm, and should be able to blow bubbles through the heater with no problem at all.

Instead, I would be looking for anything that mechanically restricts the water flow, especially the return tube along the LH side of the engine.  I've seen several of them now that were almost entirely blocked with sediment.  Also check that the tap on the head is really open, and so on.  With the stock heater and ordinary heater hose, the hoses tend to kink on top of the heater where you can't see them.  I'm not sure how your Maradyne is configured, but it's something to think about.

Randall